269704 2024-02-19 05:19:38 -0800 OffscreenCanvas flickers during rendering 2024-06-30 17:21:59 -0700 1 1 1 Unclassified WebKit Canvas Safari 17 Unspecified Unspecified NEW https://bugs.webkit.org/show_bug.cgi?id=269544 InRadar P2 Normal --- 1 ashley webkit-unassigned dino heycam hunter mattwoodrow webkit-bug-importer oldest_to_newest 2015072 0 ashley 2024-02-19 05:19:38 -0800 We make a web-based game engine Construct (www.construct.net). It supports running the engine both in the DOM with a standard HTML canvas, and in a Web Worker and rendering with OffscreenCanvas. Only in Safari and only when using OffscreenCanvas, sometimes the displayed canvas flickers. It looks like perhaps the canvas is not drawn for a single frame, causing its content to momentarily disappear and then reappear, which looks like a distracting flicker. Repro URLs: Using DOM canvas: https://downloads.scirra.com/labs/bugs/canvasflicker/dom/index.html Using OffscreenCanvas: https://downloads.scirra.com/labs/bugs/canvasflicker/worker/index.html Steps to reproduce: 1. Visit the first URL using DOM canvas 2. Wait for the content to load 3. Press the "Spin" button several times, waiting for the animation to finish each time 4. Repeat with second URL using OffscreenCanvas Observed result: In Safari and when using OffscreenCanvas only, sometimes the canvas momentarily disappears, resulting in a flicker. This can most obviously be seen in the "Flicker check" box at the top. This reproduces in Safari 17 on both macOS and iOS. Expected result: No flickering. This is how it appears in DOM mode in Safari, but also both modes always display correctly in Chrome and Firefox on Windows and Chrome on Android. 2016826 1 webkit-bug-importer 2024-02-26 05:20:13 -0800 <rdar://problem/123626765>