293284 2025-05-20 01:25:10 -0700 In WebGPU when calling copyExternalImageToTexture, the results are different if called in the 'load' event vs after 2025-07-02 18:52:49 -0700 1 1 1 Unclassified WebKit WebGPU Safari Technology Preview Mac (Apple Silicon) macOS 15 REOPENED InRadar P2 Normal --- 295357 1 gman mwyrzykowski mwyrzykowski tzagallo webkit-bug-importer oldest_to_newest 2118362 0 475317 gman 2025-05-20 01:25:10 -0700 Created attachment 475317 image via decode vs addEventListener In WebGPU these two snippets of code should load the same data ```js const img = new Image(); img.src = 'noise.png' await img.decode(); device.queue.copyExternalImageToTexture(...) ``` vs ```js const img = new Image(); img.src = 'noise.png' img.addEventListener('load', () => { device.queue.copyExternalImageToTexture(...) }); ``` They don't. Note, if you run the first one in first in the same page then the 2nd one will get the same results Repo attached 2118395 1 mwyrzykowski 2025-05-20 07:22:28 -0700 Likely a bug in the external texture import path 2118396 2 webkit-bug-importer 2025-05-20 07:22:39 -0700 <rdar://problem/151696944> 2118408 3 mwyrzykowski 2025-05-20 08:24:34 -0700 I think this is above WebGPU in the general webkit image loading path, confirming 2118412 4 mwyrzykowski 2025-05-20 08:32:58 -0700 CGImageGetAlphaInfo(...) is returning a different value in both cases. When the image is darker (matching Chrome), CGImageGetAlphaInfo(...) returns kCGImageAlphaPremultipliedFirst (0x2), /* For example, premultiplied ARGB */ When the image is brighter (problem case), CGImageGetAlphaInfo(...) returns kCGImageAlphaLast (0x3), /* For example, non-premultiplied RGBA */ 2118719 5 mwyrzykowski 2025-05-21 10:59:44 -0700 This is indeed at least partly a WebGPU issue, we are not handling when WebCore gives us back a premultiplied image (which appears to differ based on explicit call to decode). After the image is cached, we get back the same image. Though it also seems odd WebCore is giving us a premultiplied image in some cases when the source image in this repro is not premultiplied 2118721 6 mwyrzykowski 2025-05-21 11:11:24 -0700 Change to match between the two versions and also match Chrome is quite simple, just checking the CTS to ensure zero regressions. 2118879 7 mwyrzykowski 2025-05-21 17:51:49 -0700 Pull request: https://github.com/WebKit/WebKit/pull/45744 2121127 8 ews-feeder 2025-06-02 09:08:44 -0700 Committed 295690@main (b8888bb0a749): <https://commits.webkit.org/295690@main> Reviewed commits have been landed. Closing PR #45744 and removing active labels. 2127494 9 mwyrzykowski 2025-07-02 18:52:48 -0700 Reopened Bugzilla. [WebGPU] bloooooom.vercel.app appears different in Safari/FireFox than Chrome, tracking revert in https://bugs.webkit.org/show_bug.cgi?id=295357. 475317 2025-05-20 01:25:10 -0700 2025-05-20 01:25:10 -0700 image via decode vs addEventListener webgpu-texture-issue.zip application/zip 5716 gman UEsDBBQAAAAAAKiKtFoAAAAAAAAAAAAAAAAVACAAd2ViZ3B1LXRleHR1cmUtaXNzdWUvdXgLAAEE DkABAARTXwEAVVQNAAd9OyxoijssaIY7LGhQSwMEFAAIAAgAboq0WgAAAAAAAAAAAAAAAE8AIAB3 ZWJncHUtdGV4dHVyZS1pc3N1ZS9qc2dpc3QtV2ViR1BVIFNhZmFyaSBUZXh0dXJlIHZpYSBpbWcu YWRkRXZlbnRMaXN0ZW5lci5odG1sdXgLAAEEDkABAARTXwEAVVQNAAcQOyxoEDssaH07LGiVGPtT 28j5d/6K75h0JF9tGUiayQibCwE3zcwleLBz7Q1hYC2t5L1IWt3uyuBy/t/77UMP29BemcFa7/d+ f/Loh8uri/mv0wksVZ6dHYzsA2C0pCTWBzzmVBGIlkRIqsaHlUoG7w5h2AUWJKfjwxWjDyUX6hAi XihaIPIDi9VyHNMVi+jAfOkDK5hiJBvIiGR0fNyyUkxl9OyfdPFx+hVmJCGCwZw+qkpQWDECLE8D EseTFbL+mUmUQMVoaKksB6nW+hwKzhU84V3EMy5Q0pLmNISMpUsFMRHfTw82B5Zk6Gj0sbZ5tODx 2hwiUqyIPBsN3cGgNVAZCVYqUOsSrc95XGX08OzggMh1EUFSFZFivIAHukjLyn+yLPqQcRLPkWTT 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