Add image viewer widget

[alanpoon]

Fixes #327

in replacement of #443

Waiting for this PR to be merged: makepad/makepad#788.

[alanpoon]

Intention of adding an image magnifier and the ability to pan image.

The image's image_scale, image_pan will always be set to default in draw_walk. Hence unable to dynamically scale and pan image.
makepad/makepad#785

[kevinaboos]

Intention of adding an image magnifier and the ability to pan image.

The image's image_scale, image_pan will always be set to default in draw_walk. Hence unable to dynamically scale and pan image. makepad/makepad#785

@alanpoon I just checked with Rik, and this line should not be present in the Image widget. It's some errant code left over from dealing with animations in a strange way.

You can submit a PR to makepad that removes that line, and then continue with this issue here.

[alanpoon]

Sure, the makepad PR is here: makepad/makepad#788

[alanpoon]

[kevinaboos]

Thanks Alan, nice work here.

My main comment is that we should decouple the ImageViewer widget from the RoomScreen. It doesn't need to know anything about the RoomScreen except for being able to access the RoomScreen's MediaCache instance (technically even that is not required, see Aarav's PR for an example of just passing the image data directly from the media fetch background task to the ImageViewer via an action).

Also, Aarav and I had a lot of discussions about using actions to communicate with the ImageViewer widget in PR#443. I think you can combine your approach (of storing images in the RoomScreen's MediaCache) with the action-based design from #443 (in which you emit an action including the image data/status instead of directly accessing the widget and calling a function on it). Actions are more idiomatic and also allow easy communication from any context, both in a background task and in a RoomScreen TimelineUpdate handler.

[kevinaboos]

nit: you left out the bullet points in my suggested text, which means that it won't render as three separate lines/points.

GitHub has a "commit suggestion" button (or you can batch multiple suggestions at once), so you should use that when possible to avoid copy/paste accidents like this.

[kevinaboos]

what's the reason for all the version changes to windows-sys crates? Those are all unrelated to this PR.

[kevinaboos]

ok... that's a small improvement, but not a full fix.

Why not just allow it to fill the entire space as needed? You can just have two views: the metadata on the top left, and then the image name and size can be immediately to the right of that. If you make all content have a known width (either a number or Fit), then you can use flow: RightWrap to ensure that they'll automatically flow onto the next line if the screen isn't narrow enough, which removes the need to have special cases for Mobile view mode.

[kevinaboos]

is there some particular reason (or benefit) for why you're using a placeholder instead of just directly putting the avatar here? Seems like it'd be a lot easier just to define an Avatar widget here as normal, and then you can get rid of all the complex logic for the placeholder rectangle and the avatar template.

[kevinaboos]

this is not necessary — see my other comment.