C#图像透明度调整的方法

本文实例讲述了c#图像透明度调整的方法。分享给大家供大家参考。具体如下：

//定义图像透明度调整函数
public bitmap ptransparentadjust(bitmap src,int num)
{
  try
  {
   int w = src.width;
   int h = src.height;
   bitmap dstbitmap = new bitmap(src.width, src.height, system.drawing.imaging.pixelformat.format32bppargb);
   system.drawing.imaging.bitmapdata srcdata = src.lockbits(new rectangle(0, 0, w, h), system.drawing.imaging.imagelockmode.readonly, system.drawing.imaging.pixelformat.format32bppargb);
   system.drawing.imaging.bitmapdata dstdata = dstbitmap.lockbits(new rectangle(0, 0, w, h), system.drawing.imaging.imagelockmode.writeonly, system.drawing.imaging.pixelformat.format32bppargb);
   unsafe
   {
     byte* pin = (byte*)srcdata.scan0.topointer();
     byte* pout = (byte*)dstdata.scan0.topointer();
     byte* p;
     int stride = srcdata.stride;
     int r, g, b;
     for (int y = 0; y < h; y++)
     {
     for (int x = 0; x < w; x++)
     {
       p = pin;
       b = pin[0];
       g = pin[1];
       r = pin[2];
       pout[1] = (byte)g;
       pout[2] = (byte)r;
       pout[3] = (byte)num;
       pout[0] = (byte)b;
       pin += 4;
       pout += 4;
     }
     pin += srcdata.stride - w * 4;
     pout += srcdata.stride - w * 4;
     }
     src.unlockbits(srcdata);
     dstbitmap.unlockbits(dstdata);
     return dstbitmap;
   }
  }
  catch (exception e)
  {
   messagebox.show(e.message.tostring());
   return null;
  }
}

原图：

效果图(50%)：

希望本文所述对大家的c#程序设计有所帮助。