windows phone中的WriteableBitmapEx错误

Question

嗨，我试着在windows phone中使用WriteableBitmapEx，但是代码不是working...what，我做错了吗？

        double height = image1.ActualHeight;
        double width = image1.ActualWidth;
        BitmapImage img = new BitmapImage(new Uri("Tulips.png", UriKind.RelativeOrAbsolute));
        BitmapImage newImg = image1.Source as BitmapImage;

        for (int i = 0; i < height; i++)
        {
            for (int j = 0; j < width; j++)
            {

                int grayScale = (int)((image1.writeableBmp.GetPixel(j, i).R * 0.3) + (image1.writeableBmp.GetPixel(j, i).G * 0.59) + (image1.GetPixel(j, i).B * 0.11));
                Color nc = Color.FromArgb (grayScale, grayScale, grayScale);
                newImg.SetPixel(j, i, nc);

            }
        }

Answer 1

您正在尝试修改BitmapImage (newImg)。您必须创建一个WriteableBitmap

var newImg = new WriteableBitmap(image1.Source);

以便能够在之后修改位图图像。

然后(如果引用的是WriteableBitmapEx)应该能够直接从newImg获得grayScale表达式中的像素值

byte grayScale = Convert.ToByte((newImg.GetPixel(j, i).R * 0.3) + 
    (newImg.GetPixel(j, i).G * 0.59) + (newImg.GetPixel(j, i).B * 0.11));

然后还有一个Color.FromArgb语句，应该看起来像这样：

Color nc = Color.FromArgb (255, grayScale, grayScale, grayScale);