winfrom 改变图片透明度 Alpha

效果图： 

核心代码：

　　　　　　/// <summary>
        /// 方法一  设置图像透明度
        /// </summary>
        /// <param name="srcImage"></param>
        /// <param name="opacity"></param>
        /// <returns></returns>
        public static Image TransparentImage(Image srcImage, float opacity)
        {
            float[][] nArray ={ new float[] {1, 0, 0, 0, 0},
                        new float[] {0, 1, 0, 0, 0},
                        new float[] {0, 0, 1, 0, 0},
                        new float[] {0, 0, 0, opacity, 0},
                        new float[] {0, 0, 0, 0, 1}};
            ColorMatrix matrix = new ColorMatrix(nArray);
            ImageAttributes attributes = new ImageAttributes();
            attributes.SetColorMatrix(matrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
            Bitmap resultImage = new Bitmap(srcImage.Width, srcImage.Height);
            Graphics g = Graphics.FromImage(resultImage);
            g.DrawImage(srcImage, new Rectangle(0, 0, srcImage.Width, srcImage.Height), 0, 0, srcImage.Width, srcImage.Height, GraphicsUnit.Pixel, attributes);

            return resultImage;
        }

　　

Demo下载 https://download.csdn.net/download/u011392711/11144010