RFR: 8269806: Emoji rendering on Linux [v17]

[Phil Race]

On Wed, 25 Jan 2023 13:22:31 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 one additional commit since the last revision:
> 
>   Skip tests if required font is absent

src/java.desktop/share/classes/sun/font/CMap.java line 1173:

> 1171: 
> 1172:     char getVariationGlyph(int charCode, int variationSelector) {
> 1173:         if (variationSelector == 0) return getGlyph(charCode);

another place for braces

src/java.desktop/share/classes/sun/font/CompositeGlyphMapper.java line 142:

> 140:     @Override
> 141:     public int charToVariationGlyph(int unicode, int variationSelector) {
> 142:         if (variationSelector == 0) return charToGlyph(unicode);

more missing braces. I'm going to stop pointing these out, please just find and fix any others

src/java.desktop/share/native/libfontmanager/freetypeScaler.c line 52:

> 50: // to build on older Linuxes, this is not a big problem,
> 51: // as Linux uses bitmap emoji anyway.
> 52: #if defined(_WIN32) || defined(__APPLE__)

Do we really have to disable coloured outlines because of what's available at build time ? Why can't we dynamically locate all the needed symbols at runtime ?

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