github.com/Kintar/etxt@v0.0.0-20221224033739-2fc69f000137/esizer/sizer.go (about)

     1  package esizer
     2  
     3  import "golang.org/x/image/font"
     4  import "golang.org/x/image/math/fixed"
     5  
     6  // When drawing or traversing glyphs, we need some information
     7  // related to the "font metrics". For example, how much we need
     8  // to advance after drawing a glyph or what's the kerning between
     9  // a specific pair of glyphs.
    10  //
    11  // Sizers are the interface that Renderers use to access that
    12  // information.
    13  //
    14  // You rarely need to care about Sizers, but they can be useful
    15  // in the following cases:
    16  //   - Disable kerning and adjust horizontal spacing.
    17  //   - Make full size adjustments for a custom rasterizer (e.g.,
    18  //     a rasterizer that puts glyphs into boxes, bubbles or frames).
    19  type Sizer interface {
    20  	Metrics(*Font, fixed.Int26_6) font.Metrics
    21  	Advance(*Font, GlyphIndex, fixed.Int26_6) fixed.Int26_6
    22  	Kern(*Font, GlyphIndex, GlyphIndex, fixed.Int26_6) fixed.Int26_6
    23  
    24  	// We could have a method for bounds too, but we
    25  	// don't need it in etxt, so it doesn't exist yet.
    26  	//Bounds(*Font, GlyphIndex, fixed.Int26_6, *sfnt.Buffer) fixed.Rect26_6
    27  }