asp.net生成高质量缩略图通用函数(c#代码),支持多种生成方式
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2023-03-14 12:15:12
/// /// 生成缩略...
/// <summary>
/// 生成缩略图
/// </summary>
/// <param name="originalimagepath">源图路径(物理路径)</param>
/// <param name="thumbnailpath">缩略图路径(物理路径)</param>
/// <param name="width">缩略图宽度</param>
/// <param name="height">缩略图高度</param>
/// <param name="mode">生成缩略图的方式</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 system.drawing.bitmap(towidth,toheight);
//新建一个画板
graphics g = system.drawing.graphics.fromimage(bitmap);
//设置高质量插值法
g.interpolationmode = system.drawing.drawing2d.interpolationmode.high;
//设置高质量,低速度呈现平滑程度
g.smoothingmode = system.drawing.drawing2d.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, system.drawing.imaging.imageformat.jpeg);
}
catch(system.exception e)
{
throw e;
}
finally
{
originalimage.dispose();
bitmap.dispose();
g.dispose();
}
}
/// 生成缩略图
/// </summary>
/// <param name="originalimagepath">源图路径(物理路径)</param>
/// <param name="thumbnailpath">缩略图路径(物理路径)</param>
/// <param name="width">缩略图宽度</param>
/// <param name="height">缩略图高度</param>
/// <param name="mode">生成缩略图的方式</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 system.drawing.bitmap(towidth,toheight);
//新建一个画板
graphics g = system.drawing.graphics.fromimage(bitmap);
//设置高质量插值法
g.interpolationmode = system.drawing.drawing2d.interpolationmode.high;
//设置高质量,低速度呈现平滑程度
g.smoothingmode = system.drawing.drawing2d.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, system.drawing.imaging.imageformat.jpeg);
}
catch(system.exception e)
{
throw e;
}
finally
{
originalimage.dispose();
bitmap.dispose();
g.dispose();
}
}