More support on italic effect

[SDLBugzilla]

This bug report was migrated from our old Bugzilla tracker.

Reported in version: 2.0.10
Reported for operating system, platform: Linux, x86_64

Comments on the original bug report:

On 2014-09-15 09:55:42 +0000, Jerry wrote:

I'm using SDL_TTF library to display characters with italic effect.
With TTF_STYLE_ITALIC set, the characters displayed are always skewed to the right.

I would be grateful if characters can be displayed with the following italic effects:

1. Italic characters skewed to the left.
2. Italic characters skewed upwards or downwards, which has the effect of the Asian characters in this website, http://koji.ec/italics-in-vertical/.

On 2018-11-10 14:08:13 +0000, Sylvain wrote:

BTW, having "Italic characters skewed to the left." is an easy patch by setting a negative value to "shear.xy" (code applying italics style).