ASP.NET技术

[z511273571]

上传的图片，将宽度大于640px的图片保存成宽为640px的等比例缩小的图片，怎么做？

[qq497525725]

哥们 这是一个图片缩略方法,里面的高和宽: 如果图片实际宽度小于设置的宽度不做处理,高也是这样.
还有就是这个是等比例缩放.
16:9 的原始图片 ,缩放后也是16:9

这是原始方法,肯定是没有问题,我一直用这个.

 /// <summary>
        /// 缩放图片不带水印
        /// </summary>
        /// <param name="hifile"></param>
        /// <param name="imgName"></param>
        /// <param name="aWidth"></param>
        /// <param name="aHeight"></param>
        /// <returns></returns>
        public string UpImages(FileUpload hifile, string imgName, Unit aWidth, Unit aHeight)
        {
            string strOldFilePath = hifile.PostedFile.FileName;
            //取得上传文件的扩展名
            string strExtension = strOldFilePath.Substring(strOldFilePath.LastIndexOf("."));
            //生成原图 
            Byte[] oFileByte = new byte[hifile.PostedFile.ContentLength];
            System.IO.Stream oStream = hifile.PostedFile.InputStream;
            System.Drawing.Image oImage = System.Drawing.Image.FromStream(oStream);

            int oWidth = oImage.Width; //原图宽度 
            int oHeight = oImage.Height; //原图高度 
            int tWidth = Convert.ToInt32(aWidth.Value); //设置缩略图初始宽度 
            int tHeight = Convert.ToInt32(aHeight.Value); //设置缩略图初始高度
            if (imgName == "")
            {
                //图片名
                imgName = DateTime.Now.ToString("yyyyMMddHHmmss") + DateTime.Now.Millisecond.ToString() + strExtension;
                //图片存储相对路径
            }
            string path = WebPath.PhysicalApplicationPath + "/UpImage/" + imgName;
            if (oWidth <= tWidth && oHeight <= tHeight)
            {
                try
                {
                    hifile.PostedFile.SaveAs(path);
                }
                catch
                {
                    imgName = "no";
                }
            }
            else
            {
                //按比例计算出缩略图的宽度和高度 
                if (oWidth >= oHeight)
                {
                    tHeight = (int)Math.Floor(Convert.ToDouble(oHeight) * (Convert.ToDouble(tWidth) / Convert.ToDouble(oWidth)));
                }
                else
                {
                    tWidth = (int)Math.Floor(Convert.ToDouble(oWidth) * (Convert.ToDouble(tHeight) / Convert.ToDouble(oHeight)));
                }

                //生成缩略原图 
                Bitmap tImage = new Bitmap(tWidth, tHeight);
                Graphics g = Graphics.FromImage(tImage);
                g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; //设置高质量插值法 
                g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;//设置高质量,低速度呈现平滑程度 
                g.Clear(Color.Transparent); //清空画布并以透明背景色填充 


                g.DrawImage(oImage, new Rectangle(0, 0, tWidth, tHeight), new Rectangle(0, 0, oWidth, oHeight), GraphicsUnit.Pixel);

                //存储图片所需的绝对路径
                try
                {
                    //以JPG格式保存图片 
                    tImage.Save(path, System.Drawing.Imaging.ImageFormat.Jpeg);
                }
                catch
                {
                    imgName = "no";
                }
                finally
                {
                    //释放资源 
                    oImage.Dispose();
                    g.Dispose();
                    tImage.Dispose();
                }
            }
            return imgName;
        }

[wuyq11]

通过比例生成缩略图
public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
{
Image originalImage = Image.FromFile(originalImagePath);
int towidth = width;
int toheight = height;
int x = 0;
int y = 0;
int ow = originalImage.Width;
int oh = originalImage.Height;
switch (mode)
{
case "HW":
break;
case "W":
toheight = originalImage.Height * width/originalImage.Width;
break;
case "H":
towidth = originalImage.Width * height/originalImage.Height;
break;
case "Cut":
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*height/towidth;
x = 0;
y = (originalImage.Height - oh)/2;
}
break;
default :
break;
}
Image bitmap = new System.Drawing.Bitmap(towidth,toheight);
Graphics g = System.Drawing.Graphics.FromImage(bitmap);
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.Clear(Color.Transparent);
g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
new Rectangle(x, y, ow,oh),
GraphicsUnit.Pixel);

try
{
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch(System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}

<script language="JavaScript">
var flag=false;
function DrawImage(ImgD,iwidth,iheight){
var image=new Image();
image.src=ImgD.src;
if(image.width>0 && image.height>0){
flag=true;
if(image.width/image.height>= iwidth/iheight){
if(image.width>iwidth){
ImgD.width=iwidth;
ImgD.height=(image.height*iwidth)/image.width;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
ImgD.alt=image.width+"×"+image.height;
}
else{
if(image.height>iheight){
ImgD.height=iheight;
ImgD.width=(image.width*iheight)/image.height;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
ImgD.alt=image.width+"×"+image.height;
}

}
}

[duxj007]

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