Mercurial > projects > dwt-addons
view dwtx/jface/resource/ImageDescriptor.d @ 4:c87617952847
some JFace modules
author | Frank Benoit <benoit@tionex.de> |
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date | Fri, 28 Mar 2008 17:08:33 +0100 |
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children | c884a1ab6db3 |
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/******************************************************************************* * Copyright (c) 2000, 2006 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 * Port to the D programming language: * Frank Benoit <benoit@tionex.de> *******************************************************************************/ module dwtx.jface.resource.ImageDescriptor; import dwtx.jface.resource.DeviceResourceDescriptor; import dwtx.jface.resource.FileImageDescriptor; import dwtx.jface.resource.URLImageDescriptor; import dwtx.jface.resource.ImageDataImageDescriptor; import dwtx.jface.resource.DerivedImageDescriptor; import dwtx.jface.resource.DeviceResourceException; import dwtx.jface.resource.MissingImageDescriptor; import tango.net.Uri; import dwt.DWTException; import dwt.graphics.Device; import dwt.graphics.Image; import dwt.graphics.ImageData; import dwt.graphics.PaletteData; import dwt.graphics.RGB; import dwt.widgets.Display; import dwt.dwthelper.utils; /** * An image descriptor is an object that knows how to create * an DWT image. It does not hold onto images or cache them, * but rather just creates them on demand. An image descriptor * is intended to be a lightweight representation of an image * that can be manipulated even when no DWT display exists. * <p> * This package defines a concrete image descriptor implementation * which reads an image from a file (<code>FileImageDescriptor</code>). * It also provides abstract framework classes (this one and * <code>CompositeImageDescriptor</code>) which may be subclassed to define * news kinds of image descriptors. * </p> * <p> * Using this abstract class involves defining a concrete subclass * and providing an implementation for the <code>getImageData</code> * method. * </p> * <p> * There are two ways to get an Image from an ImageDescriptor. The method * createImage will always return a new Image which must be disposed by * the caller. Alternatively, createResource() returns a shared * Image. When the caller is done with an image obtained from createResource, * they must call destroyResource() rather than disposing the Image directly. * The result of createResource() can be safely cast to an Image. * </p> * * @see dwt.graphics.Image */ public abstract class ImageDescriptor : DeviceResourceDescriptor { /** * A small red square used to warn that an image cannot be created. * <p> */ protected static const ImageData DEFAULT_IMAGE_DATA; static this(){ DEFAULT_IMAGE_DATA = new ImageData(6, 6, 1, new PaletteData( [ new RGB(255, 0, 0) ] )); } /** * Constructs an image descriptor. */ protected this() { // do nothing } /** * Creates and returns a new image descriptor from a file. * Convenience method for * <code>new FileImageDescriptor(location,filename)</code>. * * @param location the class whose resource directory contain the file * @param filename the file name * @return a new image descriptor */ public static ImageDescriptor createFromFile(ClassInfo location, String filename) { return new FileImageDescriptor(location, filename); } /** * Creates and returns a new image descriptor given ImageData * describing the image. * * @since 3.1 * * @param data contents of the image * @return newly created image descriptor */ public static ImageDescriptor createFromImageData(ImageData data) { return new ImageDataImageDescriptor(data); } /** * Creates and returns a new image descriptor for the given image. Note * that disposing the original Image will cause the descriptor to become invalid. * * @since 3.1 * * @param img image to create * @return a newly created image descriptor */ public static ImageDescriptor createFromImage(Image img) { return new ImageDataImageDescriptor(img); } /** * Creates an ImageDescriptor based on the given original descriptor, but with additional * DWT flags. * * <p> * Note that this sort of ImageDescriptor is slower and consumes more resources than * a regular image descriptor. It will also never generate results that look as nice as * a hand-drawn image. Clients are encouraged to supply their own disabled/grayed/etc. images * rather than using a default image and transforming it. * </p> * * @param originalImage image to transform * @param swtFlags any flag that can be passed to the flags argument of Image#Image(Device, Image, int) * @return an ImageDescriptor that creates new images by transforming the given image descriptor * * @see Image#Image(Device, Image, int) * @since 3.1 * */ public static ImageDescriptor createWithFlags(ImageDescriptor originalImage, int swtFlags) { return new DerivedImageDescriptor(originalImage, swtFlags); } /** * Creates and returns a new image descriptor for the given image. This * method takes the Device that created the Image as an argument, allowing * the original Image to be reused if the descriptor is asked for another * Image on the same device. Note that disposing the original Image will * cause the descriptor to become invalid. * * @deprecated use {@link ImageDescriptor#createFromImage(Image)} * @since 3.1 * * @param img image to create * @param theDevice the device that was used to create the Image * @return a newly created image descriptor */ public static ImageDescriptor createFromImage(Image img, Device theDevice) { return new ImageDataImageDescriptor(img); } /** * Creates and returns a new image descriptor from a URL. * * @param url The URL of the image file. * @return a new image descriptor */ public static ImageDescriptor createFromURL(Uri url) { if (url is null) { return getMissingImageDescriptor(); } return new URLImageDescriptor(url); } /* (non-Javadoc) * @see dwtx.jface.resource.DeviceResourceDescriptor#createResource(dwt.graphics.Device) */ public Object createResource(Device device) { Image result = createImage(false, device); if (result is null) { throw new DeviceResourceException(this); } return result; } /* (non-Javadoc) * @see dwtx.jface.resource.DeviceResourceDescriptor#destroyResource(Object) */ public void destroyResource(Object previouslyCreatedObject) { (cast(Image)previouslyCreatedObject).dispose(); } /** * Creates and returns a new DWT image for this image descriptor. Note that * each call returns a new DWT image object. The returned image must be * explicitly disposed using the image's dispose call. The image will not be * automatically garbage collected. A default image is returned in the event * of an error. * * <p> * Note: this method differs from createResource(Device) in that the returned image * must be disposed directly, whereas an image obtained from createResource(...) * must be disposed by calling destroyResource(...). It is not possible to * mix-and-match. If you obtained the Image from this method, you must not dispose * it by calling destroyResource. Clients are encouraged to use * create/destroyResource and downcast the result to Image rather than using * createImage. * </p> * * <p> * Note: it is still possible for this method to return <code>null</code> * in extreme cases, for example if DWT runs out of image handles. * </p> * * @return a new image or <code>null</code> if the image could not be * created */ public Image createImage() { return createImage(true); } /** * Creates and returns a new DWT image for this image descriptor. The * returned image must be explicitly disposed using the image's dispose * call. The image will not be automatically garbage collected. In the event * of an error, a default image is returned if * <code>returnMissingImageOnError</code> is true, otherwise * <code>null</code> is returned. * <p> * Note: Even if <code>returnMissingImageOnError</code> is true, it is * still possible for this method to return <code>null</code> in extreme * cases, for example if DWT runs out of image handles. * </p> * * @param returnMissingImageOnError * flag that determines if a default image is returned on error * @return a new image or <code>null</code> if the image could not be * created */ public Image createImage(bool returnMissingImageOnError) { return createImage(returnMissingImageOnError, Display.getCurrent()); } /** * Creates and returns a new DWT image for this image descriptor. The * returned image must be explicitly disposed using the image's dispose * call. The image will not be automatically garbage collected. A default * image is returned in the event of an error. * <p> * Note: it is still possible for this method to return <code>null</code> * in extreme cases, for example if DWT runs out of image handles. * </p> * * @param device * the device on which to create the image * @return a new image or <code>null</code> if the image could not be * created * @since 2.0 */ public Image createImage(Device device) { return createImage(true, device); } /** * Creates and returns a new DWT image for this image descriptor. The * returned image must be explicitly disposed using the image's dispose * call. The image will not be automatically garbage collected. In the even * of an error, a default image is returned if * <code>returnMissingImageOnError</code> is true, otherwise * <code>null</code> is returned. * <p> * Note: Even if <code>returnMissingImageOnError</code> is true, it is * still possible for this method to return <code>null</code> in extreme * cases, for example if DWT runs out of image handles. * </p> * * @param returnMissingImageOnError * flag that determines if a default image is returned on error * @param device * the device on which to create the image * @return a new image or <code>null</code> if the image could not be * created * @since 2.0 */ public Image createImage(bool returnMissingImageOnError, Device device) { ImageData data = getImageData(); if (data is null) { if (!returnMissingImageOnError) { return null; } data = DEFAULT_IMAGE_DATA; } /* * Try to create the supplied image. If there is an DWT Exception try and create * the default image if that was requested. Return null if this fails. */ try { if (data.transparentPixel >= 0) { ImageData maskData = data.getTransparencyMask(); return new Image(device, data, maskData); } return new Image(device, data); } catch (DWTException exception) { if (returnMissingImageOnError) { try { return new Image(device, DEFAULT_IMAGE_DATA); } catch (DWTException nextException) { return null; } } return null; } } /** * Creates and returns a new DWT <code>ImageData</code> object * for this image descriptor. * Note that each call returns a new DWT image data object. * <p> * This framework method is declared public so that it is * possible to request an image descriptor's image data without * creating an DWT image object. * </p> * <p> * Returns <code>null</code> if the image data could not be created. * </p> * * @return a new image data or <code>null</code> */ public abstract ImageData getImageData(); /** * Returns the shared image descriptor for a missing image. * * @return the missing image descriptor */ public static ImageDescriptor getMissingImageDescriptor() { return MissingImageDescriptor.getInstance(); } }