TextOptions.TextFormattingMode affecting text with bold font weight

Question

I\'ve had a problem where making the font weight of some text Bold made it smaller than the Normal font weighted text. I\'ve worked out that this is because I\'ve got the Te

Answer 1

Unfortunately you've answered your question already. The answer is no. I am not sure why this is happening. I looked at it and pulled it up in SNOOP and sure enough it is rendering smaller.

It seems all font settings between 10.5 and 12.4 have this problem. Fonts 8, 9, or 10, 10.4 and 12.5, 13, 14 do not.

Sounds like time to contact Microsoft. Submit a bug.

Also, this has to do with your Windows Display Settings. When I switched my Display settings from 100% to 125%, then the issue changed. They now both look approximately the same size, not smaller.

Answer 2

The problem is not that the bold text is too short, it is that the normal text is too long.

There's history behind this, WPF originally shipped at .NET 3.0 supporting only the "Ideal" mode for scaling text. This mode supports true resolution independent text scaling, a line of text will have a predictable length in inches on various display devices with different dots-per-inch resolution. This was not received well, it caused massive complaints from WPF programmers that didn't like the blurry text that this produces. This is visible in your screen-shot. Note how the left stem of the bold letter m is too fat in Ideal mode but not in Display mode.

At .NET 4.0, the WPF team supported a new way to render text, called "Display". Which renders text the way GDI does it, applying font hinting rules to tweak the letter shape so it coincides better with the pixel grid of the monitor. This tends to stretch the letters, especially when their stem only has a single pixel. The smaller the point size, the more pronounced this becomes. The text is highly readable because of it, but true resolution independent rendering is lost.

Winforms also went through a similar evolution, from Graphics.DrawString() to TextRenderer.DrawText().

This blog post from the WPF team has the details.

The answer to your question is thus No.