RFR: 8269806: Emoji rendering on Linux [v4]

[Nikita Gubarkov]

On Sat, 25 Jun 2022 01:11:59 GMT, Nikita Gubarkov <duke at openjdk.org> wrote:

>> It was implemented in JetBrains Runtime a year ago and was ported & refactored for this PR
>> It includes:
>> - Bitmap glyph loading via Freetype
>> - Manual scaling & transformation of bitmap glyphs with nearest-neighbor or bilinear-mipmap style algorithms depending on the text antialiasing hint
>> - Storing BGRA glyphs in glyph cache & rendering them as plain images, as currently used XRender text drawing functions doesn't support colored glyphs
>> - Small fixes in related code like null-checks which could cause NPE & comment typos
>
> Nikita Gubarkov has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - 8269806: Fix rendering of colored glyphs on big font sizes
>    
>    When using OutlineTextRenderer, fallback to GlyphListPipe for glyphs which doesn't have outlines.
>  - 8269806: Fix glyph advance rounding with FM=OFF

src/java.desktop/share/classes/sun/java2d/pipe/OutlineTextRenderer.java line 75:

> 73:     public void drawString(SunGraphics2D g2d, String str, double x, double y) {
> 74: 
> 75:         StandardGlyphVector sgv = new StandardGlyphVector(g2d.getFont(), str, g2d.getFontRenderContext());

I started using `GlyphVector` instead of `TextLayout` because it gives more consistent look for animated text. For example, earlier text which has ligatures rendered with `drawString` was drawn with ligatures on `OutlineTextRenderer` and without on `GlyphListPipe`, which caused artifacts when text size crosses 100 threshold.

-------------

PR: https://git.openjdk.org/jdk/pull/4798