red
[GTK] Extremely slow text rendering
Describe the bug
Same Spaces demo boots quickly under Windows, but takes over 3 minutes per frame on GTK.
To reproduce
Grab this minified version (warning: 500kb long string): https://gist.github.com/hiiamboris/89fa690858812af2128874dcf6564963 and run it.
Output on Windows:
509 ms [view [box 400x400 draw drawn rate 3 on-time [unview]]]
Output on GTK:
190612 ms [view [box 400x400 draw drawn rate 3 on-time [unview]]]
To double-check remove unview (but then can't measure the timing).
Expected behavior
Reasonable rendering speed. Currently it's 370x times slower.
Screenshots
Without unview the output must look like:
Platform version
-----------RED & PLATFORM VERSION-----------
RED: [ branch: "master" tag: #v0.6.4 ahead: 4805 date: 18-Jul-2023/19:56:01 commit: #af3d35a2f444b3d02058226effd63714eb4bf2bc ]
PLATFORM: [ name: "Windows 10" OS: 'Windows arch: 'x86-64 version: 10.0.0 build: 19044 ]
--------------------------------------------
-----------RED & PLATFORM VERSION-----------
RED: [ branch: "master" tag: #v0.6.4 ahead: 4805 date: 18-Jul-2023/19:56:01 commit: #af3d35a2f444b3d02058226effd63714eb4bf2bc ]
PLATFORM: [ name: "Ubuntu 20.04.1 LTS" OS: 'Linux arch: 'x86_64 version: 5.15.90 build: "#1 SMP Fri Jan 27 02:56:13 UTC 2023" ]
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I'm running it on WSL2, so it could be that WSL or VcXsrv are culprits.
Reproduced with Red 0.6.5 on native Ubuntu :
-----------RED & PLATFORM VERSION-----------
RED: [ branch: "master" tag: #v0.6.5 ahead: 39 date: 8-May-2024/8:49:36 commit: #27b2a730b6178928c0f205718d903e0edb546ee0 ]
PLATFORM: [ name: "Ubuntu 22.04.4 LTS" OS: 'Linux arch: 'x86_64 version: 5.15.0 build: "#117-Ubuntu SMP Fri Apr 26 12:26:49 UTC 2024" ]
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pango_cairo_* related functions are quite slow. If I comment those functions in draw-text-at, the speed is on par with Windows.
cairo_show_text is fast, we should use it.
