On Fri, 7 May 2021 08:02:36 GMT, Dmitry Batrak <dbat...@openjdk.org> wrote:
>> This is the implementation used by JetBrains Runtime for the last 4 years, >> after some cleanup, and with one problem, >> found while preparing the pull request, fixed. >> Even though typical scenarios for a UI application should be covered, it's >> not a complete solution. In particular, emoji-s >> still won't be rendered for large font sizes (more than 100pt), and for >> non-trivial composite/painting modes. >> Notable implementation details are listed below. >> >> **Glyph image generation** >> >> Deprecated CGContextShowGlyphsAtPoint function, used by JDK on macOS to >> render text, cannot render emojis, >> CTFontDrawGlyphs is used instead. It ignores the scale component of text >> transformation matrix, so a 'real-sized' >> CTFont object should be passed to it. The same sizing procedure is done when >> calculating glyph metrics, because they >> are not scaled proportionally with font size (as they do for vector fonts). >> >> **Glyph image storage** >> >> Existing GlyphInfo structure is used to store color glyph image. Color glyph >> can be distinguished by having 4 bytes >> of storage per pixel. Color components are stored in pre-multiplied alpha >> format. >> >> **Glyph rendering** >> >> Previously, GlyphList instance always contained glyphs in the same format >> (solid, grayscale or LCD), determined by the >> effective rendering hint. Now the renderers must be prepared to GlyphList >> having 'normal' glyphs interspersed with >> color glyphs (they can appear due to font fallback). This isn't a problem >> for OpenGL renderer (used for on-screen painting), >> but GlyphListLoopPipe-based renderers (used for off-screen painting) needed >> an adjustment to be able to operate on >> specific segments of GlyphList. >> As an incidental optimization, calculation of GlyphList bounds ('getBounds' >> method) is performed now only when needed >> (most text renderers don't need this information). >> Speaking of the actual rendering of the glyph image, it's done by the >> straightforward glDrawPixels call in OpenGL renderer, >> and by re-using existing Blit primitive in off-screen renderers. >> >> **Testing** >> >> There's no good way to test the new functionality automatically, but I've >> added a test verifying that 'something' is >> rendered for the emoji character, when painting to BufferedImage. >> >> Existing tests pass after the change. > > Dmitry Batrak has updated the pull request incrementally with one additional > commit since the last revision: > > 8263583: Emoji rendering on macOS > > add 'static' modifier to a variable It is not necessary to get reapprove for push, it is just a good style to do. ------------- PR: https://git.openjdk.java.net/jdk/pull/3007