I have the Image of a PictureBox pointing to a certain file "A". At execution time I want to change the Image of the PictureBox to a different one "B" but I get the following error:
"A first chance exception of type 'System.IO.IOException' occurred in mscorlib.dll
Additional information: The process cannot access the file "A" because it is being used by another process."
I'm setting the Image as follows:
pbAvatar.Image = new Bitmap(filePath);
How can I unlock the first file?
Here is my approach to opening an image without locking the file...
public static Image FromFile(string path)
{
var bytes = File.ReadAllBytes(path);
var ms = new MemoryStream(bytes);
var img = Image.FromStream(ms);
return img;
}
UPDATE: I did some perf tests to see which method was the fastest. I compared it to #net_progs "copy from bitmap" answer (which seems to be the closest to correct, though does have some issues). I loaded the image 10000 times for each method and calculated the average time per image. Here are the results:
Loading from bytes: ~0.26 ms per image.
Copying from bitmap: ~0.50 ms per image.
The results seem to make sense since you have to create the image twice using the copy from bitmap method.
UPDATE:
if you need a BitMap you can do:
return (Bitmap)Image.FromStream(ms);
This is a common locking question widely discussed over the web.
The suggested trick with stream will not work, actually it works initially, but causes problems later. For example, it will load the image and the file will remain unlocked, but if you try to save the loaded image via Save() method, it will throw a generic GDI+ exception.
Next, the way with per pixel replication doesn't seem to be solid, at least it is noisy.
What I found working is described here: http://www.eggheadcafe.com/microsoft/Csharp/35017279/imagefromfile--locks-file.aspx
This is how the image should be loaded:
Image img;
using (var bmpTemp = new Bitmap("image_file_path"))
{
img = new Bitmap(bmpTemp);
}
I was looking for a solution to this problem and this method works fine for me so far, so I decided to describe it, since I found that many people advise the incorrect stream approach here and over the web.
Using a filestream will unlock the file once it has been read from and disposed:
using (var fs = new System.IO.FileStream("c:\\path to file.bmp", System.IO.FileMode.Open))
{
var bmp = new Bitmap(fs);
pct.Image = (Bitmap) bmp.Clone();
}
Edit: Updated to allow the original bitmap to be disposed, and allow the FileStream to be closed.
THIS ANSWER IS NOT SAFE - See comments, and see discussion in net_prog's answer. The Edit to use Clone does not make it any safer - Clone clones all fields, including the filestream reference, which in certain circumstances will cause a problem.
You can't dispose / close a stream while a bitmap object is still using it. (Whether the bitmap object will need access to it again is only deterministic if you know what type of file you are working with and exactly what operations you will be performing. -- for example for SOME .gif format images, the stream is closed before the constructor returns.)
Clone creates an "exact copy" of the bitmap (per documentation; ILSpy shows it calling native methods, so it's too much to track down right now) likely, it copies that Stream data as well -- or else it wouldn't be an exact copy.
Your best bet is creating a pixel-perfect replica of the image -- though YMMV (with certain types of images there may be more than one frame, or you may have to copy palette data as well.) But for most images, this works:
static Bitmap LoadImage(Stream stream)
{
Bitmap retval = null;
using (Bitmap b = new Bitmap(stream))
{
retval = new Bitmap(b.Width, b.Height, b.PixelFormat);
using (Graphics g = Graphics.FromImage(retval))
{
g.DrawImage(b, Point.Empty);
g.Flush();
}
}
return retval;
}
And then you can invoke it like such:
using (Stream s = ...)
{
Bitmap x = LoadImage(s);
}
As far as I know, this is 100% safe, since the resulting image is 100% created in memory, without any linked resources, and with no open streams left behind in memory. It acts like any other Bitmap that's created from a constructor that doesn't specify any input sources, and unlike some of the other answers here, it preserves the original pixel format, meaning it can be used on indexed formats.
Based on this answer, but with extra fixes and without external library import.
/// <summary>
/// Clones an image object to free it from any backing resources.
/// Code taken from http://stackoverflow.com/a/3661892/ with some extra fixes.
/// </summary>
/// <param name="sourceImage">The image to clone</param>
/// <returns>The cloned image</returns>
public static Bitmap CloneImage(Bitmap sourceImage)
{
Rectangle rect = new Rectangle(0, 0, sourceImage.Width, sourceImage.Height);
Bitmap targetImage = new Bitmap(rect.Width, rect.Height, sourceImage.PixelFormat);
targetImage.SetResolution(sourceImage.HorizontalResolution, sourceImage.VerticalResolution);
BitmapData sourceData = sourceImage.LockBits(rect, ImageLockMode.ReadOnly, sourceImage.PixelFormat);
BitmapData targetData = targetImage.LockBits(rect, ImageLockMode.WriteOnly, targetImage.PixelFormat);
Int32 actualDataWidth = ((Image.GetPixelFormatSize(sourceImage.PixelFormat) * rect.Width) + 7) / 8;
Int32 h = sourceImage.Height;
Int32 origStride = sourceData.Stride;
Boolean isFlipped = origStride < 0;
origStride = Math.Abs(origStride); // Fix for negative stride in BMP format.
Int32 targetStride = targetData.Stride;
Byte[] imageData = new Byte[actualDataWidth];
IntPtr sourcePos = sourceData.Scan0;
IntPtr destPos = targetData.Scan0;
// Copy line by line, skipping by stride but copying actual data width
for (Int32 y = 0; y < h; y++)
{
Marshal.Copy(sourcePos, imageData, 0, actualDataWidth);
Marshal.Copy(imageData, 0, destPos, actualDataWidth);
sourcePos = new IntPtr(sourcePos.ToInt64() + origStride);
destPos = new IntPtr(destPos.ToInt64() + targetStride);
}
targetImage.UnlockBits(targetData);
sourceImage.UnlockBits(sourceData);
// Fix for negative stride on BMP format.
if (isFlipped)
targetImage.RotateFlip(RotateFlipType.Rotate180FlipX);
// For indexed images, restore the palette. This is not linking to a referenced
// object in the original image; the getter of Palette creates a new object when called.
if ((sourceImage.PixelFormat & PixelFormat.Indexed) != 0)
targetImage.Palette = sourceImage.Palette;
// Restore DPI settings
targetImage.SetResolution(sourceImage.HorizontalResolution, sourceImage.VerticalResolution);
return targetImage;
}
To call, simply use:
/// <summary>Loads an image without locking the underlying file.</summary>
/// <param name="path">Path of the image to load</param>
/// <returns>The image</returns>
public static Bitmap LoadImageSafe(String path)
{
using (Bitmap sourceImage = new Bitmap(path))
{
return CloneImage(sourceImage);
}
}
Or, from bytes:
/// <summary>Loads an image from bytes without leaving open a MemoryStream.</summary>
/// <param name="fileData">Byte array containing the image to load.</param>
/// <returns>The image</returns>
public static Bitmap LoadImageSafe(Byte[] fileData)
{
using (MemoryStream stream = new MemoryStream(fileData))
using (Bitmap sourceImage = new Bitmap(stream)) {
{
return CloneImage(sourceImage);
}
}
Here's the technique I'm currently using, and seems to work best. It has the advantage of producing a Bitmap object with the same pixel format (24-bit or 32-bit) and resolution (72 dpi, 96 dpi, whatever) as the source file.
// ImageConverter object used to convert JPEG byte arrays into Image objects. This is static
// and only gets instantiated once.
private static readonly ImageConverter _imageConverter = new ImageConverter();
This can be used as often as needed, as follows:
Bitmap newBitmap = (Bitmap)_imageConverter.ConvertFrom(File.ReadAllBytes(fileName));
Edit:
Here's an update of the above technique: https://stackoverflow.com/a/16576471/253938
(The accepted answer is wrong. When you try to LockBits(...) on the cloned bitmap eventually you will encounter GDI+ errors.)
I see only 3 ways to get out of this:
copy your file to a temporary file and open that the easy way new Bitmap(temp_filename)
open your file, read image, create a pixel-size-pixelformat copy (don't Clone()) and dispose the first bitmap
(accept the locked-file-feature)
I suggest to use PixelMap which is available on NuGet
Very easy to use and much faster than standard Bitmap from .NET
PixelMap pixelMap = new PixelMap(path);
pictureBox1.Image = pixelMap.GetBitmap();
Read it into the stream, create bitmap, close the stream.
Related
I have the following codes to convert an image(bitmap) to byte array:
public byte[] ConvertImageToByteArray(Image imageToConvert, ImageFormat formatOfImage)
{
byte[] Ret;
try
{
using (MemoryStream ms = new MemoryStream())
{
imageToConvert.Save(ms, formatOfImage);
Ret = ms.ToArray();
}
}
catch (Exception)
{
throw;
}
return Ret;
}
and Convert byte array back to image(bitmap):
public Bitmap ConvertByteArrayToImage(byte[] myByteArray)
{
Image newImage;
using (MemoryStream ms = new MemoryStream(myByteArray, 0, myByteArray.Length))
{
ms.Write(myByteArray, 0, myByteArray.Length);
newImage = Image.FromStream(ms, true);
}
return newImage;
}
Here's my Main Program:
byte[] test = ConvertImageToByteArray(Image.FromFile("oldImage.bmp"), ImageFormat.Bmp);
Bitmap bmp = ConvertByteArrayToImage(test);
bmp.Save("newImage.bmp");
But when I compare both of the image files(old & new bitmap images), their checksum appeared to be different. Any reason for that happening? How to fix it to maintain its integrity?
Basically, there are many ways an identical image can be encoded in a BMP file. If I try your example on a random image I found, I see the .NET Bitmap class saves the file without filling the biSizeImage field in the BITMAPINFOHEADER structure in the BMP header (but the original image produced by IrfanView has it filled), which is a completely correct and documented possibility. (“This may be set to zero for BI_RGB bitmaps.”)
And this is definitely not the only variable thing in the BMP format. For instance, there are multiple possible orderings of pixel data in the image (top-to-bottom, bottom-to-top), specified in the header. (“If biHeight is positive, the bitmap is a bottom-up DIB and its origin is the lower-left corner. If biHeight is negative, the bitmap is a top-down DIB and its origin is the upper-left corner.”)
So, if you receive any BMP file from a source not under your control and really need to produce an image using exactly the same BMP variant, you have a lot work to do, and I don’t think you could use the standard .NET helper classes for that.
See also this question: Save bitmap to file has zero in image size field
After chatting a bit, you solution comes down to reading and writing bytes, take the image object out the equation and just deal with the raw bytes.
To read the file:
MemoryStream ms = new MemoryStream(File.ReadAllBytes("filename"));
To write the file:
File.WriteAllBytes("outputfile", ms.ToArray());
I am using .NET4.5, Windows Forms and C#.
I am loading an image onto a button using:
theButton.BackgroundImage = Image.FromFile("file.png");
The issue is that my button is 128x128 and the image is 4000x8000. The line above consumes very large amounts of memory because file.png is so large.
Does anyone know of a technique I can use to reduce this memory footprint? I am thinking of some function like this:
Image.FromFile(file,width,height);
Any pointers? Thanks.
Yes it works. It's quite simple to resize the image and then display it on button.
But, I don't think that the above code maintains the aspect ratio of the image.
It's quite simple to resize the image with aspect ratio; and then display it on button.
Below is the sample code helps you to resize the image by maintaining the aspect ratio.
You can define a new class or implement the "ResizeImage" method in an existing class. Whichever is comfortable to you.
public class ImageManipulation
{
public static Bitmap ResizeImage(Bitmap originalBitmap, int newWidth, int maxHeight, bool onlyResizeIfWider)
{
if (onlyResizeIfWider)
{
if (originalBitmap.Width <= newWidth)
{
newWidth = originalBitmap.Width;
}
}
int newHeight = originalBitmap.Height * newWidth / originalBitmap.Width;
if (newHeight > maxHeight)
{
// Resize with height instead
newWidth = originalBitmap.Width * maxHeight / originalBitmap.Height;
newHeight = maxHeight;
}
var alteredImage = new Bitmap(originalBitmap, new Size(newWidth, newHeight));
alteredImage.SetResolution(72, 72);
return alteredImage;
}
}
USAGE:
private void DisplayPhoto()
{
// make sure the file is JPEG or GIF
System.IO.FileInfo testFile = new System.IO.FileInfo(myFile);
// Create a new stream to load this photo into
FileStream myFileStream = new FileStream(myFile, FileMode.Open, FileAccess.Read);
// Create a buffer to hold the stream of bytes
photo = new byte[myFileStream.Length];
// Read the bytes from this stream and put it into the image buffer
myStream.Read(photo, 0, (int)myFileStream.Length);
// Close the stream
myFileStream.Close();
// Create a new MemoryStream and write all the information from
// the byte array into the stream
MemoryStream myStream = new MemoryStream(photo, true);
myStream.Write(photo, 0, photo.Length);
// Use the MemoryStream to create the new BitMap object
Bitmap FinalImage = new Bitmap(myStream);
upicPhoto.Image = ImageManipulation.ResizeImage(
FinalImage,
upicPhoto.Width,
upicPhoto.Height,
true);
// Close the stream
myStream.Close();
}
I think your best path here is to just resize the image, to 128x128.
An image that large is always going to take up a lot of memory, no matter what you do with it.
This will also allow you to make the image something that will look good at that size.
This is quite a general problem, AFAIK you have few possibilities
Compress image before uploading , in real world this will not work.
Put a check on size and dimensions of image, in real world it works, even linkedin, facebook they won't allow us to upload images above there specified dimensions.
Use buffering, this is cleanest way you can do in .net
Use some third party plugins or development enviornment, I have done it in Silverlight
How can I load an Image in WPF using the DotNetZip ZipEntry class.
using (ZipFile file = ZipFile.Read ("Images.zip"))
{
ZipEntry entry = file["Image.png"];
uiImage.Source = ??
}
ZipEntry type exposes an OpenReader() method that returns a readable stream. This may work for you in this way:
// I don't know how to initialize these things
BitmapImage image = new BitmapImage(...?...);
ZipEntry entry = file["Image.png"];
image.StreamSource = entry.OpenReader();
I am not certain this will work because:
I don't know the BitmapImage class or how to manage it, or how to create one from a stream. I may have the code wrong there.
the ZipEntry.OpenReader() method internally sets and uses a file pointer that is managed by the ZipFile instance, and the readable stream is valid only for the lifetime of the ZipFile instance itself.
The stream returned by ZipEntry.OpenReader() must be read before any subsequent calls to ZipEntry.OpenReader() for other entries, and before the ZipFile goes out of scope. If you need to extract and read multiple images from a zip file, in no particular order, or you need to read after you're finished with the ZipFile, then you'll need to work around that limitation. To do that, you could call OpenReader() and read all the bytes for each particular entry into a distinct MemoryStream.
Something like this:
using (ZipFile file = ZipFile.Read ("Images.zip"))
{
ZipEntry entry = file["Image.png"];
uiImage.StreamSource = MemoryStreamForZipEntry(entry);
}
....
private Stream MemoryStreamForZipEntry(ZipEntry entry)
{
var s = entry.OpenReader();
var ms = new MemoryStream(entry.UncompressedSize);
int n;
var buffer = new byte[1024];
while ((n= s.Read(buffer,0,buffer.Length)) > 0)
ms.Write(buffer,0,n);
ms.Seek(0, SeekOrigin.Begin);
return ms;
}
You could potentially use a BitmapSource, but the raw image data will still need to be decompressed, I'm not sure if opening the zip in the manner that you do actually decompresses on the fly so that, or not; but once you have that you ought to be able to do something like the following:
BitmapSource bitmap = BitmapSource.Create(
width, height, 96, 96, pf, null, rawImage, rawStride);
Where rawImage would be the bytes of the images file in the form of an array. Other arguments include the DPI and pixel format, which you should now or be able to determine.
In order to get the rawStride value, MSDN has the following sample as an example:
PixelFormat pf = PixelFormats.Bgr32;
int rawStride = (width * pf.BitsPerPixel + 7) / 8;
I was working on my college project where i was trying to change bit values of a Bitmap.
I am loading the bitmap to the memory stream, then extracting it to byte[] array. Now I was changing few central bits of this byte[] array and then converting it back to a bitmap image.
But i got a run time exception that "Invalid Bitmap".
Does a bitmap have some special format instead of simple bits???
Following is the code used by me:
MemoryStream mstream = new MemoryStream();
Bitmap b = new Bitmap(#"D:\my_pic.bmp");
b.Save(mstream, System.Drawing.Imaging.ImageFormat.Bmp);
byte[] ba = mstream.ToArray();
mstream.Close();
byte[] _Buffer = null;
System.IO.FileStream _FileStream = new System.IO.FileStream(_FileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);
System.IO.BinaryReader _BinaryReader = new System.IO.BinaryReader(_FileStream);
long _TotalBytes = new System.IO.FileInfo(_FileName).Length;
_Buffer = _BinaryReader.ReadBytes((Int32)_TotalBytes);
// close file reader
_FileStream.Close();
_FileStream.Dispose();
_BinaryReader.Close();
int leng1 = ba.Length;
int leng2=_Buffer.Length;
for(i=(leng1)/2;i<leng1;i++)
{
for(j=0;j<leng2;j++)
{
ba[i]=_Buffer[j];
}
if(j==(leng2-1))
{
break;
}
}
TypeConverter tc = TypeDescriptor.GetConverter(typeof(Bitmap));
Bitmap bitmap1 = (Bitmap)tc.ConvertFrom(ba);
You must have your own goal to want to operate at this low level with a bitmap and that's fine. Unless you are performance bound it is way easier to do graphics at the graphics API level. Even if you are performance sensitive, other people have cut a path through the jungle already.
Back to the question. The BMP file format is simpler than some others but still comes in many varieties. Here is a detailed introduction to the gory details of the BMP format:
BMP file format
Now if you are just parsing your own BMP files and you know they are 32-bit RGB, and the header is going to be such-and-such a size which you can skip over, etc, then that might work for you. If you need to handle any old BMP it gets messy real fast which is why the libraries try to take care of everything for you.
I'm working with big size images (for ex. 16000x9440 px) and cut some regions for other things. I'm getting an exception "Out of memory" when create a new Bitmap instance:
using (FileStream fileStream = new FileStream(mapFileResized, FileMode.Open))
{
byte[] data = new byte[fileStream.Length];
fileStream.Read(data, 0, data.Length);
using (MemoryStream memoryStream = new MemoryStream(data))
{
using (Bitmap src = new Bitmap(memoryStream)) // <-- exception
{
tile = new Bitmap(tileWidth, tileHeight, PixelFormat.Format24bppRgb);
tile.SetResolution(src.HorizontalResolution, src.VerticalResolution);
tile.MakeTransparent();
using (Graphics grRect = Graphics.FromImage(tile))
{
grRect.CompositingQuality = CompositingQuality.HighQuality;
grRect.SmoothingMode = SmoothingMode.HighQuality;
grRect.DrawImage(
src,
new RectangleF(0, 0, tileWidth, tileHeight),
rTile,
GraphicsUnit.Pixel
);
}
}
}
}
When I use small image sizes (for ex. 8000x4720 px) then all work fine.
How can I work with big size images?
PS tile Bitmap is disposed in finally block.
Best regards, Alex.
You are using about a gigabyte of ram, not very suprising that you run out of memory.
Assuming you use a 32bpp Fileformat with 16000x9440 pixel you get a filesize of about:
16000 * 9440 * (32/8) = ~576MB
byte[] data = new byte[fileStream.Length];
fileStream.Read(data, 0, data.Length);
using (MemoryStream memoryStream = new MemoryStream(data))
{
[... snip ...]
}
You load the whole File into a memory stream, this requires 576MB.
[... snip ...]
using (Bitmap src = new Bitmap(memoryStream)) // <-- exception
{
[... snip ...]
}
[... snip ...]
You load the whole stream contents into a bitmap, this requires at least another 576MB (depending on how much memory the bitmap requires per pixel, should be at least 4, propably more). At that point you have the image twice in memory which seriously hurts for such big images.
You can reduce the memory footprint by getting rid of the memory stream and loading the bitmap directly from the file stream.
Another solution would be to load only a part of the bitmap and load the other parts on-demand (much like google maps), but i can't help you with that solution, might require reading the bitmap manually.
Not a complete answer to your question, but you are probably better of using a library like ImageMagick.NET
MemoryStream is implemented using an array of bytes that stores the data. If you read more data than the array can hold, a new array of double size is allocated and the bytes copied from one array to the other.
Since you apparently know how much data you're going to need, you can allocated the correct size up front and thus avoid the resizing.
However, once you reach a certain size you will run out of memory. .NET imposes a 2 GB limit on a single object (even on 64 bit), so the internal array in MemoryStream will never be able to grow beyond that. If your image is larger than that you'll get an out of memory exception.