Bug 64893 – Webkit does not scale fonts properly due to lack of DPI configurability

• Component: Layout and Rendering
• Status: UNCONFIRMED

[Dan McDougall]

Due to the fact that DPI cannot be configured in Webkit's rendering engine, fonts do not get scaled properly when viewing web pages.  I have written and attached a test case (also at http://riskable.com/files/font_scaling_test.html) which clearly demonstrates the problem.  Simply open font_scaling_test.html on a system/display with any DPI higher or lower than 96 and you'll wind up with broken font rendering.  The greater the distance from 96 dpi, the more inaccurate (and broken) font rendering will be.

The point measurement system is defined as 1 point == 1/72 of an inch.  This means:

 * If you have a 10-inch display with 300 dpi, a font at 72pt should appear one inch tall.
 * If you have a 22-inch display with 96 dpi, a font at 72pt should appear one inch tall.
 * If you have a 80-inch display with 50 dpi, a font at 72pt should appear one inch tall.

See what I'm getting at?  As long as the Webkit page renderer doesn't allow configuration of display DPI, fonts will be scaled incorrectly on any display that isn't precisely 96dpi.

References:

http://en.wikipedia.org/wiki/Point_(typography)

--
Dan McDougall
"Zero-day events occur because somebody *didn't* disclose a security vulnerability."

[Dan McDougall]

Created attachment 101506 [details]
Font scaling test case

This HTML file can be used to determine if fonts are being scaled properly by your web browser.

[Jeremy Nickurak]

Dupe of https://bugs.webkit.org/show_bug.cgi?id=18001