/// /// 缩小图片 /// ///
原图片路径 /// 生成后的图片路径 /// 生成后的图片宽度 /// 生成后的图片高度 /// 图片按照什么方式伸缩 public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode) { Image originalImage = Image.FromFile(originalImagePath);int towidth = width;
int toheight = height;
int x = 0;
int y = 0;
int ow = originalImage.Width;
int oh = originalImage.Height;
switch (mode) {
case "HW": //指定高宽缩放（可能变形）
break;
case "W": //指定宽，高按比例
toheight = originalImage.Height * width / originalImage.Width;
break;
case "H": //指定高，宽按比例
towidth = originalImage.Width * height / originalImage.Height;
break; case "Cut": //指定高宽裁减（不变形）
if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight) {
oh = originalImage.Height;
ow = originalImage.Height * towidth / toheight;
y = 0;
x = (originalImage.Width - ow) / 2; }
else
{
ow = originalImage.Width;
oh = originalImage.Width * height / towidth;
x = 0;
y = (originalImage.Height - oh) / 2; }
break; default: break;
} //新建一个bmp图片
Image bitmap = new Bitmap(towidth, toheight); //新建一个画板
Graphics g = Graphics.FromImage(bitmap); //设置高质量插值法
g.InterpolationMode = InterpolationMode.High; //设置高质量,低速度呈现平滑程度
g.SmoothingMode = SmoothingMode.HighQuality; //清空画布并以透明背景色填充
g.Clear(Color.Transparent); //在指定位置并且按指定大小绘制原图片的指定部分
g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
new Rectangle(x, y, ow, oh),
GraphicsUnit.Pixel);
try { //以jpg格式保存缩略图
bitmap.Save(thumbnailPath, ImageFormat.Jpeg); }
catch (Exception e)
{ throw e; }
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}