JavaFX实现android中的9patch功能

/**
 * javafx实现android的9patch
 *
 * @author zhou
 *
 */
public final class NinePatch{
  private Image origin;
  private int top;
  private int right;
  private int bottom;
  private int left;

  public NinePatch(Image origin, int topRightBottomLeft){
    this(origin, topRightBottomLeft, topRightBottomLeft);
  }

  public NinePatch(Image origin, int topBottom, int leftRight){
    this(origin, topBottom, leftRight, topBottom, leftRight);
  }

  public NinePatch(Image origin, int top, int right, int bottom, int left){
    if(left + right > origin.getWidth())
      throw new IllegalArgumentException("left add right must less than origin width");

    if(top + bottom > origin.getHeight())
      throw new IllegalArgumentException("top add bottom must less than origin height");

    this.origin = origin;
    this.top = top;
    this.right = right;
    this.bottom = bottom;
    this.left = left;
  }

  /**
   * 生成指定宽高图片
   *
   * @param scaledWidth
   * @param scaledHeight
   * @return
   */
  public Image generate(int scaledWidth, int scaledHeight){
    WritableImage result = new WritableImage(scaledWidth, scaledHeight);
    PixelReader reader = origin.getPixelReader();
    PixelWriter writer = result.getPixelWriter();
    int originHCenterWidth = (int) origin.getWidth() - right - left;
    int originVCenterWidth = (int) origin.getHeight() - top - bottom;

    /* first row */
    writer.setPixels(0, 0, left, top, reader, 0, 0);
    for(int y = 0; y < top; y++){
      for(int x = left; x < scaledWidth - right; x++){
        writer.setArgb(x, y, reader.getArgb(left + (x - left) % originHCenterWidth, y));
      }
    }

    writer.setPixels(scaledWidth - right, 0, right, top, reader, (int) origin.getWidth() - right, 0);

    /* second row */
    for(int y = top; y < scaledHeight - bottom; y++){
      for(int x = 0; x < left; x++){
        writer.setArgb(x, y, reader.getArgb(x, top + (y - top) % originVCenterWidth));
      }
    }

    for(int y = top; y < scaledHeight - bottom; y++){
      for(int x = left; x < scaledWidth - right; x++){
        writer.setArgb(x, y,
            reader.getArgb(left + (x - left) % originHCenterWidth, top + (y - top) % originVCenterWidth));
      }
    }

    for(int y = top; y < scaledHeight - bottom; y++){
      for(int x = scaledWidth - right; x < scaledWidth; x++){
        writer.setArgb(x, y,
            reader.getArgb((int) origin.getWidth() + x - scaledWidth, top + (y - top) % originVCenterWidth));
      }
    }

    /* third row */
    writer.setPixels(0, scaledHeight - bottom, left, bottom, reader, 0, (int) origin.getHeight() - bottom);
    for(int y = scaledHeight - bottom; y < scaledHeight; y++){
      for(int x = left; x < scaledWidth - right; x++){
        writer.setArgb(x, y,
            reader.getArgb(left + (x - left) % originHCenterWidth, (int) origin.getHeight() + y - scaledHeight));
      }
    }
    writer.setPixels(scaledWidth - right, scaledHeight - bottom, right, bottom, reader,
        (int) origin.getWidth() - right, (int) origin.getHeight() - bottom);

    return result;
  }

  /**
   *
   * @param gc
   * @param x
   * @param y
   * @param scaledWidth
   * @param scaledWidth
   */
  public void draw(GraphicsContext gc, int x, int y, int scaledWidth, int scaledHeight){
    gc.drawImage(generate(scaledWidth, scaledHeight), x, y);
  }

}