需要帮助来理解这个示例代码

private void SetAlpha(string location)
{
    //bmp is a bitmap source that I load from an image
    bmp = new BitmapImage(new Uri(location));
    int[] pixels = new int[(int)bmp.Width * (int)bmp.Height];
    //still not sure what 'stride' is.  Got this part from a tutorial
    int stride = (bmp.PixelWidth * bmp.Format.BitsPerPixel + 7)/8;

    bmp.CopyPixels(pixels, stride, 0);
    int oldColor = pixels[0];
    int red = 255;
    int green = 255;
    int blue = 255;
    int alpha = 0;
    int color = (alpha << 24) + (red << 16) + (green << 8) + blue;

    for (int i = 0; i < (int)bmp.Width * (int)bmp.Height; i++)
    {
        if (pixels[i] == oldColor)
        {
            pixels[i] = color;
        }
    }
        //remake the bitmap source with these pixels
        bmp = BitmapSource.Create(bmp.PixelWidth, bmp.PixelHeight, bmp.DpiX, bmp.DpiY, bmp.Format, bmp.Palette, pixels, stride);
    }

}

Could you explain this code for me? What does color and oldColor mean?

你能帮我解释一下这段代码吗？ color和oldColor是什么意思？

1 个解决方案

#1

This code substitutes and oldColor by a new color in a RGBA bitmap.

此代码用RGBA位图中的新颜色替换oldColor。

The new color is full - copmletely opaque white. The old color is taken from the first pixel. many icons and masks do

新的颜色是完整的 - 不透明的白色。旧颜色取自第一个像素。许多图标和面具

Stride is how many bytes per scan line / row there are.

Stride是每个扫描行/行的字节数。

Bugs:

错误：

1) bmp.CopyPixels(pixels, stride, 0); only copies the first row. it shouls be bmp.CopyPixels(pixels, stride * bmp.Height, 0);

1）bmp.CopyPixels（像素，步幅，0）;只复制第一行。它应该是bmp.CopyPixels（像素，步幅* bmp.Height，0）;

2) It assusmes a particualr layout of the RGB colors. It allo does not check the results of "new BitmapImage" "new int[]" and BitmapSource.Create

2）它特定于RGB颜色的特定布局。它不会检查“new BitmapImage”“new int []”和BitmapSource.Create的结果

3) the function's name is wrong.

3）函数的名称错误。

#1