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/*******************************************************************************
* Copyright (c) 2004, 2005 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.ui.internal.layout;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.widgets.Control;
/**
* Caches the preferred sizes of an array of controls
*
* @since 3.0
*/
public class LayoutCache {
private SizeCache[] caches = new SizeCache[0];
/**
* Creates an empty layout cache
*/
public LayoutCache() {
}
/**
* Creates a cache for the given array of controls
*
* @param controls
*/
public LayoutCache(Control[] controls) {
rebuildCache(controls);
}
/**
* Returns the size cache for the given control
*
* @param idx
* @return
*/
public SizeCache getCache(int idx) {
return caches[idx];
}
/**
* Sets the controls that are being cached here. If these are the same
* controls that were used last time, this method does nothing. Otherwise,
* the cache is flushed and a new cache is created for the new controls.
*
* @param controls
*/
public void setControls(Control[] controls) {
// If the number of controls has changed, discard the entire cache
if (controls.length != caches.length) {
rebuildCache(controls);
return;
}
for (int idx = 0; idx < controls.length; idx++) {
caches[idx].setControl(controls[idx]);
}
}
/**
* Creates a new size cache for the given set of controls, discarding any
* existing cache.
*
* @param controls the controls whose size is being cached
*/
private void rebuildCache(Control[] controls) {
SizeCache[] newCache = new SizeCache[controls.length];
for (int idx = 0; idx < controls.length; idx++) {
// Try to reuse existing caches if possible
if (idx < caches.length) {
newCache[idx] = caches[idx];
newCache[idx].setControl(controls[idx]);
} else {
newCache[idx] = new SizeCache(controls[idx]);
}
}
caches = newCache;
}
/**
* Computes the preferred size of the nth control
*
* @param controlIndex index of the control whose size will be computed
* @param widthHint width of the control (or SWT.DEFAULT if unknown)
* @param heightHint height of the control (or SWT.DEFAULT if unknown)
* @return the preferred size of the control
*/
public Point computeSize(int controlIndex, int widthHint, int heightHint) {
return caches[controlIndex].computeSize(widthHint, heightHint);
}
/**
* Flushes the cache for the given control. This should be called if exactly
* one of the controls has changed but the remaining controls remain unmodified
*
* @param controlIndex
*/
public void flush(int controlIndex) {
caches[controlIndex].flush();
}
/**
* Flushes the cache.
*/
public void flush() {
for (int idx = 0; idx < caches.length; idx++) {
caches[idx].flush();
}
}
}
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