Java example source code file (XCanvasPeer.java)

This example Java source code file (XCanvasPeer.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

awt, graphicsconfiguration, graphicsenvironment, x11graphicsconfig, x11graphicsdevice, xcanvaspeer, xcomponentpeer

The XCanvasPeer.java Java example source code

/*
 * Copyright (c) 2002, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package sun.awt.X11;

import java.awt.*;
import java.awt.peer.*;

import sun.awt.SunToolkit;

import sun.awt.X11GraphicsConfig;
import sun.awt.X11GraphicsDevice;

class XCanvasPeer extends XComponentPeer implements CanvasPeer {

    private boolean eraseBackgroundDisabled;

    XCanvasPeer() {}

    XCanvasPeer(XCreateWindowParams params) {
        super(params);
    }

    XCanvasPeer(Component target) {
        super(target);
    }

    void preInit(XCreateWindowParams params) {
        super.preInit(params);
        if (SunToolkit.getSunAwtNoerasebackground()) {
            disableBackgroundErase();
        }
    }

    /* Get a GraphicsConfig with the same visual on the new
     * screen, which should be easy in Xinerama mode.
     */
    public GraphicsConfiguration getAppropriateGraphicsConfiguration(
                                    GraphicsConfiguration gc)
    {
        if (graphicsConfig == null || gc == null) {
            return gc;
        }
        // Opt: Only need to do if we're not using the default GC

        int screenNum = ((X11GraphicsDevice)gc.getDevice()).getScreen();

        X11GraphicsConfig parentgc;
        // save vis id of current gc
        int visual = graphicsConfig.getVisual();

        X11GraphicsDevice newDev = (X11GraphicsDevice) GraphicsEnvironment.
            getLocalGraphicsEnvironment().
            getScreenDevices()[screenNum];

        for (int i = 0; i < newDev.getNumConfigs(screenNum); i++) {
            if (visual == newDev.getConfigVisualId(i, screenNum)) {
                // use that
                graphicsConfig = (X11GraphicsConfig)newDev.getConfigurations()[i];
                break;
            }
        }
        // just in case...
        if (graphicsConfig == null) {
            graphicsConfig = (X11GraphicsConfig) GraphicsEnvironment.
                getLocalGraphicsEnvironment().
                getScreenDevices()[screenNum].
                getDefaultConfiguration();
        }

        return graphicsConfig;
    }

    protected boolean shouldFocusOnClick() {
        // Canvas should always be able to be focused by mouse clicks.
        return true;
    }

    public void disableBackgroundErase() {
        eraseBackgroundDisabled = true;
    }
    protected boolean doEraseBackground() {
        return !eraseBackgroundDisabled;
    }
}