/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 * - Redistribution of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * 
 * - Redistribution in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of Sun Microsystems, Inc. or the names of
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
 * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN
 * MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR
 * ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR
 * DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE
 * DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
 * ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF
 * SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 * 
 * You acknowledge that this software is not designed or intended for use
 * in the design, construction, operation or maintenance of any nuclear
 * facility.
 * 
 * Sun gratefully acknowledges that this software was originally authored
 * and developed by Kenneth Bradley Russell and Christopher John Kline.
 */

package com.sun.opengl.util;

import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.image.*;

import javax.media.opengl.*;
import javax.media.opengl.glu.*;
import com.sun.opengl.util.texture.*;

/** Provides the ability to render into an OpenGL {@link
    com.sun.opengl.util.texture.Texture Texture} using the Java 2D
    APIs. This renderer class uses an internal Java 2D image (of
    unspecified type) for its backing store and flushes portions of
    that image to an OpenGL texture on demand. The resulting OpenGL
    texture can then be mapped on to a polygon for display. */

public class J2DTextureRenderer {
  // For now, we supply only a BufferedImage back-end for this
  // renderer. In theory we could use the Java 2D/JOGL bridge to fully
  // accelerate the rendering paths, but there are restrictions on
  // what work can be done where; for example, Graphics2D-related work
  // must not be done on the Queue Flusher Thread, but JOGL's
  // OpenGL-related work must be. This implies that the user's code
  // would need to be split up into multiple callbacks run from the
  // appropriate threads, which would be somewhat unfortunate.
  private boolean alpha;
  private BufferedImage image;

  private Texture texture;
  private TextureData textureData;
  private boolean mustReallocateTexture;

  private GLU glu = new GLU();

  /** Creates a new renderer with backing store of the specified width
      and height. If alpha is true, allocates an alpha channel in the
      backing store image.

      @param width the width of the texture to render into
      @param height the height of the texture to render into
      @param alpha whether to allocate an alpha channel for the texture
  */
  public J2DTextureRenderer(int width, int height, boolean alpha) {
    this.alpha = alpha;
    init(width, height);
  }

  /** Returns the width of the backing store of this renderer.

      @return the width of the backing store of this renderer
  */
  public int getWidth() {
    return image.getWidth();
  }

  /** Returns the height of the backing store of this renderer.

      @return the height of the backing store of this renderer
  */
  public int getHeight() {
    return image.getHeight();
  }

  /** Returns the size of the backing store of this renderer in a
      newly-allocated {@link java.awt.Dimension Dimension} object.

      @return the size of the backing store of this renderer
  */
  public Dimension getSize() {
    return getSize(null);
  }

  /** Returns the size of the backing store of this renderer. Uses the
      {@link java.awt.Dimension Dimension} object if one is supplied,
      or allocates a new one if null is passed.

      @param d a {@link java.awt.Dimension Dimension} object in which
        to store the results, or null to allocate a new one

      @return the size of the backing store of this renderer
  */
  public Dimension getSize(Dimension d) {
    if (d == null)
      d = new Dimension();
    d.setSize(image.getWidth(), image.getHeight());
    return d;
  }

  /** Sets the size of the backing store of this renderer. This may
      cause the OpenGL texture object associated with this renderer to
      be invalidated; it is not recommended to cache this texture
      object outside this class but to instead call {@link #getTexture
      getTexture} when it is needed.

      @param width the new width of the backing store of this renderer
      @param height the new height of the backing store of this renderer
  */
  public void setSize(int width, int height) {
    init(width, height);
  }
  

  /** Sets the size of the backing store of this renderer. This may
      cause the OpenGL texture object associated with this renderer to
      be invalidated.

      @param d the new size of the backing store of this renderer
  */
  public void setSize(Dimension d) {
    setSize(d.width, d.height);
  }

  /** Creates a {@link java.awt.Graphics2D Graphics2D} instance for
      rendering to the backing store of this renderer. The returned
      object should be disposed of using the normal {@link
      java.awt.Graphics#dispose() Graphics.dispose()} method once it
      is no longer being used.

      @return a new {@link java.awt.Graphics2D Graphics2D} object for
        rendering into the backing store of this renderer
  */
  public Graphics2D createGraphics() {
    return image.createGraphics();
  }

  /** Synchronizes the specified region of the backing store down to
      the underlying OpenGL texture.

      @param x the x coordinate (in Java 2D coordinates -- relative to
        upper left) of the region to update
      @param y the y coordinate (in Java 2D coordinates -- relative to
        upper left) of the region to update
      @param width the width of the region to update
      @param height the height of the region to update

      @throws GLException If an OpenGL context is not current when this method is called
  */
  public void sync(int x, int y, int width, int height) throws GLException {
    // Force allocation if necessary
    boolean canSkipUpdate = ensureTexture();

    if (!canSkipUpdate) {
      // Update specified region
      texture.updateSubImage(textureData, 0, x, y, x, y, width, height);
    }
  }

  /** Returns the underlying OpenGL Texture object associated with
      this renderer.

      @throws GLException If an OpenGL context is not current when this method is called
  */
  public Texture getTexture() throws GLException {
    ensureTexture();
    return texture;
  }

  /** Disposes all resources associated with this renderer. It is not
      valid to use this renderer after calling this method.

      @throws GLException If an OpenGL context is not current when this method is called
  */
  public void dispose() throws GLException {
    if (texture != null) {
      texture.dispose();
      texture = null;
    }
    if (image != null) {
      image.flush();
      image = null;
    }
  }

  /** Convenience method which assists in rendering portions of the
      OpenGL texture to the screen, if the application intends to draw
      them as a flat overlay on to the screen. Sets up the viewing
      matrices, for orthographic rendering where the coordinates go
      from (0, 0) at the lower left to (width, height) at the upper
      right; disables the depth test and lighting; and enables the
      texture in this renderer. {@link #endOrthoRendering} must be
      used in conjunction with this method to restore all OpenGL
      states.

      @param width the width of the current on-screen OpenGL drawable
      @param height the height of the current on-screen OpenGL drawable

      @throws GLException If an OpenGL context is not current when this method is called
  */
  public void beginOrthoRendering(int width, int height) throws GLException {
    GL gl = GLU.getCurrentGL();
    gl.glPushAttrib(GL.GL_ENABLE_BIT | GL.GL_DEPTH_BUFFER_BIT | GL.GL_TRANSFORM_BIT);
    gl.glDisable(GL.GL_DEPTH_TEST);
    gl.glDisable(GL.GL_CULL_FACE);
    gl.glDisable(GL.GL_LIGHTING);
    gl.glMatrixMode(GL.GL_PROJECTION);
    gl.glPushMatrix();
    gl.glLoadIdentity();
    glu.gluOrtho2D(0, width, 0, height);
    gl.glMatrixMode(GL.GL_MODELVIEW);
    gl.glPushMatrix();
    gl.glLoadIdentity();
    gl.glEnable(GL.GL_BLEND);
    gl.glBlendFunc(GL.GL_ONE, GL.GL_ONE_MINUS_SRC_ALPHA);
    Texture texture = getTexture();
    texture.enable();
    texture.bind();
    gl.glTexEnvi(GL.GL_TEXTURE_ENV, GL.GL_TEXTURE_ENV_MODE, GL.GL_REPLACE);
  }

  /** Draws an orthographically projected rectangle of the underlying
      texture to the specified location on the screen. All (x, y)
      coordinates are specified relative to the lower left corner of
      either the texture image or the current OpenGL drawable.

      @param screenx the on-screen x coordinate at which to draw the rectangle
      @param screeny the on-screen y coordinate (relative to lower left) at
        which to draw the rectangle
      @param texturex the x coordinate of the pixel in the texture of
        the lower left portion of the rectangle to draw
      @param texturey the y coordinate of the pixel in the texture
        (relative to lower left) of the lower left portion of the
        rectangle to draw
      @param width the width of the rectangle to draw
      @param height the height of the rectangle to draw
      
      @throws GLException If an OpenGL context is not current when this method is called
  */
  public void drawOrthoRect(int screenx, int screeny,
                            int texturex, int texturey,
                            int width, int height) throws GLException {
    GL gl = GLU.getCurrentGL();
    Texture texture = getTexture();
    TextureCoords coords = texture.getSubImageTexCoords(texturex, texturey,
                                                        texturex + width,
                                                        texturey + height);
    gl.glBegin(GL.GL_QUADS);
    gl.glTexCoord2f(coords.left(), coords.bottom());
    gl.glVertex3f(screenx, screeny, 0);
    gl.glTexCoord2f(coords.right(), coords.bottom());
    gl.glVertex3f(screenx + width, screeny, 0);
    gl.glTexCoord2f(coords.right(), coords.top());
    gl.glVertex3f(screenx + width, screeny + height, 0);
    gl.glTexCoord2f(coords.left(), coords.top());
    gl.glVertex3f(screenx, screeny + height, 0);
    gl.glEnd();
  }

  /** Convenience method which assists in rendering portions of the
      OpenGL texture to the screen, if the application intends to draw
      them as a flat overlay on to the screen. Must be used if {@link
      #beginOrthoRendering} is used to set up the rendering stage for
      this overlay. 

      @throws GLException If an OpenGL context is not current when this method is called
  */
  public void endOrthoRendering() throws GLException {
    GL gl = GLU.getCurrentGL();
    Texture texture = getTexture();
    texture.disable();
    gl.glMatrixMode(GL.GL_PROJECTION);
    gl.glPopMatrix();
    gl.glMatrixMode(GL.GL_MODELVIEW);
    gl.glPopMatrix();
    gl.glPopAttrib();
  }

  //----------------------------------------------------------------------
  // Internals only below this point
  //

  private void init(int width, int height) {
    // Discard previous BufferedImage if any
    if (image != null) {
      image.flush();
      image = null;
    }

    int imageType = (alpha ?  BufferedImage.TYPE_INT_ARGB_PRE : BufferedImage.TYPE_INT_RGB);
    image = new BufferedImage(width, height, imageType);
    // Always realllocate the TextureData associated with this
    // BufferedImage; it's just a reference to the contents but we
    // need it in order to update sub-regions of the underlying
    // texture
    textureData = TextureIO.newTextureData(image, false);
    // For now, always reallocate the underlying OpenGL texture when
    // the backing store size changes
    mustReallocateTexture = true;
  }

  // Returns true if the texture was newly allocated, false if not
  private boolean ensureTexture() {
    if (mustReallocateTexture) {
      if (texture != null) {
        texture.dispose();
        texture = null;
      }
    }

    if (texture == null) {
      texture = TextureIO.newTexture(textureData);
      return true;
    }

    return false;
  }
}