Java tutorial
/******************************************************************************* * 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.SWT; import org.eclipse.swt.graphics.Point; import org.eclipse.swt.internal.SerializableCompatibility; import org.eclipse.swt.widgets.Control; /** * <code>GridData</code> is the layout data object associated with * <code>GridLayout</code>. To set a <code>GridData</code> object into a * control, you use the <code>Control.setLayoutData(Object)</code> method. * <p> * There are two ways to create a <code>GridData</code> object with certain * fields set. The first is to set the fields directly, like this: * <pre> * GridData gridData = new GridData(); * gridData.horizontalAlignment = GridData.FILL; * gridData.grabExcessHorizontalSpace = true; * button1.setLayoutData(gridData); * * gridData = new GridData(); * gridData.horizontalAlignment = GridData.FILL; * gridData.verticalAlignment = GridData.FILL; * gridData.grabExcessHorizontalSpace = true; * gridData.grabExcessVerticalSpace = true; * gridData.horizontalSpan = 2; * button2.setLayoutData(gridData); * </pre> * The second is to take advantage of <code>GridData</code> convenience constructors, for example: * <pre> * button1.setLayoutData(new GridData (SWT.FILL, SWT.CENTER, true, false)); * button2.setLayoutData(new GridData (SWT.FILL, SWT.FILL, true, true, 2, 1)); * </pre> * </p> * <p> * NOTE: Do not reuse <code>GridData</code> objects. Every control in a * <code>Composite</code> that is managed by a <code>GridLayout</code> * must have a unique <code>GridData</code> object. If the layout data * for a control in a <code>GridLayout</code> is null at layout time, * a unique <code>GridData</code> object is created for it. * </p> * * @see GridLayout * @see Control#setLayoutData * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a> * @since 1.0 */ public final class GridData implements SerializableCompatibility { /** * verticalAlignment specifies how controls will be positioned * vertically within a cell. * * The default value is CENTER. * * Possible values are: <ul> * <li>SWT.BEGINNING (or SWT.TOP): Position the control at the top of the cell</li> * <li>SWT.CENTER: Position the control in the vertical center of the cell</li> * <li>SWT.END (or SWT.BOTTOM): Position the control at the bottom of the cell</li> * <li>SWT.FILL: Resize the control to fill the cell vertically</li> * </ul> */ public int verticalAlignment = CENTER; /** * horizontalAlignment specifies how controls will be positioned * horizontally within a cell. * * The default value is BEGINNING. * * Possible values are: <ul> * <li>SWT.BEGINNING (or SWT.LEFT): Position the control at the left of the cell</li> * <li>SWT.CENTER: Position the control in the horizontal center of the cell</li> * <li>SWT.END (or SWT.RIGHT): Position the control at the right of the cell</li> * <li>SWT.FILL: Resize the control to fill the cell horizontally</li> * </ul> */ public int horizontalAlignment = BEGINNING; /** * widthHint 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 widthHint = SWT.DEFAULT; /** * heightHint 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 heightHint = SWT.DEFAULT; /** * horizontalIndent specifies the number of pixels of indentation * that will be placed along the left side of the cell. * * The default value is 0. */ public int horizontalIndent = 0; /** * verticalIndent specifies the number of pixels of indentation * that will be placed along the top side of the cell. * * The default value is 0. */ public int verticalIndent = 0; /** * horizontalSpan specifies the number of column cells that the control * will take up. * * The default value is 1. */ public int horizontalSpan = 1; /** * verticalSpan specifies the number of row cells that the control * will take up. * * The default value is 1. */ public int verticalSpan = 1; /** * <p>grabExcessHorizontalSpace specifies whether the width of the cell * changes depending on the size of the parent Composite. If * grabExcessHorizontalSpace is <code>true</code>, the following rules * apply to the width of the cell:</p> * <ul> * <li>If extra horizontal space is available in the parent, the cell will * grow to be wider than its preferred width. The new width * will be "preferred width + delta" where delta is the extra * horizontal space divided by the number of grabbing columns.</li> * <li>If there is not enough horizontal space available in the parent, the * cell will shrink until it reaches its minimum width as specified by * GridData.minimumWidth. The new width will be the maximum of * "minimumWidth" and "preferred width - delta", where delta is * the amount of space missing divided by the number of grabbing columns.</li> * <li>If the parent is packed, the cell will be its preferred width * as specified by GridData.widthHint.</li> * <li>If the control spans multiple columns and there are no other grabbing * controls in any of the spanned columns, the last column in the span will * grab the extra space. If there is at least one other grabbing control * in the span, the grabbing will be spread over the columns already * marked as grabExcessHorizontalSpace.</li> * </ul> * * <p>The default value is false.</p> * * @see GridData#minimumWidth * @see GridData#widthHint */ public boolean grabExcessHorizontalSpace = false; /** * <p>grabExcessVerticalSpace specifies whether the height of the cell * changes depending on the size of the parent Composite. If * grabExcessVerticalSpace is <code>true</code>, the following rules * apply to the height of the cell:</p> * <ul> * <li>If extra vertical space is available in the parent, the cell will * grow to be taller than its preferred height. The new height * will be "preferred height + delta" where delta is the extra * vertical space divided by the number of grabbing rows.</li> * <li>If there is not enough vertical space available in the parent, the * cell will shrink until it reaches its minimum height as specified by * GridData.minimumHeight. The new height will be the maximum of * "minimumHeight" and "preferred height - delta", where delta is * the amount of space missing divided by the number of grabbing rows.</li> * <li>If the parent is packed, the cell will be its preferred height * as specified by GridData.heightHint.</li> * <li>If the control spans multiple rows and there are no other grabbing * controls in any of the spanned rows, the last row in the span will * grab the extra space. If there is at least one other grabbing control * in the span, the grabbing will be spread over the rows already * marked as grabExcessVerticalSpace.</li> * </ul> * * <p>The default value is false.</p> * * @see GridData#minimumHeight * @see GridData#heightHint */ public boolean grabExcessVerticalSpace = false; /** * minimumWidth specifies the minimum width in pixels. This value * applies only if grabExcessHorizontalSpace is true. A value of * SWT.DEFAULT means that the minimum width will be the result * of Control.computeSize(int, int, boolean) where wHint is * determined by GridData.widthHint. * * The default value is 0. * * @see Control#computeSize(int, int, boolean) * @see GridData#widthHint */ public int minimumWidth = 0; /** * minimumHeight specifies the minimum height in pixels. This value * applies only if grabExcessVerticalSpace is true. A value of * SWT.DEFAULT means that the minimum height will be the result * of Control.computeSize(int, int, boolean) where hHint is * determined by GridData.heightHint. * * The default value is 0. * * @see Control#computeSize(int, int, boolean) * @see GridData#heightHint */ public int minimumHeight = 0; /** * exclude informs the layout to ignore this control when sizing * and positioning controls. If this value is <code>true</code>, * the size and position of the control will not be managed by the * layout. If this value is <code>false</code>, the size and * position of the control will be computed and assigned. * * The default value is <code>false</code>. */ public boolean exclude = false; /** * Value for horizontalAlignment or verticalAlignment. * Position the control at the top or left of the cell. * Not recommended. Use SWT.BEGINNING, SWT.TOP or SWT.LEFT instead. */ public static final int BEGINNING = SWT.BEGINNING; /** * Value for horizontalAlignment or verticalAlignment. * Position the control in the vertical or horizontal center of the cell * Not recommended. Use SWT.CENTER instead. */ public static final int CENTER = 2; /** * Value for horizontalAlignment or verticalAlignment. * Position the control at the bottom or right of the cell * Not recommended. Use SWT.END, SWT.BOTTOM or SWT.RIGHT instead. */ public static final int END = 3; /** * Value for horizontalAlignment or verticalAlignment. * Resize the control to fill the cell horizontally or vertically. * Not recommended. Use SWT.FILL instead. */ public static final int FILL = SWT.FILL; /** * Style bit for <code>new GridData(int)</code>. * Position the control at the top of the cell. * Not recommended. Use * <code>new GridData(int, SWT.BEGINNING, boolean, boolean)</code> * instead. */ public static final int VERTICAL_ALIGN_BEGINNING = 1 << 1; /** * Style bit for <code>new GridData(int)</code> to position the * control in the vertical center of the cell. * Not recommended. Use * <code>new GridData(int, SWT.CENTER, boolean, boolean)</code> * instead. */ public static final int VERTICAL_ALIGN_CENTER = 1 << 2; /** * Style bit for <code>new GridData(int)</code> to position the * control at the bottom of the cell. * Not recommended. Use * <code>new GridData(int, SWT.END, boolean, boolean)</code> * instead. */ public static final int VERTICAL_ALIGN_END = 1 << 3; /** * Style bit for <code>new GridData(int)</code> to resize the * control to fill the cell vertically. * Not recommended. Use * <code>new GridData(int, SWT.FILL, boolean, boolean)</code> * instead */ public static final int VERTICAL_ALIGN_FILL = 1 << 4; /** * Style bit for <code>new GridData(int)</code> to position the * control at the left of the cell. * Not recommended. Use * <code>new GridData(SWT.BEGINNING, int, boolean, boolean)</code> * instead. */ public static final int HORIZONTAL_ALIGN_BEGINNING = 1 << 5; /** * Style bit for <code>new GridData(int)</code> to position the * control in the horizontal center of the cell. * Not recommended. Use * <code>new GridData(SWT.CENTER, int, boolean, boolean)</code> * instead. */ public static final int HORIZONTAL_ALIGN_CENTER = 1 << 6; /** * Style bit for <code>new GridData(int)</code> to position the * control at the right of the cell. * Not recommended. Use * <code>new GridData(SWT.END, int, boolean, boolean)</code> * instead. */ public static final int HORIZONTAL_ALIGN_END = 1 << 7; /** * Style bit for <code>new GridData(int)</code> to resize the * control to fill the cell horizontally. * Not recommended. Use * <code>new GridData(SWT.FILL, int, boolean, boolean)</code> * instead. */ public static final int HORIZONTAL_ALIGN_FILL = 1 << 8; /** * Style bit for <code>new GridData(int)</code> to resize the * control to fit the remaining horizontal space. * Not recommended. Use * <code>new GridData(int, int, true, boolean)</code> * instead. */ public static final int GRAB_HORIZONTAL = 1 << 9; /** * Style bit for <code>new GridData(int)</code> to resize the * control to fit the remaining vertical space. * Not recommended. Use * <code>new GridData(int, int, boolean, true)</code> * instead. */ public static final int GRAB_VERTICAL = 1 << 10; /** * Style bit for <code>new GridData(int)</code> to resize the * control to fill the cell vertically and to fit the remaining * vertical space. * FILL_VERTICAL = VERTICAL_ALIGN_FILL | GRAB_VERTICAL * Not recommended. Use * <code>new GridData(int, SWT.FILL, boolean, true)</code> * instead. */ public static final int FILL_VERTICAL = VERTICAL_ALIGN_FILL | GRAB_VERTICAL; /** * Style bit for <code>new GridData(int)</code> to resize the * control to fill the cell horizontally and to fit the remaining * horizontal space. * FILL_HORIZONTAL = HORIZONTAL_ALIGN_FILL | GRAB_HORIZONTAL * Not recommended. Use * <code>new GridData(SWT.FILL, int, true, boolean)</code> * instead. */ public static final int FILL_HORIZONTAL = HORIZONTAL_ALIGN_FILL | GRAB_HORIZONTAL; /** * Style bit for <code>new GridData(int)</code> to resize the * control to fill the cell horizontally and vertically and * to fit the remaining horizontal and vertical space. * FILL_BOTH = FILL_VERTICAL | FILL_HORIZONTAL * Not recommended. Use * <code>new GridData(SWT.FILL, SWT.FILL, true, true)</code> * instead. */ public static final int FILL_BOTH = FILL_VERTICAL | FILL_HORIZONTAL; int cacheWidth = -1, cacheHeight = -1; int defaultWhint, defaultHhint, defaultWidth = -1, defaultHeight = -1; int currentWhint, currentHhint, currentWidth = -1, currentHeight = -1; /** * Constructs a new instance of GridData using * default values. */ public GridData() { super(); } /** * Constructs a new instance based on the GridData style. * This constructor is not recommended. * * @param style the GridData style */ public GridData(int style) { super(); if ((style & VERTICAL_ALIGN_BEGINNING) != 0) verticalAlignment = BEGINNING; if ((style & VERTICAL_ALIGN_CENTER) != 0) verticalAlignment = CENTER; if ((style & VERTICAL_ALIGN_FILL) != 0) verticalAlignment = FILL; if ((style & VERTICAL_ALIGN_END) != 0) verticalAlignment = END; if ((style & HORIZONTAL_ALIGN_BEGINNING) != 0) horizontalAlignment = BEGINNING; if ((style & HORIZONTAL_ALIGN_CENTER) != 0) horizontalAlignment = CENTER; if ((style & HORIZONTAL_ALIGN_FILL) != 0) horizontalAlignment = FILL; if ((style & HORIZONTAL_ALIGN_END) != 0) horizontalAlignment = END; grabExcessHorizontalSpace = (style & GRAB_HORIZONTAL) != 0; grabExcessVerticalSpace = (style & GRAB_VERTICAL) != 0; } /** * Constructs a new instance of GridData according to the parameters. * * @param horizontalAlignment how control will be positioned horizontally within a cell, * one of: SWT.BEGINNING (or SWT.LEFT), SWT.CENTER, SWT.END (or SWT.RIGHT), or SWT.FILL * @param verticalAlignment how control will be positioned vertically within a cell, * one of: SWT.BEGINNING (or SWT.TOP), SWT.CENTER, SWT.END (or SWT.BOTTOM), or SWT.FILL * @param grabExcessHorizontalSpace whether cell will be made wide enough to fit the remaining horizontal space * @param grabExcessVerticalSpace whether cell will be made high enough to fit the remaining vertical space */ public GridData(int horizontalAlignment, int verticalAlignment, boolean grabExcessHorizontalSpace, boolean grabExcessVerticalSpace) { this(horizontalAlignment, verticalAlignment, grabExcessHorizontalSpace, grabExcessVerticalSpace, 1, 1); } /** * Constructs a new instance of GridData according to the parameters. * * @param horizontalAlignment how control will be positioned horizontally within a cell, * one of: SWT.BEGINNING (or SWT.LEFT), SWT.CENTER, SWT.END (or SWT.RIGHT), or SWT.FILL * @param verticalAlignment how control will be positioned vertically within a cell, * one of: SWT.BEGINNING (or SWT.TOP), SWT.CENTER, SWT.END (or SWT.BOTTOM), or SWT.FILL * @param grabExcessHorizontalSpace whether cell will be made wide enough to fit the remaining horizontal space * @param grabExcessVerticalSpace whether cell will be made high enough to fit the remaining vertical space * @param horizontalSpan the number of column cells that the control will take up * @param verticalSpan the number of row cells that the control will take up */ public GridData(int horizontalAlignment, int verticalAlignment, boolean grabExcessHorizontalSpace, boolean grabExcessVerticalSpace, int horizontalSpan, int verticalSpan) { super(); this.horizontalAlignment = horizontalAlignment; this.verticalAlignment = verticalAlignment; this.grabExcessHorizontalSpace = grabExcessHorizontalSpace; this.grabExcessVerticalSpace = grabExcessVerticalSpace; this.horizontalSpan = horizontalSpan; this.verticalSpan = verticalSpan; } /** * Constructs a new instance of GridData 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 column * @param height a minimum height for the row */ public GridData(int width, int height) { super(); this.widthHint = width; this.heightHint = height; } void computeSize(Control control, int wHint, int hHint, boolean flushCache) { if (cacheWidth != -1 && cacheHeight != -1) return; if (wHint == this.widthHint && hHint == this.heightHint) { 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; defaultWidth = defaultHeight = -1; currentWidth = currentHeight = -1; } String getName() { String string = getClass().getName(); int index = string.lastIndexOf('.'); if (index == -1) return string; return string.substring(index + 1, string.length()); } /** * Returns a string containing a concise, human-readable * description of the receiver. * * @return a string representation of the GridData object */ public String toString() { String hAlign = ""; switch (horizontalAlignment) { case SWT.FILL: hAlign = "SWT.FILL"; break; case SWT.BEGINNING: hAlign = "SWT.BEGINNING"; break; case SWT.LEFT: hAlign = "SWT.LEFT"; break; case SWT.END: hAlign = "SWT.END"; break; case END: hAlign = "GridData.END"; break; case SWT.RIGHT: hAlign = "SWT.RIGHT"; break; case SWT.CENTER: hAlign = "SWT.CENTER"; break; case CENTER: hAlign = "GridData.CENTER"; break; default: hAlign = "Undefined " + horizontalAlignment; break; } String vAlign = ""; switch (verticalAlignment) { case SWT.FILL: vAlign = "SWT.FILL"; break; case SWT.BEGINNING: vAlign = "SWT.BEGINNING"; break; case SWT.TOP: vAlign = "SWT.TOP"; break; case SWT.END: vAlign = "SWT.END"; break; case END: vAlign = "GridData.END"; break; case SWT.BOTTOM: vAlign = "SWT.BOTTOM"; break; case SWT.CENTER: vAlign = "SWT.CENTER"; break; case CENTER: vAlign = "GridData.CENTER"; break; default: vAlign = "Undefined " + verticalAlignment; break; } String string = getName() + " {"; string += "horizontalAlignment=" + hAlign + " "; if (horizontalIndent != 0) string += "horizontalIndent=" + horizontalIndent + " "; if (horizontalSpan != 1) string += "horizontalSpan=" + horizontalSpan + " "; if (grabExcessHorizontalSpace) string += "grabExcessHorizontalSpace=" + grabExcessHorizontalSpace + " "; if (widthHint != SWT.DEFAULT) string += "widthHint=" + widthHint + " "; if (minimumWidth != 0) string += "minimumWidth=" + minimumWidth + " "; string += "verticalAlignment=" + vAlign + " "; if (verticalIndent != 0) string += "verticalIndent=" + verticalIndent + " "; if (verticalSpan != 1) string += "verticalSpan=" + verticalSpan + " "; if (grabExcessVerticalSpace) string += "grabExcessVerticalSpace=" + grabExcessVerticalSpace + " "; if (heightHint != SWT.DEFAULT) string += "heightHint=" + heightHint + " "; if (minimumHeight != 0) string += "minimumHeight=" + minimumHeight + " "; if (exclude) string += "exclude=" + exclude + " "; string = string.trim(); string += "}"; return string; } }