/// <summary>
/// 生成缩略图
/// </summary>
/// <param name="orginalImagePat">原图片地址</param>
/// <param name="thumNailPath">缩略图地址</param>
/// <param name="width">缩略图宽度</param>
/// <param name="height">缩略图高度</param>
/// <param name="model">生成缩略的模式</param>
public void MakeThumNail(string originalImagePath, string thumNailPath, int width, int height, string model)
{
System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);
int thumWidth = width; //缩略图的宽度
int thumHeight = height; //缩略图的高度
int x = 0;
int y = 0;
int originalWidth = originalImage.Width; //原始图片的宽度
int originalHeight = originalImage.Height; //原始图片的高度
switch (model)
{
case "HW": //指定高宽缩放,可能变形
break;
case "W": //指定宽度,高度按照比例缩放
thumHeight = originalImage.Height * width / originalImage.Width;
break;
case "H": //指定高度,宽度按照等比例缩放
thumWidth = originalImage.Width * height / originalImage.Height;
break;
case "Cut":
if ((double)originalImage.Width / (double)originalImage.Height > (double)thumWidth / (double)thumHeight)
{
originalHeight = originalImage.Height;
originalWidth = originalImage.Height * thumWidth / thumHeight;
y = 0;
x = (originalImage.Width - originalWidth) / 2;
}
else
{
originalWidth = originalImage.Width;
originalHeight = originalWidth * height / thumWidth;
x = 0;
y = (originalImage.Height - originalHeight) / 2;
}
break;
default:
break;
}
//新建一个bmp图片
System.Drawing.Image bitmap = new System.Drawing.Bitmap(thumWidth, thumHeight);
//新建一个画板
System.Drawing.Graphics graphic = System.Drawing.Graphics.FromImage(bitmap);
//设置高质量查值法
graphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
//设置高质量，低速度呈现平滑程度
graphic.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//清空画布并以透明背景色填充
graphic.Clear(System.Drawing.Color.Transparent);
//在指定位置并且按指定大小绘制原图片的指定部分
graphic.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, thumWidth, thumHeight)
, new System.Drawing.Rectangle(x, y, originalWidth, originalHeight), System.Drawing.GraphicsUnit.Pixel);
try
{
bitmap.Save(thumNailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch (Exception ex)
{
throw ex;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
graphic.Dispose();
}
}