Can't convert image to bytes[] C# - c#

I'm very new to this stuff of saving images to the DB, and even when I thought it was very straight forward, it wasn't. What I'm trying to do is read and image file from the same computer in any format, display it in a picture box, and then convert the image to bytes to save it in the DB. Until now, I can display the image in the picture box, but I can't convert the image to bytes. Here's my code:
private void DisplayImage()
{
if (openFileDialog.ShowDialog(this) == DialogResult.OK)
{
try
{
Stream file;
if ((archivo = openFileDialog.OpenFile()) != null)
{
using (file)
{
pictureBox.Image = Image.FromStream(file);
}
}
}
catch (Exception ex)
{
...
}
}
}
That's a simple method that just displays the image in the picture box. The real problem is with the following method:
public static byte[] ConvertImageToBytes(Image image)
{
if (image != null)
{
MemoryStream ms = new MemoryStream();
using (ms)
{
image.Save(ms, ImageFormat.Bmp);
byte[] bytes = ms.ToArray();
return bytes;
}
}
else
{
return null;
}
}
When it tries to save the image to the memory stream, I get the error:
System.Runtime.InteropServices.ExternalException: A generic error occurred in GDI+.
Any ideas on what's happening?

You should use the RawFormat property of the original image as a parameter to the Save method, not default to a Bitmap. This will avoid image format type errors. eg:
image.Save(ms, image.RawFormat);
ms.Position = 0;
byte [] bytes=ms.ToArray();
I'd advise actually saving images to the file-system and simply storing the file path (preferably relative) in the database.
BLOBs (ie images etc) in a database cannot be indexed, are often stored in a secondary, slower access database area and will quickly blow out the size of the database (slower backups etc).

Cant you simply Read the file and load it to a byte[] using the File class:
byte[] imgData = System.IO.File.ReadAllBytes(#"C:\My Pic\Myfile.jpg");
You can pick the image path from your Open Dialog box.

That particular exception generally means that you are trying to save the image as the wrong format. In your code you specify ImageFormat.Bmp - is it actually a bitmap image, or did you perhaps load it from a JPEG or PNG? Attempting to save as a different format from the one you loaded will fail with ExternalException, as specified in the documentation.
Incidentally, I don't recommend storing images in a database and I believe most people here will agree. Databases may be able to handle this task but they are not optimized for it, and you end up hurting the performance of both your database and your application. Unless you are using SQL Server 2008 FILESTREAM columns, it is more efficient to store images on the file system.

It may be stupid to answer my own question, but I just found out that if I want to convert the Image object to bytes, I have to leave the original stream open. I saw this issue in another page I can't quite remember, and I tested it by leaving the stream open and it's true. So the format wasn't the problem. But I will take the advice of all of you and store the images in a separate directory. Thanks for your help guys!

The problem with this is that stream must be open during the lifetime of of the image otherwise will fail.
One solution that worked for me is just to create a copy of the image like this:
using (var ms = new MemoryStream(bytes))
{
_image = new Bitmap(Image.FromStream(ms));
}

Related

How can I get image content as pixel and create image from it in ASP.NET Core 6 Web API?

I try to save my images on my server, but I can't let my server save file and virus because of that I want to get image content as pixels of rgb and after that I create image by myself.
I can't use bitmap (or other type in C# like bitmapImage, ... etc) and I don't know how I can do this with sixlabors.ImageSharp.
I have some code that I tried but I can't implement the exact logic that I want (code shown here):
[HttpPost("[action]")]
public async Task<IActionResult> Get([FromForm] ImageFormat file)
{
await using var memoryStream = new MemoryStream();
await file.File.CopyToAsync(memoryStream);
IImageFormat format;
using (var image = Image.Load(memoryStream.ToArray(), out format))
{
using (var output = new MemoryStream())
{
image.Save(output, format);
var responseType = format.Name.ToLower();
return File(output.ToArray(), "application/octet-stream", file.File.FileName);
}
}
return null;
}
Can anybody help me with this problem?
i don't see a reason to convert image into image: there are several format zip-algorythms etc.wich you have to support in that case. example jpg is not bitmap, there is convertion issue - quality of image becomes less each conversion time. Image itself is not executable - it can be used only as container for virus body, can't harm your OSystem itself, another executable part should works somewhere.
But even if you would like to store images on disk, in other format - you can convert image to base64 text (one line of code, like example) - it less harmful and well known way to work with any file type. you can zip image by cszip, you can change file name and extension to hide file type.
I don't see a reasson to convert one image to another for this scenario/task.

Overwrite Existing Jpeg File/Replace Existing Jpeg File with edited jpeg file

I have build a program which allows me to insert comment and the title of an Image through System.Image.Drawing so right now, I have trouble trying to overwrite the existing Jpeg file with the one that has comment and title added into it, but I am encountering error while deleting the file, so I'm not sure what to do as I have tried disposing the file but I cant saved it in that case, due to the fact that I disposed it too early, but I cant saved it because the existing file name is not deleted so I'm kinda stuck in the middle right now.
Here are my codes for it:
public string EditComment(string OriginalFilepath, string newFilename)
{
image = System.Drawing.Image.FromFile(OriginalFilepath);
PropertyItem propItem = image.PropertyItems[0];
using (var file = System.Drawing.Image.FromFile(OriginalFilepath))
{
propItem.Id = 0x9286; // this is the id for 'UserComment'
propItem.Type = 2;
propItem.Value = System.Text.Encoding.UTF8.GetBytes("HelloWorld\0");
propItem.Len = propItem.Value.Length;
file.SetPropertyItem(propItem);
PropertyItem propItem1 = file.PropertyItems[file.PropertyItems.Count() - 1];
file.Dispose();
image.Dispose();
string filepath = Filepath;
if (File.Exists(#"C:\Desktop\Metadata"))
{
System.IO.File.Delete(#"C:\Desktop\Metadata");
}
string newFilepath = filepath + newFilename;
file.Save(newFilepath, ImageFormat.Jpeg);//error appears here
return filepath;
}
}
The Error shown are:
An exception of type 'System.ArgumentException' occurred in System.Drawing.dll but was not handled in user code
Additional information: Parameter is not valid.
The problem is that opening an image from file locks the file. You can get around that by reading the file into a byte array, creating a memory stream from that, and then opening the image from that stream:
public string EditComment(string originalFilepath, string newFilename)
{
Byte[] bytes = File.ReadAllBytes(originalFilepath);
using (MemoryStream stream = new MemoryStream(bytes))
using (Bitmap image = new Bitmap(stream))
{
PropertyItem propItem = image.PropertyItems[0];
// Processing code
propItem.Id = 0x9286; // this is the id for 'UserComment'
propItem.Type = 2;
propItem.Value = System.Text.Encoding.UTF8.GetBytes("HelloWorld\0");
propItem.Len = propItem.Value.Length;
image.SetPropertyItem(propItem);
// Not sure where your FilePath comes from but I'm just
// putting it in the same folder with the new name.
String newFilepath;
if (newFilename == null)
newFilepath = originalFilePath;
else
newFilepath = Path.Combine(Path.GetDirectory(originalFilepath), newFilename);
image.Save(newFilepath, ImageFormat.Jpeg);
return newFilepath;
}
}
Make sure you do not dispose your image object inside the using block as you did in your test code. Not only does the using block exist exactly so you don't have to dispose manually, but it's also rather hard to save an image to disk that no longer exists in memory. Similarly, you seem to open the image from file twice. I'm just going to assume all of those were experiments to try to get around the problem, but do make sure to clean those up.
The basic rules to remember when opening images are these:
An Image object created from a file will lock the file during the life cycle of the image object, preventing the file from being overwritten or deleted until the image is disposed.
An Image object created from a stream will need the stream to remain open for the entire life cycle of the image object. Unlike with files, there is nothing actively enforcing this, but after the stream is closed, the image will give errors when saved, cloned or otherwise manipulated.
Contrary to what some people believe, a basic .Clone() call on the image object will not change this behaviour. The cloned object will still keep the reference to the original source.
Note, if you actually want a usable image object that is not contained in a using block, you can use LockBits and Marshal.Copy to copy the byte data of the image object into a new image with the same dimensions and the same PixelFormat, effectively making a full data clone of the original image. (Note: I don't think this works on animated GIF files) After doing that, you can safely dispose the original and just use the new cleanly-cloned version.
There are some other workarounds for actually getting the image out, but most of them I've seen aren't optimal. These are the two most common other valid workarounds for the locking problem:
Create a new Bitmap from an image loaded from file using the Bitmap(Image image) constructor. This new object will not have the link to that file, leaving you free to dispose the one that's locking the file. This works perfectly, but it changes the image's colour depth to 32-bit ARGB, which might not be desired. If you just need to show an image on the UI, this is an excellent solution, though.
Create a MemoryStream as shown in my code, but not in a using block, leaving the stream open as required. Leaving streams open doesn't really seem like a good idea to me. Though some people have said that, since a MemoryStream is just backed by a simple array, and not some external resource, the garbage collector apparently handles this case fine...
I've also seen some people use System.Drawing.ImageConverter to convert from bytes, but I looked into the internals of that process, and what it does is actually identical to the last method here, which leaves a memory stream open.

how i can save image in picturebox without generic error [duplicate]

This seems to be a bit of an infamous error all over the web. So much so that I have been unable to find an answer to my problem as my scenario doesn't fit. An exception gets thrown when I save the image to the stream.
Weirdly this works perfectly with a png but gives the above error with jpg and gif which is rather confusing.
Most similar problem out there relate to saving images to files without permissions. Ironically the solution is to use a memory stream as I am doing....
public static byte[] ConvertImageToByteArray(Image imageToConvert)
{
using (var ms = new MemoryStream())
{
ImageFormat format;
switch (imageToConvert.MimeType())
{
case "image/png":
format = ImageFormat.Png;
break;
case "image/gif":
format = ImageFormat.Gif;
break;
default:
format = ImageFormat.Jpeg;
break;
}
imageToConvert.Save(ms, format);
return ms.ToArray();
}
}
More detail to the exception. The reason this causes so many issues is the lack of explanation :(
System.Runtime.InteropServices.ExternalException was unhandled by user code
Message="A generic error occurred in GDI+."
Source="System.Drawing"
ErrorCode=-2147467259
StackTrace:
at System.Drawing.Image.Save(Stream stream, ImageCodecInfo encoder, EncoderParameters encoderParams)
at System.Drawing.Image.Save(Stream stream, ImageFormat format)
at Caldoo.Infrastructure.PhotoEditor.ConvertImageToByteArray(Image imageToConvert) in C:\Users\Ian\SVN\Caldoo\Caldoo.Coordinator\PhotoEditor.cs:line 139
at Caldoo.Web.Controllers.PictureController.Croppable() in C:\Users\Ian\SVN\Caldoo\Caldoo.Web\Controllers\PictureController.cs:line 132
at lambda_method(ExecutionScope , ControllerBase , Object[] )
at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)
at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClassa.<InvokeActionMethodWithFilters>b__7()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
InnerException:
OK things I have tried so far.
Cloning the image and working on that.
Retrieving the encoder for that MIME passing that with jpeg quality setting.
OK I seem to have found the cause just by sheer luck and its nothing wrong with that particular method, it's further back up the call stack.
Earlier I resize the image and as part of that method I return the resized object as follows. I have inserted two calls to the above method and a direct save to a file.
// At this point the new bitmap has no MimeType
// Need to output to memory stream
using (var m = new MemoryStream())
{
dst.Save(m, format);
var img = Image.FromStream(m);
//TEST
img.Save("C:\\test.jpg");
var bytes = PhotoEditor.ConvertImageToByteArray(img);
return img;
}
It appears that the memory stream that the object was created on has to be open at the time the object is saved. I am not sure why this is. Is anyone able to enlighten me and how I can get around this.
I only return from a stream because after using the resize code similar to this the destination file has an unknown mime type (img.RawFormat.Guid) and Id like the Mime type to be correct on all image objects as it makes it hard write generic handling code otherwise.
EDIT
This didn't come up in my initial search but here's the answer from Jon Skeet
If you are getting that error , then I can say that your application doesn't have a write permission on some directory.
For example, if you are trying to save the Image from the memory stream to the file system , you may get that error.
Please if you are using XP, make sure to add write permission for the aspnet account on that folder.
If you are using windows server (2003,2008) or Vista, make sure that add write permission for the Network service account.
Hope it help some one.
I'll add this cause of the error as well in hopes it helps some future internet traveler. :)
GDI+ limits the maximum height of an image to 65500
We do some basic image resizing, but in resizing we try to maintain aspect ratio. We have a QA guy who's a little too good at this job; he decided to test this with a ONE pixel wide photo that was 480 pixels tall. When the image was scaled to meet our dimensions, the height was north of 68,000 pixels and our app exploded with A generic error occurred in GDI+.
You can verify this yourself with test:
int width = 480;
var height = UInt16.MaxValue - 36; //succeeds at 65499, 65500
try
{
while(true)
{
var image = new Bitmap(width, height);
using(MemoryStream ms = new MemoryStream())
{
//error will throw from here
image.Save(ms, ImageFormat.Jpeg);
}
height += 1;
}
}
catch(Exception ex)
{
//explodes at 65501 with "A generic error occurred in GDI+."
}
It's too bad there's not a friendly .net ArgumentException thrown in the constructor of Bitmap.
This article explains in detail what exactly happens: Bitmap and Image constructor dependencies
In short, for a lifetime of an Image constructed from a stream, the stream must not be destroyed.
So, instead of
using (var strm = new ... ) {
myImage = Image.FromStream(strm);
}
try this
Stream imageStream;
...
imageStream = new ...;
myImage = Image.FromStream(strm);
and close imageStream at the form close or web page close.
You'll also get this exception if you try to save to an invalid path or if there's a permissions issue.
If you're not 100% sure that the file path is available and permissions are correct then try writing a to a text file. This takes just a few seconds to rule out what would be a very simple fix.
var img = System.Drawing.Image.FromStream(incomingStream);
// img.Save(path);
System.IO.File.WriteAllText(path, "Testing valid path & permissions.");
And don't forget to clean up your file.
Save image to bitmap variable
using (var ms = new MemoryStream())
{
Bitmap bmp = new Bitmap(imageToConvert);
bmp.Save(ms, format);
return ms.ToArray();
}
Just in case if someone is doing as stupid stuff as I was.
1. make sure path does exist.
2. make sure you have permissions to write.
3. make sure your path is correct, in my case I was missing file name in the TargetPath :(
it should have said, your path sucks than "A generic error occurred in GDI+"
I also got this error when saving JPEGs, but only for certain images.
My final code:
try
{
img.SaveJpeg(tmpFile, quality); // This is always successful for say image1.jpg, but always throws the GDI+ exception for image2.jpg
}
catch (Exception ex)
{
// Try HU's method: Convert it to a Bitmap first
img = new Bitmap(img);
img.SaveJpeg(tmpFile, quality); // This is always successful
}
I didn't create the images so I can't tell what the difference is.
I'd appreciate if anyone could explain that.
This is my SaveJpeg function just FYI:
private static void SaveJpeg(this Image img, string filename, int quality)
{
EncoderParameter qualityParam = new EncoderParameter(Encoder.Quality, (long)quality);
ImageCodecInfo jpegCodec = GetEncoderInfo("image/jpeg");
EncoderParameters encoderParams = new EncoderParameters(1);
encoderParams.Param[0] = qualityParam;
img.Save(filename, jpegCodec, encoderParams);
}
private static ImageCodecInfo GetEncoderInfo(string mimeType)
{
var encoders = ImageCodecInfo.GetImageEncoders();
var encoder = encoders.SingleOrDefault(c => string.Equals(c.MimeType, mimeType, StringComparison.InvariantCultureIgnoreCase));
if (encoder == null) throw new Exception($"Encoder not found for mime type {mimeType}");
return encoder;
}
I found that if one of the parent folders where I was saving the file had a trailing space then GDI+ would throw the generic exception.
In other words, if I tried to save to "C:\Documents and Settings\myusername\Local Settings\Temp\ABC DEF M1 Trended Values \Images\picture.png" then it threw the generic exception.
My folder name was being generated from a file name that happened to have a trailing space so it was easy to .Trim() that and move on.
if your code is as follows then also this error occurs
private Image GetImage(byte[] byteArray)
{
using (var stream = new MemoryStream(byteArray))
{
return Image.FromStream(stream);
}
}
The correct one is
private Image GetImage(byte[] byteArray)
{
var stream = new MemoryStream(byteArray))
return Image.FromStream(stream);
}
This may be because we are returning from the using block
Had a very similar problem and also tried cloning the image which doesn't work. I found that the best solution was to create a new Bitmap object from the image that was loaded from the memory stream. That way the stream can be disposed of e.g.
using (var m = new MemoryStream())
{
var img = new Bitmap(Image.FromStream(m));
return img;
}
Hope this helps.
This is an expansion / qualification of Fred's response which stated: "GDI limits the height of an image to 65534". We ran into this issue with one of our .NET applications, and having seen the post, our outsourcing team raised their hands in the air and said they couldn't fix the problem without major changes.
Based on my testing, it's possible to create / manipulate images with a height larger than 65534, but the issue arises when saving to a stream or file IN CERTAIN FORMATS. In the following code, the t.Save() method call throws our friend the generic exception when the pixel height is 65501 for me. For reasons of curiosity, I repeated the test for width, and the same limit applied to saving.
for (int i = 65498; i <= 100000; i++)
{
using (Bitmap t = new Bitmap(800, i))
using (Graphics gBmp = Graphics.FromImage(t))
{
Color green = Color.FromArgb(0x40, 0, 0xff, 0);
using (Brush greenBrush = new SolidBrush(green))
{
// draw a green rectangle to the bitmap in memory
gBmp.FillRectangle(greenBrush, 0, 0, 799, i);
if (File.Exists("c:\\temp\\i.jpg"))
{
File.Delete("c:\\temp\\i.jpg");
}
t.Save("c:\\temp\\i.jpg", ImageFormat.Jpeg);
}
}
GC.Collect();
}
The same error also occurs if you write to a memory stream.
To get round it, you can repeat the above code and substitute ImageFormat.Tiff or ImageFormat.Bmp for ImageFormat.Jpeg.
This runs up to heights / widths of 100,000 for me - I didn't test the limits. As it happens .Tiff was a viable option for us.
BE WARNED
The in memory TIFF streams / files consume more memory than their JPG counterparts.
Error occurring because of Permission. make sure folder have ALL THE PERMISSION.
public Image Base64ToImage(string base64String)
{
// Convert Base64 String to byte[]
byte[] imageBytes = Convert.FromBase64String(base64String);
MemoryStream ms = new MemoryStream(imageBytes, 0,
imageBytes.Length);
// Convert byte[] to Image
ms.Write(imageBytes, 0, imageBytes.Length);
Image image = Image.FromStream(ms, true);
return image;
}
img.Save("YOUR PATH TO SAVE IMAGE")
SOLVED - I had this exact problem. The fix, for me, was to up the disk quota for IUSR on the IIS server. In this instance, we have a catalog app with images of items and such. The upload quota for the "Anonymous Web User" was set to 100MB, which is the default for this particular hosting company's IIS servers. I upped it to 400MB and was able to upload images without error.
This might not be your issue, but if it is, it's an easy fix.
In my case the problem was in the path I was saving (the root C:\). Changing it to D:\111\ made the exception go away.
Another cause for this error - the path you indicate in the Save method of the Bitmap instance doesn't exist or you haven't supplied a full / valid path.
Just had this error because I was passing in a filename and not a full path!
It happens!
My turn!
using (System.Drawing.Image img = Bitmap.FromFile(fileName))
{
... do some manipulation of img ...
img.Save(fileName, System.Drawing.Imaging.ImageFormat.Jpeg);
}
Got it on the .Save... because the using() is holding the file open, so I can't overwrite it. Maybe this will help someone in the future.
Same problem I was facing. But in my case, I was trying to save file in C drive and it was not accessible. So I tried it to save in D drive which was fully accessible and I succeeded.
So first check your folders in which you are trying to save. You must have all (read and write) rights for that particular folder.
Simple, create a new instance of Bitmap solves the problem.
string imagePath = Path.Combine(Environment.CurrentDirectory, $"Bhatti{i}.png");
Bitmap bitmap = new Bitmap(image);
bitmap.Save(imagePath);
I notice that your "jpeg" case is actually:
default:
format = ImageFormat.Jpeg;
break;
Are you sure that the format is jpeg and not something else?
I'd try:
case "image/jpg": // or "image/jpeg" !
format = ImageFormat.Jpeg;
break;
Or check what imageToConvert.MimeType() is actually returning.
UPDATE
Is there any other initialisation you need to do to the MemoryStream object?
I had this issue on a test server but not on the live server.
I was writing the image to a stream, so it wasn't a permission issue.
I'd been directly deploying some of the .dll's to the test server.
Deploying the entire solution fixed the issue, so it was probably a weird compilation mismatch
Just to throw another possible solution on the pile, I'll mention the case I ran into with this error message. The method Bitmap.Save would throw this exception when saving an bitmap I had transformed and was displaying. I discovered it would not throw the exception if the statement had a breakpoint on it, nor would it if the Bitmap.Save was preceeded by Thread.Sleep(500) so I suppose there is some sort of resource contention going on.
Simply copying the image to a new Bitmap object was enough to prevent this exception from appearing:
new Bitmap(oldbitmap).Save(filename);
One other cause of this error and that solve my problème is that your application doesn't have a write permission on some directory.
so to complete the answer of savindra : https://stackoverflow.com/a/7426516/6444829.
Here is how you Grant File Access to IIS_IUSERS
To provide access to an ASP.NET application, you must grant access to the IIs_IUSERS.
To grant read, write, and modify permissions to a specific File or Folder
In Windows Explorer, locate and select the required file.
Right click the file, and then click Properties.
In the Properties dialog box, click the Security tab.
On the Security tab, examine the list of users.
(If your application is running as a Network Service, add the network service account in the list and grant it the permission.
In the Properties dialog box, click IIs_IUSERS, and in the Permissions for NETWORK SERVICE section, select the Read, Write, and Modify permissions.
Click Apply, and then click OK.
this worked for me in my IIS of windows server 2016 and local IIS windows 10.
We had a similar problem on generating a PDF or resize image using ImageProcessor lib on production server.
Recycle the application pool fix the issue.
If you are trying to save an image to a remote location be sure to add the NETWORK_SERVICE user account into the security settings and give that user read and write permissions. Otherwise it is not going to work.
byte[] bts = (byte[])page1.EnhMetaFileBits;
using (var ms = new MemoryStream(bts))
{
var image = System.Drawing.Image.FromStream(ms);
System.Drawing.Image img = image.GetThumbnailImage(200, 260, null, IntPtr.Zero);
img.Save(NewPath, System.Drawing.Imaging.ImageFormat.Png);
}
I also get this error because i'm trying to save images with the same name of previous saved images.
Make sure that you don't save images with duplicate name.
Use for thar for example a 'Random' function (How does C#'s random number generator work?)
or for example generate a Guid (http://betterexplained.com/articles/the-quick-guide-to-guids/)
in my case, path was wrong
just use this
String path = Server.MapPath("~/last_img.png");//Path
For me I was using the Image.Save(Stream, ImageCodecInfo, EncoderParameters) and apparently this was causing the infamous A generic error occurred in GDI+ error.
I was trying to use EncoderParameter to save the jpegs in 100% quality. This was working perfectly on "my machine" (doh!) and not on production.
When I used the Image.Save(Stream, ImageFormat) instead, the error disappeared! So like an idiot I continued to use the latter although it saves them in default quality which I assume is just 50%.
Hope this info helps someone.
I encountered the problem too. The problem was due to the loading stream being disposed. But I did not dispose it, it was inside .Net framework. All I had to do was use:
image_instance = Image.FromFile(file_name);
instead of
image_instance.Load(file_name);
image_instance is of type System.Windows.Forms.PictureBox!
PictureBox's Load() disposes the stream which the image was loaded from, and I did not know that.

How can I clone FileStream type?

How can I clone FileStream type?
The problem is that I using MagickNet.Image(inputStream) to get the image distentions before saving it, but it seems to closing the inputStream.
So, I can send a clone of inputStream to the function, so the function cannot edit the real inputStream object?
This is my function:
public Picture GetPictureDimension(Stream inputStream, Picture picture)
{
var img = new MagickNet.Image(inputStream);
picture.Width = img.Columns;
picture.Height = img.Rows;
return picture;
}
You could just re-open the file? But to keep a single Stream without it getting closed, you could try NonClosingStreamWrapper in MiscUtil. Just be sure to reset the Position if appropriate.
You didn't post full code, but I imagine that MagickNet.Image(inputStream) gets the full image and you only use the Size from that, and later you load the Image a second time.
So a more practical solution would be to get and hold the Image in memory just once. That gives you access to the Size.
Edit:
You don't seem to realize it but you are asking how to load the Image twice (w/o reopening the stream). I do think it is more efficient to load it just once.
Picture is a XNA class, right? I don't know to much about that but you could try something like:
public Picture GetPictureDimension(Stream inputStream, ref Picture picture)
{
var img = new MagickNet.Image(inputStream);
picture = new Picture(img); // just guessing here
//picture.Width = img.Columns;
//picture.Height = img.Rows;
return picture;
}

Saving a modified image to the original file using GDI+

I was loading a Bitmap Image from a File. When I tried to save the Image to another file I got the following error "A generic error occurred in GDI+". I believe this is because the file is locked by the image object.
Ok so tried calling the Image.Clone function. This still locks the file.
hmm. Next I try loading a Bitmap Image from a FileStream and load the image into memory so GDI+ doesn't lock the file. This works great except I need to generate thumbnails using Image.GetThumbnailImage method it throws an out of memory exception. Apparently I need to keep the stream open to stop this exception but if I keep the stream open then the file remains locked.
So no good with that method. In the end I created a copy of the file. So now I have 2 versions of the file. 1 I can lock and manipulate in my c# program. This other original file remains unlocked to which I can save modifications to. This has the bonus of allowing me to revert changes even after saving them because I'm manipulating the copy of the file which cant change.
Surely there is a better way of achieving this without having to have 2 versions of the image file. Any ideas?
Well if you're looking for other ways to do what you're asking, I reckon it should work to create a MemoryStream, and read out the FileStream to it, and load the Image from that stream...
var stream = new FileStream("original-image", FileMode.Open);
var bufr = new byte[stream.Length];
stream.Read(bufr, 0, (int)stream.Length);
stream.Dispose();
var memstream = new MemoryStream(bufr);
var image = Image.FromStream(memstream);
Or something prettier to that extent.
Whether or not that's the way you should go about solving that problem, I don't know. :)
I've had a similar problem and wound up fixing it like this.
I have since found an alternative method to clone the image without locking the file. Bob Powell has it all plus more GDI resources.
//open the file
Image i = Image.FromFile(path);
//create temporary
Image t=new Bitmap(i.Width,i.Height);
//get graphics
Graphics g=Graphics.FromImage(t);
//copy original
g.DrawImage(i,0,0);
//close original
i.Dispose();
//Can now save
t.Save(path)
I had a similar problem. But I knew, that I will save the image as a bitmap-file. So I did this:
public void SaveHeightmap(string path)
{
if (File.Exists(path))
{
Bitmap bitmap = new Bitmap(image); //create bitmap from image
image.Dispose(); //delete image, so the file
bitmap.Save(path); //save bitmap
image = (Image) bitmap; //recreate image from bitmap
}
else
//...
}
Sure, thats not the best way, but its working :-)

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