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.graphics; import org.eclipse.swt.*; import org.eclipse.swt.internal.wpf.*; /** * Instances of this class represent patterns to use while drawing. Patterns * can be specified either as bitmaps or gradients. * <p> * Application code must explicitly invoke the <code>Pattern.dispose()</code> * method to release the operating system resources managed by each instance * when those instances are no longer required. * </p> * <p> * This class requires the operating system's advanced graphics subsystem * which may not be available on some platforms. * </p> * * @see <a href="http://www.eclipse.org/swt/snippets/#path">Path, Pattern snippets</a> * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: GraphicsExample</a> * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a> * * @since 3.1 */ public class Pattern extends Resource { /** * the OS resource for the Pattern * (Warning: This field is platform dependent) * <p> * <b>IMPORTANT:</b> This field is <em>not</em> part of the SWT * public API. It is marked public only so that it can be shared * within the packages provided by SWT. It is not available on all * platforms and should never be accessed from application code. * </p> * * @noreference This field is not intended to be referenced by clients. */ public int handle; /** * Constructs a new Pattern given an image. Drawing with the resulting * pattern will cause the image to be tiled over the resulting area. * <p> * This operation requires the operating system's advanced * graphics subsystem which may not be available on some * platforms. * </p> * * @param device the device on which to allocate the pattern * @param image the image that the pattern will draw * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the device is null and there is no current device, or the image is null</li> * <li>ERROR_INVALID_ARGUMENT - if the image has been disposed</li> * </ul> * @exception SWTException <ul> * <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li> * </ul> * @exception SWTError <ul> * <li>ERROR_NO_HANDLES if a handle for the pattern could not be obtained</li> * </ul> * * @see #dispose() */ public Pattern(Device device, Image image) { super(device); if (image == null) SWT.error(SWT.ERROR_NULL_ARGUMENT); if (image.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT); handle = OS.gcnew_ImageBrush(image.handle); if (handle == 0) SWT.error(SWT.ERROR_NO_HANDLES); OS.TileBrush_TileMode(handle, OS.TileMode_Tile); OS.TileBrush_Stretch(handle, OS.Stretch_Fill); OS.TileBrush_ViewportUnits(handle, OS.BrushMappingMode_Absolute); int rect = OS.gcnew_Rect(0, 0, OS.BitmapSource_PixelWidth(image.handle), OS.BitmapSource_PixelHeight(image.handle)); OS.TileBrush_Viewport(handle, rect); OS.GCHandle_Free(rect); init(); } /** * Constructs a new Pattern that represents a linear, two color * gradient. Drawing with the pattern will cause the resulting area to be * tiled with the gradient specified by the arguments. * <p> * This operation requires the operating system's advanced * graphics subsystem which may not be available on some * platforms. * </p> * * @param device the device on which to allocate the pattern * @param x1 the x coordinate of the starting corner of the gradient * @param y1 the y coordinate of the starting corner of the gradient * @param x2 the x coordinate of the ending corner of the gradient * @param y2 the y coordinate of the ending corner of the gradient * @param color1 the starting color of the gradient * @param color2 the ending color of the gradient * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the device is null and there is no current device, * or if either color1 or color2 is null</li> * <li>ERROR_INVALID_ARGUMENT - if either color1 or color2 has been disposed</li> * </ul> * @exception SWTException <ul> * <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li> * </ul> * @exception SWTError <ul> * <li>ERROR_NO_HANDLES if a handle for the pattern could not be obtained</li> * </ul> * * @see #dispose() */ public Pattern(Device device, float x1, float y1, float x2, float y2, Color color1, Color color2) { this(device, x1, y1, x2, y2, color1, 0xFF, color2, 0xFF); } /** * Constructs a new Pattern that represents a linear, two color * gradient. Drawing with the pattern will cause the resulting area to be * tiled with the gradient specified by the arguments. * <p> * This operation requires the operating system's advanced * graphics subsystem which may not be available on some * platforms. * </p> * * @param device the device on which to allocate the pattern * @param x1 the x coordinate of the starting corner of the gradient * @param y1 the y coordinate of the starting corner of the gradient * @param x2 the x coordinate of the ending corner of the gradient * @param y2 the y coordinate of the ending corner of the gradient * @param color1 the starting color of the gradient * @param alpha1 the starting alpha value of the gradient * @param color2 the ending color of the gradient * @param alpha2 the ending alpha value of the gradient * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the device is null and there is no current device, * or if either color1 or color2 is null</li> * <li>ERROR_INVALID_ARGUMENT - if either color1 or color2 has been disposed</li> * </ul> * @exception SWTException <ul> * <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li> * </ul> * @exception SWTError <ul> * <li>ERROR_NO_HANDLES if a handle for the pattern could not be obtained</li> * </ul> * * @see #dispose() * * @since 3.2 */ public Pattern(Device device, float x1, float y1, float x2, float y2, Color color1, int alpha1, Color color2, int alpha2) { super(device); if (color1 == null) SWT.error(SWT.ERROR_NULL_ARGUMENT); if (color1.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT); if (color2 == null) SWT.error(SWT.ERROR_NULL_ARGUMENT); if (color2.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT); int startColor = OS.Color_FromArgb((byte) (alpha1 & 0xFF), OS.Color_R(color1.handle), OS.Color_G(color1.handle), OS.Color_B(color1.handle)); if (x1 == x2 && y1 == y2) { handle = OS.gcnew_SolidColorBrush(startColor); if (handle == 0) SWT.error(SWT.ERROR_NO_HANDLES); } else { int startPoint = OS.gcnew_Point(x1, y1); int endColor = OS.Color_FromArgb((byte) (alpha2 & 0xFF), OS.Color_R(color2.handle), OS.Color_G(color2.handle), OS.Color_B(color2.handle)); int endPoint = OS.gcnew_Point(x2, y2); handle = OS.gcnew_LinearGradientBrush(startColor, endColor, startPoint, endPoint); if (handle == 0) SWT.error(SWT.ERROR_NO_HANDLES); OS.GradientBrush_MappingMode(handle, OS.BrushMappingMode_Absolute); OS.GradientBrush_SpreadMethod(handle, OS.GradientSpreadMethod_Repeat); OS.GCHandle_Free(endColor); OS.GCHandle_Free(endPoint); OS.GCHandle_Free(startPoint); } OS.GCHandle_Free(startColor); init(); } void destroy() { OS.GCHandle_Free(handle); handle = 0; } /** * Returns <code>true</code> if the Pattern has been disposed, * and <code>false</code> otherwise. * <p> * This method gets the dispose state for the Pattern. * When a Pattern has been disposed, it is an error to * invoke any other method (except {@link #dispose()}) using the Pattern. * * @return <code>true</code> when the Pattern is disposed, and <code>false</code> otherwise */ public boolean isDisposed() { return handle == 0; } /** * Returns a string containing a concise, human-readable * description of the receiver. * * @return a string representation of the receiver */ public String toString() { if (isDisposed()) return "Pattern {*DISPOSED*}"; return "Pattern {" + handle + "}"; } }