OpenGL: Pinch zoom to magnify text fails

[sonora]

It may not be easy to fix, but let me trigger the investgation anyway: Using legacy rendering, if in bad light conditions like direct sunlight, and trying to read text on the map, you can use "pinch zoom and hold", i.e. pinch-zooming the map and leaving your fingers in position, to temporarily magnify a map area (including all text) without it getting re-rendered, this e.g. facititates reading small or tilted map text.

Using OpenGL rendering, this trick fails, because map text immediately disappears during the maneuver, thus is never magnified.

Any chance to fix OpenGL to support that trick again?

[vshcherb]

This wouldn't work with Intermediate zoom feature which we plan to fix. So text should be increased only with a setting of Text size.

[vshcherb]

#15009

[sonora]

Let me perhaps reopen this to see if we can find a solution.

This issue is about (with the OpenGL engine) being able to use pinch zoom as an on-the-fly screen magnifier, like the V1 engine allows. (For text, contour lines, etc. in difficult lighting.)

The basic idea so far was if we could not simply during a pinch zoom action pause displaying the re-rendered screen content (produced in the background by the GPU) until the user takes the fingers off the screen, and before that simply display the scaled former bitmap.

We had interim linked this to #15009, but unfortunately the fix for that one did not solve this issue here.

[vshcherb]

I still don't think we should change anything, I don't think it's important feature but let's keep it open

[Gregor0000]

I think this feature is quite important and it is one of the major reasons, I don't use OpenGL rendering yet.
It is so convenient to be able to increase the text size with pinch&zoom in situations where the readability of the screen is bad (bad light - too dark, too bright, when wearing sunglasses). For me, those situations happen all the time during my hikes. Increasing the overall text size is not a good solution: It clutters the map view and makes a good overview more difficult.
I would very much appreciate if such a functionality could be implemented.

[sonora]

@Gregor0000 Exactly.

And it"s not just for text. It temporarily magnifies everything, e.g. also contour lines, which normally you may only have as a background feature with intentionally less visibility.