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SWT is an open source widget toolkit for Java designed to provide efficient, portable access to the user-interface facilities of the operating systems on which it is implemented.
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/*******************************************************************************
* 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.layout;
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;
/**
* Instances of this class are used to define the attachments
* of a control in a FormLayout.
*
* To set a FormData object into a control, you use the
* setLayoutData () method. To define attachments for the
* FormData, set the fields directly, like this:
*
* FormData data = new FormData();
* data.left = new FormAttachment(0,5);
* data.right = new FormAttachment(100,-5);
* button.setLayoutData(formData);
*
*
*
* FormData contains the FormAttachments for
* each edge of the control that the FormLayout uses to
* determine the size and position of the control. FormData
* objects also allow you to set the width and height of controls within
* a FormLayout.
*
*
* @see FormLayout
* @see FormAttachment
* @see Sample code and further information
*
* @since 2.0
*/
public final class FormData {
/**
* width specifies the preferred width in pixels. This value
* is the wHint passed into Control.computeSize(int, int, boolean)
* to determine the preferred size of the control.
*
* The default value is SWT.DEFAULT.
*
* @see Control#computeSize(int, int, boolean)
*/
public int width = SWT.DEFAULT;
/**
* height specifies the preferred height in pixels. This value
* is the hHint passed into Control.computeSize(int, int, boolean)
* to determine the preferred size of the control.
*
* The default value is SWT.DEFAULT.
*
* @see Control#computeSize(int, int, boolean)
*/
public int height = SWT.DEFAULT;
/**
* left specifies the attachment of the left side of
* the control.
*/
public FormAttachment left;
/**
* right specifies the attachment of the right side of
* the control.
*/
public FormAttachment right;
/**
* top specifies the attachment of the top of the control.
*/
public FormAttachment top;
/**
* bottom specifies the attachment of the bottom of the
* control.
*/
public FormAttachment bottom;
int cacheWidth = -1, cacheHeight = -1;
int defaultWhint, defaultHhint, defaultWidth = -1, defaultHeight = -1;
int currentWhint, currentHhint, currentWidth = -1, currentHeight = -1;
FormAttachment cacheLeft, cacheRight, cacheTop, cacheBottom;
boolean isVisited, needed;
/**
* Constructs a new instance of FormData using
* default values.
*/
public FormData () {
}
/**
* Constructs a new instance of FormData according to the parameters.
* A value of SWT.DEFAULT indicates that no minimum width or
* no minimum height is specified.
*
* @param width a minimum width for the control
* @param height a minimum height for the control
*/
public FormData (int width, int height) {
this.width = width;
this.height = height;
}
void computeSize (Control control, int wHint, int hHint, boolean flushCache) {
if (cacheWidth != -1 && cacheHeight != -1) return;
if (wHint == this.width && hHint == this.height) {
if (defaultWidth == -1 || defaultHeight == -1 || wHint != defaultWhint || hHint != defaultHhint) {
Point size = control.computeSize (wHint, hHint, flushCache);
defaultWhint = wHint;
defaultHhint = hHint;
defaultWidth = size.x;
defaultHeight = size.y;
}
cacheWidth = defaultWidth;
cacheHeight = defaultHeight;
return;
}
if (currentWidth == -1 || currentHeight == -1 || wHint != currentWhint || hHint != currentHhint) {
Point size = control.computeSize (wHint, hHint, flushCache);
currentWhint = wHint;
currentHhint = hHint;
currentWidth = size.x;
currentHeight = size.y;
}
cacheWidth = currentWidth;
cacheHeight = currentHeight;
}
void flushCache () {
cacheWidth = cacheHeight = -1;
defaultHeight = defaultWidth = -1;
currentHeight = currentWidth = -1;
}
int getWidth (Control control, boolean flushCache) {
needed = true;
computeSize (control, width, height, flushCache);
return cacheWidth;
}
int getHeight (Control control, boolean flushCache) {
computeSize (control, width, height, flushCache);
return cacheHeight;
}
FormAttachment getBottomAttachment (Control control, int spacing, boolean flushCache) {
if (cacheBottom != null) return cacheBottom;
if (isVisited) return cacheBottom = new FormAttachment (0, getHeight (control, flushCache));
if (bottom == null) {
if (top == null) return cacheBottom = new FormAttachment (0, getHeight (control, flushCache));
return cacheBottom = getTopAttachment (control, spacing, flushCache).plus (getHeight (control, flushCache));
}
Control bottomControl = bottom.control;
if (bottomControl != null) {
if (bottomControl.isDisposed ()) {
bottom.control = bottomControl = null;
} else {
if (bottomControl.getParent () != control.getParent ()) {
bottomControl = null;
}
}
}
if (bottomControl == null) return cacheBottom = bottom;
isVisited = true;
FormData bottomData = (FormData) bottomControl.getLayoutData ();
FormAttachment bottomAttachment = bottomData.getBottomAttachment (bottomControl, spacing, flushCache);
switch (bottom.alignment) {
case SWT.BOTTOM:
cacheBottom = bottomAttachment.plus (bottom.offset);
break;
case SWT.CENTER: {
FormAttachment topAttachment = bottomData.getTopAttachment (bottomControl, spacing, flushCache);
FormAttachment bottomHeight = bottomAttachment.minus (topAttachment);
cacheBottom = bottomAttachment.minus (bottomHeight.minus (getHeight (control, flushCache)).divide (2));
break;
}
default: {
FormAttachment topAttachment = bottomData.getTopAttachment (bottomControl, spacing, flushCache);
cacheBottom = topAttachment.plus (bottom.offset - spacing);
break;
}
}
isVisited = false;
return cacheBottom;
}
FormAttachment getLeftAttachment (Control control, int spacing, boolean flushCache) {
if (cacheLeft != null) return cacheLeft;
if (isVisited) return cacheLeft = new FormAttachment (0, 0);
if (left == null) {
if (right == null) return cacheLeft = new FormAttachment (0, 0);
return cacheLeft = getRightAttachment (control, spacing, flushCache).minus (getWidth (control, flushCache));
}
Control leftControl = left.control;
if (leftControl != null) {
if (leftControl.isDisposed ()) {
left.control = leftControl = null;
} else {
if (leftControl.getParent () != control.getParent ()) {
leftControl = null;
}
}
}
if (leftControl == null) return cacheLeft = left;
isVisited = true;
FormData leftData = (FormData) leftControl.getLayoutData ();
FormAttachment leftAttachment = leftData.getLeftAttachment (leftControl, spacing, flushCache);
switch (left.alignment) {
case SWT.LEFT:
cacheLeft = leftAttachment.plus (left.offset);
break;
case SWT.CENTER: {
FormAttachment rightAttachment = leftData.getRightAttachment (leftControl, spacing, flushCache);
FormAttachment leftWidth = rightAttachment.minus (leftAttachment);
cacheLeft = leftAttachment.plus (leftWidth.minus (getWidth (control, flushCache)).divide (2));
break;
}
default: {
FormAttachment rightAttachment = leftData.getRightAttachment (leftControl, spacing, flushCache);
cacheLeft = rightAttachment.plus (left.offset + spacing);
}
}
isVisited = false;
return cacheLeft;
}
String getName () {
String string = getClass ().getName ();
int index = string.lastIndexOf ('.');
if (index == -1) return string;
return string.substring (index + 1, string.length ());
}
FormAttachment getRightAttachment (Control control, int spacing, boolean flushCache) {
if (cacheRight != null) return cacheRight;
if (isVisited) return cacheRight = new FormAttachment (0, getWidth (control, flushCache));
if (right == null) {
if (left == null) return cacheRight = new FormAttachment (0, getWidth (control, flushCache));
return cacheRight = getLeftAttachment (control, spacing, flushCache).plus (getWidth (control, flushCache));
}
Control rightControl = right.control;
if (rightControl != null) {
if (rightControl.isDisposed ()) {
right.control = rightControl = null;
} else {
if (rightControl.getParent () != control.getParent ()) {
rightControl = null;
}
}
}
if (rightControl == null) return cacheRight = right;
isVisited = true;
FormData rightData = (FormData) rightControl.getLayoutData ();
FormAttachment rightAttachment = rightData.getRightAttachment (rightControl, spacing, flushCache);
switch (right.alignment) {
case SWT.RIGHT:
cacheRight = rightAttachment.plus (right.offset);
break;
case SWT.CENTER: {
FormAttachment leftAttachment = rightData.getLeftAttachment (rightControl, spacing, flushCache);
FormAttachment rightWidth = rightAttachment.minus (leftAttachment);
cacheRight = rightAttachment.minus (rightWidth.minus (getWidth (control, flushCache)).divide (2));
break;
}
default: {
FormAttachment leftAttachment = rightData.getLeftAttachment (rightControl, spacing, flushCache);
cacheRight = leftAttachment.plus (right.offset - spacing);
break;
}
}
isVisited = false;
return cacheRight;
}
FormAttachment getTopAttachment (Control control, int spacing, boolean flushCache) {
if (cacheTop != null) return cacheTop;
if (isVisited) return cacheTop = new FormAttachment (0, 0);
if (top == null) {
if (bottom == null) return cacheTop = new FormAttachment (0, 0);
return cacheTop = getBottomAttachment (control, spacing, flushCache).minus (getHeight (control, flushCache));
}
Control topControl = top.control;
if (topControl != null) {
if (topControl.isDisposed ()) {
top.control = topControl = null;
} else {
if (topControl.getParent () != control.getParent ()) {
topControl = null;
}
}
}
if (topControl == null) return cacheTop = top;
isVisited = true;
FormData topData = (FormData) topControl.getLayoutData ();
FormAttachment topAttachment = topData.getTopAttachment (topControl, spacing, flushCache);
switch (top.alignment) {
case SWT.TOP:
cacheTop = topAttachment.plus (top.offset);
break;
case SWT.CENTER: {
FormAttachment bottomAttachment = topData.getBottomAttachment (topControl, spacing, flushCache);
FormAttachment topHeight = bottomAttachment.minus (topAttachment);
cacheTop = topAttachment.plus (topHeight.minus (getHeight (control, flushCache)).divide (2));
break;
}
default: {
FormAttachment bottomAttachment = topData.getBottomAttachment (topControl, spacing, flushCache);
cacheTop = bottomAttachment.plus (top.offset + spacing);
break;
}
}
isVisited = false;
return cacheTop;
}
/**
* Returns a string containing a concise, human-readable
* description of the receiver.
*
* @return a string representation of the FormData object
*/
public String toString () {
String string = getName()+" {";
if (width != SWT.DEFAULT) string += "width="+width+" ";
if (height != SWT.DEFAULT) string += "height="+height+" ";
if (left != null) string += "left="+left+" ";
if (right != null) string += "right="+right+" ";
if (top != null) string += "top="+top+" ";
if (bottom != null) string += "bottom="+bottom+" ";
string = string.trim();
string += "}";
return string;
}
}