Png image is being converted to jpg when selected from gallery in case of iOS

[HabibAli]

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Bug Information

Version Number of Plugin: 2.6.2
Device Tested On: Any iOS Device
Simulator Tested On: Any iOS Simulator
Version of VS: Testing it on Mac Mini
Version of Xamarin: 2.3.3.193
Versions of other things you are using: -

Steps to reproduce the Behavior

Just select a png photo from gallery using following code snippet

Expected Behavior

Image should be png and file path should end with .png

Actual Behavior

Image is jpg and filepath is ending with .jpg

Code snippet

if (CrossMedia.Current.IsPickPhotoSupported)
                        {
                            string filePath = null;

                            using (MediaFile file = await CrossMedia.Current.PickPhotoAsync())
                            {
                                InsightsFacade.Track("ImageReceivedFromGallery");

                                if (file != null)
                                {
                                    filePath = file.Path;

                                    if (filePath != null)
                                        await this.OnPhotoReceived(filePath);
                                }
                            }
                        }

Screenshotst

[Nerololo]

I think iOS store images in gallery as .jpg by default, try to take a photo with the camera an you will see is a .jpg

[jamesmontemagno]

Everything is stored as jpg by design

[jgold6]

@jamesmontemagno
I suggest you re-open this. The gallery can store PNG files and you can get them back as PNG files.

I just had a case where a customer added a PNG file to the gallery and when getting it back it lost transparency because it was returned as a jpg. However I was able to have them workaround this issue by creating their own dependency service, checking the path of the image returned from the iOS UIImagePickerController and if it is PNG, then you can create a stream as a PNG. So it is possible to store and retrieve PNG images in the iOS photo gallery. The lines where you are forcing the image to be a JPG are similar to this line:
https://github.com/jamesmontemagno/MediaPlugin/blob/master/src/Media.Plugin/iOS/MediaPickerDelegate.cs#L477

Our guide for a Forms pick photo dependency service does the same thing:
https://docs.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/dependency-service/photo-picker#ios-implementation

See this code:

void OnImagePickerFinishedPickingMedia(object sender, UIImagePickerMediaPickedEventArgs args)
    {
        UIImage image = args.EditedImage ?? args.OriginalImage;

        if (image != null)
        {
            // Convert UIImage to .NET Stream object
            NSData data = image.AsJPEG(1);
            Stream stream = data.AsStream();
            ...
    }

The above forces the image to be returned to the caller as a JPG, but if you do this:

void OnImagePickerFinishedPickingMedia(object sender, UIImagePickerMediaPickedEventArgs args)
    {
        UIImage image = args.EditedImage ?? args.OriginalImage;

        if (image != null)
        {
            // Convert UIImage to .NET Stream object
            NSData data;
            if (args.ReferenceUrl.PathExtension == "PNG" || args.ReferenceUrl.PathExtension == "png")
                data = image.AsPNG();
            else
                data = image.AsJPEG(1);
            Stream stream = data.AsStream();
            ...
    }

Then you get a PNG back. There would seem to be no reason why you can't do similar in this library.

I will work on a pull request.

[jgold6]

@Nerololo

Yes, if you take a picture, it will store as a JPEG, but there are other ways to get images into the Photos app, like saving a PNG image from a website for one.

I just did a pull request that should fix this issue. It checks the file extension of the selected image, and if a PNG saves it and passes it back as a PNG instead of a JPG.