/// <summary>
/// 保存缩略图
/// </summary>
/// <param name="savePath">保存路径</param>
/// <param name="thumbWidth">缩略图限制宽度</param>
/// <param name="thumbHeight">缩略图限制高度（为null时 表示不限制高度）</param>
public void Save(string savePath, int thumbWidth, int?thumbHeight)
{
using (Image originalImg = Image.FromStream(_stream))
{
Size size = originalImg.Size;
switch (_zoomMode)
{
case ZoomMode.GeometricProportion:
if (size.Width > thumbWidth || size.Height > thumbHeight)
{
float scale;
if (thumbHeight.HasValue)
{
scale = Math.Min((float)thumbWidth / size.Width, (float)thumbHeight / size.Height);
}
else
{
scale = (float)thumbWidth / size.Width;
}
size = new Size((int)(scale * size.Width), (int)(scale * size.Height));
}
break;
case ZoomMode.Fixed:
if (thumbHeight.HasValue == false)
{
throw new ArgumentNullException("thumbHeight", "固定缩放模式下必须指定高度");
}
size = new Size(thumbWidth, thumbHeight.Value);
break;
}
using (Bitmap bmp = new Bitmap(size.Width, size.Height))
using (Graphics g = Graphics.FromImage(bmp))
{
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.Clear(Color.Transparent);
g.DrawImage(originalImg, 0, 0, size.Width, size.Height);
FileUtils.AutoCreateDir(savePath);
bmp.Save(savePath, ImageFormat.Jpeg);
}
}
}
