C#图片处理之:图片缩放和剪裁

  1string strFileNameOld = @"D:/png/fenge/129267877539521154.png";  
  2    string strFileNameNew = @"D:/png/fenge/"+DateTime.Now.ToFileTime().ToString()+".png ";  
  3    int iWidth, iHeight, iMagnify;  
  4    Color myColor;  
  5    int i, j, i0, j0, i1, j1;  
  6      
  7    iMagnify = 8;  
  8    Bitmap bmpTmp = (Bitmap)System.Drawing.Image.FromFile(strFileNameOld);  
  9    Bitmap bmpNew = new Bitmap(bmpTmp.Width * iMagnify, bmpTmp.Height * iMagnify);  
 10    Graphics g = Graphics.FromImage(bmpNew);  
 11      
 12    iWidth = bmpTmp.Width;  
 13    iHeight = bmpTmp.Height;  
 14      
 15    try  
 16    {  
 17        for (i = 0; i < iWidth; i++)  
 18        {  
 19            i0 = i * iMagnify;  
 20            for (j = 0; j < iHeight; j++)  
 21            {  
 22                j0 = j * iMagnify;  
 23                myColor = bmpTmp.GetPixel(i, j);  
 24                for (i1 = i0; i1 < i0 + iMagnify; i1++)  
 25                    for (j1 = j0; j1 < j0 + iMagnify; j1++)  
 26                        bmpNew.SetPixel(i1, j1, myColor);  
 27            }  
 28        }  
 29    }  
 30    catch  
 31    {  
 32        string errormsg;  
 33        errormsg = "hi ";  
 34    }  
 35      
 36      
 37    bmpTmp.Dispose();  
 38    g.Dispose();  
 39    bmpNew.Save(strFileNameNew, System.Drawing.Imaging.ImageFormat.Bmp);   
 40
 41[c-sharp] view plain copy
 42
 43    应听众点播要求，今天说说用C#做图片的缩放和剪裁，相信很多人会对这部分内容感兴趣，毕竟这个操作太实用了。  
 44      
 45    其实在GDI+中，缩放和剪裁可以看作同一个操作，无非就是原始区域的选择不同罢了。空口无凭，先看具体算法可能更好理解。  
 46      
 47            /// <summary>  
 48            /// Resize图片  
 49            /// </summary>  
 50            /// <param name="bmp">原始Bitmap</param>  
 51            /// <param name="newW">新的宽度</param>  
 52            /// <param name="newH">新的高度</param>  
 53            /// <param name="Mode">保留着，暂时未用</param>  
 54            /// <returns>处理以后的图片</returns>  
 55            public static Bitmap KiResizeImage(Bitmap bmp, int newW, int newH, int Mode)  
 56            {  
 57                try  
 58                {  
 59                    Bitmap b = new Bitmap(newW, newH);  
 60                    Graphics g = Graphics.FromImage(b);  
 61      
 62                    // 插值算法的质量  
 63                    g.InterpolationMode = InterpolationMode.HighQualityBicubic;  
 64      
 65                    g.DrawImage(bmp, new Rectangle(0, 0, newW, newH), new Rectangle(0, 0, bmp.Width, bmp.Height), GraphicsUnit.Pixel);  
 66                    g.Dispose();  
 67      
 68                    return b;  
 69                }  
 70                catch  
 71                {  
 72                    return null;  
 73                }  
 74            }  
 75      
 76    // ===============================  
 77      
 78             /// <summary>  
 79            /// 剪裁 -- 用GDI+  
 80            /// </summary>  
 81            /// <param name="b">原始Bitmap</param>  
 82            /// <param name="StartX">开始坐标X</param>  
 83            /// <param name="StartY">开始坐标Y</param>  
 84            /// <param name="iWidth">宽度</param>  
 85            /// <param name="iHeight">高度</param>  
 86            /// <returns>剪裁后的Bitmap</returns>  
 87            public static Bitmap KiCut(Bitmap b, int StartX, int StartY, int iWidth, int iHeight)  
 88            {  
 89                if (b == null)  
 90                {  
 91                    return null;  
 92                }  
 93      
 94                int w = b.Width;  
 95                int h = b.Height;  
 96      
 97                if (StartX >= w || StartY >= h)  
 98                {  
 99                    return null;  
100                }  
101      
102                if (StartX + iWidth > w)  
103                {  
104                    iWidth = w - StartX;  
105                }  
106      
107                if (StartY + iHeight > h)  
108                {  
109                    iHeight = h - StartY;  
110                }  
111      
112                try  
113                {  
114                    Bitmap bmpOut = new Bitmap(iWidth, iHeight, PixelFormat.Format24bppRgb);  
115      
116                    Graphics g = Graphics.FromImage(bmpOut);  
117                    g.DrawImage(b, new Rectangle(0, 0, iWidth, iHeight), new Rectangle(StartX, StartY, iWidth, iHeight), GraphicsUnit.Pixel);  
118                    g.Dispose();  
119      
120                    return bmpOut;  
121                }  
122                catch  
123                {  
124                    return null;  
125                }  
126            }