Qt:sizePolicy属性

1. Fixed: 大小不能改变

2. Minimum: 已经是最小, 不能再被缩小, 但能放大.

3. Maximum: 已经是最大, 不能再被放大, 但能缩小.

4. Preferred: 控件的sizeHint()是他的sizeHint, 能被缩小, 放大.

5. Expanding: 控件可以自行增大或者缩小.

Preferred与Expanding的区别: 当有Preferred与Expanding的控件时, 只有Expanding的会被缩小与放大, Preferred的控件使用其sizeHint()作为大小, 大小不发生变化.

 

• QSizePolicy::NoDirection - the widget cannot make use of extra space in any direction.
• QSizePolicy::Horizontally - the widget can usefully be wider than the sizeHint().
• QSizePolicy::Vertically - the widget can usefully be taller than the sizeHint().
• QSizePolicy::BothDirections - the widget can usefully be both wider and taller than the sizeHint().

QSizePolicy::SizeType

The per-dimension sizing types used when constructing a QSizePolicy are:

• QSizePolicy::Fixed - the QWidget::sizeHint() is the only acceptable alternative, so the widget can never grow or shrink (e.g. the vertical direction of a push button).
• QSizePolicy::Minimum - the sizeHint() is minimal, and sufficient. The widget can be expanded, but there is no advantage to it being larger (e.g. the horizontal direction of a push button).
• QSizePolicy::Maximum - the sizeHint() is a maximum. The widget can be shrunk any amount without detriment if other widgets need the space (e.g. a separator line).
• QSizePolicy::Preferred - the sizeHint() is best, but the widget can be shrunk and still be useful. The widget can be expanded, but there is no advantage to it being larger than sizeHint() (the default QWidget policy).
• QSizePolicy::Expanding - the sizeHint() is a sensible size, but the widget can be shrunk and still be useful. The widget can make use of extra space, so it should get as much space as possible (e.g. the horizontal direction of a slider).
• QSizePolicy::MinimumExpanding - the sizeHint() is minimal, and sufficient. The widget can make use of extra space, so it should get as much space as possible (e.g. the horizontal direction of a slider).
• QSizePolicy::Ignored - the sizeHint() is ignored. The widget will get as much space as possible.