Class Layout
- java.lang.Object
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- org.eclipse.swt.widgets.Layout
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- Direct Known Subclasses:
AbstractColumnLayout
,BorderLayout
,ColumnLayout
,FillLayout
,FormLayout
,GridLayout
,PageBook.PageBookLayout
,RowLayout
,SourceViewer.RulerLayout
,StackLayout
,TableLayout
,TableWrapLayout
,WizardDialog.PageContainerFillLayout
public abstract class Layout extends Object
A layout controls the position and size of the children of a composite widget. This class is the abstract base class for layouts.
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Constructor Summary
Constructors Constructor Description Layout()
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description protected abstract Point
computeSize(Composite composite, int wHint, int hHint, boolean flushCache)
Computes and returns the size of the specified composite's client area according to this layout.protected boolean
flushCache(Control control)
Instruct the layout to flush any cached values associated with the control specified in the argumentcontrol
.protected abstract void
layout(Composite composite, boolean flushCache)
Lays out the children of the specified composite according to this layout.
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Method Detail
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computeSize
protected abstract Point computeSize(Composite composite, int wHint, int hHint, boolean flushCache)
Computes and returns the size of the specified composite's client area according to this layout.This method computes the size that the client area of the composite must be in order to position all children at their preferred size inside the composite according to the layout algorithm encoded by this layout.
When a width or height hint is supplied, it is used to constrain the result. For example, if a width hint is provided that is less than the width of the client area, the layout may choose to wrap and increase height, clip, overlap, or otherwise constrain the children.
- Parameters:
composite
- a composite widget using this layoutwHint
- width (SWT.DEFAULT
for preferred size)hHint
- height (SWT.DEFAULT
for preferred size)flushCache
-true
means flush cached layout values- Returns:
- a point containing the computed size (width, height)
- See Also:
layout(org.eclipse.swt.widgets.Composite, boolean)
,Control.getBorderWidth()
,Control.getBounds()
,Control.getSize()
,Control.pack(boolean)
, "computeTrim, getClientArea for controls that implement them"
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flushCache
protected boolean flushCache(Control control)
Instruct the layout to flush any cached values associated with the control specified in the argumentcontrol
.- Parameters:
control
- a control managed by this layout- Returns:
- true if the Layout has flushed all cached information associated with control
- Since:
- 3.1
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layout
protected abstract void layout(Composite composite, boolean flushCache)
Lays out the children of the specified composite according to this layout.This method positions and sizes the children of a composite using the layout algorithm encoded by this layout. Children of the composite are positioned in the client area of the composite. The position of the composite is not altered by this method.
When the flush cache hint is true, the layout is instructed to flush any cached values associated with the children. Typically, a layout will cache the preferred sizes of the children to avoid the expense of computing these values each time the widget is laid out.
When layout is triggered explicitly by the programmer the flush cache hint is true. When layout is triggered by a resize, either caused by the programmer or by the user, the hint is false.
- Parameters:
composite
- a composite widget using this layoutflushCache
-true
means flush cached layout values
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