Java/OpenGL:将Canvas的图像作为BufferedImage获取

Question

我有一些代码初始化OpenGL以呈现给java.awt.Canvas.问题是,我无法弄清楚如何获取画布的缓冲区并将其转换为BufferedImage.

我已经尝试重写getGraphics(),克隆Raster,并用自定义替换CanvasPeer.

我猜测OpenGL不会以任何方式使用java图形,那么我如何获得OpenGL的缓冲区并将其转换为BufferedImage？

我正在使用LWJGL的代码来设置父级:

Display.setParent(display_parent);
Display.create();

Answer 1

您需要从OpenGL缓冲区复制数据.我正在使用这种方法:

FloatBuffer grabScreen(GL gl) 
{       
    int w = SCREENWITDH;
    int h = SCREENHEIGHT;
    FloatBuffer bufor = FloatBuffer.allocate(w*h*4); // 4 = rgba

    gl.glReadBuffer(GL.GL_FRONT);
    gl.glReadPixels(0, 0, w, h, GL.GL_RGBA, GL.GL_FLOAT, bufor); //Copy the image to the array imageData

    return bufor;
}

您需要根据OpenGL包装器使用类似的东西.这是JOGL的例子.

这里是LWJGL包装器:

private static synchronized byte[] grabScreen()
{
    int w = screenWidth;
    int h = screenHeight;
    ByteBuffer bufor = BufferUtils.createByteBuffer(w * h * 3);

    GL11.glReadPixels(0, 0, w, h, GL11.GL_RGB, GL11.GL_UNSIGNED_BYTE, bufor); //Copy the image to the array imageData

    byte[] byteimg = new byte[w * h * 3];
    bufor.get(byteimg, 0, byteimg.length);
    return byteimg;
}

编辑

这也许有用(它不完全是我的,也应该调整):

BufferedImage toImage(byte[] data, int w, int h)
{
    if (data.length == 0)
        return null;

    DataBuffer buffer = new DataBufferByte(data, w * h);

    int pixelStride = 3; //assuming r, g, b, skip, r, g, b, skip...
    int scanlineStride = 3 * w; //no extra padding   
    int[] bandOffsets = { 0, 1, 2 }; //r, g, b
    WritableRaster raster = Raster.createInterleavedRaster(buffer, w, h, scanlineStride, pixelStride, bandOffsets,
            null);

    ColorSpace colorSpace = ColorSpace.getInstance(ColorSpace.CS_sRGB);
    boolean hasAlpha = false;
    boolean isAlphaPremultiplied = true;
    int transparency = Transparency.TRANSLUCENT;
    int transferType = DataBuffer.TYPE_BYTE;
    ColorModel colorModel = new ComponentColorModel(colorSpace, hasAlpha, isAlphaPremultiplied, transparency,
            transferType);

    BufferedImage image = new BufferedImage(colorModel, raster, isAlphaPremultiplied, null);

    AffineTransform flip;
    AffineTransformOp op;
    flip = AffineTransform.getScaleInstance(1, -1);
    flip.translate(0, -image.getHeight());
    op = new AffineTransformOp(flip, AffineTransformOp.TYPE_NEAREST_NEIGHBOR);
    image = op.filter(image, null);

    return image;
}