QDial 类提供四舍五入范围控制 (像速度计或电位计)。 更多...
| 头： | #include <QDial> |
| qmake: | QT += widgets |
| 继承： | QAbstractSlider |
| QDial (QWidget * parent = nullptr) | |
| virtual | ~QDial () |
| int | notchSize () const |
| qreal | notchTarget () const |
| bool | notchesVisible () const |
| void | setNotchTarget (double target ) |
| bool | wrapping () const |
| virtual QSize | minimumSizeHint () const override |
| virtual QSize | sizeHint () const override |
| void | setNotchesVisible (bool visible ) |
| void | setWrapping (bool on ) |
| void | initStyleOption (QStyleOptionSlider * option ) const |
| virtual bool | event (QEvent * e ) override |
| virtual void | mouseMoveEvent (QMouseEvent * e ) override |
| virtual void | mousePressEvent (QMouseEvent * e ) override |
| virtual void | mouseReleaseEvent (QMouseEvent * e ) override |
| virtual void | paintEvent (QPaintEvent * pe ) override |
| virtual void | resizeEvent (QResizeEvent * e ) override |
| virtual void | sliderChange (QAbstractSlider::SliderChange change ) override |
QDial is used when the user needs to control a value within a program-definable range, and the range either wraps around (for example, with angles measured from 0 to 359 degrees) or the dialog layout needs a square widget.
由于 QDial 继承自 QAbstractSlider , the dial behaves in a similar way to a slider 。当 wrapping () is false (the default setting) there is no real difference between a slider and a dial. They both share the same signals, slots and member functions. Which one you use depends on the expectations of your users and on the type of application.
The dial initially emits valueChanged () signals continuously while the slider is being moved; you can make it emit the signal less often by disabling the tracking property. The sliderMoved () signal is emitted continuously even when tracking is disabled.
The dial also emits sliderPressed () 和 sliderReleased () signals when the mouse button is pressed and released. Note that the dial's value can change without these signals being emitted since the keyboard and wheel can also be used to change the value.
Unlike the slider, QDial attempts to draw a "nice" number of notches rather than one per line step. If possible, the number of notches drawn is one per line step, but if there aren't enough pixels to draw every one, QDial will skip notches to try and draw a uniform set (e.g. by drawing every second or third notch).
Like the slider, the dial makes the QAbstractSlider function setValue () available as a slot.
The dial's keyboard interface is fairly simple: The left / up and right / down arrow keys adjust the dial's value by the defined singleStep , Page Up and Page Down by the defined pageStep ，和 首页 and End keys set the value to the defined minimum and maximum 值。
If you are using the mouse wheel to adjust the dial, the increment value is determined by the lesser value of wheelScrollLines multiplied by singleStep ，和 pageStep .
另请参阅 QScrollBar , QSpinBox , QSlider , GUI 设计手册：滑块 ，和 滑块范例 .
This property holds the current notch size
The notch size is in range control units, not pixels, and if possible it is a multiple of singleStep () that results in an on-screen notch size near notchTarget ().
默认情况下，此特性拥有 1 值。
访问函数：
| int | notchSize () const |
另请参阅 notchTarget () 和 singleStep ().
This property holds the target number of pixels between notches
The notch target is the number of pixels QDial attempts to put between each notch.
The actual size may differ from the target size.
The default notch target is 3.7 pixels.
访问函数：
| qreal | notchTarget () const |
| void | setNotchTarget (double target ) |
This property holds whether the notches are shown
If the property is
true
, a series of notches are drawn around the dial to indicate the range of values available; otherwise no notches are shown.
By default, this property is disabled.
访问函数：
| bool | notchesVisible () const |
| void | setNotchesVisible (bool visible ) |
This property holds whether wrapping is enabled
If true, wrapping is enabled; otherwise some space is inserted at the bottom of the dial to separate the ends of the range of valid values.
If enabled, the arrow can be oriented at any angle on the dial. If disabled, the arrow will be restricted to the upper part of the dial; if it is rotated into the space at the bottom of the dial, it will be clamped to the closest end of the valid range of values.
默认情况下此特性为
false
.
访问函数：
| bool | wrapping () const |
| void | setWrapping (bool on ) |
Constructs a dial.
The parent 自变量被发送给 QAbstractSlider 构造函数。
[虚拟]
QDial::
~QDial
()
Destroys the dial.
[override virtual protected]
bool
QDial::
event
(
QEvent
*
e
)
重实现： QAbstractSlider::event (QEvent *e).
[protected]
void
QDial::
initStyleOption
(
QStyleOptionSlider
*
option
) const
初始化 option 采用值来自此 QDial 。此方法对子类是有用的，当需要 QStyleOptionSlider ，但不希望自己填充所有信息。
另请参阅 QStyleOption::initFrom ().
[override virtual]
QSize
QDial::
minimumSizeHint
() const
重实现访问函数为特性： QWidget::minimumSizeHint .
[override virtual protected]
void
QDial::
mouseMoveEvent
(
QMouseEvent
*
e
)
重实现： QWidget::mouseMoveEvent (QMouseEvent *event).
[override virtual protected]
void
QDial::
mousePressEvent
(
QMouseEvent
*
e
)
重实现： QWidget::mousePressEvent (QMouseEvent *event).
[override virtual protected]
void
QDial::
mouseReleaseEvent
(
QMouseEvent
*
e
)
重实现： QWidget::mouseReleaseEvent (QMouseEvent *event).
[override virtual protected]
void
QDial::
paintEvent
(
QPaintEvent
*
pe
)
重实现： QWidget::paintEvent (QPaintEvent *event).
[override virtual protected]
void
QDial::
resizeEvent
(
QResizeEvent
*
e
)
重实现： QWidget::resizeEvent (QResizeEvent *event).
[override virtual]
QSize
QDial::
sizeHint
() const
重实现访问函数为特性： QWidget::sizeHint .
[override virtual protected]
void
QDial::
sliderChange
(
QAbstractSlider::SliderChange
change
)
重实现： QAbstractSlider::sliderChange (QAbstractSlider::SliderChange change).