//drawType=0表示是预览绘制，1表示是从本地选择了的绘制
private Bitmap DrawImg(Image img, Size container, int drawType = 0)
{
System.Drawing.Imaging.ImageFormat thisFormat = img.RawFormat;
int sW = 0, sH = 0;
// 按比例缩放
int sWidth = img.Width;
int sHeight = img.Height;
if ((sHeight > container.Height || sWidth > container.Width) && (sHeight != sWidth))
{
if ((sWidth * container.Height) > (sHeight * container.Width))
{
sW = container.Width;
sH = (container.Height * sHeight) / sWidth;
}
else
{
sH = container.Height;
sW = (sWidth * container.Height) / sHeight;
}
}
else
{
sW = sWidth;
sH = sHeight;
}
Bitmap outBmp = new Bitmap(container.Width, container.Height);
Graphics g = Graphics.FromImage(outBmp);
g.Clear(Color.Transparent);
// 设置画布的描绘质量
g.CompositingQuality = CompositingQuality.HighQuality;
g.SmoothingMode = SmoothingMode.HighQuality;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.DrawImage(img, new Rectangle((container.Width - sW) / 2, (container.Height - sH) / 2, sW, sH), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel);
//1表示是从本地选择了的绘制
if (drawType == 1)
{
//保存压缩图片
_imgZip = new Bitmap(sW, sH);
Graphics g2 = Graphics.FromImage(_imgZip);
g2.DrawImage(img, new Rectangle(0, 0, sW, sH), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel);
g2.Dispose();
}
g.Dispose();
return outBmp;
}