Posted on 2007-07-11 00:58
停留的風(fēng) 閱讀(285)
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.NET技術(shù)
在網(wǎng)站開發(fā)時(shí),生成縮略圖是一個(gè)非常常見和實(shí)用的功能.以前在asp里只能借助com組件實(shí)現(xiàn),現(xiàn)在在.net里可以利用框架的強(qiáng)大的類庫(kù)輕松實(shí)現(xiàn).下面帖出完整的代碼(帶詳細(xì)注釋),參考了網(wǎng)上的一些文章及.net sdk相關(guān)內(nèi)容.QQROOM網(wǎng)絡(luò)家園的圖片上傳用到了所有的4種生成方式.
/**//// <summary>
/// 生成縮略圖
/// </summary>
/// <param name="originalImagePath">源圖路徑（物理路徑）</param>
/// <param name="thumbnailPath">縮略圖路徑（物理路徑）</param>
/// <param name="width">縮略圖寬度</param>
/// <param name="height">縮略圖高度</param>
/// <param name="mode">生成縮略圖的方式</param> 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"://指定高寬縮放（可能變形）
break;
case "W"://指定寬，高按比例
toheight = originalImage.Height * width/originalImage.Width;
break;
case "H"://指定高，寬按比例
towidth = originalImage.Width * height/originalImage.Height;
break;
case "Cut"://指定高寬裁減（不變形）
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;
}
//新建一個(gè)bmp圖片
Image bitmap = new System.Drawing.Bitmap(towidth,toheight);
//新建一個(gè)畫板
Graphics g = System.Drawing.Graphics.FromImage(bitmap);
//設(shè)置高質(zhì)量插值法
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
//設(shè)置高質(zhì)量,低速度呈現(xiàn)平滑程度
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//清空畫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繪制原圖片的指定部分
g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
new Rectangle(x, y, ow,oh),
GraphicsUnit.Pixel);
try
{
//以jpg格式保存縮略圖
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch(System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}