1767368 - canvas text rendering issue because of Direct2d backend in Windows

Status: UNCONFIRMED

(Core :: Graphics: Canvas2D, defect, P3)

Description

[854185073]

Attachment: canvas-text-bug.html

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:99.0) Gecko/20100101 Firefox/99.0

Steps to reproduce:

i put one chinese character across two adjacent canvases to draw.

Actual results:

i found that the right-side canvas has a wrong result. the pixels in the first one-pixel-width column are vanished, i think the left position of the text is calculated is wrong.
but chrome which is using skia performed well.

i spent a long time to investigate it, and i found that if the flag 'gfx.direct2d.disabled' is enabled, the problem is solved. or change rendering backend by removing 'direct2d1.1' in 'gfx.canvas.azure.backends' and restart firefox.

so i assume that it's a direct2d problem, i create a visual studio project and a Direct2D example, using the same transform and text layout rect to draw the text, the rendered result is totally same buggy.

Expected results:

the character is drawn normal just like it's in one canvas.

Comment 1

[BugBot [:suhaib / :marco]]

The Bugbug bot thinks this bug should belong to the 'Core::Graphics' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Lee Salzman [:lsalzman]]

Jonathan, ideas?

Comment 3

[854185073]

Attachment: canvas-text-bug.html

install the font "宋体"(SimSun) first to reproduce this.

Comment 4

[854185073]

Attachment: firefox-behavior.png

Comment 5

[854185073]

Attachment: expected.png

Comment 6

[854185073]

Attachment: canvas-text-bug-minimal-reproduce.html

just 5 lines of js codes to reproduce this.