Win32 | Android | Browser | iOS - Support reading from and copying images to clipboard

[emmauss]

What does the pull request do?

This PR allows users to directly get a Bitmap bitmap from clipboard if a supported image format is available. This is in addition to the currently supported text and file formats. This only supports images copied to clipboard directly, and not from a file in disk. Depending on platform, we choose the most suitable format among the available formats as the default Image data format.
On Windows, the priority is; CF_BITMAP > CF_DIB > png > jpg.
On Android, we attempt to load the file in clipboard as a Bitmap, since apps can decide not to use full mimetypes when copying files to clipboard.

This pr also supports copying a Bitmap to clipboard. This is currently supported on Windows

What is the current behavior?

Users can't retrieve image data formats from clipboard on some platforms without creating a DataFormat of byte matching the system type of the image data. The process would normally be like this

1. Get the formats supported for the data in the clipboard.
2. Find a suitable format they what
3. Create a DataFormat<byte> with the format name and a internal hidden AppId
4. Retrieve the data
5. Load that data as a bitmap.

The format names are also platform specific, so each platform would need to have their own image loading logic.

What is the updated/expected behavior with this PR?

Common image formats that we know skia supports on all platforms can now be retrieved directly as a Bitmap instance.
For example, retrieving a image in clipboard can be easily done like this;

using var data = await clipboard.TryGetDataAsync();
Bitmap? source = null;
if (data != null)
{
    source = await data!.TryGetValueAsync(DataFormat.Image);
}
ClipboardImage.Source = source;

How was the solution implemented (if it's not obvious)?

Checklist

• Added unit tests (if possible)?
• Added XML documentation to any related classes?
• Consider submitting a PR to https://github.com/AvaloniaUI/avalonia-docs with user documentation

Breaking changes

Obsoletions / Deprecations

Fixed issues

[avaloniaui-bot]

You can test this PR using the following package version. 12.0.999-cibuild0059590-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[danipen]

is this feature going to be supported in the other platforms? (macOS, Linux ...)

[emmauss]

is this feature going to be supported in the other platforms? (macOS, Linux ...)

Linux, Mac and iOS will be supported

[avaloniaui-bot]

You can test this PR using the following package version. 12.0.999-cibuild0059600-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[emmauss]

Added Browser support

[avaloniaui-bot]

You can test this PR using the following package version. 12.0.999-cibuild0059606-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[kekekeks]

On Android, we attempt to load the file in clipboard as a Bitmap, since apps can decide not to use full mimetypes when copying files to clipboard.

Do we attempt that before or after advertising DataFormat.Bitmap being present?

[emmauss]

On Android, we attempt to load the file in clipboard as a Bitmap, since apps can decide not to use full mimetypes when copying files to clipboard.

Do we attempt that before or after advertising DataFormat.Bitmap being present?

When GetDataFormatsAsync, we add DataFormat.Image if there's a image mimetype. But from my tests with my gallery app, the source app can just use image/* as mimetype since it's not binary data in memory, but a file thats being referenced. This makes it hard to limit the formats to png or jpg. So when TryGetValueAsync is called with Image format, we attempt to load whatever is in the clipboard as a bitmap, since its not guaranteed to know the actual format before hand.

[avaloniaui-bot]

You can test this PR using the following package version. 12.0.999-cibuild0059722-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[avaloniaui-bot]

You can test this PR using the following package version. 12.0.999-cibuild0059726-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]