Blur does not work correctly under different display resolutions. |
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Issue descriptionThere are two issues: 1. For linux build, when use different display resolutions, the boarder black is not removed. 2. However at real device, 1) is not observed. But, when device_scale_factor changed from 1->2, the blur radius changed (less blurry on the background). Seems we did not take account of the device_scale_factor in the radius.
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Jul 14 2017
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Jul 14 2017
Real device means ChromeBooks, tested at kevin and link. Not the zoom. It is the resolution, which will affect UI_scale and device_scale_factor.
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Jul 17 2017
Note that the underlying Skia infrastructure will respect the CTM, and will apply any scaling in the CTM to the filter parameters which need it (many filters other than blur also need such treatment: drop-shadow, FEMorphology, etc). However, for web content, we apply device scale factor and page zoom for foreground filters at record time in Blink, by modifying the filter parameters directly, so we don't use the CTM for this. We *do* use the CTM for pinch zoom, IIRC. Backdrop filters in web content seem to do the correct thing (by applying the DSF and page zoom at record time, as foreground filters do; tested by passing --force-device-scale-factor=2). So the calling code in ChromeOS should probably take care of DSF for filter parameters, since making those changes in cc would likely break web content.
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Jul 17 2017
Just FYI, the Blink-side code that applies DSF and page zoom is in FilterOperationResolver, e.g., https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/css/resolver/FilterOperationResolver.cpp?sq=package:chromium&l=182
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Jul 17 2017
Thanks senorblanco@, if we want to keep the blur looks the same under different resolution, we might need to adjust the blur radius/sigma with the DSF before we send to skia? Seems a small change and I will leave it to PM to decide. For issue 1) at desktop, looks some artifact when using different resolution. I will resolve this bug for now. |
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Comment 1 by omrilio@chromium.org
, Jul 14 2017