GDI+图片毛玻璃效果的实现

Yale_Yange 2013-03-15 03:10:01

分享一个图片毛玻璃效果的算法
原理：
从原像素的某个范围内随机选取一部分像素，讲其进行Alpha混合模糊得到目标像素值
下面上代码：



/// <summary>

        /// 对颜色数组进行混合

        /// </summary>

        /// <param name="colors"></param>

        /// <returns></returns>

        public static Color BlendColor(Color[] colors)

        {

            if (colors.Length <= 0)

                return Color.Transparent;

            ulong asum = 0, rsum = 0, gsum = 0, bsum = 0;

            for (int i = 0, len = colors.Length; i < len; i++)

            {

                asum += colors[i].A;

                rsum += (ulong)(colors[i].A*colors[i].R);

                gsum += (ulong)(colors[i].G*colors[i].A);

                bsum += (ulong)(colors[i].B*colors[i].A);

            }

            if (asum == 0)

                return Color.Transparent;

            rsum /= asum;

            gsum /= asum;

            bsum /= asum;

            asum /= (ulong)colors.Length;

            return Color.FromArgb((int)asum, (int)rsum, (int)gsum, (int)bsum);

        }



        /// <summary>

        /// 毛玻璃效果

        /// </summary>

        /// <param name="srcBmp">源图片</param>

        /// <param name="minRadius">最小离散半径</param>

        /// <param name="maxRadius">最大离散半径</param>

        /// <param name="samples">采样点数</param>

        /// <returns></returns>

        public static Bitmap FrostedEffect(Bitmap srcBmp, int minRadius, int maxRadius, int samples)

        {

            int width = srcBmp.Width;

            int height = srcBmp.Height;

            Bitmap targBmp = new Bitmap(width, height, srcBmp.PixelFormat);

            BitmapData srcData = srcBmp.LockBits(new Rectangle(0, 0, width, height), 

                ImageLockMode.ReadOnly, srcBmp.PixelFormat);

            BitmapData targData = targBmp.LockBits(new Rectangle(0, 0, width, height),

                ImageLockMode.WriteOnly, targBmp.PixelFormat);

            int pxsize = Image.GetPixelFormatSize(srcBmp.PixelFormat) / 8;//像素大小

            bool bAlpha = Image.IsAlphaPixelFormat(srcBmp.PixelFormat);

            int offset = srcData.Stride - srcData.Width * pxsize;

            Random rand = new Random();

            Color[] sampleColors = new Color[samples];

            unsafe

            {

                byte* srcptr = (byte*)srcData.Scan0;

                for (int i = 0; i < height; i++)

                {

                    for (int j = 0; j < width; j++)

                    {

                        for (int s = 0; s < samples; s++)

                        {

                            double d = rand.Next(minRadius, maxRadius);

                            double angle = rand.NextDouble() * Math.PI * 2;

                            double p = Math.Sin(angle);

                            int samh = (int)(i + Math.Sin(angle) * d);

                            int samw = (int)(j + Math.Cos(angle) * d);

                            samh = samh < 0 ? 0 : samh > height - 1 ? height - 1 : samh;

                            samw = samw < 0 ? 0 : samw > width ? width : samw;

                            byte* ptr = srcptr + samh * srcData.Stride + samw * pxsize;

                            if (bAlpha)

                                sampleColors[s] = Color.FromArgb(*(ptr + 3), *(ptr + 2), *(ptr + 1), *ptr);

                            else

                                sampleColors[s] = Color.FromArgb(*(ptr + 2), *(ptr + 1), *ptr);

                        }

                        Color col = BlendColor(sampleColors);

                        byte* targptr = (byte*)targData.Scan0 + srcData.Stride * i + j*pxsize;

                        *targptr = col.B;

                        *(targptr + 1) = col.G;

                        *(targptr + 2) = col.R;

                        if (bAlpha)

                            *(targptr + 3) = col.A;

                    }

                }

            }

            srcBmp.UnlockBits(srcData);

            targBmp.UnlockBits(targData);

            return targBmp;

        }