我有一个 aspx 页面，它将图像从客户端 pc 上传到服务器硬盘
但现在我需要更改我的程序，以便在上传时调整图像大小。
有人对此有任何想法吗？我无法使用输入文件服务器控件找到此类属性/方法
有人指导我吗？
问问题
75933 次
14 回答
15
将文件保存到服务器后，您可以使用这样的代码来调整大小。此代码将处理调整大小时的长/宽比。
public static Bitmap CreateThumbnail(string lcFilename, int lnWidth, int lnHeight)
{
System.Drawing.Bitmap bmpOut = null;
try
{
Bitmap loBMP = new Bitmap(lcFilename);
ImageFormat loFormat = loBMP.RawFormat;
decimal lnRatio;
int lnNewWidth = 0;
int lnNewHeight = 0;
if (loBMP.Width < lnWidth && loBMP.Height < lnHeight)
return loBMP;
if (loBMP.Width > loBMP.Height)
{
lnRatio = (decimal)lnWidth / loBMP.Width;
lnNewWidth = lnWidth;
decimal lnTemp = loBMP.Height * lnRatio;
lnNewHeight = (int)lnTemp;
}
else
{
lnRatio = (decimal)lnHeight / loBMP.Height;
lnNewHeight = lnHeight;
decimal lnTemp = loBMP.Width * lnRatio;
lnNewWidth = (int)lnTemp;
}
bmpOut = new Bitmap(lnNewWidth, lnNewHeight);
Graphics g = Graphics.FromImage(bmpOut);
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
g.FillRectangle(Brushes.White, 0, 0, lnNewWidth, lnNewHeight);
g.DrawImage(loBMP, 0, 0, lnNewWidth, lnNewHeight);
loBMP.Dispose();
}
catch
{
return null;
}
return bmpOut;
}
于 2008-10-31T18:33:10.493 回答
5
您将无法“即时”调整大小，因为在执行任何图像转换之前您需要拥有完整的图像。但是，在上传完成之后，在向用户显示任何结果之前，您可以使用我现在在几个应用程序中使用的这种基本的图像大小调整方法：
''' <summary>
''' Resize image with GDI+ so that image is nice and clear with required size.
''' </summary>
''' <param name="SourceImage">Image to resize</param>
''' <param name="NewHeight">New height to resize to.</param>
''' <param name="NewWidth">New width to resize to.</param>
''' <returns>Image object resized to new dimensions.</returns>
''' <remarks></remarks>
Public Shared Function ImageResize(ByVal SourceImage As Image, ByVal NewHeight As Int32, ByVal NewWidth As Int32) As Image
Dim bitmap As System.Drawing.Bitmap = New System.Drawing.Bitmap(NewWidth, NewHeight, SourceImage.PixelFormat)
If bitmap.PixelFormat = Drawing.Imaging.PixelFormat.Format1bppIndexed Or _
bitmap.PixelFormat = Drawing.Imaging.PixelFormat.Format4bppIndexed Or _
bitmap.PixelFormat = Drawing.Imaging.PixelFormat.Format8bppIndexed Or _
bitmap.PixelFormat = Drawing.Imaging.PixelFormat.Undefined Or _
bitmap.PixelFormat = Drawing.Imaging.PixelFormat.DontCare Or _
bitmap.PixelFormat = Drawing.Imaging.PixelFormat.Format16bppArgb1555 Or _
bitmap.PixelFormat = Drawing.Imaging.PixelFormat.Format16bppGrayScale Then
Throw New NotSupportedException("Pixel format of the image is not supported.")
End If
Dim graphicsImage As System.Drawing.Graphics = System.Drawing.Graphics.FromImage(bitmap)
graphicsImage.SmoothingMode = Drawing.Drawing2D.SmoothingMode.HighQuality
graphicsImage.InterpolationMode = Drawing.Drawing2D.InterpolationMode.HighQualityBicubic
graphicsImage.DrawImage(SourceImage, 0, 0, bitmap.Width, bitmap.Height)
graphicsImage.Dispose()
Return bitmap
End Function
于 2008-10-31T18:19:27.730 回答
4
这就是我在项目中所做的，根据您的条件（高度/宽度），您可以更改参数，即（MaxHeight）
public static System.Drawing.Image ScaleImage(System.Drawing.Image image, int maxHeight)
{
var ratio = (double)maxHeight / image.Height;
var newWidth = (int)(image.Width * ratio);
var newHeight = (int)(image.Height * ratio);
var newImage = new Bitmap(newWidth, newHeight);
using (var g = Graphics.FromImage(newImage))
{
g.DrawImage(image, 0, 0, newWidth, newHeight);
}
return newImage;
}
在按钮上单击：
protected void Button1_Click(object sender, EventArgs e)
{
lblmsg.Text="";
if ((File1.PostedFile != null) && (File1.PostedFile.ContentLength > 0))
{
Guid uid = Guid.NewGuid();
string fn = System.IO.Path.GetFileName(File1.PostedFile.FileName);
string SaveLocation = Server.MapPath("LogoImagesFolder") + "\\" + uid+fn;
try
{
string fileExtention = File1.PostedFile.ContentType;
int fileLenght = File1.PostedFile.ContentLength;
if (fileExtention == "image/png" || fileExtention == "image/jpeg" || fileExtention == "image/x-png")
{
if (fileLenght <= 1048576)
{
System.Drawing.Bitmap bmpPostedImage = new System.Drawing.Bitmap(File1.PostedFile.InputStream);
System.Drawing.Image objImage = ScaleImage(bmpPostedImage, 81);
objImage.Save(SaveLocation,ImageFormat.Png);
lblmsg.Text = "The file has been uploaded.";
lblmsg.Style.Add("Color", "Green");
}
else
{
lblmsg.Text = "Image size cannot be more then 1 MB.";
lblmsg.Style.Add("Color", "Red");
}
}
else {
lblmsg.Text = "Invaild Format!";
lblmsg.Style.Add("Color", "Red");
}
}
catch (Exception ex)
{
lblmsg.Text= "Error: " + ex.Message;
lblmsg.Style.Add("Color", "Red");
}
}
}
于 2012-08-17T08:02:23.680 回答
4
另一种方法是允许用户在浏览器中调整大小，然后按照其他答案中的描述调整图像大小。
所以看看这个解决方案，它允许您使用 jQuery、jCrop 和 ASP.NET 上传和裁剪图像。
于 2010-02-23T08:54:55.757 回答
4
如何仅为 .jpg 扩展调整大小和上传图像：
在 upload.aspx 页面中
<asp:FileUpload ID="ProductImage" runat="server"/>
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Upload" />
<asp:TextBox runat="server" ID="txtProductName" CssClass="form-control" />
<asp:RequiredFieldValidator runat="server" ControlToValidate="txtProductName" ErrorMessage="The Product name field is required." />
并上传.aspx.cs
用于调整大小
/// <summary>
/// Created By Rajib Chowdhury Mob. 01766-306306; Web: http://onlineshoping.somee.com/
/// Complete This Page Coding On January 05, 2014
/// Programing C# By Visual Studio 2013 For Web
/// Dot Net Version 4.5
/// Database Virsion MSSQL Server 2005
/// </summary>
public bool ResizeImageAndUpload(System.IO.FileStream newFile, string folderPathAndFilenameNoExtension, double maxHeight, double maxWidth)
{
try
{
// Declare variable for the conversion
float ratio;
// Create variable to hold the image
System.Drawing.Image thisImage = System.Drawing.Image.FromStream(newFile);
// Get height and width of current image
int width = (int)thisImage.Width;
int height = (int)thisImage.Height;
// Ratio and conversion for new size
if (width > maxWidth)
{
ratio = (float)width / (float)maxWidth;
width = (int)(width / ratio);
height = (int)(height / ratio);
}
// Ratio and conversion for new size
if (height > maxHeight)
{
ratio = (float)height / (float)maxHeight;
height = (int)(height / ratio);
width = (int)(width / ratio);
}
// Create "blank" image for drawing new image
Bitmap outImage = new Bitmap(width, height);
Graphics outGraphics = Graphics.FromImage(outImage);
SolidBrush sb = new SolidBrush(System.Drawing.Color.White);
// Fill "blank" with new sized image
outGraphics.FillRectangle(sb, 0, 0, outImage.Width, outImage.Height);
outGraphics.DrawImage(thisImage, 0, 0, outImage.Width, outImage.Height);
sb.Dispose();
outGraphics.Dispose();
thisImage.Dispose();
// Save new image as jpg
outImage.Save(Server.MapPath(folderPathAndFilenameNoExtension + ".jpg"), System.Drawing.Imaging.ImageFormat.Jpeg);
outImage.Dispose();
return true;
}
catch (Exception)
{
return false;
}
}
和 Button1_Click 事件
string filePath = "~\\Image\\";//your normal image path
if (Page.IsValid)
{
HttpPostedFile myFile = ProductImage.PostedFile;//Get Slected Image
int nFileLen = myFile.ContentLength;//Get slected Image Size
string myimag = txtProductName.Text;//Get user input image name
Guid ImageName = Guid.NewGuid();//get unique id
if ((myFile != null) && (nFileLen > 1048576))
{
LabelAddStatus.Text = "minimum size exceed"; //If file image size 1 MB above
}
else
{
try
{
if (ProductImage.HasFile)
{
String fileExtension = System.IO.Path.GetExtension(ProductImage.FileName).ToLower();
String[] allowedExtensions = { ".jpg" };//Declare For Allowed Extension
for (int i = 0; i < allowedExtensions.Length; i++)
{
if (fileExtension == allowedExtensions[i])
{
// Read file into a data stream
byte[] myData = new Byte[nFileLen];
myFile.InputStream.Read(myData, 0, nFileLen);
myFile.InputStream.Dispose();
// Save the stream to disk as temporary file. make sure the path is unique!
System.IO.FileStream newFile
= new System.IO.FileStream(Server.MapPath(filePath + "_temp.jpg"),
System.IO.FileMode.Create);
newFile.Write(myData, 0, myData.Length);
bool success = ResizeImageAndUpload(newFile, filePath + ("thumbs"+myimag + ImageName), 100, 100);//Save image your thumb image path
success = ResizeImageAndUpload(newFile, filePath + (myimag + ImageName), 768, 1024);//Save image your normal image path
//delete the temp file.
newFile.Close();
System.IO.File.Delete(Server.MapPath(filePath + "_temp.jpg"));
LabelAddStatus.Text = "File uploaded.";
}
else
{
LabelAddStatus.Text = "Unable to accept file type..";
}
}
}
}
catch (Exception)
{
//No Exception Message
}
}
}
谢谢...
于 2014-02-16T16:47:20.670 回答
2
您需要使用 WebClient 类来下载远程图像。
之后，您可以调整它的大小...使用 DrawImage，而不是 GetThumbnailImage。确保处理掉您的位图和图形句柄..（使用 using{}）。将所有质量设置设置为高。
你可能想先看看我流行的图像调整器的源代码......它将帮助你避免一些常见的问题区域。
于 2008-11-05T21:10:52.263 回答
1
要缩小图像并获得更小的尺寸，只需进行以下更改
bmpOut = new Bitmap(lnNewWidth, lnNewHeight, **System.Drawing.Imaging.PixelFormat.Format24bppRgb**);
Graphics g = Graphics.FromImage(bmpOut);
正如您在上面将 imagem 设置为 Format24bppRgb PixelFormat。
当你保存文件时，你也设置了 ImageFormat。像这样：
bmpOut.Save(PathImage, System.Drawing.Imaging.ImageFormat.Jpeg);
于 2009-02-26T15:49:05.623 回答
1
//Here is another WAY fox!!! i have actually modify the code from You all. HIHI
//First, add one textBox and one FileUpload Control, and a button
//paste this in your code behind file... after public partial class admin : System.Web.UI.Page
string OriPath;
string ImageName;
public Size NewImageSize(int OriginalHeight, int OriginalWidth, double FormatSize)
{
Size NewSize;
double tempval;
if (OriginalHeight > FormatSize && OriginalWidth > FormatSize)
{
if (OriginalHeight > OriginalWidth)
tempval = FormatSize / Convert.ToDouble(OriginalHeight);
else
tempval = FormatSize / Convert.ToDouble(OriginalWidth);
NewSize = new Size(Convert.ToInt32(tempval * OriginalWidth), Convert.ToInt32(tempval * OriginalHeight));
}
else
NewSize = new Size(OriginalWidth, OriginalHeight); return NewSize;
}
//Now, On Button click add the folwing code.
if (FileUpload1.PostedFile != null)
{
ImageName = TextBox1.Text+".jpg";
OriPath = Server.MapPath("pix\\") + ImageName;
//Gets the Full Path using Filecontrol1 which points to actual location in the hardisk :)
using (System.Drawing.Image Img = System.Drawing.Image.FromFile(System.IO.Path.GetFullPath(FileUpload1.PostedFile.FileName)))
{
Size ThumbNailSize = NewImageSize(Img.Height, Img.Width, 800);
using (System.Drawing.Image ImgThnail = new Bitmap(Img, ThumbNailSize.Width, ThumbNailSize.Height))
{
ImgThnail.Save(OriPath, Img.RawFormat);
ImgThnail.Dispose();
}
Img.Dispose();
}
}
//Enjoy. If any problem,, mail me at izacmail@gmail.com
于 2009-02-06T00:14:13.853 回答
1
你可以用这个，它对我来说很不错。但它对我来说不能很好地处理低分辨率图像。谢天谢地，我已经习惯了其中的许多人。只需将图像byte[]和预期输出发送给它，您就可以开始了。
public static byte[] ResizeImageFile(byte[] imageFile, int targetSize)
{
using (System.Drawing.Image oldImage = System.Drawing.Image.FromStream(new MemoryStream(imageFile)))
{
Size newSize = CalculateDimensions(oldImage.Size, targetSize);
using (Bitmap newImage = new Bitmap(newSize.Width, newSize.Height, PixelFormat.Format32bppRgb))
{
newImage.SetResolution(oldImage.HorizontalResolution, oldImage.VerticalResolution);
using (Graphics canvas = Graphics.FromImage(newImage))
{
canvas.SmoothingMode = SmoothingMode.AntiAlias;
canvas.InterpolationMode = InterpolationMode.HighQualityBicubic;
canvas.PixelOffsetMode = PixelOffsetMode.HighQuality;
canvas.DrawImage(oldImage, new Rectangle(new Point(0, 0), newSize));
MemoryStream m = new MemoryStream();
newImage.Save(m, ImageFormat.Jpeg);
return m.GetBuffer();
}
}
}
}
private static Size CalculateDimensions(Size oldSize, int targetSize)
{
Size newSize = new Size();
if (oldSize.Width > oldSize.Height)
{
newSize.Width = targetSize;
newSize.Height = (int)(oldSize.Height * (float)targetSize / (float)oldSize.Width);
}
else
{
newSize.Width = (int)(oldSize.Width * (float)targetSize / (float)oldSize.Height);
newSize.Height = targetSize;
}
return newSize;
}
于 2010-02-22T17:34:35.857 回答
0
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
public partial class admin_AddPhoto : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string reportPath = Server.MapPath("../picnic");
if (!Directory.Exists(reportPath))
{
Directory.CreateDirectory(Server.MapPath("../picnic"));
}
}
protected void PhotoForm_ItemInserting(object sender, FormViewInsertEventArgs e)
{
FormView uploadForm = sender as FormView;
FileUpload uploadedFile = uploadForm.FindControl("uploadedFile") as FileUpload;
if (uploadedFile != null)
{
string fileName = uploadedFile.PostedFile.FileName;
string pathFile = System.IO.Path.GetFileName(fileName);
try
{
uploadedFile.SaveAs(Server.MapPath("../picnic/") + pathFile);
}
catch (Exception exp)
{
//catch exception here
}
try
{
Bitmap uploadedimage = new Bitmap(uploadedFile.PostedFile.InputStream);
e.Values["ImageWidth"] = uploadedimage.Width.ToString();
e.Values["ImageHeight"] = uploadedimage.Height.ToString();
// Make output File Name
char[] splitter = { '.' };
string[] splitFile = pathFile.Split(splitter);
string OutputFilename = splitFile[0] + "s";
System.Drawing.Image.GetThumbnailImageAbort myCallback = new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback);
System.Drawing.Image thumbImage = uploadedimage.GetThumbnailImage(74, 54, myCallback, IntPtr.Zero);
thumbImage.Save(Server.MapPath("../picnic/") + OutputFilename + ".jpg");
e.Values["Thumbnail"] = "./picnic/" + OutputFilename + ".jpg";
}
catch (Exception ex)
{
//catch exception here
}
e.Values["Pic"] = "./picnic/" + pathFile;
e.Values["Url"] = "./picnic/" + pathFile;
e.Values["dateEntered"] = DateTime.Now.ToString();
}
}
public bool ThumbnailCallback()
{
return false;
}
}
这使用 FileUpload 和 FormView 来插入。然后我使用 System.Drawing.Imaging 中提供的GetThumnailImage()方法。您可以输入任何宽度和高度值，它会相应地收缩/拉伸。
uploadedimage.GetThumbnailImage(W, H, myCallback, IntPtr.Zero);
希望这可以帮助。
于 2008-10-31T18:50:37.917 回答
0
您可以在使用 ActiveX 控件发送到服务器之前调整大小。这里有一个免费的 ASP.net 图片上传组件（我相信这与 Facebook 实际使用的组件相同）：
http://forums.aurigma.com/yaf_postst2145_Image-Uploader-ASPNET-Control.aspx
让我知道它是否有效，我正在考虑在我的工作项目中实施它。
编辑：看起来对象的包装器是免费的，但实际组件本身将花费您大约 200 美元。我确认它与 Facebook 使用的组件相同。
于 2008-10-31T20:16:21.050 回答
0
图像文件的上传由 ASP.NET 4.0 客户端回调执行。如果您不熟悉客户端回调，那么我建议您查看 ASP.Net AJAX Control Toolkit AsyncFileUpload Control without page refresh or PostBack in ASP.Net Web Page 或 ASP.Net AJAX Update Panel。一旦用户使用文件字段控件选择文件，就会触发回调。
于 2012-08-09T05:28:27.867 回答
0
public string ResizeImageAndSave(int Width, int Height, string imageUrl, string destPath)
{
System.Drawing.Image fullSizeImg = System.Drawing.Image.FromFile(imageUrl);
double widthRatio = (double)fullSizeImg.Width / (double)Width;
double heightRatio = (double)fullSizeImg.Height / (double)Height;
double ratio = Math.Max(widthRatio, heightRatio);
int newWidth = (int)(fullSizeImg.Width / ratio);
int newHeight = (int)(fullSizeImg.Height / ratio);
//System.Drawing.Image.GetThumbnailImageAbort dummyCallBack = new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback);
System.Drawing.Image thumbNailImg = fullSizeImg.GetThumbnailImage(newWidth, newHeight, new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback), IntPtr.Zero);
//DateTime MyDate = DateTime.Now;
//String MyString = MyDate.ToString("ddMMyyhhmmss") + imageUrl.Substring(imageUrl.LastIndexOf("."));
thumbNailImg.Save(destPath, ImageFormat.Jpeg);
thumbNailImg.Dispose();
return "";
}
public bool ThumbnailCallback() { return false; }
于 2015-10-09T19:40:36.350 回答
-1
private void ResizeImage(FileUpload fileUpload)
{
// First we check to see if the user has selected a file
if (fileUpload.HasFile)
{
// Find the fileUpload control
string filename = fileUpload.FileName;
// Check if the directory we want the image uploaded to actually exists or not
if (!Directory.Exists(MapPath(@"Uploaded-Files")))
{
// If it doesn't then we just create it before going any further
Directory.CreateDirectory(MapPath(@"Uploaded-Files"));
}
// Specify the upload directory
string directory = Server.MapPath(@"Uploaded-Files\");
// Create a bitmap of the content of the fileUpload control in memory
Bitmap originalBMP = new Bitmap(fileUpload.FileContent);
// Calculate the new image dimensions
int origWidth = originalBMP.Width;
int origHeight = originalBMP.Height;
int sngRatio = origWidth / origHeight;
int newWidth = 100;
int newHeight = newWidth / sngRatio;
// Create a new bitmap which will hold the previous resized bitmap
Bitmap newBMP = new Bitmap(originalBMP, newWidth, newHeight);
// Create a graphic based on the new bitmap
Graphics oGraphics = Graphics.FromImage(newBMP);
// Set the properties for the new graphic file
oGraphics.SmoothingMode = SmoothingMode.AntiAlias;
oGraphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
// Draw the new graphic based on the resized bitmap
oGraphics.DrawImage(originalBMP, 0, 0, newWidth, newHeight);
// Save the new graphic file to the server
newBMP.Save(directory + "tn_" + filename);
// Once finished with the bitmap objects, we deallocate them.
originalBMP.Dispose();
newBMP.Dispose();
oGraphics.Dispose();
// Write a message to inform the user all is OK
label.Text = "File Name: <b style='color: red;'>" + filename + "</b><br>";
label.Text += "Content Type: <b style='color: red;'>" + fileUpload.PostedFile.ContentType + "</b><br>";
label.Text += "File Size: <b style='color: red;'>" + fileUpload.PostedFile.ContentLength.ToString() + "</b>";
// Display the image to the user
Image1.Visible = true;
Image1.ImageUrl = @"Uploaded-Files/tn_" + filename;
}
else
{
label.Text = "No file uploaded!";
}
}
于 2012-02-15T07:22:11.707 回答