5/17/2023 0 Comments Glyphs meaningA typical kerning table lists pairs of glyphs and specifies how much space a text-processing client should add or remove between the glyphs to properly display each pair. The only positioning adjustment defined in TrueType is pair kerning, which modifies the horizontal spacing between two glyphs. Placement and advance may need adjustment vertically, as well as horizontally. But, for texts that require more sophisticated layout, the values must cover a richer range. ![]() ![]() For simple Latin text layout, these two values may be adequate to position glyphs correctly. TrueType specifies placement and advance only in the X direction for horizontal layout and only in the Y direction for vertical layout. For horizontal text, placement corresponds to the left side bearing, and advance corresponds to the advance width. If glyphs are positioned with respect to a virtual “pen point” that moves along a line of text, placement describes the glyph’s position with respect to the current pen point, and advance describes where to move the pen point to position the next glyph (see Figure 4c). Glyph positioning in TrueType uses only two values, placement and advance, to specify a glyph’s position for text layout. GPOS data, organized by script and language system, is easy for a text-processing client to use to position glyphs. With the GPOS table, a font developer can define a complete set of positioning adjustment features in an OpenType font. Urdu layout requires glyph positioning control, as well as contextual substitution ![]() To properly render Urdu, a text-processing client must modify both the horizontal (X) and vertical (Y) positions of each glyph. For instance, Urdu glyphs are calligraphic and connect to one another along a descending, diagonal text line that proceeds from right to left. Other writing systems require sophisticated glyph positioning for correct typographic composition. These writing systems require controlled placement of all marks in relation to one another for legibility and linguistic accuracy. The Glyph Positioning table (GPOS) provides precise control over glyph placement for sophisticated text layout and rendering in each script and language system that a font supports.Ĭomplex glyph positioning becomes an issue in writing systems, such as Vietnamese, that use diacritical and other marks to modify the sound or meaning of characters.
0 Comments
Leave a Reply. |