Ensure that rendering of thumbnails work correctly on HiDPI displays (issue 9820) #12618
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…(issue 9820) *Note that I wasn't able to reproduce the issue in Firefox, but only in Chromium-browsers.* The bug, and it's feels almost trivial once you've found it, is that we're not passing the `transform` parameter as intended to `PDFPageProxy.render` when drawing thumbnails on HiDPI displays. Instead the canvas context is, for reasons that I don't even pretent to understand, *manually* scaled in `PDFThumbnailView._getPageDrawContext`, which thus doesn't guarantee that the `baseTransform` property on the `CanvasGraphics`-instances becomes correct. The solution is really simple though, just handle the `transform` the same way in `PDFThumbnailView.draw` as in `PDFPageView.paintOnCanvas` and things should just work.
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/botio-linux preview |
From: Bot.io (Linux m4)ReceivedCommand cmd_preview from @timvandermeij received. Current queue size: 0 Live output at: http://54.67.70.0:8877/8b2644cb0c868a2/output.txt |
From: Bot.io (Linux m4)SuccessFull output at http://54.67.70.0:8877/8b2644cb0c868a2/output.txt Total script time: 4.13 mins Published |
timvandermeij
approved these changes
Nov 14, 2020
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Nice find! |
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Note that I wasn't able to reproduce the issue in Firefox, but only in Chromium-browsers.
The bug, and it's feels almost trivial once you've found it, is that we're not passing the
transformparameter as intended toPDFPageProxy.renderwhen drawing thumbnails on HiDPI displays. Instead the canvas context is, for reasons that I don't even pretent to understand, manually scaled inPDFThumbnailView._getPageDrawContext, which thus doesn't guarantee that thebaseTransformproperty on theCanvasGraphics-instances becomes correct.The solution is really simple though, just handle the
transformthe same way inPDFThumbnailView.drawas inPDFPageView.paintOnCanvasand things should just work.Fixes #9820