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org.eclipse.swt.widgets
Class Layout
java.lang.Object
org.eclipse.swt.widgets.Layout
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Direct Known Subclasses:
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FillLayout,
FormLayout,
GridLayout,
RowLayout,
StackLayout
- 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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See Also:
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Composite.setLayout(Layout)
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Method Summary
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protected abstract
Point
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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
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flushCache
(
Control control)
Instruct the layout to flush any cached values
associated with the control specified in the argument
control. |
protected abstract void
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layout
(
Composite composite,
boolean flushCache)
Lays out the children of the specified composite according to this
layout. |
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Methods inherited from class java.lang.
Object
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clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait
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Layout
public Layout()
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.
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Parameters:
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composite - a composite widget using this layout -
flushCache - true means flush cached layout values
flushCache
protected boolean flushCache(
Control control)
- Instruct the layout to flush any cached values
associated with the control specified in the argument
control.
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Parameters:
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control - a control managed by this layout
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Returns:
- true if the Layout has flushed all cached information associated with control
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.
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Parameters:
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composite - a composite widget using this layout -
wHint - width (SWT.DEFAULT for preferred size) -
hHint - height (SWT.DEFAULT for preferred size) -
flushCache - true means flush cached layout values
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Returns:
- a point containing the computed size (width, height)
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See Also:
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layout(org.eclipse.swt.widgets.Composite, boolean),
Control.getBorderWidth(),
Control.getBounds(),
Control.getSize(),
Control.pack(boolean),
"computeTrim, getClientArea for controls that implement them"
Copyright (c) Innoopract Informationssysteme GmbH and others 2002, 2008. All rights reserved.
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