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 * Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package sun.java2d.opengl;

import java.awt.Graphics;
import java.awt.GraphicsConfiguration;
import java.awt.Rectangle;
import sun.java2d.SunGraphics2D;
import sun.java2d.SurfaceData;
import sun.java2d.pipe.Region;

/**
 * This class contains a number of static utility methods that may be
 * called (via reflection) by a third-party library, such as JOGL, in order
 * to interoperate with the OGL-based Java 2D pipeline.
 *
 * WARNING: These methods are being made available as a temporary measure
 * until we offer a more complete, public solution.  Like any sun.* class,
 * this class is not an officially supported public API; it may be modified
 * at will or removed completely in a future release.
 */
class OGLUtilities {

    /**
     * These OGL-specific surface type constants are the same as those
     * defined in the OGLSurfaceData class and are duplicated here so that
     * clients of this API can access them more easily via reflection.
     */
    public static final int UNDEFINED       = OGLSurfaceData.UNDEFINED;
    public static final int WINDOW          = OGLSurfaceData.WINDOW;
    public static final int TEXTURE         = OGLSurfaceData.TEXTURE;
    public static final int FLIP_BACKBUFFER = OGLSurfaceData.FLIP_BACKBUFFER;
    public static final int FBOBJECT        = OGLSurfaceData.FBOBJECT;

    private OGLUtilities() {
    }

    /**
     * Returns true if the current thread is the OGL QueueFlusher thread.
     */
    public static boolean isQueueFlusherThread() {
        return OGLRenderQueue.isQueueFlusherThread();
    }

    /**
     * Invokes the given Runnable on the OGL QueueFlusher thread with the
     * OpenGL context corresponding to the given Graphics object made
     * current.  It is legal for OpenGL code executed in the given
     * Runnable to change the current OpenGL context; it will be reset
     * once the Runnable completes.  No guarantees are made as to the
     * state of the OpenGL context of the Graphics object; for
     * example, calling code must set the scissor box using the return
     * value from {@link #getOGLScissorBox} to avoid drawing
     * over other Swing components, and must typically set the OpenGL
     * viewport using the return value from {@link #getOGLViewport} to
     * make the client's OpenGL rendering appear in the correct place
     * relative to the scissor region.
     *
     * In order to avoid deadlock, it is important that the given Runnable
     * does not attempt to acquire the AWT lock, as that will be handled
     * automatically as part of the {@code rq.flushAndInvokeNow()} step.
     *
     * @param g the Graphics object for the corresponding destination surface;
     * if null, the step making a context current to the destination surface
     * will be skipped
     * @param r the action to be performed on the QFT; cannot be null
     * @return true if the operation completed successfully, or false if
     * there was any problem making a context current to the surface
     * associated with the given Graphics object
     */
    public static boolean invokeWithOGLContextCurrent(Graphics g, Runnable r) {
        OGLRenderQueue rq = OGLRenderQueue.getInstance();
        rq.lock();
        try {
            if (g != null) {
                if (!(g instanceof SunGraphics2D)) {
                    return false;
                }
                SurfaceData sData = ((SunGraphics2D)g).surfaceData;
                if (!(sData instanceof OGLSurfaceData)) {
                    return false;
                }

                // make a context current to the destination surface
                OGLContext.validateContext((OGLSurfaceData)sData);
            }

            // invoke the given runnable on the QFT
            rq.flushAndInvokeNow(r);

            // invalidate the current context so that the next time we render
            // with Java 2D, the context state will be completely revalidated
            OGLContext.invalidateCurrentContext();
        } finally {
            rq.unlock();
        }

        return true;
    }

    /**
     * Invokes the given Runnable on the OGL QueueFlusher thread with the
     * "shared" OpenGL context (corresponding to the given
     * GraphicsConfiguration object) made current.  This method is typically
     * used when the Runnable needs a current context to complete its
     * operation, but does not require that the context be made current to
     * a particular surface.  For example, an application may call this
     * method so that the given Runnable can query the OpenGL capabilities
     * of the given GraphicsConfiguration, without making a context current
     * to a dummy surface (or similar hacky techniques).
     *
     * In order to avoid deadlock, it is important that the given Runnable
     * does not attempt to acquire the AWT lock, as that will be handled
     * automatically as part of the {@code rq.flushAndInvokeNow()} step.
     *
     * @param config the GraphicsConfiguration object whose "shared"
     * context will be made current during this operation; if this value is
     * null or if OpenGL is not enabled for the GraphicsConfiguration, this
     * method will return false
     * @param r the action to be performed on the QFT; cannot be null
     * @return true if the operation completed successfully, or false if
     * there was any problem making the shared context current
     */
    public static boolean
        invokeWithOGLSharedContextCurrent(GraphicsConfiguration config,
                                          Runnable r)
    {
        if (!(config instanceof OGLGraphicsConfig)) {
            return false;
        }

        OGLRenderQueue rq = OGLRenderQueue.getInstance();
        rq.lock();
        try {
            // make the "shared" context current for the given GraphicsConfig
            OGLContext.setScratchSurface((OGLGraphicsConfig)config);

            // invoke the given runnable on the QFT
            rq.flushAndInvokeNow(r);

            // invalidate the current context so that the next time we render
            // with Java 2D, the context state will be completely revalidated
            OGLContext.invalidateCurrentContext();
        } finally {
            rq.unlock();
        }

        return true;
    }

    /**
     * Returns the Rectangle describing the OpenGL viewport on the
     * Java 2D surface associated with the given Graphics object and
     * component width and height. When a third-party library is
     * performing OpenGL rendering directly into the visible region of
     * the associated surface, this viewport helps the application
     * position the OpenGL output correctly on that surface.
     *
     * Note that the x/y values in the returned Rectangle object represent
     * the lower-left corner of the viewport region, relative to the
     * lower-left corner of the given surface.
     *
     * @param g the Graphics object for the corresponding destination surface;
     * cannot be null
     * @param componentWidth width of the component to be painted
     * @param componentHeight height of the component to be painted
     * @return a Rectangle describing the OpenGL viewport for the given
     * destination surface and component dimensions, or null if the given
     * Graphics object is invalid
     */
    public static Rectangle getOGLViewport(Graphics g,
                                           int componentWidth,
                                           int componentHeight)
    {
        if (!(g instanceof SunGraphics2D)) {
            return null;
        }

        SunGraphics2D sg2d = (SunGraphics2D)g;
        SurfaceData sData = sg2d.surfaceData;

        // this is the upper-left origin of the region to be painted,
        // relative to the upper-left origin of the surface
        // (in Java2D coordinates)
        int x0 = sg2d.transX;
        int y0 = sg2d.transY;

        // this is the lower-left origin of the region to be painted,
        // relative to the lower-left origin of the surface
        // (in OpenGL coordinates)
        Rectangle surfaceBounds = sData.getBounds();
        int x1 = x0;
        int y1 = surfaceBounds.height - (y0 + componentHeight);

        return new Rectangle(x1, y1, componentWidth, componentHeight);
    }

    /**
     * Returns the Rectangle describing the OpenGL scissor box on the
     * Java 2D surface associated with the given Graphics object.  When a
     * third-party library is performing OpenGL rendering directly
     * into the visible region of the associated surface, this scissor box
     * must be set to avoid drawing over existing rendering results.
     *
     * Note that the x/y values in the returned Rectangle object represent
     * the lower-left corner of the scissor region, relative to the
     * lower-left corner of the given surface.
     *
     * @param g the Graphics object for the corresponding destination surface;
     * cannot be null
     * @return a Rectangle describing the OpenGL scissor box for the given
     * Graphics object and corresponding destination surface, or null if the
     * given Graphics object is invalid or the clip region is non-rectangular
     */
    public static Rectangle getOGLScissorBox(Graphics g) {
        if (!(g instanceof SunGraphics2D)) {
            return null;
        }

        SunGraphics2D sg2d = (SunGraphics2D)g;
        SurfaceData sData = sg2d.surfaceData;
        Region r = sg2d.getCompClip();
        if (!r.isRectangular()) {
            // caller probably doesn't know how to handle shape clip
            // appropriately, so just return null (Swing currently never
            // sets a shape clip, but that could change in the future)
            return null;
        }

        // this is the upper-left origin of the scissor box relative to the
        // upper-left origin of the surface (in Java 2D coordinates)
        int x0 = r.getLoX();
        int y0 = r.getLoY();

        // this is the width and height of the scissor region
        int w = r.getWidth();
        int h = r.getHeight();

        // this is the lower-left origin of the scissor box relative to the
        // lower-left origin of the surface (in OpenGL coordinates)
        Rectangle surfaceBounds = sData.getBounds();
        int x1 = x0;
        int y1 = surfaceBounds.height - (y0 + h);

        return new Rectangle(x1, y1, w, h);
    }

    /**
     * Returns an Object identifier for the Java 2D surface associated with
     * the given Graphics object.  This identifier may be used to determine
     * whether the surface has changed since the last invocation of this
     * operation, and thereby whether the OpenGL state corresponding to the
     * old surface must be destroyed and recreated.
     *
     * @param g the Graphics object for the corresponding destination surface;
     * cannot be null
     * @return an identifier for the surface associated with the given
     * Graphics object, or null if the given Graphics object is invalid
     */
    public static Object getOGLSurfaceIdentifier(Graphics g) {
        if (!(g instanceof SunGraphics2D)) {
            return null;
        }
        return ((SunGraphics2D)g).surfaceData;
    }

    /**
     * Returns one of the OGL-specific surface type constants (defined in
     * this class), which describes the surface associated with the given
     * Graphics object.
     *
     * @param g the Graphics object for the corresponding destination surface;
     * cannot be null
     * @return a constant that describes the surface associated with the
     * given Graphics object; if the given Graphics object is invalid (i.e.
     * is not associated with an OpenGL surface) this method will return
     * {@code OGLUtilities.UNDEFINED}
     */
    public static int getOGLSurfaceType(Graphics g) {
        if (!(g instanceof SunGraphics2D)) {
            return UNDEFINED;
        }
        SurfaceData sData = ((SunGraphics2D)g).surfaceData;
        if (!(sData instanceof OGLSurfaceData)) {
            return UNDEFINED;
        }
        return ((OGLSurfaceData)sData).getType();
    }

    /**
     * Returns the OpenGL texture target constant (either GL_TEXTURE_2D
     * or GL_TEXTURE_RECTANGLE_ARB) for the surface associated with the
     * given Graphics object.  This method is only useful for those surface
     * types that are backed by an OpenGL texture, namely {@code TEXTURE},
     * {@code FBOBJECT}, and (on Windows only) {@code PBUFFER}.
     *
     * @param g the Graphics object for the corresponding destination surface;
     * cannot be null
     * @return the texture target constant for the surface associated with the
     * given Graphics object; if the given Graphics object is invalid (i.e.
     * is not associated with an OpenGL surface), or the associated surface
     * is not backed by an OpenGL texture, this method will return zero.
     */
    public static int getOGLTextureType(Graphics g) {
        if (!(g instanceof SunGraphics2D)) {
            return 0;
        }
        SurfaceData sData = ((SunGraphics2D)g).surfaceData;
        if (!(sData instanceof OGLSurfaceData)) {
            return 0;
        }
        return ((OGLSurfaceData)sData).getTextureTarget();
    }
}
