与Config.ALPHA_8的像素完美碰撞

Question

我找到了像素完美碰撞检查的代码，并在我的代码中使用了它：

public  boolean isCollisionDetected(Bitmap bitmap1, int x1, int y1,
        Bitmap bitmap2, int x2, int y2) {
    Rect bounds1 = new Rect(x1, y1, x1 + bitmap1.getWidth(), y1
            + bitmap1.getHeight());
    Rect bounds2 = new Rect(x2, y2, x2 + bitmap2.getWidth(), y2
            + bitmap2.getHeight());

    if (Rect.intersects(bounds1, bounds2)) {
        Rect collisionBounds = getCollisionBounds(bounds1, bounds2);
        for (int i = collisionBounds.left; i < collisionBounds.right; i++) {
            for (int j = collisionBounds.top; j < collisionBounds.bottom; j++) {
                int bitmap1Pixel = bitmap1.getPixel(i - x1, j - y1);
                int bitmap2Pixel = bitmap2.getPixel(i - x2, j - y2);
                if (isFilled(bitmap1Pixel) && isFilled(bitmap2Pixel)) {
                    return true;
                }
            }
        }
    }
    return false;
}

private  Rect getCollisionBounds(Rect rect1, Rect rect2) {
    int left = (int) Math.max(rect1.left, rect2.left);
    int top = (int) Math.max(rect1.top, rect2.top);
    int right = (int) Math.min(rect1.right, rect2.right);
    int bottom = (int) Math.min(rect1.bottom, rect2.bottom);
    return new Rect(left, top, right, bottom);
}

private  boolean isFilled(int pixel) {
    return pixel != Color.TRANSPARENT;
}

它运行完美，从来没有任何问题。直到我使用以下代码将图像设置为Config_Alpha_8为止（由于ram问题）：

    private Bitmap convert(Bitmap bitmap, Bitmap.Config config) {
    Bitmap convertedBitmap = 
                  Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), config);
    Canvas canvas = new Canvas(convertedBitmap);
    Paint paint = new Paint();
    paint.setColor(Color.BLACK);
    canvas.drawBitmap(bitmap, 0, 0, paint);
    return convertedBitmap;
}

为什么什么都不会发生，它确实被CollisioDetected装入了，我已经检查了日志！但是它不会检测到冲突。有人可以使用config_alpha_8提供工作功能来检查位图的像素完美冲突吗？

Answer 1

在具有ALPHA_8配置的位图上调用getPixel（）将始终返回零。这似乎是一个错误

您可以通过将每个位图的像素存储为字节数组来解决此问题：

byte[] pixelData = getPixels(convert(bitmap, Bitmap.Config.ALPHA_8));

...

 public byte[] getPixels(Bitmap bmp) {
    int bytes = bmp.getRowBytes() * bmp.getHeight();
    ByteBuffer buffer = ByteBuffer.allocate(bytes);
    bmp.copyPixelsToBuffer(buffer);
    return buffer.array();
}

您将需要稍微修改碰撞检测功能：

public  boolean isCollisionDetected(byte[] pixels1, Bitmap bitmap1, int x1, int y1,
            byte[] pixels2, Bitmap bitmap2, int x2, int y2) {

        int width1 =bitmap1.getWidth();
        int height1=bitmap1.getHeight();
        int width2 =bitmap2.getWidth();
        int height2=bitmap2.getHeight();

        Rect bounds1 = new Rect(x1, y1, x1 + width1, y1 + height1);
        Rect bounds2 = new Rect(x2, y2, x2 + width2, y2 + height2);

        if (Rect.intersects(bounds1, bounds2)) {
            Rect collisionBounds = getCollisionBounds(bounds1, bounds2);
            for (int i = collisionBounds.left; i < collisionBounds.right; i++) {
                for (int j = collisionBounds.top; j < collisionBounds.bottom; j++) {
                    byte bitmap1Pixel = pixels1[((j - y1) * width1) + (i - x1)];
                    byte bitmap2Pixel = pixels2[((j - y2) * width2) + (i - x2)];
                    if (isFilled(bitmap1Pixel) && isFilled(bitmap2Pixel)) {
                        return true;
                    }
                }
            }
        }
        return false;
    }

（…您可能希望将位图参数更改为这些位图的相应宽度和高度，然后调用recycle（）。）