Develop Reference

Resize image and save as file

My objective is to resize an image that I create and after resizing it with the same ratio and finally save it on my drive.
so just below the code is working I'm 100% sure that the code work
The problem is on the ResizeImage method.
Everything work well until the decoder, I don't know why but it always return me the code:
System.Exception: 'The component was not found. (Exception from HRESULT: 0x88982F50)'
private async Task<StorageFile> SaveSquaresPhotos(WriteableBitmap WB, FileFormat fileFormat, string username) {
string FileName = username + "-Carre.";
Guid BitmapEncoderGuid = BitmapEncoder.JpegEncoderId;
switch (fileFormat)
{
case FileFormat.Jpeg:
FileName += "jpeg";
BitmapEncoderGuid = BitmapEncoder.JpegEncoderId;
break;
case FileFormat.Png:
FileName += "png";
BitmapEncoderGuid = BitmapEncoder.PngEncoderId;
break;
case FileFormat.Bmp:
FileName += "bmp";
BitmapEncoderGuid = BitmapEncoder.BmpEncoderId;
break;
case FileFormat.Tiff:
FileName += "tiff";
BitmapEncoderGuid = BitmapEncoder.TiffEncoderId;
break;
case FileFormat.Gif:
FileName += "gif";
BitmapEncoderGuid = BitmapEncoder.GifEncoderId;
break;
}
if (config.getFolder() == null)
{
try
{
var resourceLoader = Windows.ApplicationModel.Resources.ResourceLoader.GetForCurrentView();
var folder = await StorageFolder.GetFolderFromPathAsync(resourceLoader.GetString("Folder"));
var file = await folder.CreateFileAsync(FileName, CreationCollisionOption.GenerateUniqueName);
using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite))
{
BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoderGuid, stream);
Stream pixelStream = WB.PixelBuffer.AsStream();
byte[] pixels = new byte[pixelStream.Length];
await pixelStream.ReadAsync(pixels, 0, pixels.Length);
encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore,
(uint)WB.PixelWidth,
(uint)WB.PixelHeight,
96.0,
96.0,
pixels);
await ResizeImage(pixels, 75, 75, pixelStream);
await encoder.FlushAsync();
}
return file;
}
catch {
var file = await _captureFolder.CreateFileAsync(FileName, CreationCollisionOption.GenerateUniqueName);
using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite))
{
BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoderGuid, stream);
Stream pixelStream = WB.PixelBuffer.AsStream();
byte[] pixels = new byte[pixelStream.Length];
await pixelStream.ReadAsync(pixels, 0, pixels.Length);
encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore,
(uint)WB.PixelWidth,
(uint)WB.PixelHeight,
96.0,
96.0,
pixels);
await ResizeImage(pixels, 75, 75, pixelStream);
await encoder.FlushAsync();
}
return file;
}
}
else
{
var file = await config.getFolder().CreateFileAsync(FileName, CreationCollisionOption.GenerateUniqueName);
using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite))
{
BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoderGuid, stream);
Stream pixelStream = WB.PixelBuffer.AsStream();
byte[] pixels = new byte[pixelStream.Length];
await pixelStream.ReadAsync(pixels, 0, pixels.Length);
encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore,
(uint)WB.PixelWidth,
(uint)WB.PixelHeight,
96.0,
96.0,
pixels);
await ResizeImage(pixels, 75, 75, pixelStream);
await encoder.FlushAsync();
}
return file;
}
}
public async Task<byte[]> ResizeImage(byte[] imageData, int reqWidth, int reqHeight, Stream stream)
{
var memStream = new MemoryStream();
stream.Position = 0;
await stream.CopyToAsync(memStream);
IRandomAccessStream imageStream = memStream.AsRandomAccessStream();
imageStream.Seek(0);
//The problem start just below
var decoder = await BitmapDecoder.CreateAsync(imageStream);
if (decoder.PixelHeight > reqHeight || decoder.PixelWidth > reqWidth)
{
using (imageStream)
{
var resizedStream = new InMemoryRandomAccessStream();
BitmapEncoder encoder = await BitmapEncoder.CreateForTranscodingAsync(resizedStream, decoder);
double widthRatio = (double)reqWidth / decoder.PixelWidth;
double heightRatio = (double)reqHeight / decoder.PixelHeight;
double scaleRatio = Math.Min(widthRatio, heightRatio);
if (reqWidth == 0)
scaleRatio = heightRatio;
if (reqHeight == 0)
scaleRatio = widthRatio;
uint aspectHeight = (uint)Math.Floor(decoder.PixelHeight * scaleRatio);
uint aspectWidth = (uint)Math.Floor(decoder.PixelWidth * scaleRatio);
encoder.BitmapTransform.InterpolationMode = BitmapInterpolationMode.Linear;
encoder.BitmapTransform.ScaledHeight = aspectHeight;
encoder.BitmapTransform.ScaledWidth = aspectWidth;
await encoder.FlushAsync();
resizedStream.Seek(0);
var outBuffer = new byte[resizedStream.Size];
uint x = await resizedStream.WriteAsync(outBuffer.AsBuffer());
return outBuffer;
}
}
return imageData;
}
if someone can tell me where the problem is from, I'll be very grateful.
Edit:
I found the solution.
First my call for the second method was not on the correct line.
Finally I found an other method for resizing my file, that was more close to what I had.
private async Task<StorageFile> SaveThumbsPhotos(WriteableBitmap WB, FileFormat fileFormat, string username)
{
string FileName = username + "-Thumbs.";
Guid BitmapEncoderGuid = BitmapEncoder.JpegEncoderId;
switch (fileFormat)
{
case FileFormat.Jpg:
FileName += "jpg";
BitmapEncoderGuid = BitmapEncoder.JpegEncoderId;
break;
case FileFormat.Png:
FileName += "png";
BitmapEncoderGuid = BitmapEncoder.PngEncoderId;
break;
case FileFormat.Bmp:
FileName += "bmp";
BitmapEncoderGuid = BitmapEncoder.BmpEncoderId;
break;
case FileFormat.Tiff:
FileName += "tiff";
BitmapEncoderGuid = BitmapEncoder.TiffEncoderId;
break;
case FileFormat.Gif:
FileName += "gif";
BitmapEncoderGuid = BitmapEncoder.GifEncoderId;
break;
}
if (config.getFolder() == null)
{
try
{
var resourceLoader = Windows.ApplicationModel.Resources.ResourceLoader.GetForCurrentView();
var folder = await StorageFolder.GetFolderFromPathAsync(resourceLoader.GetString("Folder"));
var file = await folder.CreateFileAsync(FileName, CreationCollisionOption.GenerateUniqueName);
using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite))
{
BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoderGuid, stream);
Stream pixelStream = WB.PixelBuffer.AsStream();
byte[] pixels = new byte[pixelStream.Length];
await pixelStream.ReadAsync(pixels, 0, pixels.Length);
encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore,
(uint)WB.PixelWidth,
(uint)WB.PixelHeight,
96.0,
96.0,
pixels);
await encoder.FlushAsync();
}
await RescaleImage(file, 75, 75, username);
return file;
}
catch
{
var file = await _captureFolder.CreateFileAsync(FileName, CreationCollisionOption.GenerateUniqueName);
using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite))
{
BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoderGuid, stream);
Stream pixelStream = WB.PixelBuffer.AsStream();
byte[] pixels = new byte[pixelStream.Length];
await pixelStream.ReadAsync(pixels, 0, pixels.Length);
encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore,
(uint)WB.PixelWidth,
(uint)WB.PixelHeight,
96.0,
96.0,
pixels);
await encoder.FlushAsync();
}
await RescaleImage(file, 75, 75, username);
return file;
}
}
else
{
var file = await config.getFolder().CreateFileAsync(FileName, CreationCollisionOption.GenerateUniqueName);
using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite))
{
BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoderGuid, stream);
Stream pixelStream = WB.PixelBuffer.AsStream();
byte[] pixels = new byte[pixelStream.Length];
await pixelStream.ReadAsync(pixels, 0, pixels.Length);
encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore,
(uint)WB.PixelWidth,
(uint)WB.PixelHeight,
96.0,
96.0,
pixels);
await encoder.FlushAsync();
}
await RescaleImage(file, 75, 75, username);
return file;
}
}
private async Task<StorageFile> RescaleImage(StorageFile source, uint width, uint height, string username)
{
var imageStream = await source.OpenReadAsync();
var decoder = await BitmapDecoder.CreateAsync(imageStream);
using (var resizedStream = await source.OpenAsync(FileAccessMode.ReadWrite))
{
var encoder = await BitmapEncoder.CreateForTranscodingAsync(resizedStream, decoder);
encoder.BitmapTransform.InterpolationMode = BitmapInterpolationMode.Linear;
encoder.BitmapTransform.ScaledWidth = width;
encoder.BitmapTransform.ScaledHeight = height;
await encoder.FlushAsync();
}
return source;
}

BitmapEncoder FlushAsync throws Argument Exception - c#

When I'm using below code for image processing it throws exception at FlushAsync(). Strangely this issue happens for some video files only. Can you help why this happen ?
private async Task<String> PreProcessVideoToGetTextAsync(StorageFile file, int i)
{ /*--------To get frame from video----------*/
var thumbnail = await GetThumbnailAsync(file, i);
BitmapImage bitmapImage = new BitmapImage();
StringBuilder ocr = null;
InMemoryRandomAccessStream randomAccessStream = new InMemoryRandomAccessStream();
await RandomAccessStream.CopyAsync(thumbnail, randomAccessStream);
randomAccessStream.Seek(0);
SoftwareBitmap inputBitmap;
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(randomAccessStream);
// create a new stream and encoder for the new image
InMemoryRandomAccessStream ras = new InMemoryRandomAccessStream();
BitmapEncoder enc = await BitmapEncoder.CreateForTranscodingAsync(ras, decoder);
BitmapBounds bounds = new BitmapBounds();
bounds.Height = 270;//screnheight/4 =270
bounds.Width = 960;//screenwidth/2 =960
bounds.X = 960;//screenwidth/2 =960
bounds.Y = 810;
enc.BitmapTransform.Bounds = bounds;
// write out to the stream
try
{
await enc.FlushAsync();
}
catch (Exception ex)
{
string exx = ex.ToString();
var dialog = new MessageDialog(exx);
await dialog.ShowAsync();
}
//Remain portion of code
}

I've already used the following code snippet to save video thumbnails in my uwp app, hopefully you can apply a little bit of changes as you want to use it.
private async Task PreProcessVideoToGetTextAsync(string videopath)
{
try
{
SoftwareBitmap softwareBitmap = null;
StorageFile videofile = await StorageFile.GetFileFromPathAsync(videopath);
var thumbnail = await GetThumbnailAsync(videofile);
Windows.Storage.Streams.InMemoryRandomAccessStream randomAccessStream = new Windows.Storage.Streams.InMemoryRandomAccessStream();
await Windows.Storage.Streams.RandomAccessStream.CopyAsync(thumbnail, randomAccessStream);
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(randomAccessStream);
softwareBitmap = await decoder.GetSoftwareBitmapAsync();
StorageFile outputFile = await ApplicationData.Current.LocalCacheFolder.CreateFileAsync(Path.GetFileNameWithoutExtension(videopath) + ".jpg");//save path for video thumbnail image in app cache folder
using (Windows.Storage.Streams.IRandomAccessStream stream = await outputFile.OpenAsync(FileAccessMode.ReadWrite))
{
BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, stream);
encoder.SetSoftwareBitmap(softwareBitmap);
encoder.BitmapTransform.ScaledWidth = 128;//thumbnail width
encoder.BitmapTransform.ScaledHeight = 128;//thumbnail height
encoder.IsThumbnailGenerated = true;
try
{
await encoder.FlushAsync();
if (softwareBitmap.BitmapPixelFormat != BitmapPixelFormat.Bgra8 || softwareBitmap.BitmapAlphaMode == BitmapAlphaMode.Straight)
{
softwareBitmap = SoftwareBitmap.Convert(softwareBitmap, BitmapPixelFormat.Bgra8, BitmapAlphaMode.Premultiplied);
}
var source = new Windows.UI.Xaml.Media.Imaging.SoftwareBitmapSource();
await source.SetBitmapAsync(softwareBitmap);
return;
}
catch (Exception err)
{
switch (err.HResult)
{
case unchecked((int)0x88982F81): //WINCODEC_ERR_UNSUPPORTEDOPERATION
// If the encoder does not support writing a thumbnail, then try again
// but disable thumbnail generation.
encoder.IsThumbnailGenerated = false;
break;
default:
throw err;
}
}
if (encoder.IsThumbnailGenerated == false)
{
await encoder.FlushAsync();
}
}
return;
}
catch (Exception)
{
return;
}
finally
{
GC.Collect();
}
}
private async Task<Windows.Storage.Streams.IInputStream> GetThumbnailAsync(StorageFile file)
{
var mediaClip = await Windows.Media.Editing.MediaClip.CreateFromFileAsync(file);
var mediaComposition = new Windows.Media.Editing.MediaComposition();
mediaComposition.Clips.Add(mediaClip);
return await mediaComposition.GetThumbnailAsync(
TimeSpan.Zero, 0, 0, Windows.Media.Editing.VideoFramePrecision.NearestFrame);
}
}

UWP application hangs when converting a canvas to image

I trying to convert the canvas in UWP to image (RenderTargetBitmap). I have two options to return the image to end user.
StorageFile
System.IO.Stream
When I use the storage file everything works as expected. But when I use a memory stream, the application hangs. I have created a simple sample to reproduce the issue.
<Grid Background="White" Name ="Main_Grid">
<Button Content="UIToImage" Margin="141,159,0,0" VerticalAlignment="Top" Click="UIToImageAsync"></Button>
</Grid>
private async void UIToImageAsync(object sender, RoutedEventArgs e)
{
//Pick a folder
var folder = KnownFolders.PicturesLibrary;
var storageFile = await folder.CreateFileAsync("Output.png", CreationCollisionOption.ReplaceExisting);
//using (var inputImgStream = await storageFile.OpenStreamForWriteAsync())//this works
using (var inputImgStream = new MemoryStream())//this doesn't work
{
//Draw a line
Windows.UI.Xaml.Shapes.Path path = new Windows.UI.Xaml.Shapes.Path();
DrawShape(path);
//The canvas to hold the above shape - line
var canvas = new Canvas();
//Add canvas to the grid in XAML
Main_Grid.Children.Add(canvas);
canvas.Children.Add(path);
//Draw the canvas to the image
RenderTargetBitmap bitmap = null;
await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
bitmap = new RenderTargetBitmap();
canvas.Height = 800;
canvas.Width = 1380;
canvas.RenderTransform = new TranslateTransform { X = 1, Y = 100
};
});
//Render a bitmap image
await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,async () =>
{
await bitmap.RenderAsync(canvas, 1380, 800);
});
var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, inputImgStream.AsRandomAccessStream());// I suspect passing the MemoryStream is the issue. While 'StorageFile' is used there are no issues.
IBuffer pixelBuffer = await bitmap.GetPixelsAsync();
encoder.SetPixelData(
BitmapPixelFormat.Bgra8,
BitmapAlphaMode.Ignore,
(uint)bitmap.PixelWidth,
(uint)bitmap.PixelHeight,
DisplayInformation.GetForCurrentView().LogicalDpi,
DisplayInformation.GetForCurrentView().LogicalDpi,
pixelBuffer.ToArray());
await encoder.FlushAsync(); // The application hangs here
}
}
private void DrawShape(Windows.UI.Xaml.Shapes.Path path)
{
PathGeometry lineGeometry = new PathGeometry();
PathFigure lineFigure = new PathFigure();
LineSegment lineSegment = new LineSegment();
lineFigure.StartPoint = new Point(100, 100);
lineSegment.Point = new Point(200, 200);
lineFigure.Segments.Add(lineSegment);
path.Data = lineGeometry;
SolidColorBrush strokeBrush = new SolidColorBrush(Windows.UI.Color.FromArgb(255, 255, 0, 0));
path.Stroke = strokeBrush;
path.StrokeThickness = 5;
lineGeometry.Figures.Add(lineFigure);
}
Can anyone point me out about what causing this?

It really seems that using a simple MemoryStream with AsRandomAccessStream does not workm, although I am not sure about the reason. Instead, you can use InMemoryRandomAccessStream, which will work as expected.
There is however another problem, which might be a source of problems, or at least it caused it to crash on my machine:
//Render a bitmap image
await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(
CoreDispatcherPriority.Normal, async () =>
{
await bitmap.RenderAsync(canvas, 1380, 800);
});
Although it seems that the await will wait for the RenderAsync call to finish, it unfortunately does not. The second parameter is only a DispatchedHandler. This delegate has the following signature:
public delegate void DispatchedHandler()
As you can see there is no Task return value. That means it will create just a async void lambda. The lambda will start running and when it reaches the RenderAsync, it will start executing it, but hte RunAsync's await may (and most likely will) finish before the RunAsync does. So it is likely, that you will start to execute the bitmap.GetPixelAsync while the bitmap is still completely empty.
To fix this, you should move the code inside the lambda:
//Render a bitmap image
await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, async () =>
{
await bitmap.RenderAsync(canvas, 1380, 800);
using (var inputImgStream = new InMemoryRandomAccessStream()) //this doesn't work
{
var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId,
inputImgStream
); // I suspect passing the MemoryStream is the issue. While 'StorageFile' is used there are no issues.
IBuffer pixelBuffer = await bitmap.GetPixelsAsync();
Debug.WriteLine($"Capacity = {pixelBuffer.Capacity}, Length={pixelBuffer.Length}");
var pixelArray = pixelBuffer.ToArray();
encoder.SetPixelData(
BitmapPixelFormat.Bgra8,
BitmapAlphaMode.Ignore,
(uint) bitmap.PixelWidth,
(uint) bitmap.PixelHeight,
DisplayInformation.GetForCurrentView().LogicalDpi,
DisplayInformation.GetForCurrentView().LogicalDpi,
pixelArray
);
await encoder.FlushAsync(); // The application hangs here
}
});
As you can see, you must also move the using block for the stream inside the lambda, because if it were outside, the same fate would happen - the using might Dispose of the stream before the RenderAsync finished.

How to save <Image /> content to file

I have to save a content from Image tag to a file. I used a lot of Uncle Google but he doesn't know :(
private void QRbutton_Click(object sender, RoutedEventArgs e)
{
IBarcodeWriter writer = new BarcodeWriter
{
Format = BarcodeFormat.QR_CODE,
Options = new ZXing.Common.EncodingOptions
{
Height = 1200,
Width = 1200
}
};
String message = "";
if (String.IsNullOrEmpty(QRtxt.Text))
{
message = "You send empty message. ";
}
else
{
//Saving Input to string
message = QRtxt.Text;
StckPnlProfile_Layout.Visibility = Visibility.Collapsed;
QRsendbtn.Visibility = Visibility.Visible;
}
var result = writer.Write(message);
var wb = result.ToBitmap() as WriteableBitmap;
System.Diagnostics.Debug.WriteLine("BEFORE[Saving image to file]");
QRimage.Source = wb;
}
And there is XAML code of Image:
<Image x:Name="QRimage" Height="300"/>

I think your only option can be using RenderTargetBitmap class , it captures an image from any UIElement inherited class type like Image.
https://msdn.microsoft.com/library/windows/apps/xaml/windows.ui.xaml.media.imaging.rendertargetbitmap.aspx

HesamM, thank you for your response. Actually I did it in this way:
private async void saveImage(object sender, RoutedEventArgs e)
{
Debug.WriteLine("********** Function STARTED: Save QR code as image to jpg **********");
try
{
System.Diagnostics.Debug.WriteLine("Searching for assets folder.");
var package = Windows.ApplicationModel.Package.Current.InstalledLocation;
StorageFolder localFolder = await package.GetFolderAsync("Assets");
StorageFile file = await localFolder.CreateFileAsync("savedimage.jpg", CreationCollisionOption.ReplaceExisting);
var renderTargetBitmap = new RenderTargetBitmap();
System.Diagnostics.Debug.WriteLine("Rendering an image.");
await renderTargetBitmap.RenderAsync(QRimage);
var pixels = await renderTargetBitmap.GetPixelsAsync();
using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite))
{
System.Diagnostics.Debug.WriteLine("Save QR code to jpg.");
var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, stream);
byte[] bytes = pixels.ToArray();
encoder.SetPixelData(
BitmapPixelFormat.Bgra8,
BitmapAlphaMode.Straight,
(uint)renderTargetBitmap.PixelWidth,
(uint)renderTargetBitmap.PixelHeight,
DisplayInformation.GetForCurrentView().LogicalDpi,
DisplayInformation.GetForCurrentView().LogicalDpi,
bytes);
await encoder.FlushAsync();
}
MessageDialog SuccessMsg = new MessageDialog("Code QR saved.");
await SuccessMsg.ShowAsync();
}
catch (Exception ex)
{
//MessageDialog ErrMsg = new MessageDialog("Error Ocuured!");
System.Diagnostics.Debug.WriteLine("ERROR ZAPISU PLIKU: " + ex);
}
Debug.WriteLine("********** Function STOPPED: Save QR code as image to jpg **********");
}

BitmapEncoder flush throws Argument Exception

I'm trying to resize images in my UWP application. Most of the time the appended code works, but sometimes await encoder.FlushAsync(); throws an ArgumentException.
I've headed over to MSDN (https://msdn.microsoft.com/en-us/library/windows/apps/windows.graphics.imaging.bitmapencoder.bitmaptransform.aspx) and they tell me (at "Remarks"):
If you try scale an image stored in an indexed pixel format using the BitmapTransform member, FlushAsync fails with HRESULT WINCODEC_ERR_INVALIDPARAMETER . Instead, you must use GetPixelDataAsync to obtain the scaled pixel data and then use SetPixelData to set it on the encoder.
I've tried to do that, see the two commented lines (which look somehow wrong to me due to the repetition). On the second line (where I try to SetPixelData) the Encoder rewards me with an buffer allocated not sufficient Exception.
var decoder = await BitmapDecoder.CreateAsync(streamToReadFrom.AsStream().AsRandomAccessStream());
if (decoder.OrientedPixelHeight > height ||
decoder.OrientedPixelWidth > width)
{
var resizedStream = new InMemoryRandomAccessStream();
BitmapEncoder encoder = await BitmapEncoder.CreateForTranscodingAsync(resizedStream, decoder);
encoder.BitmapTransform.InterpolationMode = BitmapInterpolationMode.Fant;
encoder.BitmapTransform.ScaledHeight = newHeight;
encoder.BitmapTransform.ScaledWidth = newWidth;
//"buffer allocated not sufficient"
// var pd = await decoder.GetPixelDataAsync(BitmapPixelFormat.Rgba16, BitmapAlphaMode.Ignore,
// encoder.BitmapTransform, ExifOrientationMode.IgnoreExifOrientation, ColorManagementMode.DoNotColorManage);
// encoder.SetPixelData(BitmapPixelFormat.Rgba16, BitmapAlphaMode.Ignore,
// decoder.OrientedPixelWidth, decoder.OrientedPixelHeight, decoder.DpiX, decoder.DpiY, pd.DetachPixelData());
// write out to the stream
// might fail cause https://msdn.microsoft.com/en-us/library/windows/apps/windows.graphics.imaging.bitmapencoder.bitmaptransform.aspx
await encoder.FlushAsync();
// Read out resizedStream and return
}
Example image which causes this issue: http://www.spiegel.de/images/image-1028227-hppano-lqbn.jpg. Unit Test here: https://github.com/famoser/OfflineMedia/blob/master/Famoser.OfflineMedia.UnitTests/Presentation/ImageResizeTest.cs
How can I avoid the ArgumentException? How do I know an image is in an "indexed pixel format", and how can I resize this format too?

On the second line (where I try to SetPixelData) the Encoder rewards me with an buffer allocated not sufficient Exception.
This is because when you SetPixelData, the pixel data doesn't match it from GetPixelDataAsync. You can for example code like this:
if (file != null)
{
BitmapImage bmp = new BitmapImage();
using(var imageStream = await file.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite))
{
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(imageStream);
InMemoryRandomAccessStream pixelras = new InMemoryRandomAccessStream();
BitmapEncoder pixelencoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, pixelras);
BitmapTransform transform = new BitmapTransform();
transform.InterpolationMode = BitmapInterpolationMode.Fant;
transform.ScaledHeight = 400;
transform.ScaledWidth = 400;
var provider = await decoder.GetPixelDataAsync(BitmapPixelFormat.Bgra8,
BitmapAlphaMode.Ignore,
transform,
ExifOrientationMode.RespectExifOrientation,
ColorManagementMode.DoNotColorManage);
var pixels = provider.DetachPixelData();
pixelencoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore, 400,
400, decoder.DpiX, decoder.DpiY, pixels);
try
{
await pixelencoder.FlushAsync();
}
catch(Exception ex)
{
}
bmp.SetSource(pixelras);
img.Source = bmp;
}
}
How do I know an image is in an "indexed pixel format", and how can I resize this format too?
I couldn't find any effective way to detect an indexed pixel format image, but since it is said
If you try scale an image stored in an indexed pixel format using the BitmapTransform member, FlushAsync fails with HRESULT WINCODEC_ERR_INVALIDPARAMETER . Instead, you must use GetPixelDataAsync to obtain the scaled pixel data and then use SetPixelData to set it on the encoder.
It is a method to use catch the exception and use SetPixelData again, for example:
if (file != null)
{
BitmapImage bmp = new BitmapImage();
using(var imageStream = await file.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite))
{
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(imageStream);
InMemoryRandomAccessStream ras = new InMemoryRandomAccessStream();
BitmapEncoder encoder = await BitmapEncoder.CreateForTranscodingAsync(ras, decoder);
encoder.BitmapTransform.InterpolationMode = BitmapInterpolationMode.Fant;
encoder.BitmapTransform.ScaledHeight = 400;
encoder.BitmapTransform.ScaledWidth = 400;
try
{
await encoder.FlushAsync();
bmp.SetSource(ras);
}
catch (Exception ex)
{
if (ex.HResult.ToString() == "WINCODEC_ERR_INVALIDPARAMETER")
{
InMemoryRandomAccessStream pixelras = new InMemoryRandomAccessStream();
BitmapEncoder pixelencoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, pixelras)
BitmapTransform transform = new BitmapTransform();
transform.InterpolationMode = BitmapInterpolationMode.Fant;
transform.ScaledHeight = 400;
transform.ScaledWidth = 400;
var provider = await decoder.GetPixelDataAsync(BitmapPixelFormat.Bgra8,
BitmapAlphaMode.Ignore,
transform,
ExifOrientationMode.RespectExifOrientation,
ColorManagementMode.DoNotColorManage);
var pixels = provider.DetachPixelData();
pixelencoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore, 400,
400, decoder.DpiX, decoder.DpiY, pixels);
try
{
await pixelencoder.FlushAsync();
bmp.SetSource(pixelras);
}
catch
{
}
}
}
img.Source = bmp;
}
}