dynamic-zoom: add dynamic zoom to impress

[printfdebugging]

• Resolves: #
• Target version: main

Summary

TODO

• use a more appropriate icon for impress.

Checklist

• I have run make prettier-write and formatted the code.
• All commits have Change-Id
• I have run tests with make check
• I have issued make run and manually verified that everything looks okay
• Documentation (manuals or wiki) has been updated or is not required

[pedropintosilva]

Thanks for the update:

• The slide zoom needs to change according to the available space
  • and it should happen with window resize , not just on load)
  • the slide should be fully visible (not partly)
  • We shouldn't allow the slide to be smaller than the minimum zoom that we have (20%)
  • Ideally we would allow to zoom past 200% when in super bug screens such as TVs but for not stick with the maximum 200% zoom that we already have.

[mmeeks]

I seem to get some grim tiling problems with this - but perhaps without as well:

$ make run
load stock impress test - see broken and missing tiles left & right, not repaired by explicit zooming either.

@gokaysatir is that a known issue ?

[printfdebugging]

@mmeeks & @gokaysatir i tried to reproduce this and i noticed a significant delay in receiving/rendering new tiles.
steps:

• make run, open impress-edit (as suggested above)
• open the third slide & zoom in or out by a large amount
• for a few seconds, i don't see anything (the first screenshot below)
• then as i kept doing it, i got a dialog complaining about long event handling delays.

[printfdebugging]

i also noticed flickers when i resize the window, i will look into that first since that is a part of "dynamic zoom" and i might find something related to the above issue in the process, let's see.

[printfdebugging]

so it seems that the invalidation code is running a few times more than it should (ideally once).

/* we have this in CanvasTileLayer.js */
this.resObserver = new ResizeObserver(function() {
    that._layer._syncTileContainerSize();
});
this.resObserver.observe(canvasContainer);

/* and later down the line we have this */
this._map.on('resize', this._syncTileContainerSize, this);

/* `_syncTileContainerSize` calls  `this._map.invalidateSize` which
 * fires a 'resize' event at the end, which then again triggers
 * `_syncTileContainerSize`. and it also calls `_fitWidthZoom` which
 * itself is listening for 'resize' events.
 */

[gokaysatir]

$ make run load stock impress test - see broken and missing tiles left & right, not repaired by explicit zooming either.

@gokaysatir is that a known issue ?

I couldn't see the tile rendering issues with the test file but the 3rd slide takes really long time to load. Not sure if that's related to images.

[mmeeks]

The images are 4k images I think, or bigger but are block colors so they compress small. They stress our scaling code. But we badly need to make sure we are not re-scaling them multiple times - so we should get our zoom level right on the wire message from JS -> browser as early as possible I think. It would be really bad to render once in the backend at one zoom, then zoom and re-render and re-scale the images to another size - incredibly inefficient.

[printfdebugging]

https://gerrit.collaboraoffice.com/c/online/+/2588 moved to gerrit