[Win32] Reuse zoom handle for drawing image at size if appropriate

[HeikoKlare]

When drawing an image at a specified size, currently a new image handle is always created based on on-demand loaded image data. In case the fallback to loading image data for the best fitting zoom is used, a handle for that zoom may already exist and could be reused but is currently not considered.

With this change, an existing handle is used if appropriate instead of unnecessarily creating a temporary handle.

[github-actions]

Test Results

  118 files    118 suites   14m 14s ⏱️
4 649 tests 4 632 ✅ 17 💤 0 ❌
  330 runs    326 ✅  4 💤 0 ❌

Results for commit 3d1c6f4.

♻️ This comment has been updated with latest results.

[akoch-yatta]

Overall this PR looks good and seem to work properly due to my testing.

But I was wondering, why don't we do a similar check in HandleAtSize#createHandleAtExactSize as well? So iterating over the handles and seeing of one size matches - each ImageHandle knows its size. With CTabRendering you immediately run into the scenario where a handle (for a SVG) is created unnecessarily. I am fine with doing that in a separate PR, but does anything speak against it?

[akoch-yatta]

Code looks solid. I did not really run into the scenario to resuse a handle from the zoomLevelToImageHandle map in HandleAtSize#getOrCreateImageHandleAtClosestSize without making sure to create a fitting handle first in the runtime. But doing that it worked as expected.

[HeikoKlare]

But I was wondering, why don't we do a similar check in HandleAtSize#createHandleAtExactSize as well? So iterating over the handles and seeing of one size matches - each ImageHandle knows its size. With CTabRendering you immediately run into the scenario where a handle (for a SVG) is created unnecessarily. I am fine with doing that in a separate PR, but does anything speak against it?

That definitely makes sense. I added the simple required logic with 12d5fc5.
I am not completely sure anymore why I didn't do it before. As you pointed out for the already implemented case of searching for a fitting handle first, you need to be in a situation where a zoom-based handle has been created at all. In many cases, you may only use the draw-at-size functionality without ever requesting a handle at zoom. Maybe that's why I didn't implement it (along with thinking that the implementation would be more complicated). Anyway, now all potential reuse scenarios should be covered.

[arunjose696]

I think this would cause a slight issue as if the image was requested at for eg 2X the height elsewhere, they would not be loaded with imageDataAtSizeProvider, we would then end up using this image while doing the drawing even though it is possible to load the image at the given target size.

[HeikoKlare]

Thank you! That was exactly the reason for not doing it. I just adapted the PR again. Maybe we can still integrate something like this as a follow up in case we maybe revise the ImageDataAtSizeProvider.