org.eclipse.swt.graphics.Pattern.java Source code

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/*******************************************************************************
 * Copyright (c) 2000, 2016 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.graphics;

import org.eclipse.swt.*;
import org.eclipse.swt.internal.*;
import org.eclipse.swt.internal.gdip.*;
import org.eclipse.swt.internal.win32.*;

/**
 * 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 long 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>
     * <p>
     * You must dispose the pattern when it is no longer required.
     * </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);
        this.device.checkGDIP();
        long[] gdipImage = image.createGdipImage();
        long img = gdipImage[0];
        int width = Gdip.Image_GetWidth(img);
        int height = Gdip.Image_GetHeight(img);
        handle = Gdip.TextureBrush_new(img, Gdip.WrapModeTile, 0, 0, width, height);
        Gdip.Bitmap_delete(img);
        if (gdipImage[1] != 0) {
            long hHeap = OS.GetProcessHeap();
            OS.HeapFree(hHeap, 0, gdipImage[1]);
        }
        if (handle == 0)
            SWT.error(SWT.ERROR_NO_HANDLES);
        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>
     * <p>
     * You must dispose the pattern when it is no longer required.
     * </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>
     * <p>
     * You must dispose the pattern when it is no longer required.
     * </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);
        x1 = DPIUtil.autoScaleUp(x1);
        y1 = DPIUtil.autoScaleUp(y1);
        x2 = DPIUtil.autoScaleUp(x2);
        y2 = DPIUtil.autoScaleUp(y2);
        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);
        this.device.checkGDIP();
        int colorRef1 = color1.handle;
        int foreColor = ((alpha1 & 0xFF) << 24) | ((colorRef1 >> 16) & 0xFF) | (colorRef1 & 0xFF00)
                | ((colorRef1 & 0xFF) << 16);
        if (x1 == x2 && y1 == y2) {
            handle = Gdip.SolidBrush_new(foreColor);
            if (handle == 0)
                SWT.error(SWT.ERROR_NO_HANDLES);
        } else {
            int colorRef2 = color2.handle;
            int backColor = ((alpha2 & 0xFF) << 24) | ((colorRef2 >> 16) & 0xFF) | (colorRef2 & 0xFF00)
                    | ((colorRef2 & 0xFF) << 16);
            PointF p1 = new PointF();
            p1.X = x1;
            p1.Y = y1;
            PointF p2 = new PointF();
            p2.X = x2;
            p2.Y = y2;
            handle = Gdip.LinearGradientBrush_new(p1, p2, foreColor, backColor);
            if (handle == 0)
                SWT.error(SWT.ERROR_NO_HANDLES);
            if (alpha1 != 0xFF || alpha2 != 0xFF) {
                int a = (int) ((alpha1 & 0xFF) * 0.5f + (alpha2 & 0xFF) * 0.5f);
                int r = (int) (((colorRef1 & 0xFF) >> 0) * 0.5f + ((colorRef2 & 0xFF) >> 0) * 0.5f);
                int g = (int) (((colorRef1 & 0xFF00) >> 8) * 0.5f + ((colorRef2 & 0xFF00) >> 8) * 0.5f);
                int b = (int) (((colorRef1 & 0xFF0000) >> 16) * 0.5f + ((colorRef2 & 0xFF0000) >> 16) * 0.5f);
                int midColor = a << 24 | r << 16 | g << 8 | b;
                Gdip.LinearGradientBrush_SetInterpolationColors(handle,
                        new int[] { foreColor, midColor, backColor }, new float[] { 0, 0.5f, 1 }, 3);
            }
        }
        init();
    }

    @Override
    void destroy() {
        int type = Gdip.Brush_GetType(handle);
        switch (type) {
        case Gdip.BrushTypeSolidColor:
            Gdip.SolidBrush_delete(handle);
            break;
        case Gdip.BrushTypeHatchFill:
            Gdip.HatchBrush_delete(handle);
            break;
        case Gdip.BrushTypeLinearGradient:
            Gdip.LinearGradientBrush_delete(handle);
            break;
        case Gdip.BrushTypeTextureFill:
            Gdip.TextureBrush_delete(handle);
            break;
        }
        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
     */
    @Override
    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
     */
    @Override
    public String toString() {
        if (isDisposed())
            return "Pattern {*DISPOSED*}";
        return "Pattern {" + handle + "}";
    }

}