/// <summary>
/// 生成缩略图
/// </summary>
/// <param name="sourceImagePath">源图路径（带文件名的完整物理路径）</param>
/// <param name="thumbImagePath">缩略图路径（带文件名的完整物理路径）</param>
/// <param name="width">缩略图宽度</param>
/// <param name="height">缩略图高度</param>
/// <param name="thumbMode">生成缩略图的方式</param>
public static void MakeThumb(string sourceImagePath, string thumbImagePath, int width, int height, ThumbMode thumbMode)
{
if (string.IsNullOrEmpty(sourceImagePath))
{
throw new SourceImagePathIsNullOrEmptyException();
}
if (!File.Exists(sourceImagePath))
{
throw new SourceFileNotExistException();
}
if (string.IsNullOrEmpty(thumbImagePath))
{
throw new ThumbImagePathIsNullOrEmptyException();
}
string directory = Path.GetDirectoryName(thumbImagePath);
if (!Directory.Exists(directory))
{
throw new ThumbImagePathNotExistException();
}
try
{
using (Image sourceImage = Image.FromFile(sourceImagePath))
{
if (width <= 0 && width >= sourceImage.Width)
{
throw new ThumbImageWidthIsErrorException();
}
if (height <= 0 && height >= sourceImage.Height)
{
throw new ThumbImageHeigthIsErrorException();
}
int towidth = width;
int toheight = height;
int x = 0;
int y = 0;
int ow = sourceImage.Width;
int oh = sourceImage.Height;
switch (thumbMode)
{
case ThumbMode.HW: //指定高宽缩放（不变形）
int tempheight = sourceImage.Height * width / sourceImage.Width;
if (tempheight > height)
{
towidth = sourceImage.Width * height / sourceImage.Height;
}
else
{
toheight = sourceImage.Height * width / sourceImage.Width;
}
break;
case ThumbMode.W: //指定宽，高按比例
toheight = sourceImage.Height * width / sourceImage.Width;
break;
case ThumbMode.H: //指定高，宽按比例
towidth = sourceImage.Width * height / sourceImage.Height;
break;
case ThumbMode.CUT: //指定高宽裁减（不变形）
if ((double)sourceImage.Width / (double)sourceImage.Height > (double)towidth / (double)toheight)
{
oh = sourceImage.Height;
ow = sourceImage.Height * towidth / toheight;
y = 0;
x = (sourceImage.Width - ow) / 2;
}
else
{
ow = sourceImage.Width;
oh = sourceImage.Width * height / towidth;
x = 0;
y = (sourceImage.Height - oh) / 2;
}
break;
}
//新建一个bmp图片
using (Image bitmap = new Bitmap(towidth, toheight))
{
//新建一个画板
using (Graphics g = Graphics.FromImage(bitmap))
{
//设置高质量插值法
g.InterpolationMode = InterpolationMode.High;
//设置高质量,低速度呈现平滑程度
g.SmoothingMode = 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(sourceImage, new Rectangle(0, 0, towidth, toheight),
new Rectangle(x, y, ow, oh),
GraphicsUnit.Pixel);
}
//验证缩略图的保存路径是否带有文件名,如果没有带文件名则用 thumb_原文件名
if (!Regex.IsMatch(thumbImagePath, @"[^\\\/:\*\?""<>\|]+\.[^\\\/:\*\?""<>\|]+$", RegexOptions.Compiled))
{
thumbImagePath = thumbImagePath + "thumb_" + sourceImagePath.Remove(0, sourceImagePath.LastIndexOf(@"\") + 1);
}
//以源文件相同的格式保存缩略图
bitmap.Save(thumbImagePath, sourceImage.RawFormat);
}
}
}
catch (OutOfMemoryException)
{
throw new SourceFileIsNotImageException();
}
}
public void resetlog()
{
//w.Close()
File.WriteAllText(this.fn, string.Empty);
}
