/*******************************************************************************
* Copyright (c) 2000, 2008 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.swt.custom;
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;
/**
*
* A ControlEditor is a manager for a Control that appears above a composite and tracks with the
* moving and resizing of that composite. It can be used to display one control above
* another control. This could be used when editing a control that does not have editing
* capabilities by using a text editor or for launching a dialog by placing a button
* above a control.
*
* <p> Here is an example of using a ControlEditor:
*
* <code><pre>
* Canvas canvas = new Canvas(shell, SWT.BORDER);
* canvas.setBounds(10, 10, 300, 300);
* Color color = new Color(null, 255, 0, 0);
* canvas.setBackground(color);
* ControlEditor editor = new ControlEditor (canvas);
* // The editor will be a button in the bottom right corner of the canvas.
* // When selected, it will launch a Color dialog that will change the background
* // of the canvas.
* Button button = new Button(canvas, SWT.PUSH);
* button.setText("Select Color...");
* button.addSelectionListener (new SelectionAdapter() {
* public void widgetSelected(SelectionEvent e) {
* ColorDialog dialog = new ColorDialog(shell);
* dialog.open();
* RGB rgb = dialog.getRGB();
* if (rgb != null) {
* if (color != null) color.dispose();
* color = new Color(null, rgb);
* canvas.setBackground(color);
* }
*
* }
* });
*
* editor.horizontalAlignment = SWT.RIGHT;
* editor.verticalAlignment = SWT.BOTTOM;
* editor.grabHorizontal = false;
* editor.grabVertical = false;
* Point size = button.computeSize(SWT.DEFAULT, SWT.DEFAULT);
* editor.minimumWidth = size.x;
* editor.minimumHeight = size.y;
* editor.setEditor (button);
* </pre></code>
*
* @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
*/
public class ControlEditor {
/**
* Specifies how the editor should be aligned relative to the control. Allowed values
* are SWT.LEFT, SWT.RIGHT and SWT.CENTER. The default value is SWT.CENTER.
*/
public int horizontalAlignment = SWT.CENTER;
/**
* Specifies whether the editor should be sized to use the entire width of the control.
* True means resize the editor to the same width as the cell. False means do not adjust
* the width of the editor. The default value is false.
*/
public boolean grabHorizontal = false;
/**
* Specifies the minimum width the editor can have. This is used in association with
* a true value of grabHorizontal. If the cell becomes smaller than the minimumWidth, the
* editor will not made smaller than the minimum width value. The default value is 0.
*/
public int minimumWidth = 0;
/**
* Specifies how the editor should be aligned relative to the control. Allowed values
* are SWT.TOP, SWT.BOTTOM and SWT.CENTER. The default value is SWT.CENTER.
*/
public int verticalAlignment = SWT.CENTER;
/**
* Specifies whether the editor should be sized to use the entire height of the control.
* True means resize the editor to the same height as the underlying control. False means do not adjust
* the height of the editor. The default value is false.
*/
public boolean grabVertical = false;
/**
* Specifies the minimum height the editor can have. This is used in association with
* a true value of grabVertical. If the control becomes smaller than the minimumHeight, the
* editor will not made smaller than the minimum height value. The default value is 0.
*/
public int minimumHeight = 0;
Composite parent;
Control editor;
private boolean hadFocus;
private Listener controlListener;
private Listener scrollbarListener;
private final static int [] EVENTS = {SWT.KeyDown, SWT.KeyUp, SWT.MouseDown, SWT.MouseUp, SWT.Resize};
/**
* Creates a ControlEditor for the specified Composite.
*
* @param parent the Composite above which this editor will be displayed
*
*/
public ControlEditor (Composite parent) {
this.parent = parent;
controlListener = new Listener() {
public void handleEvent(Event e) {
layout ();
}
};
for (int i=0; i<EVENTS.length; i++) {
parent.addListener (EVENTS [i], controlListener);
}
scrollbarListener = new Listener() {
public void handleEvent(Event e) {
scroll (e);
}
};
ScrollBar hBar = parent.getHorizontalBar ();
if (hBar != null) hBar.addListener (SWT.Selection, scrollbarListener);
ScrollBar vBar = parent.getVerticalBar ();
if (vBar != null) vBar.addListener (SWT.Selection, scrollbarListener);
}
Rectangle computeBounds () {
Rectangle clientArea = parent.getClientArea();
Rectangle editorRect = new Rectangle(clientArea.x, clientArea.y, minimumWidth, minimumHeight);
if (grabHorizontal)
editorRect.width = Math.max(clientArea.width, minimumWidth);
if (grabVertical)
editorRect.height = Math.max(clientArea.height, minimumHeight);
switch (horizontalAlignment) {
case SWT.RIGHT:
editorRect.x += clientArea.width - editorRect.width;
break;
case SWT.LEFT:
// do nothing - clientArea.x is the right answer
break;
default:
// default is CENTER
editorRect.x += (clientArea.width - editorRect.width)/2;
}
switch (verticalAlignment) {
case SWT.BOTTOM:
editorRect.y += clientArea.height - editorRect.height;
break;
case SWT.TOP:
// do nothing - clientArea.y is the right answer
break;
default :
// default is CENTER
editorRect.y += (clientArea.height - editorRect.height)/2;
}
return editorRect;
}
/**
* Removes all associations between the Editor and the underlying composite. The
* composite and the editor Control are <b>not</b> disposed.
*/
public void dispose () {
if (parent != null && !parent.isDisposed()) {
for (int i=0; i<EVENTS.length; i++) {
parent.removeListener (EVENTS [i], controlListener);
}
ScrollBar hBar = parent.getHorizontalBar ();
if (hBar != null) hBar.removeListener (SWT.Selection, scrollbarListener);
ScrollBar vBar = parent.getVerticalBar ();
if (vBar != null) vBar.removeListener (SWT.Selection, scrollbarListener);
}
parent = null;
editor = null;
hadFocus = false;
controlListener = null;
scrollbarListener = null;
}
/**
* Returns the Control that is displayed above the composite being edited.
*
* @return the Control that is displayed above the composite being edited
*/
public Control getEditor () {
return editor;
}
/**
* Lays out the control within the underlying composite. This
* method should be called after changing one or more fields to
* force the Editor to resize.
*
* @since 2.1
*/
public void layout () {
if (editor == null || editor.isDisposed()) return;
if (editor.getVisible ()) {
hadFocus = editor.isFocusControl();
} // this doesn't work because
// resizing the column takes the focus away
// before we get here
editor.setBounds (computeBounds ());
if (hadFocus) {
if (editor == null || editor.isDisposed()) return;
editor.setFocus ();
}
}
void scroll (Event e) {
if (editor == null || editor.isDisposed()) return;
layout();
}
/**
* Specify the Control that is to be displayed.
*
* <p>Note: The Control provided as the editor <b>must</b> be created with its parent
* being the Composite specified in the ControlEditor constructor.
*
* @param editor the Control that is displayed above the composite being edited
*/
public void setEditor (Control editor) {
if (editor == null) {
// this is the case where the caller is setting the editor to be blank
// set all the values accordingly
this.editor = null;
return;
}
this.editor = editor;
layout();
if (this.editor == null || this.editor.isDisposed()) return;
editor.setVisible(true);
}
}
