Allow viewing photos after attaching to note

[Helium314]

Fixes #2497.

See discussion in Helium314#392. The photo is shown in a dialog with transparent background.
I hope the delete button is now big enough.

[westnordost]

Nice! Hmm, the delete button is indeed a bit big now (also, scaling it will make it blurry, the actual graphic either have to be made larger or at least the view displaying it). I propose 32dp size for the delete button and 72dp or so for the image thumbnail.

How come the third picture is cut off that way? I wonder if there is a way it can be made clear that this scrolls vertically. Maybe always show the scroll bar? Or show some kind of gradient from background-color to transparent at its edges?

[Helium314]

scaling it will make it blurry

This is weird, I wonder why Android Studio can scale it without blurring (in the preview)

How come the third picture is cut off that way?

That's normal, but previously I think 4 or 5 pictures were necessary.
Is there really anything to do? When the users see that the 3rd photo they attach is cut off, they might try to scroll.
But a scrollbar might still help. Can the scrollbar be always shown, but only if scrolling is actually possible?

[Helium314]

Ok, the scrollbar shows up for a few seconds once it becomes necessary. That's hopefully enough.

[westnordost]

This is weird, I wonder why Android Studio can scale it without blurring (in the preview)

Android has some optimizations built-in for vector graphics. It usually caches a bitmap variant of the vector graphic after rendering it once. The size of that bitmap depends on the defined size of the vector graphic.

[westnordost]

I made some improvements I didn't want to bother you with