图片上传|图片按比例缩放

首先:生成缩略图,再上传到服务器.

以前做了一个图片上传的,但是他不是按比例缩放的.只需要在中间加一段判断长和宽.就可以了.还是看看代码吧.

 

//定义image类的对象
    System.Drawing.Image image;
    System.Drawing.Image newimage;
    //图片路径
    protected string imagePath;
    //图片类型
    protected string imageType;
    //图片名称
    protected string imageName;
    //提供一个回调方法，用于确定Image对象在执行生成缩略图操作时提前取消执行
    //如果此方法确定GetThumbnailImage方法应提前停止执行，则返回true;否则返回false
    System.Drawing.Image.GetThumbnailImageAbort callb = null;
    protected void Button1_Click(object sender, EventArgs e)
    ...{
        string mPath;
        //如果文件名称不为空
        if (FileUpload1.PostedFile.FileName != "")
        ...{
            imagePath = FileUpload1.PostedFile.FileName;
            //取得图片类型
            imageType = imagePath.Substring(imagePath.LastIndexOf(".") + 1).ToLower().ToString();
            //取得图片名称
            imageName = imagePath.Substring(imagePath.LastIndexOf("") + 1);
            //判断是否是jpg/gif/jpeg/jpe类型图片
            if (imageType != "jpg" && imageType != "gif" && imageType != "jpeg" && imageType != "jpe")

            ...{
                ConfirmMessageBox("对不起，请选择：jpg|jpeg|jpe|gif中的任意一种格式!");
            }
            else
            ...{
                //判断图片是否大于120K[120 * 1024]
                if (FileUpload1.PostedFile.ContentLength > 122880)
                ...{
                    Label2.Text = "对不起，文件不得大于120K(122880个字节)!";
                }
                else
                ...{
                    try
                    ...{
                        //建立虚拟路径
                        mPath = Server.MapPath("productImages");
                        //保存图片到虚拟路径
                        imageName = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + DateTime.Now.Day.ToString() + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString() + "." + imageType;
                        HiddenField1.Value = imageName;
                        FileUpload1.PostedFile.SaveAs(mPath + "" + imageName);

                        //显示原图
                        //Image1.ImageUrl = "productImages/" + imageName;

                        //为上传图片建立引用
                        image = System.Drawing.Image.FromFile(mPath + "" + imageName);
                        //==============================================================
                        //加入判断长宽的比例代码 >> Begin
                        //==============================================================
                        //生成原图 软件开发网 www.mscto.com
                        Byte[] oFileByte = new Byte[FileUpload1.PostedFile.ContentLength];
                        Stream oStream = FileUpload1.PostedFile.InputStream;
                        System.Drawing.Image oImage = System.Drawing.Image.FromStream(oStream);

                        //原图宽度和高度
                        int oWidth = oImage.Width;
                        int oHeight = oImage.Height;

                       
                        //设置缩略图的初始宽度和高度
                        int tWidth = 100;
                        int tHeight = 100;

                        //按比例计算出缩略图的宽度和高度
                        if (oWidth >= oHeight)
                        ...{
                            tWidth = (int)Math.Floor(Convert.ToDouble(oHeight) * (Convert.ToDouble(tWidth) / Convert.ToDouble(oWidth)));
                        }
                        else
                        ...{
                            tHeight = (int)Math.Floor(Convert.ToDouble(oWidth) * (Convert.ToDouble(tHeight) / Convert.ToDouble(oHeight)));
                        }

                        //==============================================================
                        //判断长宽的比例代码 >> Over
                        //==============================================================

                        /**////生成缩略图
                        newimage = image.GetThumbnailImage(tHeight, tWidth, callb, System.IntPtr.Zero);
                        //把缩略图保存到指定的虚拟路径
                        newimage.Save(Server.MapPath("productImages") + "small" + imageName);
                        //释放image对象占用的资源
                        image.Dispose();
                        //释放newimage占用的资源
                        newimage.Dispose();
                        //显示缩略图 软件开发网 www.mscto.com
                        Image1.ImageUrl = "productImages/small" + imageName;
                        Label2.Text = "上传成功!";
                    }
                    catch
                    ...{
                        Label2.Text = "上传失败!";
                    }
                }
            }
        }
        else
        ...{
            Label2.Text = "不能为空,请选择图片！";
        }
    }
 那么显示的时候长宽最大为100.

如果在一个页面需要显示长宽最大为150,怎么办呢?刚刚开始我想从服务器端得到图片的大小.但是他需要的是绝对中路径.

用那种方法只能得到客户端的图片大小.代码如下:

 

private void btnGet_Click(object sender, System.EventArgs e)
        ...{
            if(upImage.PostedFile.FileName != "")
            ...{
                imgPath =upImage.PostedFile.FileName;
                fileExtName = imgPath.Substring(imgPath.LastIndexOf(".")+1,3);

                if(fileExtName !="gif" && fileExtName != "jpg")
                ...{
                    Response.Write("请选择GIF和JPG格式的图片");
                }
                else
                ...{
//获取图片大小
                    System.Drawing.Image image =  System.Drawing.Image.FromFile(imgPath);
                    txtHeight.Text = image.Height.ToString();
                    txtWidth.Text = image.Width.ToString();
                }
            }
            else
            ...{
                Response.Write("请选择图片!");
            }
        }
没有办法,只好在显示到客户端时用onLoad事件来完成对图片大小的改造了.

此方法参考Winner.Net@2007的图片超过规定的大小就按原图片大小缩小

1，不按照比例的缩放

 

<script language="javascript"> 
function changeImg(mypic)...{ 
    alert("OK");
    var xw=130; 
    var xl=160; 

    var width = mypic.width; 
    var height = mypic.height; 
                     
    if (width > xw ) mypic.width = xw; 
    if (height > xl ) mypic.height = xl; 
} 
</script> 
<img src="sh180.jpg" onload="changeImg(this)">    

2，按照比例的缩放 

 

<script language="javascript"> 
function changeImg1(mypic)...{ 

alert("OK");
    var xw=160; 
    var xl=180; 
         
    var width = mypic.width; 
    var height = mypic.height; 
    var bili = width/height;         
         
    var A=xw/width; 
    var B=xl/height; 
         
    if(A>1||B>1) 
    ...{ 
        if(A<B) 
        ...{ 
            mypic.width=xw; 
            mypic.height=xw/bili; 
        } 
        if(A>B) 
        ...{ 
            mypic.width=xl*bili; 
            mypic.height=xl; 
        } 
    } 
} 
</script>