1916781 - Canvas font size in `px` should not be affected by text zoom

Status: RESOLVED DUPLICATE of bug 1909625

(Core :: CSS Parsing and Computation, defect, P3)

Description

[Tim Guan-tin Chien [:timdream] (please needinfo)]

Attachment: canvas-text-size.html

Canvas font size in px should not be affected by text zoom

STR:

1. Load the test case
2. Turn on text zoom and zoom in the text

Expected:

1. All text in layout gets bigger including the one with font size set to 16px.
2. Text size on canvas remain unchanged.

Actual:

1. All font sizes, including the one on canvas, is inflated.

Note:

1. One may be tempted to argue that the current behavior provides consistency between layout and canvas, but custom layout on canvas is much more limited; As demonstrated here, canvas layout cannot expand the bounding boxes and flow automatically like web layout. Developer will not be able to accommodate canvas font size changes in all cases.
2. Chrome does not change font sizes specified in px, in web layout nor canvas. macOS Safari does change font sizes specified in px but in web layout only, not on canvas. Firefox is the outlier here which web developers will likely ignore/unaware. This creates web compact issue.

Comment 1

[Emilio Cobos Álvarez [:emilio]]

Entry point is probably this one

Comment 2

[Emilio Cobos Álvarez [:emilio]]

I'll fix this along with bug 1909625.