/// <summary>
/// 获取缩放后图片
/// </summary>
/// <param name="originalImage">原始图片</param>
/// <param name="fixedWidth">固定宽度</param>
/// <param name="fixedHeight">固定高度</param>
/// <param name="changedMode">改变模式</param>
/// <param name="disposeOriginalImage">释放原始照片</param>
/// <returns></returns>
public Bitmap ZoomBitmap(Bitmap originalImage, int fixedWidth, int fixedHeight, ImageChangedMode changedMode, bool disposeOriginalImage)
{
int towidth = fixedWidth;
int toheight = fixedHeight;
int x = 0;
int y = 0;
int ow = originalImage.Width;
int oh = originalImage.Height;
switch (changedMode)
{
case ImageChangedMode.FixedWH: //指定高宽缩放（可能变形）
break;
case ImageChangedMode.ZoomHByW: //指定宽，高按比例
toheight = originalImage.Height * fixedWidth / originalImage.Width;
break;
case ImageChangedMode.ZoomWByH: //指定高，宽按比例
towidth = originalImage.Width * fixedHeight / originalImage.Height;
break;
case ImageChangedMode.ZoomBySacle: //根据源/目标 的宽高比例，哪个指标大，固定哪个指标，缩放另一个指标
double scaleW = originalImage.Width / fixedWidth;
double scaleH = originalImage.Height / fixedHeight;
if (scaleW > scaleH)
{
toheight = originalImage.Height * fixedWidth / originalImage.Width;
}
else
{
towidth = originalImage.Width * fixedHeight / originalImage.Height;
}
break;
case ImageChangedMode.CutByFixedWH: //指定高宽裁减（不变形）
default:
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 * fixedHeight / towidth;
x = 0;
y = (originalImage.Height - oh) / 2;
}
break;
}
//新建一个bmp图片
System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(towidth, toheight);
//新建一个画板
Graphics g = System.Drawing.Graphics.FromImage(bitmap);
try
{
//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);
}
catch (System.Exception e)
{
throw e;
}
finally
{
if (disposeOriginalImage)
{
originalImage.Dispose();
}
g.Dispose();
}
return(bitmap);
}
public Bitmap ZoomBitmap(Bitmap originalImage, Size fixedSize, ImageChangedMode changedMode, bool disposeOriginalImage)
{
return(ZoomBitmap(originalImage, fixedSize.Width, fixedSize.Height, changedMode, disposeOriginalImage));
}
