c# - 如何在asp.net中将图像变灰

Question

我需要在 asp 页面中将禁用的图像变灰，但我不知道如何实现

我当前的代码如下

<ul class="flag">
                <li>
                    <img src="flag-china.png" alt="china" onclick="setLanguage('Chinese');"   style="cursor:pointer"/></li>
                <li>
                    <img src="flag-france.png" alt="france" onclick="setLanguage('French');" style="cursor:pointer" /></li>

                    <img src="us.png" alt="us" onclick="setLanguage('English');" style="cursor:pointer" /></li>
            </ul>

我需要禁用和灰色除最后一个标志之外的所有标志

Answer 1

在此处找到以下代码示例。需要时调用灰色版本。

public static Bitmap MakeGrayscale3(Bitmap original)
{
   //create a blank bitmap the same size as original
   Bitmap newBitmap = new Bitmap(original.Width, original.Height);

   //get a graphics object from the new image
   Graphics g = Graphics.FromImage(newBitmap);

   //create the grayscale ColorMatrix
   ColorMatrix colorMatrix = new ColorMatrix(
      new float[][] 
      {
         new float[] {.3f, .3f, .3f, 0, 0},
         new float[] {.59f, .59f, .59f, 0, 0},
         new float[] {.11f, .11f, .11f, 0, 0},
         new float[] {0, 0, 0, 1, 0},
         new float[] {0, 0, 0, 0, 1}
      });

   //create some image attributes
   ImageAttributes attributes = new ImageAttributes();

   //set the color matrix attribute
   attributes.SetColorMatrix(colorMatrix);

   //draw the original image on the new image
   //using the grayscale color matrix
   g.DrawImage(original, new Rectangle(0, 0, original.Width, original.Height),
      0, 0, original.Width, original.Height, GraphicsUnit.Pixel, attributes);

   //dispose the Graphics object
   g.Dispose();
   return newBitmap;
}