如何将按比例生成的缩略图用白色背景填充丢失的部分?
如何将按比例生成的缩略图用白色背景填充丢失的部分?
如宽高是100PX时,有时候可能高度不足100,如何用白色背景补上不足部分?
以下是原来的代码:
public bool GetThumbNail( FileUpload file, string savePath, int width, int height, string mode )
{
//缩略图
System.Drawing.Image originalImage = System.Drawing.Image.FromStream(file.PostedFile.InputStream);
file.Dispose();
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
System.Drawing.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(savePath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch
{
return false;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
return true;
}