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Starred by 3 users

Issue metadata

Status: Available
Owner: ----
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: Windows
Pri: 2
Type: Bug



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Canvas scaling image by x.5 causes jagged pixelated edges does not happen on x.501/x.499

Reported by smann...@gmail.com, Jun 27 2017

Issue description

UserAgent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3143.0 Safari/537.36

Steps to reproduce the problem:
1. Created a canvas with large width/height greater than 500 
2. Draw an image with ctx.scale(2.5, 2.5)
3. The image will be weird pixelated and jagged

What is the expected behavior?
Image doesn't bleed or display jagged. Hard to explain the effect that is happening because I'm not sure this has ever happened before! :]

What went wrong?
The image will be weird pixelated and jagged.

Did this work before? N/A 

Chrome version: 61.0.3143.0  Channel: stable
OS Version: 10.0
Flash Version: 

JS Fiddle:
https://jsfiddle.net/up0anw40/1/

Computer Specifications:
Operating System: Windows 10 Pro 64-Bit (10.0, Build 15063)
Processor: Intel i7-4790K
Video 1: Intel HD Graphics 4600
Video 2: ATI Radeon HD 4300/4500 Series

I tested this seems to render fine on:
Chrome 58.0.3029.110
Edge 40.15063
Trusty Internet Explorer 11
Firefox 55.0b3

If we make the canvas size smaller example 200 the drawing is not pixelated. Could this be related to my video card?

Thank you so much!!!
 
canvas scaling chromium windows 10.gif
4.4 MB View Download
chromium scaling weird.PNG
9.3 KB View Download

Comment 1 by tkent@chromium.org, Jun 28 2017

Components: -Blink Blink>Canvas
Labels: Needs-Triage-M61

Comment 3 by ajha@chromium.org, Jun 29 2017

Cc: pbomm...@chromium.org
Labels: TE-NeedsTriageFromMTV
Tested this on the latest canary(61.0.3144.0) and the latest stable(59.0.3071.115) on Windows-10 and didn't observe any pixelated behavior on both chrome versions. Tested on Intel Core i7-6700 CPU @3.40 GHz.

Don't have exact configuration as updated in C#0 to test and confirm this. Hence looping MTV team for help in triaging this further.
737289.mp4
913 KB View Download

Comment 4 by junov@chromium.org, Jul 17 2017

Components: Internals>Skia Internals>GPU>VendorSpecific
Wow, very weird behavior.  I am not able to repro either, but I do not have the exact same GPU and driver as reported.  Since this only happens on large canvases (greater than 256x256), it means the bug is tied to the GPU-accelerated code path.  My best guess is that there is a problem with texture coordinate interpolation precision.  Adding skia/gpu components to get more eyes on this.

Comment 5 by junov@chromium.org, Jul 17 2017

Cc: yunchao...@intel.com yang...@intel.com

Comment 6 by enne@chromium.org, Jul 21 2017

Status: Available (was: Unconfirmed)

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