Question

我需要在旧图像上绘制新图像。我首先在BufferedImage中打开了两个图像，并将其白色背景更改为透明。然后我从旧图像的bufferedImage获得了一个Graphics2D对象，并调用了Graphics2D类的drawImage方法。然后我将旧图像保存到磁盘。当我打开保存的图像时，我发现只有白色背景的旧图像变为透明。任何人都可以告诉我我的代码有什么错误，或者如何解决我的错误？

    BufferedImage newImage = ImageIO.read(new File("new.png"));
    BufferedImage oldImage = ImageIO.read(new File("old.png"));

    newImage = makeWhiteTransparent(newImage);
    oldImage = makeWhiteTransparent(oldImage);

    Graphics2D graphics = (Graphics2D) oldImage.getGraphics();
    graphics.drawImage(newImage,null, 0,0);

    File outputImage = new File("merged.png");
    ImageIO.write(oldImage, "png", outputImage);

我的makeWhiteTransparent方法是这样的：

    public static BufferedImage makeWhiteTransparent(BufferedImage img){
        BufferedImage dst = new BufferedImage(img.getWidth(), img.getHeight(), BufferedImage.TYPE_4BYTE_ABGR);
        dst.getGraphics().drawImage(img, 0, 0, null);
        int markerRGB = Color.WHITE.getRGB() | 0xFF000000;
        int width = dst.getWidth();
        int height = dst.getHeight();
        for(int x = 0; x < width; x++){
            for(int y = 0; y < height; y++){
                int rgb = dst.getRGB(x, y);
                if ( ( rgb | 0xFF000000 ) == markerRGB ) {
                    int value = 0x00FFFFFF & rgb;
                    dst.setRGB(x, y, value); 
                }
            }
        }
        return dst;
    }

我尝试将graphics.drawImage（newImage，null，0,0）更改为graphics.drawImage（newImage，0,0，null），并按照建议将TYPE_4BYTE_ABGR更改为TYPE_INT_ARGB，但它什么也没做。错误仍然存在。

Answer 1

这需要改变：

graphics.drawImage(newImage,null, 0,0);

到

graphics.drawImage(newImage, 0,0, null);

您使用的是错误版本的drawImage - 请检查http://docs.oracle.com/javase/7/docs/api/java/awt/Graphics2D.html

-

还将类型TYPE_4BYTE_ABGR更改为TYPE_INT_ARGB

-

以下是它对我有用的方法：

public BufferedImage makeWhiteTransparent(BufferedImage img){
    BufferedImage dst = new BufferedImage(img.getWidth(), img.getHeight(), BufferedImage.TYPE_INT_ARGB);
    dst.getGraphics().drawImage(img, 0, 0, null);
    int markerRGB = 0x00ffffff; // Color.WHITE.getRGB() | 0xFF000000;
    int width = dst.getWidth();
    int height = dst.getHeight();
    for(int x = 0; x < width; x++){
        for(int y = 0; y < height; y++){
            int rgb = dst.getRGB(x, y)&0x00ffffff;
            if ( rgb  == markerRGB ) {
                int value = 0x00FFFFFF & rgb;
                dst.setRGB(x, y, value); 
            }
        }
    }
    return dst;
}

bim = makeWhiteTransparent(bim);
bim2 = makeWhiteTransparent(bim2);

Graphics2D graphics = (Graphics2D) bim.getGraphics();
graphics.drawImage(bim2,0,0, null);

g2.drawImage(bim, w/2-wc/2, h/2-hc/2, null);

Answer 2

我最终得到了我的问题的答案。我所要做的就是创建一个新的BufferedImage并在其上绘制两个图像。下面是按预期工作的代码：

        BufferedImage newImage = ImageIO.read(new File("new.png"));
        BufferedImage oldImage = ImageIO.read(new File("old.png"));


        oldImage = makeWhiteTransparent(oldImage);
        newImage = makeWhiteTransparent(newImage);

        int width = Math.max(newImage.getWidth(),  oldImage.getWidth());
        int height = Math.max(newImage.getHeight(), oldImage.getHeight());
        BufferedImage combined = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);

        Graphics graphics = combined.getGraphics();

        graphics.drawImage(oldImage, 0, 0, null);
        graphics.drawImage(newImage, 0, 0, null);

        File outputImage = new File("merged.png");
        ImageIO.write(combined, "PNG", outputImage);

在旧图像java

2 个答案: