asp.net generates high quality thumbnail common functions (C # code), supports a variety of build methods _ practical skills

<summary>
Generate thumbnails
</summary>
<param name= "Originalimagepath" > Source map Path (physical path) </param>
<param name= "Thumbnailpath" > Thumbnail path (physical path) </param>
<param name= "width" > Thumbnail width </param>
<param name= "height" > thumbnail height </param>
<param name= "mode" > How to Generate Thumbnails </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"://Specify width scaling (possibly distorted)
Break
Case "W"://Specify wide, high proportionally
Toheight = Originalimage.height * width/originalimage.width;
Break
Case "H"://specified high, wide proportional
Towidth = Originalimage.width * height/originalimage.height;
Break
Case "cut"://Specify width trim (not deformed)
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
}

Create a new BMP picture
Image bitmap = new System.Drawing.Bitmap (towidth,toheight);

Create a new artboard
Graphics g = System.Drawing.Graphics.FromImage (bitmap);

Set high quality interpolation method
G.interpolationmode = System.Drawing.Drawing2D.InterpolationMode.High;

Set high quality, low speed rendering smooth degree
G.smoothingmode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

Empty the canvas and fill with a transparent background color
G.clear (color.transparent);

Draws the specified portion of the original picture at the specified location and at the specified size
G.drawimage (Originalimage, New Rectangle (0, 0, Towidth, toheight),
New Rectangle (x, Y, Ow,oh),
GraphicsUnit.Pixel);

Try
{
Save thumbnails in JPG format
Bitmap. Save (Thumbnailpath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch (System.Exception e)
{
Throw e;
}
Finally
{
Originalimage.dispose ();
Bitmap. Dispose ();
G.dispose ();
}
}