BitmapEncoder SetPixelData memory allocation

Question

I'm working on a Metro application where I need to generate an animated GIF image.

I've found this tutorial, witch seems to be the one and only resource on animated GIFs for Metro apps.

When running this code, an Exception is thrown on the SetPixelData method, telling me that the allocated buffer memory is insufficient (The message is in my OS language even though my Visual Studio environnement is in English, I think it might be relevant).

I've reduced image size (source and output) and frame number, but I still get this error. (I manipulate way bigger images and byte array in the same application).

Any idea where this memory problem can come from ? A problem with my StorageFile maybe ?

Answer 1

I was seeing this exception when the frameWidth\Height being passed into SetPixelData didn't match the pixel data.

I ended up with this example below. I was seeing the exception you mentioned when the dimensions didn't match the pixelData.

I think this is more stable in Windows 8.1 as it doesn't repro on it.

BitmapDecoder decoder = await BitmapDecoder.CreateAsync(sourceStream);
                BitmapTransform transform = new BitmapTransform()
                {
                    ScaledHeight = 900,
                    ScaledWidth = 600
                };
                PixelDataProvider pixelData = await decoder.GetPixelDataAsync(BitmapPixelFormat.Rgba8,
                                                                              BitmapAlphaMode.Straight,
                                                                              transform,
                                                                              ExifOrientationMode.RespectExifOrientation,
                                                                              ColorManagementMode.DoNotColorManage);

                StorageFile destinationFile = await ApplicationData.Current.LocalFolder.CreateFileAsync(Path.Combine(Database.rootMoviesFoldersPaths, movie.LocalId + ".jpg"));
                using (var destinationStream = await destinationFile.OpenAsync(FileAccessMode.ReadWrite))
                {
                    BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, destinationStream);
                    encoder.SetPixelData(BitmapPixelFormat.Rgba8, BitmapAlphaMode.Premultiplied, 600, 900, 96, 96, pixelData.DetachPixelData());
                    await encoder.FlushAsync();

                    movie.HasFolderImage = true;

                    return true;
                }
            }