内容

• 公共类型
• 公共函数
• 相关非成员
• 详细描述

QSizePolicy 类

QSizePolicy class is a layout attribute describing horizontal and vertical resizing policy. 更多...

头：	#include <QSizePolicy>
qmake:	QT += widgets

• 所有成员列表，包括继承成员

公共类型

enum	ControlType { DefaultType, ButtonBox, CheckBox, ComboBox, ..., ToolButton }
flags	ControlTypes
enum	Policy { Fixed, Minimum, Maximum, Preferred, ..., Ignored }
enum	PolicyFlag { GrowFlag, ExpandFlag, ShrinkFlag, IgnoreFlag }

公共函数

	QSizePolicy ()
	QSizePolicy (Policy horizontal , Policy vertical , ControlType type = DefaultType)
ControlType	controlType () const
Qt::Orientations	expandingDirections () const
bool	hasHeightForWidth () const
bool	hasWidthForHeight () const
Policy	horizontalPolicy () const
int	horizontalStretch () const
bool	retainSizeWhenHidden () const
void	setControlType (ControlType type )
void	setHeightForWidth (bool dependent )
void	setHorizontalPolicy (Policy policy )
void	setHorizontalStretch (int stretchFactor )
void	setRetainSizeWhenHidden (bool retainSize )
void	setVerticalPolicy (Policy policy )
void	setVerticalStretch (int stretchFactor )
void	setWidthForHeight (bool dependent )
void	transpose ()
QSizePolicy	transposed () const
Policy	verticalPolicy () const
int	verticalStretch () const
	operator QVariant () const
bool	operator!= (const QSizePolicy & other ) const
bool	operator== (const QSizePolicy & other ) const

相关非成员

uint	qHash (QSizePolicy key , uint seed = 0)
QDataStream &	operator<< (QDataStream & stream , const QSizePolicy & policy )
QDataStream &	operator>> (QDataStream & stream , QSizePolicy & policy )

详细描述

QSizePolicy class is a layout attribute describing horizontal and vertical resizing policy.

Widget 的大小策略是其自愿以各种方式重置大小的表达，和影响小部件如何被对待通过 布局引擎 . Each widget returns a QSizePolicy that describes the horizontal and vertical resizing policy it prefers when being laid out. You can change this for a specific widget by changing its QWidget::sizePolicy 特性。

QSizePolicy contains two independent QSizePolicy::Policy 值和 2 拉伸因子；一个描述 Widget 的水平大小策略，而另一描述其垂直大小策略。它还包含指示其首选大小高度和宽度是否相关的标志。

The horizontal and vertical policies can be set in the constructor, and altered using the setHorizontalPolicy () 和 setVerticalPolicy () functions. The stretch factors can be set using the setHorizontalStretch () 和 setVerticalStretch () functions. The flag indicating whether the widget's sizeHint() is width-dependent (such as a menu bar or a word-wrapping label) can be set using the setHeightForWidth () 函数。

The current size policies and stretch factors be retrieved using the horizontalPolicy (), verticalPolicy (), horizontalStretch () 和 verticalStretch () functions. Alternatively, use the transpose () function to swap the horizontal and vertical policies and stretches. The hasHeightForWidth () function returns the current status of the flag indicating the size hint dependencies.

使用 expandingDirections () function to determine whether the associated widget can make use of more space than its sizeHint() function indicates, as well as find out in which directions it can expand.

Finally, the QSizePolicy class provides operators comparing this size policy to a given policy, as well as a QVariant operator storing this QSizePolicy 作为 QVariant 对象。

另请参阅 QSize , QWidget::sizeHint (), QWidget::sizePolicy ，和 QLayoutItem::sizeHint ().

成员类型文档编制

enum QSizePolicy:: ControlType
flags QSizePolicy:: ControlTypes

此枚举指定 Widget 的不同类型，就布局交互而言：

常量	值	描述
QSizePolicy::DefaultType	0x00000001	默认类型，当未指定时。
QSizePolicy::ButtonBox	0x00000002	A QDialogButtonBox 实例。
QSizePolicy::CheckBox	0x00000004	A QCheckBox 实例。
QSizePolicy::ComboBox	0x00000008	A QComboBox 实例。
QSizePolicy::Frame	0x00000010	A QFrame 实例。
QSizePolicy::GroupBox	0x00000020	A QGroupBox 实例。
QSizePolicy::Label	0x00000040	A QLabel 实例。
QSizePolicy::Line	0x00000080	A QFrame 实例与 QFrame::HLine or QFrame::VLine .
QSizePolicy::LineEdit	0x00000100	A QLineEdit 实例。
QSizePolicy::PushButton	0x00000200	A QPushButton 实例。
QSizePolicy::RadioButton	0x00000400	A QRadioButton 实例。
QSizePolicy::Slider	0x00000800	A QAbstractSlider 实例。
QSizePolicy::SpinBox	0x00001000	A QAbstractSpinBox 实例。
QSizePolicy::TabWidget	0x00002000	A QTabWidget 实例。
QSizePolicy::ToolButton	0x00004000	A QToolButton 实例。

该枚举在 Qt 4.3 引入或被修改。

The ControlTypes type is a typedef for QFlags <ControlType>. It stores an OR combination of ControlType values.

另请参阅 setControlType () 和 controlType ().

enum QSizePolicy:: Policy

此枚举描述使用的各种每维度大小调整类型当构造 QSizePolicy .

常量	值	描述
QSizePolicy::Fixed	0	QWidget::sizeHint () 是唯一可接受的替代，因此 Widget 可以从不增长或收缩 (如：按钮的垂直方向)。
QSizePolicy::Minimum	GrowFlag	sizeHint() 最小，且足够。Widget 可以扩展，但变大没有好处 (如：按钮的水平方向)。它不可以小于由 sizeHint() 提供的大小。
QSizePolicy::Maximum	ShrinkFlag	sizeHint() 最大。Widget 可以任意收缩且不会受到损害，若其它小部件需要空间 (如：分隔线)。它不可以大于由 sizeHint() 提供的大小。
QSizePolicy::Preferred	GrowFlag | ShrinkFlag	sizeHint() 最佳，但 Widget 可以收缩且仍然有用。小部件可以展开，但是大于 sizeHint() 没有好处 (默认 QWidget 策略)。
QSizePolicy::Expanding	GrowFlag | ShrinkFlag | ExpandFlag	sizeHint() 是合理大小，但 Widget 可以收缩且仍然有用。小部件可以利用额外空间，因此它应获得尽可能多的空间 (如：水平滑块的水平方向)。
QSizePolicy::MinimumExpanding	GrowFlag | ExpandFlag	sizeHint() 为最小，且足够。Widget 可以利用额外空间，因此应获得尽可能多的空间 (如：水平滑块的水平方向)。
QSizePolicy::Ignored	ShrinkFlag | GrowFlag | IgnoreFlag	sizeHint() 被忽略。Widget 将获得尽可能多的空间。

另请参阅 PolicyFlag , setHorizontalPolicy ()，和 setVerticalPolicy ().

enum QSizePolicy:: PolicyFlag

组合这些标志在一起以形成各种 Policy 值：

常量	值	描述
QSizePolicy::GrowFlag	1	Widget 可以增长到超出其大小提示 (若有必要)。
QSizePolicy::ExpandFlag	2	Widget 应获得尽可能多的空间。
QSizePolicy::ShrinkFlag	4	Widget 可以收缩到其大小提示以内 (若有必要)。
QSizePolicy::IgnoreFlag	8	Widget 的大小提示被忽略。小部件将获得尽可能多的空间。

另请参阅 Policy .

成员函数文档编制

QSizePolicy:: QSizePolicy ()

构造 QSizePolicy 对象采用 Fixed as its horizontal and vertical policies.

The policies can be altered using the setHorizontalPolicy () 和 setVerticalPolicy () 函数。使用 setHeightForWidth () function if the preferred height of the widget is dependent on the width of the widget (for example, a QLabel 带换行)。

另请参阅 setHorizontalStretch () 和 setVerticalStretch ().

QSizePolicy:: QSizePolicy ( Policy horizontal , Policy vertical , ControlType type = DefaultType)

构造 QSizePolicy 对象采用给定 horizontal and vertical 策略，并指定控件 type .

使用 setHeightForWidth () if the preferred height of the widget is dependent on the width of the widget (for example, a QLabel 带换行)。

该函数在 Qt 4.3 引入。

另请参阅 setHorizontalStretch (), setVerticalStretch ()，和 controlType ().

ControlType QSizePolicy:: controlType () const

返回应用此大小策略的 Widget 的关联控件类型。

该函数在 Qt 4.3 引入。

另请参阅 setControlType ().

Qt::Orientations QSizePolicy:: expandingDirections () const

Returns whether a widget can make use of more space than the QWidget::sizeHint () 函数指示。

A value of Qt::Horizontal or Qt::Vertical means that the widget can grow horizontally or vertically (i.e., the horizontal or vertical policy is Expanding or MinimumExpanding ), whereas Qt::Horizontal | Qt::Vertical means that it can grow in both dimensions.

另请参阅 horizontalPolicy () 和 verticalPolicy ().

bool QSizePolicy:: hasHeightForWidth () const

返回 true 若 Widget 的首选高度取决于其宽度；否则返回 false .

另请参阅 setHeightForWidth ().

bool QSizePolicy:: hasWidthForHeight () const

返回 true if the widget's width depends on its height; otherwise returns false .

另请参阅 setWidthForHeight ().

Policy QSizePolicy:: horizontalPolicy () const

Returns the horizontal component of the size policy.

另请参阅 setHorizontalPolicy (), verticalPolicy ()，和 horizontalStretch ().

int QSizePolicy:: horizontalStretch () const

Returns the horizontal stretch factor of the size policy.

另请参阅 setHorizontalStretch (), verticalStretch ()，和 horizontalPolicy ().

bool QSizePolicy:: retainSizeWhenHidden () const

Returns whether the layout should retain the widget's size when it is hidden. This is false 在默认情况下。

该函数在 Qt 5.2 引入。

另请参阅 setRetainSizeWhenHidden ().

void QSizePolicy:: setControlType ( ControlType type )

Sets the control type associated with the widget for which this size policy applies to type .

The control type specifies the type of the widget for which this size policy applies. It is used by some styles, notably QMacStyle, to insert proper spacing between widgets. For example, the macOS Aqua guidelines specify that push buttons should be separated by 12 pixels, whereas vertically stacked radio buttons only require 6 pixels.

该函数在 Qt 4.3 引入。

另请参阅 controlType () 和 QStyle::layoutSpacing ().

void QSizePolicy:: setHeightForWidth ( bool dependent )

将 Widget 首选高度是否从属其宽度的确定标志设为 dependent .

另请参阅 hasHeightForWidth () 和 setWidthForHeight ().

void QSizePolicy:: setHorizontalPolicy ( Policy policy )

Sets the horizontal component to the given policy .

另请参阅 horizontalPolicy (), setVerticalPolicy ()，和 setHorizontalStretch ().

void QSizePolicy:: setHorizontalStretch ( int stretchFactor )

Sets the horizontal stretch factor of the size policy to the given stretchFactor . stretchFactor must be in the range [0,255].

When two widgets are adjacent to each other in a horizontal layout, setting the horizontal stretch factor of the widget on the left to 2 and the factor of widget on the right to 1 will ensure that the widget on the left will always be twice the size of the one on the right.

另请参阅 horizontalStretch (), setVerticalStretch ()，和 setHorizontalPolicy ().

void QSizePolicy:: setRetainSizeWhenHidden ( bool retainSize )

Sets whether a layout should retain the widget's size when it is hidden. If retainSize is true , the layout will not be changed by hiding the widget.

该函数在 Qt 5.2 引入。

另请参阅 retainSizeWhenHidden ().

void QSizePolicy:: setVerticalPolicy ( Policy policy )

Sets the vertical component to the given policy .

另请参阅 verticalPolicy (), setHorizontalPolicy ()，和 setVerticalStretch ().

void QSizePolicy:: setVerticalStretch ( int stretchFactor )

Sets the vertical stretch factor of the size policy to the given stretchFactor . stretchFactor must be in the range [0,255].

When two widgets are adjacent to each other in a vertical layout, setting the vertical stretch factor of the widget on the top to 2 and the factor of widget on the bottom to 1 will ensure that the widget on the top will always be twice the size of the one on the bottom.

另请参阅 verticalStretch (), setHorizontalStretch ()，和 setVerticalPolicy ().

void QSizePolicy:: setWidthForHeight ( bool dependent )

Sets the flag determining whether the widget's width depends on its height, to dependent .

This is only supported for QGraphicsLayout 's subclasses. It is not possible to have a layout with both height-for-width and width-for-height constraints at the same time.

另请参阅 hasWidthForHeight () 和 setHeightForWidth ().

void QSizePolicy:: transpose ()

Swaps the horizontal and vertical policies and stretches.

另请参阅 transposed ().

QSizePolicy QSizePolicy:: transposed () const

Returns a size policy object with the horizontal and vertical policies and stretches swapped.

该函数在 Qt 5.9 引入。

另请参阅 transpose ().

Policy QSizePolicy:: verticalPolicy () const

返回大小策略的垂直组件。

另请参阅 setVerticalPolicy (), horizontalPolicy ()，和 verticalStretch ().

int QSizePolicy:: verticalStretch () const

返回大小策略的垂直拉伸因子。

另请参阅 setVerticalStretch (), horizontalStretch ()，和 verticalPolicy ().

QSizePolicy:: operator QVariant () const

返回 QVariant storing this QSizePolicy .

bool QSizePolicy:: operator!= (const QSizePolicy & other ) const

返回 true 若此策略异于 other ；否则返回 false .

另请参阅 operator== ().

bool QSizePolicy:: operator== (const QSizePolicy & other ) const

返回 true 若此策略等于 other ；否则返回 false .

另请参阅 operator!= ().

相关非成员

uint qHash ( QSizePolicy key , uint seed = 0)

返回哈希值为 key ，使用 seed 做计算种子。

该函数在 Qt 5.6 引入。

QDataStream & operator<< ( QDataStream & stream , const QSizePolicy & policy )

Writes the size policy 到数据流 stream .

该函数在 Qt 4.2 引入。

另请参阅 QDataStream 运算符格式 .

QDataStream & operator>> ( QDataStream & stream , QSizePolicy & policy )

Reads the size policy 从数据流 stream .

该函数在 Qt 4.2 引入。

另请参阅 QDataStream 运算符格式 .