/// <summary>
/// 生成缩略图 (高清缩放)
/// </summary>
/// <param name="originalImage">原图片</param>
/// <param name="width">缩放宽度</param>
/// <param name="height">缩放高度</param>
/// <returns></returns>
public static Image Makesmallimage(System.Drawing.Image originalImage, int width, int height)
{
int towidth = 0;
int toheight = 0;
if (originalImage.Width > width && originalImage.Height < height)
{
towidth = width;
toheight = originalImage.Height;
}
if (originalImage.Width < width && originalImage.Height > height)
{
towidth = originalImage.Width;
toheight = height;
}
if (originalImage.Width > width && originalImage.Height > height)
{
towidth = width;
toheight = height;
}
if (originalImage.Width < width && originalImage.Height < height)
{
towidth = originalImage.Width;
toheight = originalImage.Height;
}
int x = 0;//左上角的x坐标
int y = 0;//左上角的y坐标
//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, x, y, towidth, toheight);
originalImage.Dispose();
//bitmap.Dispose();
g.Dispose();
return bitmap;
}