内容

• 公共类型
• 公共函数
• 详细描述
• 设置
• 绘制
• 绘制像素图和图像
• 渲染品质
• 坐标变换
• 裁剪
• 合成模式
• 局限性
• 性能

QPainter 类

QPainter class performs low-level painting on widgets and other paint devices. 更多...

• 所有成员列表，包括继承成员
• 过时成员

注意： 此类的所有函数 可重入 .

公共类型

公共函数

详细描述

QPainter class performs low-level painting on widgets and other paint devices.

QPainter provides highly optimized functions to do most of the drawing GUI programs require. It can draw everything from simple lines to complex shapes like pies and chords. It can also draw aligned text and pixmaps. Normally, it draws in a "natural" coordinate system, but it can also do view and world transformation. QPainter can operate on any object that inherits the QPaintDevice 类。

The common use of QPainter is inside a widget's paint event: Construct and customize (e.g. set the pen or the brush) the painter. Then draw. Remember to destroy the QPainter object after drawing. For example:

void SimpleExampleWidget::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setPen(Qt::blue);
    painter.setFont(QFont("Arial", 30));
    painter.drawText(rect(), Qt::AlignCenter, "Qt");
}
					

The core functionality of QPainter is drawing, but the class also provide several functions that allows you to customize QPainter 's settings and its rendering quality, and others that enable clipping. In addition you can control how different shapes are merged together by specifying the painter's composition mode.

isActive () 函数指示描绘器是否活动。激活描绘器通过 begin () 函数且构造函数接受 QPaintDevice 自变量。 end () 函数，和析构函数将其取消激活。

连同 QPaintDevice and QPaintEngine 类， QPainter form the basis for Qt's paint system. QPainter is the class used to perform drawing operations. QPaintDevice represents a device that can be painted on using a QPainter . QPaintEngine 提供用于在不同类型设备上描绘的描绘器接口。若描绘器活动， device () 返回描绘器在其上描绘的描绘设备，和 paintEngine () 返回描绘器目前正在操作的描绘引擎。更多信息，见 描绘系统 .

有时，可能期望其它人去描绘在不寻常 QPaintDevice . QPainter supports a static function to do this, setRedirected().

警告： When the paintdevice is a widget, QPainter can only be used inside a paintEvent() function or in a function called by paintEvent().

设置

There are several settings that you can customize to make QPainter draw according to your preferences:

• font () 是用于绘制文本的字体。若描绘器 isActive ()，可以检索目前设置字体的有关信息，及其规格，使用 fontInfo () 和 fontMetrics () 函数分别。
• brush () 定义用于填充形状的颜色或图案。
• pen () 定义用于绘制线条或边界的颜色或点画。
• backgroundMode () 定义是否有 background () 或不，即它是 Qt::OpaqueMode or Qt::TransparentMode .
• background () 才应用当 backgroundMode () 是 Qt::OpaqueMode and pen () 是点画。在此情况下，它描述点画背景像素的颜色。
• brushOrigin () 定义平铺笔刷的原点，通常是 Widget 背景原点。
• viewport (), window (), worldTransform () 构成描绘器的坐标变换系统。更多信息，见 坐标变换 章节和 坐标系 文档编制。
• hasClipping () 告诉描绘器是否可裁剪 (描绘设备也裁剪)。若描绘器裁剪，它将裁剪至 clipRegion ().
• layoutDirection () 定义用于描绘器的布局方向，当绘制文本时。
• worldMatrixEnabled () 告诉是否启用世界变换。
• viewTransformEnabled () 告诉是否启用视图变换。

注意：其中一些设置会镜像某些绘制设备设置，如 QWidget::font ()。 QPainter::begin () function (or equivalently the QPainter constructor) copies these attributes from the paint device.

You can at any time save the QPainter 's state by calling the save () 函数将所有可用设置保存在内部堆栈。 restore () 函数将它们弹回来。

绘制

QPainter provides functions to draw most primitives: drawPoint (), drawPoints (), drawLine (), drawRect (), drawRoundedRect (), drawEllipse (), drawArc (), drawPie (), drawChord (), drawPolyline (), drawPolygon (), drawConvexPolygon () 及 drawCubicBezier()。2 方便函数， drawRects () 和 drawLines ()，绘制给定数量的矩形或线条，按给定数组 QRects or QLines 使用当前钢笔和笔刷。

QPainter class also provides the fillRect () 函数填充给定 QRect ，采用给定 QBrush ，和 eraseRect () 函数擦除给定矩形内区域。

所有这些函数都有整数和浮点版本。

基本绘制范例 基本绘制 example shows how to display basic graphics primitives in a variety of styles using the QPainter 类。

若需要绘制复杂形状，尤其是当需要重复这样做时，考虑创建 QPainterPath 和绘制它使用 drawPath ().

描绘器路径范例 QPainterPath 类提供用于描绘操作的容器，使图形形状能够被构造和重用。 描绘器路径 范例展示如何使用描绘器路径以构建复杂渲染形状。

QPainter also provides the fillPath () 函数填充给定 QPainterPath 采用给定 QBrush ，和 strokePath () 函数绘制给定路径的轮廓 (即：描边路径)。

另请参阅 向量变形 范例，展示如何使用高级向量技术以绘制文本使用 QPainterPath ， 渐变 范例展示 Qt 中可用的不同渐变类型，和 路径描边 范例展示 Qt 的内置虚线模式及展示如何使用自定义模式以延伸可用模式范围。

向量变形	渐变	路径描边

文本绘制的完成是使用 drawText ()。当需要细粒度定位时， boundingRect () 告诉您哪里给定 drawText () 命令会绘制。

绘制像素图和图像

有能绘制像素图/图像的函数，也就是 drawPixmap (), drawImage () 和 drawTiledPixmap ()。两者 drawPixmap () 和 drawImage () 产生相同结果，除了 drawPixmap () 在屏幕上更快，而 drawImage () 可能更快在 QPrinter 或其它设备。

有 drawPicture () 函数绘制内容为整个 QPicture 。 drawPicture () 函数是忽视所有描绘器设置的唯一函数，因为 QPicture 拥有自己的设置。

绘制高分辨率版本的像素图和图像

像素图的高分辨率版本拥有的 设备像素比率 值大于 1 (见 QImageReader , QPixmap::devicePixelRatio ()). Should it match the value of the underlying QPaintDevice , it is drawn directly onto the device with no additional transformation applied.

This is for example the case when drawing a QPixmap of 64x64 pixels size with a device pixel ratio of 2 onto a high DPI screen which also has a device pixel ratio of 2. Note that the pixmap is then effectively 32x32 pixels in user space . Code paths in Qt that calculate layout geometry based on the pixmap size will use this size. The net effect of this is that the pixmap is displayed as high DPI pixmap rather than a large pixmap.

渲染品质

To get the optimal rendering result using QPainter , you should use the platform independent QImage 作为描绘设备；即：使用 QImage will ensure that the result has an identical pixel representation on any platform.

QPainter class also provides a means of controlling the rendering quality through its RenderHint enum and the support for floating point precision: All the functions for drawing primitives has a floating point version. These are often used in combination with the QPainter::Antialiasing 渲染提示。

同心圆范例 同心圆 example shows the improved rendering quality that can be obtained using floating point precision and anti-aliasing when drawing custom widgets. The application's main window displays several widgets which are drawn using the various combinations of precision and anti-aliasing.

RenderHint enum specifies flags to QPainter 可能或可能不被任何给定引擎所遵守。 QPainter::Antialiasing indicates that the engine should antialias edges of primitives if possible, QPainter::TextAntialiasing indicates that the engine should antialias text if possible, and the QPainter::SmoothPixmapTransform indicates that the engine should use a smooth pixmap transformation algorithm.

renderHints () function returns a flag that specifies the rendering hints that are set for this painter. Use the setRenderHint () function to set or clear the currently set RenderHints .

坐标变换

Normally, the QPainter operates on the device's own coordinate system (usually pixels), but QPainter has good support for coordinate transformations.

nop	rotate ()	scale ()	translate ()

The most commonly used transformations are scaling, rotation, translation and shearing. Use the scale () function to scale the coordinate system by a given offset, the rotate () function to rotate it clockwise and translate () to translate it (i.e. adding a given offset to the points). You can also twist the coordinate system around the origin using the shear () function. See the 仿射变换 example for a visualization of a sheared coordinate system.

另请参阅 变换 example which shows how transformations influence the way that QPainter renders graphics primitives. In particular it shows how the order of transformations affects the result.

仿射变换范例 仿射变换 example shows Qt's ability to perform affine transformations on painting operations. The demo also allows the user to experiment with the transformation operations and see the results immediately.

All the tranformation operations operate on the transformation worldTransform (). A matrix transforms a point in the plane to another point. For more information about the transformation matrix, see the 坐标系 and QTransform 文档编制。

setWorldTransform () function can replace or add to the currently set worldTransform ()。 resetTransform () function resets any transformations that were made using translate (), scale (), shear (), rotate (), setWorldTransform (), setViewport () 和 setWindow () 函数。 deviceTransform () returns the matrix that transforms from logical coordinates to device coordinates of the platform dependent paint device. The latter function is only needed when using platform painting commands on the platform dependent handle, and the platform does not do transformations nativly.

When drawing with QPainter , we specify points using logical coordinates which then are converted into the physical coordinates of the paint device. The mapping of the logical coordinates to the physical coordinates are handled by QPainter 's combinedTransform (), a combination of viewport () 和 window () 和 worldTransform ()。 viewport () represents the physical coordinates specifying an arbitrary rectangle, the window () describes the same rectangle in logical coordinates, and the worldTransform () is identical with the transformation matrix.

另请参阅 坐标系

裁剪

QPainter can clip any drawing operation to a rectangle, a region, or a vector path. The current clip is available using the functions clipRegion () 和 clipPath ()。首选 (更快) 路径还是区域从属底层 paintEngine ()。例如， QImage 描绘引擎首选路径，而 X11 描绘引擎首选区域。设置裁剪是在描绘器逻辑坐标中完成的。

After QPainter 's clipping, the paint device may also clip. For example, most widgets clip away the pixels used by child widgets, and most printers clip away an area near the edges of the paper. This additional clipping is not reflected by the return value of clipRegion () 或 hasClipping ().

合成模式

QPainter 提供 CompositionMode enum which defines the Porter-Duff rules for digital image compositing; it describes a model for combining the pixels in one image, the source, with the pixels in another image, the destination.

The two most common forms of composition are 源 and SourceOver . 源 is used to draw opaque objects onto a paint device. In this mode, each pixel in the source replaces the corresponding pixel in the destination. In SourceOver composition mode, the source object is transparent and is drawn on top of the destination.

Note that composition transformation operates pixelwise. For that reason, there is a difference between using the graphic primitive itself and its bounding rectangle: The bounding rect contains pixels with alpha == 0 (i.e the pixels surrounding the primitive). These pixels will overwrite the other image's pixels, affectively clearing those, while the primitive only overwrites its own area.

合成模式范例 合成模式 example, available in Qt's examples directory, allows you to experiment with the various composition modes and see the results immediately.

局限性

If you are using coordinates with Qt's raster-based paint engine, it is important to note that, while coordinates greater than +/- 2 ¹⁵ can be used, any painting performed with coordinates outside this range is not guaranteed to be shown; the drawing may be clipped. This is due to the use of short int 在实现中。

The outlines generated by Qt's stroker are only an approximation when dealing with curved shapes. It is in most cases impossible to represent the outline of a bezier curve segment using another bezier curve segment, and so Qt approximates the curve outlines by using several smaller curves. For performance reasons there is a limit to how many curves Qt uses for these outlines, and thus when using large pen widths or scales the outline error increases. To generate outlines with smaller errors it is possible to use the QPainterPathStroker class, which has the setCurveThreshold member function which let's the user specify the error tolerance. Another workaround is to convert the paths to polygons first and then draw the polygons instead.

性能

QPainter is a rich framework that allows developers to do a great variety of graphical operations, such as gradients, composition modes and vector graphics. And QPainter can do this across a variety of different hardware and software stacks. Naturally the underlying combination of hardware and software has some implications for performance, and ensuring that every single operation is fast in combination with all the various combinations of composition modes, brushes, clipping, transformation, etc, is close to an impossible task because of the number of permutations. As a compromise we have selected a subset of the QPainter API and backends, where performance is guaranteed to be as good as we can sensibly get it for the given combination of hardware and software.

The backends we focus on as high-performance engines are:

• Raster - This backend implements all rendering in pure software and is always used to render into QImages. For optimal performance only use the format types QImage::Format_ARGB32_Premultiplied , QImage::Format_RGB32 or QImage::Format_RGB16 . Any other format, including QImage::Format_ARGB32 , has significantly worse performance. This engine is used by default for QWidget and QPixmap .
• OpenGL 2.0 (ES) - This backend is the primary backend for hardware accelerated graphics. It can be run on desktop machines and embedded devices supporting the OpenGL 2.0 or OpenGL/ES 2.0 specification. This includes most graphics chips produced in the last couple of years. The engine can be enabled by using QPainter onto a QOpenGLWidget .

These operations are:

• Simple transformations, meaning translation and scaling, pluss 0, 90, 180, 270 degree rotations.
• drawPixmap() in combination with simple transformations and opacity with non-smooth transformation mode ( QPainter::SmoothPixmapTransform not enabled as a render hint).
• Rectangle fills with solid color, two-color linear gradients and simple transforms.
• Rectangular clipping with simple transformations and intersect clip.
• 合成模式 QPainter::CompositionMode_Source and QPainter::CompositionMode_SourceOver
• Rounded rectangle filling using solid color and two-color linear gradients fills.
• 3x3 patched pixmaps, via qDrawBorderPixmap.

This list gives an indication of which features to safely use in an application where performance is critical. For certain setups, other operations may be fast too, but before making extensive use of them, it is recommended to benchmark and verify them on the system where the software will run in the end. There are also cases where expensive operations are ok to use, for instance when the result is cached in a QPixmap .

另请参阅 QPaintDevice , QPaintEngine , Qt SVG , 基本绘制范例 ，和 Drawing Utility Functions .

成员类型文档编制

enum QPainter:: CompositionMode

Defines the modes supported for digital image compositing. Composition modes are used to specify how the pixels in one image, the source, are merged with the pixel in another image, the destination.

Please note that the bitwise raster operation modes, denoted with a RasterOp prefix, are only natively supported in the X11 and raster paint engines. This means that the only way to utilize these modes on the Mac is via a QImage . The RasterOp denoted blend modes are not supported for pens and brushes with alpha components. Also, turning on the QPainter::Antialiasing render hint will effectively disable the RasterOp modes.

The most common type is SourceOver (often referred to as just alpha blending) where the source pixel is blended on top of the destination pixel in such a way that the alpha component of the source defines the translucency of the pixel.

Several composition modes require an alpha channel in the source or target images to have an effect. For optimal performance the image format Format_ARGB32_Premultiplied is preferred.

When a composition mode is set it applies to all painting operator, pens, brushes, gradients and pixmap/image drawing.

另请参阅 compositionMode (), setCompositionMode (), 合成模式 ，和 图像合成范例 .

enum QPainter:: PixmapFragmentHint
flags QPainter:: PixmapFragmentHints

该枚举在 Qt 4.7 引入或被修改。

PixmapFragmentHints 类型是 typedef 对于 QFlags <PixmapFragmentHint>。它存储 PixmapFragmentHint 值的 OR 组合。

另请参阅 QPainter::drawPixmapFragments () 和 QPainter::PixmapFragment .

enum QPainter:: RenderHint
flags QPainter:: RenderHints

Renderhints 用于将标志指定给 QPainter 可能或可能不被任何给定引擎所遵守。

RenderHints 类型是 typedef 对于 QFlags <RenderHint>。它存储 RenderHint 值的 OR 组合。

另请参阅 renderHints (), setRenderHint (), 渲染品质 ，和 同心圆范例 .

成员函数文档编制

QPainter:: QPainter ()

构造描绘器。

另请参阅 begin () 和 end ().

QPainter:: QPainter ( QPaintDevice * device )

构造描绘器开始描绘描绘 device 立即。

此构造函数对短期活着描绘器很方便，如在 QWidget::paintEvent () 且只应使用一次。构造函数调用 begin () for you and the QPainter destructor automatically calls end ().

这是范例使用 begin () 和 end ():

void MyWidget::paintEvent(QPaintEvent *)
{
    QPainter p;
    p.begin(this);
    p.drawLine(...);        // drawing code
    p.end();
}
					

使用此构造函数的相同范例：

void MyWidget::paintEvent(QPaintEvent *)
{
    QPainter p(this);
    p.drawLine(...);        // drawing code
}
					

由于构造函数无法提供反馈当描绘器初始化失败时，因此应使用 begin () 和 end () 以在外部设备中描绘，如：打印机。

另请参阅 begin () 和 end ().

QPainter:: ~QPainter ()

销毁描绘器。

const QBrush &QPainter:: background () const

返回当前背景笔刷。

另请参阅 setBackground () 和 设置 .

Qt::BGMode QPainter:: backgroundMode () const

返回当前背景模式。

另请参阅 setBackgroundMode () 和 设置 .

bool QPainter:: begin ( QPaintDevice * device )

开始描绘描绘 device 并返回 true 若成功；否则返回 false .

预告：所有描绘器设置 ( setPen (), setBrush () 等) 被重置为默认值当 begin() 被调用时。

可能出现的错误是严重问题，譬如这些：

painter->begin(0); // impossible - paint device cannot be 0
QPixmap image(0, 0);
painter->begin(&image); // impossible - image.isNull() == true;
painter->begin(myWidget);
painter2->begin(myWidget); // impossible - only one painter at a time
					

注意：大多数时候，可以使用某一构造函数代替 begin()，且 end () 在销毁时自动完成。

警告： 描绘设备每次只可以由一个描绘器进行描绘。

警告： 描绘 QImage 采用格式 QImage::Format_Indexed8 不被支持。

另请参阅 end () 和 QPainter ().

void QPainter:: beginNativePainting ()

Flushes the painting pipeline and prepares for the user issuing commands directly to the underlying graphics context. Must be followed by a call to endNativePainting ().

Note that only the states the underlying paint engine changes will be reset to their respective default states. The states we reset may change from release to release. The following states are currently reset in the OpenGL 2 engine:

• blending is disabled
• the depth, stencil and scissor tests are disabled
• the active texture unit is reset to 0
• the depth mask, depth function and the clear depth are reset to their default values
• the stencil mask, stencil operation and stencil function are reset to their default values
• the current color is reset to solid white

If, for example, the OpenGL polygon mode is changed by the user inside a beginNativePaint()/ endNativePainting () block, it will not be reset to the default state by endNativePainting (). Here is an example that shows intermixing of painter commands and raw OpenGL commands:

QPainter painter(this);
painter.fillRect(0, 0, 128, 128, Qt::green);
painter.beginNativePainting();
glEnable(GL_SCISSOR_TEST);
glScissor(0, 0, 64, 64);
glClearColor(1, 0, 0, 1);
glClear(GL_COLOR_BUFFER_BIT);
glDisable(GL_SCISSOR_TEST);
painter.endNativePainting();
					

该函数在 Qt 4.6 引入。

另请参阅 endNativePainting ().

QRectF QPainter:: boundingRect (const QRectF & rectangle , int flags , const QString & text )

Returns the bounding rectangle of the text as it will appear when drawn inside the given rectangle 采用指定 flags using the currently set font (); i.e the function tells you where the drawText () function will draw when given the same arguments.

若 text does not fit within the given rectangle 使用指定 flags , the function returns the required rectangle.

flags argument is a bitwise OR of the following flags:

• Qt::AlignLeft
• Qt::AlignRight
• Qt::AlignHCenter
• Qt::AlignTop
• Qt::AlignBottom
• Qt::AlignVCenter
• Qt::AlignCenter
• Qt::TextSingleLine
• Qt::TextExpandTabs
• Qt::TextShowMnemonic
• Qt::TextWordWrap
• Qt::TextIncludeTrailingSpaces

If several of the horizontal or several of the vertical alignment flags are set, the resulting alignment is undefined.

另请参阅 drawText (), Qt::Alignment ，和 Qt::TextFlag .

QRect QPainter:: boundingRect (const QRect & rectangle , int flags , const QString & text )

这是重载函数。

Returns the bounding rectangle of the text as it will appear when drawn inside the given rectangle 采用指定 flags using the currently set font ().

QRect QPainter:: boundingRect ( int x , int y , int w , int h , int flags , const QString & text )

这是重载函数。

Returns the bounding rectangle of the given text as it will appear when drawn inside the rectangle beginning at the point ( x , y ) with width w 和高度 h .

QRectF QPainter:: boundingRect (const QRectF & rectangle , const QString & text , const QTextOption & option = QTextOption())

这是重载函数。

Instead of specifying flags as a bitwise OR of the Qt::AlignmentFlag and Qt::TextFlag , this overloaded function takes an option 自变量。 QTextOption class provides a description of general rich text properties.

另请参阅 QTextOption .

const QBrush &QPainter:: brush () const

返回描绘器的当前笔刷。

另请参阅 QPainter::setBrush () 和 设置 .

QPoint QPainter:: brushOrigin () const

返回目前设置的笔刷原点。

另请参阅 setBrushOrigin () 和 设置 .

QRectF QPainter:: clipBoundingRect () const

返回当前裁剪的边界矩形，若有裁剪；否则返回空矩形。注意，裁剪区域按逻辑坐标给出。

不保证边界矩形是紧密的。

该函数在 Qt 4.8 引入。

另请参阅 setClipRect (), setClipPath ()，和 setClipRegion ().

QPainterPath QPainter:: clipPath () const

按逻辑坐标返回当前裁剪路径。

警告： QPainter 不会明确存储组合剪辑，因为这的处理是通过底层 QPaintEngine ，所以路径会按需重新创建并转换到当前逻辑坐标系。这是潜在的昂贵操作。

另请参阅 setClipPath (), clipRegion ()，和 setClipping ().

QRegion QPainter:: clipRegion () const

返回目前设置的裁剪区域。注意，裁剪区域按逻辑坐标给出。

警告： QPainter 不会明确存储组合剪辑，因为这的处理是通过底层 QPaintEngine ，所以路径会按需重新创建并转换到当前逻辑坐标系。这是潜在的昂贵操作。

另请参阅 setClipRegion (), clipPath ()，和 setClipping ().

QTransform QPainter:: combinedTransform () const

返回当前窗口/视口及世界变换的组合变换矩阵。

另请参阅 setWorldTransform (), setWindow ()，和 setViewport ().

CompositionMode QPainter:: compositionMode () const

返回当前的合成模式。

另请参阅 CompositionMode and setCompositionMode ().

QPaintDevice *QPainter:: device () const

Returns the paint device on which this painter is currently painting, or 0 if the painter is not active.

另请参阅 isActive ().

const QTransform &QPainter:: deviceTransform () const

Returns the matrix that transforms from logical coordinates to device coordinates of the platform dependent paint device.

此函数是 only needed when using platform painting commands on the platform dependent handle ( Qt::HANDLE ), and the platform does not do transformations nativly.

QPaintEngine::PaintEngineFeature enum can be queried to determine whether the platform performs the transformations or not.

另请参阅 worldTransform () 和 QPaintEngine::hasFeature ().

void QPainter:: drawArc (const QRectF & rectangle , int startAngle , int spanAngle )

Draws the arc defined by the given rectangle , startAngle and spanAngle .

startAngle and spanAngle must be specified in 1/16th of a degree, i.e. a full circle equals 5760 (16 * 360). Positive values for the angles mean counter-clockwise while negative values mean the clockwise direction. Zero degrees is at the 3 o'clock position.

QRectF rectangle(10.0, 20.0, 80.0, 60.0); int startAngle = 30 * 16; int spanAngle = 120 * 16; QPainter painter(this); painter.drawArc(rectangle, startAngle, spanAngle);

另请参阅 drawPie (), drawChord ()，和 坐标系 .

void QPainter:: drawArc (const QRect & rectangle , int startAngle , int spanAngle )

这是重载函数。

Draws the arc defined by the given rectangle , startAngle and spanAngle .

void QPainter:: drawArc ( int x , int y , int width , int height , int startAngle , int spanAngle )

这是重载函数。

Draws the arc defined by the rectangle beginning at ( x , y ) with the specified width and height ，和给定 startAngle and spanAngle .

void QPainter:: drawChord (const QRectF & rectangle , int startAngle , int spanAngle )

Draws the chord defined by the given rectangle , startAngle and spanAngle . The chord is filled with the current brush ().

The startAngle and spanAngle must be specified in 1/16th of a degree, i.e. a full circle equals 5760 (16 * 360). Positive values for the angles mean counter-clockwise while negative values mean the clockwise direction. Zero degrees is at the 3 o'clock position.

QRectF rectangle(10.0, 20.0, 80.0, 60.0); int startAngle = 30 * 16; int spanAngle = 120 * 16; QPainter painter(this); painter.drawChord(rect, startAngle, spanAngle);

另请参阅 drawArc (), drawPie ()，和 坐标系 .

void QPainter:: drawChord ( int x , int y , int width , int height , int startAngle , int spanAngle )

这是重载函数。

Draws the chord defined by the rectangle beginning at ( x , y ) with the specified width and height ，和给定 startAngle and spanAngle .

void QPainter:: drawChord (const QRect & rectangle , int startAngle , int spanAngle )

这是重载函数。

Draws the chord defined by the given rectangle , startAngle and spanAngle .

void QPainter:: drawConvexPolygon (const QPointF * points , int pointCount )

Draws the convex polygon defined by the first pointCount points in the array points using the current pen.

static const QPointF points[4] = { QPointF(10.0, 80.0), QPointF(20.0, 10.0), QPointF(80.0, 30.0), QPointF(90.0, 70.0) }; QPainter painter(this); painter.drawConvexPolygon(points, 4);

The first point is implicitly connected to the last point, and the polygon is filled with the current brush (). If the supplied polygon is not convex, i.e. it contains at least one angle larger than 180 degrees, the results are undefined.

On some platforms (e.g. X11), the drawConvexPolygon() function can be faster than the drawPolygon () 函数。

另请参阅 drawPolygon (), drawPolyline ()，和 坐标系 .

void QPainter:: drawConvexPolygon (const QPolygonF & polygon )

这是重载函数。

Draws the convex polygon defined by polygon 使用当前钢笔和笔刷。

void QPainter:: drawConvexPolygon (const QPoint * points , int pointCount )

这是重载函数。

Draws the convex polygon defined by the first pointCount points in the array points using the current pen.

void QPainter:: drawConvexPolygon (const QPolygon & polygon )

这是重载函数。

Draws the convex polygon defined by polygon 使用当前钢笔和笔刷。

void QPainter:: drawEllipse (const QRectF & rectangle )

Draws the ellipse defined by the given rectangle .

A filled ellipse has a size of rectangle . size() . A stroked ellipse has a size of rectangle . size() plus the pen width.

QRectF rectangle(10.0, 20.0, 80.0, 60.0); QPainter painter(this); painter.drawEllipse(rectangle);

另请参阅 drawPie () 和 坐标系 .

void QPainter:: drawEllipse (const QRect & rectangle )

这是重载函数。

Draws the ellipse defined by the given rectangle .

void QPainter:: drawEllipse ( int x , int y , int width , int height )

这是重载函数。

Draws the ellipse defined by the rectangle beginning at ( x , y ) 采用给定 width and height .

void QPainter:: drawEllipse (const QPointF & center , qreal rx , qreal ry )

这是重载函数。

Draws the ellipse positioned at center with radii rx and ry .

该函数在 Qt 4.4 引入。

void QPainter:: drawEllipse (const QPoint & center , int rx , int ry )

这是重载函数。

Draws the ellipse positioned at center with radii rx and ry .

该函数在 Qt 4.4 引入。

void QPainter:: drawGlyphRun (const QPointF & position , const QGlyphRun & glyphs )

Draws the glyphs represented by glyphs at position 。 position gives the edge of the baseline for the string of glyphs. The glyphs will be retrieved from the font selected on glyphs and at offsets given by the positions in glyphs .

该函数在 Qt 4.8 引入。

另请参阅 QGlyphRun::setRawFont (), QGlyphRun::setPositions ()，和 QGlyphRun::setGlyphIndexes ().

void QPainter:: drawImage (const QRectF & target , const QImage & image , const QRectF & source , Qt::ImageConversionFlags flags = Qt::AutoColor)

绘制矩形部分 source 为给定 image 到 target 矩形在描绘设备中。

注意： The image is scaled to fit the rectangle, if both the image and rectangle size disagree.

注意： 见 绘制高分辨率版本的像素图和图像 on how this is affected by QImage::devicePixelRatio ().

If the image needs to be modified to fit in a lower-resolution result (e.g. converting from 32-bit to 8-bit), use the flags to specify how you would prefer this to happen.

QRectF target(10.0, 20.0, 80.0, 60.0);
QRectF source(0.0, 0.0, 70.0, 40.0);
QImage image(":/images/myImage.png");
QPainter painter(this);
painter.drawImage(target, image, source);
								

另请参阅 drawPixmap () 和 QImage::devicePixelRatio ().

void QPainter:: drawImage (const QRect & target , const QImage & image , const QRect & source , Qt::ImageConversionFlags flags = Qt::AutoColor)

这是重载函数。

绘制矩形部分 source 为给定 image 到 target 矩形在描绘设备中。

注意： The image is scaled to fit the rectangle, if both the image and rectangle size disagree.

void QPainter:: drawImage (const QPointF & point , const QImage & image , const QRectF & source , Qt::ImageConversionFlags flags = Qt::AutoColor)

这是重载函数。

绘制矩形部分 source 为给定 image 采用其原点在给定 point .

void QPainter:: drawImage (const QPoint & point , const QImage & image , const QRect & source , Qt::ImageConversionFlags flags = Qt::AutoColor)

这是重载函数。

绘制矩形部分 source 为给定 image 采用其原点在给定 point .

void QPainter:: drawImage (const QRectF & rectangle , const QImage & image )

这是重载函数。

绘制给定 image 进给定 rectangle .

注意： The image is scaled to fit the rectangle, if both the image and rectangle size disagree.

void QPainter:: drawImage (const QRect & rectangle , const QImage & image )

这是重载函数。

绘制给定 image 进给定 rectangle .

注意： The image is scaled to fit the rectangle, if both the image and rectangle size disagree.

void QPainter:: drawImage (const QPointF & point , const QImage & image )

这是重载函数。

绘制给定 image 在给定 point .

void QPainter:: drawImage (const QPoint & point , const QImage & image )

这是重载函数。

绘制给定 image 在给定 point .

void QPainter:: drawImage ( int x , int y , const QImage & image , int sx = 0, int sy = 0, int sw = -1, int sh = -1, Qt::ImageConversionFlags flags = Qt::AutoColor)

这是重载函数。

Draws an image at ( x , y ) by copying a part of image 到描绘设备。

( x , y ) specifies the top-left point in the paint device that is to be drawn onto. ( sx , sy ) specifies the top-left point in image that is to be drawn. The default is (0, 0).

( sw , sh ) specifies the size of the image that is to be drawn. The default, (0, 0) (and negative) means all the way to the bottom-right of the image.

void QPainter:: drawLine (const QLineF & line )

绘制直线定义通过 line .

QLineF line(10.0, 80.0, 90.0, 20.0); QPainter(this); painter.drawLine(line);

另请参阅 drawLines (), drawPolyline ()，和 坐标系 .

void QPainter:: drawLine (const QLine & line )

这是重载函数。

绘制直线定义通过 line .

void QPainter:: drawLine ( int x1 , int y1 , int x2 , int y2 )

这是重载函数。

绘制直线从 ( x1 , y1 ) to ( x2 , y2 ).

void QPainter:: drawLine (const QPoint & p1 , const QPoint & p2 )

这是重载函数。

绘制直线从 p1 to p2 .

void QPainter:: drawLine (const QPointF & p1 , const QPointF & p2 )

这是重载函数。

绘制直线从 p1 to p2 .

void QPainter:: drawLines (const QLineF * lines , int lineCount )

绘制第一 lineCount lines in the array lines using the current pen.

另请参阅 drawLine () 和 drawPolyline ().

void QPainter:: drawLines (const QVector < QLineF > & lines )

这是重载函数。

Draws the set of lines defined by the list lines 使用当前钢笔和笔刷。

void QPainter:: drawLines (const QPointF * pointPairs , int lineCount )

这是重载函数。

绘制第一 lineCount lines in the array pointPairs using the current pen. The lines are specified as pairs of points so the number of entries in pointPairs must be at least lineCount * 2.

void QPainter:: drawLines (const QVector < QPointF > & pointPairs )

这是重载函数。

Draws a line for each pair of points in the vector pointPairs using the current pen. If there is an odd number of points in the array, the last point will be ignored.

void QPainter:: drawLines (const QLine * lines , int lineCount )

这是重载函数。

绘制第一 lineCount lines in the array lines using the current pen.

void QPainter:: drawLines (const QVector < QLine > & lines )

这是重载函数。

Draws the set of lines defined by the list lines 使用当前钢笔和笔刷。

void QPainter:: drawLines (const QPoint * pointPairs , int lineCount )

这是重载函数。

绘制第一 lineCount lines in the array pointPairs using the current pen.

void QPainter:: drawLines (const QVector < QPoint > & pointPairs )

这是重载函数。

Draws a line for each pair of points in the vector pointPairs using the current pen.

void QPainter:: drawPath (const QPainterPath & path )

绘制给定描绘器 path 使用当前钢笔为轮廓和使用当前笔刷为填充。

QPainterPath path; path.moveTo(20, 80); path.lineTo(20, 30); path.cubicTo(80, 0, 50, 50, 80, 80); QPainter painter(this); painter.drawPath(path);

另请参阅 描绘器路径范例 and 向量变形范例 .

void QPainter:: drawPicture (const QPointF & point , const QPicture & picture )

重演给定 picture 在给定 point .

QPicture 类是描绘设备，它记录并重演 QPainter commands. A picture serializes the painter commands to an IO device in a platform-independent format. Everything that can be painted on a widget or pixmap can also be stored in a picture.

此函数做的准确如同 QPicture::play () when called with point = QPoint (0, 0).

QPicture picture;
QPointF point(10.0, 20.0)
picture.load("drawing.pic");
QPainter painter(this);
painter.drawPicture(0, 0, picture);
								

另请参阅 QPicture::play ().

void QPainter:: drawPicture ( int x , int y , const QPicture & picture )

这是重载函数。

绘制给定 picture 在点 ( x , y ).

void QPainter:: drawPicture (const QPoint & point , const QPicture & picture )

这是重载函数。

重演给定 picture 在给定 point .

void QPainter:: drawPie (const QRectF & rectangle , int startAngle , int spanAngle )

Draws a pie defined by the given rectangle , startAngle and spanAngle .

The pie is filled with the current brush ().

The startAngle and spanAngle must be specified in 1/16th of a degree, i.e. a full circle equals 5760 (16 * 360). Positive values for the angles mean counter-clockwise while negative values mean the clockwise direction. Zero degrees is at the 3 o'clock position.

QRectF rectangle(10.0, 20.0, 80.0, 60.0); int startAngle = 30 * 16; int spanAngle = 120 * 16; QPainter painter(this); painter.drawPie(rectangle, startAngle, spanAngle);

另请参阅 drawEllipse (), drawChord ()，和 坐标系 .

void QPainter:: drawPie ( int x , int y , int width , int height , int startAngle , int spanAngle )

这是重载函数。

Draws the pie defined by the rectangle beginning at ( x , y ) with the specified width and height ，和给定 startAngle and spanAngle .

void QPainter:: drawPie (const QRect & rectangle , int startAngle , int spanAngle )

这是重载函数。

Draws a pie defined by the given rectangle , startAngle and and spanAngle .

void QPainter:: drawPixmap (const QRectF & target , const QPixmap & pixmap , const QRectF & source )

绘制矩形部分 source 为给定 pixmap 进给定 target 在描绘设备中。

注意： The pixmap is scaled to fit the rectangle, if both the pixmap and rectangle size disagree.

注意： 见 绘制高分辨率版本的像素图和图像 on how this is affected by QPixmap::devicePixelRatio ().

QRectF target(10.0, 20.0, 80.0, 60.0);
QRectF source(0.0, 0.0, 70.0, 40.0);
QPixmap pixmap(":myPixmap.png");
QPainter(this);
painter.drawPixmap(target, pixmap, source);
								

若 pixmap 是 QBitmap it is drawn with the bits that are "set" using the pens color. If backgroundMode is Qt::OpaqueMode , the "unset" bits are drawn using the color of the background brush; if backgroundMode is Qt::TransparentMode , the "unset" bits are transparent. Drawing bitmaps with gradient or texture colors is not supported.

另请参阅 drawImage () 和 QPixmap::devicePixelRatio ().

void QPainter:: drawPixmap (const QRect & target , const QPixmap & pixmap , const QRect & source )

这是重载函数。

绘制矩形部分 source 为给定 pixmap 进给定 target 在描绘设备中。

注意： The pixmap is scaled to fit the rectangle, if both the pixmap and rectangle size disagree.

void QPainter:: drawPixmap ( int x , int y , int w , int h , const QPixmap & pixmap , int sx , int sy , int sw , int sh )

这是重载函数。

绘制矩形部分按原点 ( sx , sy )，宽度 sw 和高度 sh ，为给定 pixmap ，在点 ( x , y )，采用宽度 w 和高度 h . If sw or sh are equal to zero the width/height of the pixmap is used and adjusted by the offset sx/sy;

void QPainter:: drawPixmap ( int x , int y , const QPixmap & pixmap , int sx , int sy , int sw , int sh )

这是重载函数。

绘制像素图在 ( x , y ) 通过拷贝一部分的给定 pixmap 到描绘设备。

( x , y ) specifies the top-left point in the paint device that is to be drawn onto. ( sx , sy ) specifies the top-left point in pixmap that is to be drawn. The default is (0, 0).

( sw , sh ) specifies the size of the pixmap that is to be drawn. The default, (0, 0) (and negative) means all the way to the bottom-right of the pixmap.

void QPainter:: drawPixmap (const QPointF & point , const QPixmap & pixmap , const QRectF & source )

这是重载函数。

绘制矩形部分 source 为给定 pixmap 采用其原点在给定 point .

void QPainter:: drawPixmap (const QPoint & point , const QPixmap & pixmap , const QRect & source )

这是重载函数。

绘制矩形部分 source 为给定 pixmap 采用其原点在给定 point .

void QPainter:: drawPixmap (const QPointF & point , const QPixmap & pixmap )

这是重载函数。

绘制给定 pixmap 采用其原点在给定 point .

void QPainter:: drawPixmap (const QPoint & point , const QPixmap & pixmap )

这是重载函数。

绘制给定 pixmap 采用其原点在给定 point .

void QPainter:: drawPixmap ( int x , int y , const QPixmap & pixmap )

这是重载函数。

绘制给定 pixmap 在位置 ( x , y ).

void QPainter:: drawPixmap (const QRect & rectangle , const QPixmap & pixmap )

这是重载函数。

绘制给定 pixmap 进给定 rectangle .

注意： The pixmap is scaled to fit the rectangle, if both the pixmap and rectangle size disagree.

void QPainter:: drawPixmap ( int x , int y , int width , int height , const QPixmap & pixmap )

这是重载函数。

绘制 pixmap 到矩形在位置 ( x , y ) 采用给定 width and height .

void QPainter:: drawPixmapFragments (const PixmapFragment * fragments , int fragmentCount , const QPixmap & pixmap , PixmapFragmentHints hints = PixmapFragmentHints())

此函数用于绘制 pixmap , or a sub-rectangle of pixmap , at multiple positions with different scale, rotation and opacity. fragments is an array of fragmentCount elements specifying the parameters used to draw each pixmap fragment. The hints parameter can be used to pass in drawing hints.

This function is potentially faster than multiple calls to drawPixmap (), since the backend can optimize state changes.

该函数在 Qt 4.7 引入。

另请参阅 QPainter::PixmapFragment and QPainter::PixmapFragmentHint .

void QPainter:: drawPoint (const QPointF & position )

Draws a single point at the given position using the current pen's color.

另请参阅 坐标系 .

void QPainter:: drawPoint (const QPoint & position )

这是重载函数。

Draws a single point at the given position using the current pen's color.

void QPainter:: drawPoint ( int x , int y )

这是重载函数。

绘制单个点在位置 ( x , y ).

void QPainter:: drawPoints (const QPointF * points , int pointCount )

绘制第一 pointCount points in the array points using the current pen's color.

另请参阅 坐标系 .

void QPainter:: drawPoints (const QPolygonF & points )

这是重载函数。

Draws the points in the vector points .

void QPainter:: drawPoints (const QPoint * points , int pointCount )

这是重载函数。

绘制第一 pointCount points in the array points using the current pen's color.

void QPainter:: drawPoints (const QPolygon & points )

这是重载函数。

Draws the points in the vector points .

void QPainter:: drawPolygon (const QPointF * points , int pointCount , Qt::FillRule fillRule = Qt::OddEvenFill)

Draws the polygon defined by the first pointCount points in the array points 使用当前钢笔和笔刷。

static const QPointF points[4] = { QPointF(10.0, 80.0), QPointF(20.0, 10.0), QPointF(80.0, 30.0), QPointF(90.0, 70.0) }; QPainter painter(this); painter.drawPolygon(points, 4);

The first point is implicitly connected to the last point, and the polygon is filled with the current brush ().

若 fillRule is Qt::WindingFill , the polygon is filled using the winding fill algorithm. If fillRule is Qt::OddEvenFill , the polygon is filled using the odd-even fill algorithm. See Qt::FillRule for a more detailed description of these fill rules.

另请参阅 drawConvexPolygon (), drawPolyline ()，和 坐标系 .

void QPainter:: drawPolygon (const QPolygonF & points , Qt::FillRule fillRule = Qt::OddEvenFill)

这是重载函数。

Draws the polygon defined by the given points using the fill rule fillRule .

void QPainter:: drawPolygon (const QPoint * points , int pointCount , Qt::FillRule fillRule = Qt::OddEvenFill)

这是重载函数。

Draws the polygon defined by the first pointCount points in the array points .

void QPainter:: drawPolygon (const QPolygon & points , Qt::FillRule fillRule = Qt::OddEvenFill)

这是重载函数。

Draws the polygon defined by the given points using the fill rule fillRule .

void QPainter:: drawPolyline (const QPointF * points , int pointCount )

Draws the polyline defined by the first pointCount points in points using the current pen.

Note that unlike the drawPolygon () function the last point is not connected to the first, neither is the polyline filled.

static const QPointF points[3] = {
    QPointF(10.0, 80.0),
    QPointF(20.0, 10.0),
    QPointF(80.0, 30.0),
};
QPainter painter(this);
painter.drawPolyline(points, 3);
								

另请参阅 drawLines (), drawPolygon ()，和 坐标系 .

void QPainter:: drawPolyline (const QPolygonF & points )

这是重载函数。

Draws the polyline defined by the given points using the current pen.

void QPainter:: drawPolyline (const QPoint * points , int pointCount )

这是重载函数。

Draws the polyline defined by the first pointCount points in points using the current pen.

void QPainter:: drawPolyline (const QPolygon & points )

这是重载函数。

Draws the polyline defined by the given points using the current pen.

void QPainter:: drawRect (const QRectF & rectangle )

Draws the current rectangle with the current pen and brush.

A filled rectangle has a size of rectangle .size(). A stroked rectangle has a size of rectangle .size() plus the pen width.

QRectF rectangle(10.0, 20.0, 80.0, 60.0); QPainter painter(this); painter.drawRect(rectangle);

另请参阅 drawRects (), drawPolygon ()，和 坐标系 .

void QPainter:: drawRect ( int x , int y , int width , int height )

这是重载函数。

Draws a rectangle with upper left corner at ( x , y ) and with the given width and height .

void QPainter:: drawRect (const QRect & rectangle )

这是重载函数。

Draws the current rectangle with the current pen and brush.

void QPainter:: drawRects (const QRectF * rectangles , int rectCount )

绘制第一 rectCount 为给定 rectangles 使用当前钢笔和笔刷。

另请参阅 drawRect ().

void QPainter:: drawRects (const QVector < QRectF > & rectangles )

这是重载函数。

绘制给定 rectangles 使用当前钢笔和笔刷。

void QPainter:: drawRects (const QRect * rectangles , int rectCount )

这是重载函数。

绘制第一 rectCount 为给定 rectangles 使用当前钢笔和笔刷。

void QPainter:: drawRects (const QVector < QRect > & rectangles )

这是重载函数。

绘制给定 rectangles 使用当前钢笔和笔刷。

void QPainter:: drawRoundedRect (const QRectF & rect , qreal xRadius , qreal yRadius , Qt::SizeMode mode = Qt::AbsoluteSize)

绘制给定矩形 rect 带圆角。

xRadius and yRadius arguments specify the radii of the ellipses defining the corners of the rounded rectangle. When mode is Qt::RelativeSize , xRadius and yRadius are specified in percentage of half the rectangle's width and height respectively, and should be in the range 0.0 to 100.0.

A filled rectangle has a size of rect.size(). A stroked rectangle has a size of rect.size() plus the pen width.

QRectF rectangle(10.0, 20.0, 80.0, 60.0); QPainter painter(this); painter.drawRoundedRect(rectangle, 20.0, 15.0);

该函数在 Qt 4.4 引入。

另请参阅 drawRect () 和 QPen .

void QPainter:: drawRoundedRect ( int x , int y , int w , int h , qreal xRadius , qreal yRadius , Qt::SizeMode mode = Qt::AbsoluteSize)

这是重载函数。

绘制给定矩形 x , y , w , h 带圆角。

该函数在 Qt 4.4 引入。

void QPainter:: drawRoundedRect (const QRect & rect , qreal xRadius , qreal yRadius , Qt::SizeMode mode = Qt::AbsoluteSize)

这是重载函数。

绘制给定矩形 rect 带圆角。

该函数在 Qt 4.4 引入。

void QPainter:: drawStaticText (const QPointF & topLeftPosition , const QStaticText & staticText )

绘制给定 staticText 在给定 topLeftPosition .

The text will be drawn using the font and the transformation set on the painter. If the font and/or transformation set on the painter are different from the ones used to initialize the layout of the QStaticText , then the layout will have to be recalculated. Use QStaticText::prepare () to initialize staticText with the font and transformation with which it will later be drawn.

若 topLeftPosition is not the same as when staticText was initialized, or when it was last drawn, then there will be a slight overhead when translating the text to its new position.

注意： If the painter's transformation is not affine, then staticText will be drawn using regular calls to drawText (), losing any potential for performance improvement.

注意： The y-position is used as the top of the font.

该函数在 Qt 4.7 引入。

另请参阅 QStaticText .

void QPainter:: drawStaticText (const QPoint & topLeftPosition , const QStaticText & staticText )

这是重载函数。

绘制 staticText 在 topLeftPosition .

注意： The y-position is used as the top of the font.

该函数在 Qt 4.7 引入。

void QPainter:: drawStaticText ( int left , int top , const QStaticText & staticText )

这是重载函数。

绘制 staticText at coordinates left and top .

注意： The y-position is used as the top of the font.

该函数在 Qt 4.7 引入。

void QPainter:: drawText (const QPointF & position , const QString & text )

绘制给定 text with the currently defined text direction, beginning at the given position .

This function does not handle the newline character (\n), as it cannot break text into multiple lines, and it cannot display the newline character. Use the QPainter::drawText() overload that takes a rectangle instead if you want to draw multiple lines of text with the newline character, or if you want the text to be wrapped.

默认情况下， QPainter 绘制抗锯齿文本。

注意： Y 位置用作字体的基线。

另请参阅 setFont () 和 setPen ().

void QPainter:: drawText (const QPoint & position , const QString & text )

这是重载函数。

绘制给定 text with the currently defined text direction, beginning at the given position .

默认情况下， QPainter 绘制抗锯齿文本。

注意： Y 位置用作字体的基线。

另请参阅 setFont () 和 setPen ().

void QPainter:: drawText ( int x , int y , const QString & text )

这是重载函数。

绘制给定 text 在位置 ( x , y ), using the painter's currently defined text direction.

默认情况下， QPainter 绘制抗锯齿文本。

注意： Y 位置用作字体的基线。

另请参阅 setFont () 和 setPen ().

void QPainter:: drawText (const QRectF & rectangle , int flags , const QString & text , QRectF * boundingRect = Q_NULLPTR)

这是重载函数。

绘制给定 text within the provided rectangle 。 rectangle along with alignment flags defines the anchors for the text .

QPainter painter(this); painter.drawText(rect, Qt::AlignCenter, tr("Qt\nProject"));

boundingRect (if not null) is set to what the bounding rectangle should be in order to enclose the whole text. For example, in the following image, the dotted line represents boundingRect as calculated by the function, and the dashed line represents rectangle :

QPainter painter(this); QFont font = painter.font(); font.setPixelSize(48); painter.setFont(font); const QRect rectangle = QRect(0, 0, 100, 50); QRect boundingRect; painter.drawText(rectangle, 0, tr("Hello"), &boundingRect); QPen pen = painter.pen(); pen.setStyle(Qt::DotLine); painter.setPen(pen); painter.drawRect(boundingRect.adjusted(0, 0, -pen.width(), -pen.width())); pen.setStyle(Qt::DashLine); painter.setPen(pen); painter.drawRect(rectangle.adjusted(0, 0, -pen.width(), -pen.width()));

flags argument is a bitwise OR of the following flags:

• Qt::AlignLeft
• Qt::AlignRight
• Qt::AlignHCenter
• Qt::AlignJustify
• Qt::AlignTop
• Qt::AlignBottom
• Qt::AlignVCenter
• Qt::AlignCenter
• Qt::TextDontClip
• Qt::TextSingleLine
• Qt::TextExpandTabs
• Qt::TextShowMnemonic
• Qt::TextWordWrap
• Qt::TextIncludeTrailingSpaces

默认情况下， QPainter 绘制抗锯齿文本。

注意： The y-coordinate of rectangle is used as the top of the font.

另请参阅 Qt::AlignmentFlag , Qt::TextFlag , boundingRect ()，和 layoutDirection ().

void QPainter:: drawText (const QRect & rectangle , int flags , const QString & text , QRect * boundingRect = Q_NULLPTR)

这是重载函数。

绘制给定 text within the provided rectangle 根据指定 flags .

boundingRect (if not null) is set to the what the bounding rectangle should be in order to enclose the whole text. For example, in the following image, the dotted line represents boundingRect as calculated by the function, and the dashed line represents rectangle :

QPainter painter(this); QFont font = painter.font(); font.setPixelSize(48); painter.setFont(font); const QRect rectangle = QRect(0, 0, 100, 50); QRect boundingRect; painter.drawText(rectangle, 0, tr("Hello"), &boundingRect); QPen pen = painter.pen(); pen.setStyle(Qt::DotLine); painter.setPen(pen); painter.drawRect(boundingRect.adjusted(0, 0, -pen.width(), -pen.width())); pen.setStyle(Qt::DashLine); painter.setPen(pen); painter.drawRect(rectangle.adjusted(0, 0, -pen.width(), -pen.width()));

默认情况下， QPainter 绘制抗锯齿文本。

注意： The y-coordinate of rectangle is used as the top of the font.

另请参阅 setFont () 和 setPen ().

void QPainter:: drawText ( int x , int y , int width , int height , int flags , const QString & text , QRect * boundingRect = Q_NULLPTR)

这是重载函数。

绘制给定 text within the rectangle with origin ( x , y ), width and height .

boundingRect (if not null) is set to the what the bounding rectangle should be in order to enclose the whole text. For example, in the following image, the dotted line represents boundingRect as calculated by the function, and the dashed line represents the rectangle defined by x , y , width and height :

QPainter painter(this); QFont font = painter.font(); font.setPixelSize(48); painter.setFont(font); const QRect rectangle = QRect(0, 0, 100, 50); QRect boundingRect; painter.drawText(rectangle, 0, tr("Hello"), &boundingRect); QPen pen = painter.pen(); pen.setStyle(Qt::DotLine); painter.setPen(pen); painter.drawRect(boundingRect.adjusted(0, 0, -pen.width(), -pen.width())); pen.setStyle(Qt::DashLine); painter.setPen(pen); painter.drawRect(rectangle.adjusted(0, 0, -pen.width(), -pen.width()));

flags argument is a bitwise OR of the following flags:

• Qt::AlignLeft
• Qt::AlignRight
• Qt::AlignHCenter
• Qt::AlignJustify
• Qt::AlignTop
• Qt::AlignBottom
• Qt::AlignVCenter
• Qt::AlignCenter
• Qt::TextSingleLine
• Qt::TextExpandTabs
• Qt::TextShowMnemonic
• Qt::TextWordWrap

默认情况下， QPainter 绘制抗锯齿文本。

注意： The y-position is used as the top of the font.

另请参阅 Qt::AlignmentFlag , Qt::TextFlag , setFont ()，和 setPen ().

void QPainter:: drawText (const QRectF & rectangle , const QString & text , const QTextOption & option = QTextOption())

这是重载函数。

绘制给定 text 在 rectangle specified using the option to control its positioning and orientation.

默认情况下， QPainter 绘制抗锯齿文本。

注意： The y-coordinate of rectangle is used as the top of the font.

另请参阅 setFont () 和 setPen ().

void QPainter:: drawTiledPixmap (const QRectF & rectangle , const QPixmap & pixmap , const QPointF & position = QPointF())

绘制平铺 pixmap ，在给定 rectangle 采用其原点在给定 position .

调用 drawTiledPixmap() 类似调用 drawPixmap () several times to fill (tile) an area with a pixmap, but is potentially much more efficient depending on the underlying window system.

另请参阅 drawPixmap ().

void QPainter:: drawTiledPixmap ( int x , int y , int width , int height , const QPixmap & pixmap , int sx = 0, int sy = 0)

这是重载函数。

绘制平铺 pixmap 在指定矩形中。

( x , y ) specifies the top-left point in the paint device that is to be drawn onto; with the given width and height . ( sx , sy ) specifies the top-left point in the pixmap that is to be drawn; this defaults to (0, 0).

void QPainter:: drawTiledPixmap (const QRect & rectangle , const QPixmap & pixmap , const QPoint & position = QPoint())

这是重载函数。

绘制平铺 pixmap ，在给定 rectangle 采用其原点在给定 position .

bool QPainter:: end ()

结束描绘。绘制时所用的任何资源都被释放。通常不需要调用这，因为它是由析构函数调用的。

返回 true 若描绘器不再活动；否则返回 false .

另请参阅 begin () 和 isActive ().

void QPainter:: endNativePainting ()

Restores the painter after manually issuing native painting commands. Lets the painter restore any native state that it relies on before calling any other painter commands.

该函数在 Qt 4.6 引入。

另请参阅 beginNativePainting ().

void QPainter:: eraseRect (const QRectF & rectangle )

擦除区域在给定 rectangle 。相当于调用

fillRect(rectangle, background()).
					

另请参阅 fillRect ().

void QPainter:: eraseRect ( int x , int y , int width , int height )

这是重载函数。

擦除矩形内区域开始于 ( x , y ) 采用给定 width and height .

void QPainter:: eraseRect (const QRect & rectangle )

这是重载函数。

擦除区域在给定 rectangle .

void QPainter:: fillPath (const QPainterPath & path , const QBrush & brush )

填充给定 path 使用给定 brush 。轮廓不绘制。

另外，可以指定 QColor 而不是 QBrush ； QBrush 构造函数 (接受 QColor 自变量) 将自动创建纯色图案笔刷。

另请参阅 drawPath ().

void QPainter:: fillRect (const QRectF & rectangle , const QBrush & brush )

填充给定 rectangle 采用 brush 指定。

另外，可以指定 QColor 而不是 QBrush ； QBrush 构造函数 (接受 QColor 自变量) 将自动创建纯色图案笔刷。

另请参阅 drawRect ().

void QPainter:: fillRect ( int x , int y , int width , int height , const QBrush & brush )

这是重载函数。

填充矩形开始于 ( x , y ) 采用给定 width and height ，使用给定 brush .

void QPainter:: fillRect (const QRect & rectangle , const QBrush & brush )

这是重载函数。

填充给定 rectangle 采用指定 brush .

void QPainter:: fillRect (const QRectF & rectangle , const QColor & color )

这是重载函数。

填充给定 rectangle 采用 color 指定。

该函数在 Qt 4.5 引入。

void QPainter:: fillRect ( int x , int y , int width , int height , const QColor & color )

这是重载函数。

填充矩形开始于 ( x , y ) 采用给定 width and height ，使用给定 color .

该函数在 Qt 4.5 引入。

void QPainter:: fillRect (const QRect & rectangle , const QColor & color )

这是重载函数。

填充给定 rectangle 采用 color 指定。

该函数在 Qt 4.5 引入。

void QPainter:: fillRect ( int x , int y , int width , int height , Qt::GlobalColor color )

这是重载函数。

填充矩形开始于 ( x , y ) 采用给定 width and height ，使用给定 color .

该函数在 Qt 4.5 引入。

void QPainter:: fillRect (const QRect & rectangle , Qt::GlobalColor color )

这是重载函数。

填充给定 rectangle 采用指定 color .

该函数在 Qt 4.5 引入。

void QPainter:: fillRect (const QRectF & rectangle , Qt::GlobalColor color )

这是重载函数。

填充给定 rectangle 采用指定 color .

该函数在 Qt 4.5 引入。

void QPainter:: fillRect ( int x , int y , int width , int height , Qt::BrushStyle style )

这是重载函数。

填充矩形开始于 ( x , y ) 采用给定 width and height ，使用笔刷 style 指定。

该函数在 Qt 4.5 引入。

void QPainter:: fillRect (const QRect & rectangle , Qt::BrushStyle style )

这是重载函数。

填充给定 rectangle 采用笔刷 style 指定。

该函数在 Qt 4.5 引入。

void QPainter:: fillRect (const QRectF & rectangle , Qt::BrushStyle style )

这是重载函数。

填充给定 rectangle 采用笔刷 style 指定。

该函数在 Qt 4.5 引入。

const QFont &QPainter:: font () const

Returns the currently set font used for drawing text.

另请参阅 setFont (), drawText ()，和 设置 .

QFontInfo QPainter:: fontInfo () const

Returns the font info for the painter if the painter is active. Otherwise, the return value is undefined.

另请参阅 font (), isActive ()，和 设置 .

QFontMetrics QPainter:: fontMetrics () const

Returns the font metrics for the painter if the painter is active. Otherwise, the return value is undefined.

另请参阅 font (), isActive ()，和 设置 .

bool QPainter:: hasClipping () const

返回 true 若有设置裁剪；否则返回 false .

另请参阅 setClipping () 和 裁剪 .

bool QPainter:: isActive () const

返回 true if begin () has been called and end () has not yet been called; otherwise returns false .

另请参阅 begin () 和 QPaintDevice::paintingActive ().

Qt::LayoutDirection QPainter:: layoutDirection () const

Returns the layout direction used by the painter when drawing text.

另请参阅 QTextOption::textDirection (), setLayoutDirection (), drawText ()，和 设置 .

qreal QPainter:: opacity () const

返回描绘器的不透明度。默认值为 1。

该函数在 Qt 4.2 引入。

另请参阅 setOpacity ().

QPaintEngine *QPainter:: paintEngine () const

Returns the paint engine that the painter is currently operating on if the painter is active; otherwise 0.

另请参阅 isActive ().

const QPen &QPainter:: pen () const

返回描绘器的当前钢笔。

另请参阅 setPen () 和 设置 .

RenderHints QPainter:: renderHints () const

Returns a flag that specifies the rendering hints that are set for this painter.

另请参阅 setRenderHints (), testRenderHint ()，和 渲染品质 .

void QPainter:: resetTransform ()

Resets any transformations that were made using translate (), scale (), shear (), rotate (), setWorldTransform (), setViewport () 和 setWindow ().

另请参阅 坐标变换 .

void QPainter:: restore ()

Restores the current painter state (pops a saved state off the stack).

另请参阅 save ().

void QPainter:: rotate ( qreal angle )

Rotates the coordinate system clockwise. The given angle parameter is in degrees.

另请参阅 setWorldTransform () 和 坐标变换 .

void QPainter:: save ()

Saves the current painter state (pushes the state onto a stack). A save() must be followed by a corresponding restore (); the end () function unwinds the stack.

另请参阅 restore ().

void QPainter:: scale ( qreal sx , qreal sy )

比例缩放坐标系按 ( sx , sy ).

另请参阅 setWorldTransform () 和 坐标变换 .

void QPainter:: setBackground (const QBrush & brush )

将描绘器背景笔刷设为给定 brush .

The background brush is the brush that is filled in when drawing opaque text, stippled lines and bitmaps. The background brush has no effect in transparent background mode (which is the default).

另请参阅 background (), setBackgroundMode ()，和 设置 .

void QPainter:: setBackgroundMode ( Qt::BGMode mode )

将描绘器背景模式设为给定 mode

Qt::TransparentMode (默认) 绘制点画线和文本无需设置背景像素。 Qt::OpaqueMode 填充这些空间采用当前背景色。

注意：为绘制透明位图或像素图，必须使用 QPixmap::setMask ().

另请参阅 backgroundMode (), setBackground ()，和 设置 .

void QPainter:: setBrush (const QBrush & brush )

把描绘器的笔刷设为给定 brush .

描绘器的笔刷定义形状如何被填充。

另请参阅 brush () 和 设置 .

void QPainter:: setBrush ( Qt::BrushStyle style )

这是重载函数。

把描绘器的笔刷设为黑色，并指定 style .

void QPainter:: setBrushOrigin (const QPointF & position )

将笔刷原点设为 position .

The brush origin specifies the (0, 0) coordinate of the painter's brush.

Note that while the brushOrigin () was necessary to adopt the parent's background for a widget in Qt 3, this is no longer the case since the Qt 4 painter doesn't paint the background unless you explicitly tell it to do so by setting the widget's autoFillBackground 特性到 true。

另请参阅 brushOrigin () 和 设置 .

void QPainter:: setBrushOrigin (const QPoint & position )

这是重载函数。

将笔刷的原点设为给定 position .

void QPainter:: setBrushOrigin ( int x , int y )

这是重载函数。

将笔刷的原点设为点 ( x , y ).

void QPainter:: setClipPath (const QPainterPath & path , Qt::ClipOperation operation = Qt::ReplaceClip)

Enables clipping, and sets the clip path for the painter to the given path , with the clip operation .

Note that the clip path is specified in logical (painter) coordinates.

另请参阅 clipPath (), clipRegion ()，和 裁剪 .

void QPainter:: setClipRect (const QRectF & rectangle , Qt::ClipOperation operation = Qt::ReplaceClip)

启用裁剪，并将裁剪区域设为给定 rectangle 使用给定裁剪 operation . The default operation is to replace the current clip rectangle.

Note that the clip rectangle is specified in logical (painter) coordinates.

另请参阅 clipRegion (), setClipping ()，和 裁剪 .

void QPainter:: setClipRect (const QRect & rectangle , Qt::ClipOperation operation = Qt::ReplaceClip)

这是重载函数。

启用裁剪，并将裁剪区域设为给定 rectangle 使用给定裁剪 operation .

void QPainter:: setClipRect ( int x , int y , int width , int height , Qt::ClipOperation operation = Qt::ReplaceClip)

启用裁剪，并将裁剪区域设为矩形开始于 ( x , y ) 采用给定 width and height .

void QPainter:: setClipRegion (const QRegion & region , Qt::ClipOperation operation = Qt::ReplaceClip)

将裁剪区域设为给定 region 使用指定裁剪 operation 。默认裁剪操作是替换当前裁剪区域。

注意，剪辑区域按逻辑坐标给出。

另请参阅 clipRegion (), setClipRect ()，和 裁剪 .

void QPainter:: setClipping ( bool enable )

启用裁剪若 enable 为 true，或禁用裁剪若 enable 为 false。

另请参阅 hasClipping () 和 裁剪 .

void QPainter:: setCompositionMode ( CompositionMode mode )

将合成模式设为给定 mode .

警告： 仅 QPainter 运转于 QImage 完全支持所有合成模式。作为由 X11 支持 RasterOp 模式的描述在 compositionMode ().

另请参阅 compositionMode ().

void QPainter:: setFont (const QFont & font )

将描绘器的字体设为给定 font .

This font is used by subsequent drawText () functions. The text color is the same as the pen color.

If you set a font that isn't available, Qt finds a close match. font () will return what you set using setFont() and fontInfo () returns the font actually being used (which may be the same).

另请参阅 font (), drawText ()，和 设置 .

void QPainter:: setLayoutDirection ( Qt::LayoutDirection direction )

Sets the layout direction used by the painter when drawing text, to the specified direction .

默认为 Qt::LayoutDirectionAuto , which will implicitly determine the direction from the text drawn.

另请参阅 QTextOption::setTextDirection (), layoutDirection (), drawText ()，和 设置 .

void QPainter:: setOpacity ( qreal opacity )

把描绘器的不透明度设为 opacity . The value should be in the range 0.0 to 1.0, where 0.0 is fully transparent and 1.0 is fully opaque.

Opacity set on the painter will apply to all drawing operations individually.

该函数在 Qt 4.2 引入。

另请参阅 opacity ().

void QPainter:: setPen (const QPen & pen )

把描绘器的钢笔，设为给定 pen .

pen 定义如何绘制线条和轮廓，且它还定义文本颜色。

另请参阅 pen () 和 设置 .

void QPainter:: setPen (const QColor & color )

这是重载函数。

Sets the painter's pen to have style Qt::SolidLine , width 1 and the specified color .

void QPainter:: setPen ( Qt::PenStyle style )

这是重载函数。

Sets the painter's pen to have the given style , width 1 and black color.

void QPainter:: setRenderHint ( RenderHint hint , bool on = true)

设置给定渲染 hint 在描绘器若 on 为 true；否则清零渲染提示。

另请参阅 setRenderHints (), renderHints ()，和 渲染品质 .

void QPainter:: setRenderHints ( RenderHints hints , bool on = true)

设置给定渲染 hints 在描绘器若 on 为 true；否则清零渲染提示。

该函数在 Qt 4.2 引入。

另请参阅 setRenderHint (), renderHints ()，和 渲染品质 .

void QPainter:: setTransform (const QTransform & transform , bool combine = false)

设置世界变换矩阵。若 combine is true, the specified transform is combined with the current matrix; otherwise it replaces the current matrix.

该函数在 Qt 4.3 引入。

另请参阅 transform () 和 setWorldTransform ().

void QPainter:: setViewTransformEnabled ( bool enable )

Enables view transformations if enable is true, or disables view transformations if enable 为 false。

另请参阅 viewTransformEnabled () 和 窗口/视口转换 .

void QPainter:: setViewport (const QRect & rectangle )

Sets the painter's viewport rectangle to the given rectangle , and enables view transformations.

The viewport rectangle is part of the view transformation. The viewport specifies the device coordinate system. Its sister, the window (), specifies the logical coordinate system.

The default viewport rectangle is the same as the device's rectangle.

另请参阅 viewport (), viewTransformEnabled ()，和 窗口/视口转换 .

void QPainter:: setViewport ( int x , int y , int width , int height )

这是重载函数。

Sets the painter's viewport rectangle to be the rectangle beginning at ( x , y ) 采用给定 width and height .

void QPainter:: setWindow (const QRect & rectangle )

Sets the painter's window to the given rectangle , and enables view transformations.

The window rectangle is part of the view transformation. The window specifies the logical coordinate system. Its sister, the viewport (), specifies the device coordinate system.

The default window rectangle is the same as the device's rectangle.

另请参阅 window (), viewTransformEnabled ()，和 窗口/视口转换 .

void QPainter:: setWindow ( int x , int y , int width , int height )

这是重载函数。

Sets the painter's window to the rectangle beginning at ( x , y ) 和给定 width and height .

void QPainter:: setWorldMatrixEnabled ( bool enable )

Enables transformations if enable is true, or disables transformations if enable is false. The world transformation matrix is not changed.

该函数在 Qt 4.2 引入。

另请参阅 worldMatrixEnabled (), worldTransform ()，和 坐标变换 .

void QPainter:: setWorldTransform (const QTransform & matrix , bool combine = false)

设置世界变换矩阵。若 combine is true, the specified matrix is combined with the current matrix; otherwise it replaces the current matrix.

另请参阅 worldTransform (), transform ()，和 setTransform ().

void QPainter:: shear ( qreal sh , qreal sv )

剪切坐标系按 ( sh , sv ).

另请参阅 setWorldTransform () 和 坐标变换 .

void QPainter:: strokePath (const QPainterPath & path , const QPen & pen )

绘制轮廓 (描边) 路径 path 采用的钢笔指定通过 pen

另请参阅 fillPath () 和 绘制 .

bool QPainter:: testRenderHint ( RenderHint hint ) const

返回 true if hint 已设置；否则返回 false .

该函数在 Qt 4.3 引入。

另请参阅 renderHints () 和 setRenderHint ().

const QTransform &QPainter:: transform () const

返回世界变换矩阵。

另请参阅 setTransform () 和 worldTransform ().

void QPainter:: translate (const QPointF & offset )

翻译坐标系通过给定 offset ；即：给定 offset 被添加到点。

另请参阅 setWorldTransform () 和 坐标变换 .

void QPainter:: translate (const QPoint & offset )

这是重载函数。

翻译坐标系通过给定 offset .

void QPainter:: translate ( qreal dx , qreal dy )

这是重载函数。

翻译坐标系通过向量 ( dx , dy ).

bool QPainter:: viewTransformEnabled () const

返回 true 若视图变换被启用；否则返回 false。

另请参阅 setViewTransformEnabled () 和 worldTransform ().

QRect QPainter:: viewport () const

返回视口矩形。

另请参阅 setViewport () 和 setViewTransformEnabled ().

QRect QPainter:: window () const

返回窗口矩形。

另请参阅 setWindow () 和 setViewTransformEnabled ().

bool QPainter:: worldMatrixEnabled () const

返回 true 若世界变换被启用；否则返回 false。

该函数在 Qt 4.2 引入。

另请参阅 setWorldMatrixEnabled (), worldTransform ()，和 坐标系 .

const QTransform &QPainter:: worldTransform () const

返回世界变换矩阵。

另请参阅 setWorldTransform ().