Class GlyphPositioningSubtable

  • All Implemented Interfaces:
    java.lang.Comparable, GlyphPositioning

    public abstract class GlyphPositioningSubtable
    extends GlyphSubtable
    implements GlyphPositioning

    The GlyphPositioningSubtable implements an abstract base of a glyph subtable, providing a default implementation of the GlyphPositioning interface.

    This work was originally authored by Glenn Adams (gadams@apache.org).

    • Constructor Detail

      • GlyphPositioningSubtable

        protected GlyphPositioningSubtable​(java.lang.String id,
                                           int sequence,
                                           int flags,
                                           int format,
                                           GlyphCoverageTable coverage)
        Instantiate a GlyphPositioningSubtable.
        Parameters:
        id - subtable identifier
        sequence - subtable sequence
        flags - subtable flags
        format - subtable format
        coverage - subtable coverage table
    • Method Detail

      • getTableType

        public int getTableType()
        Specified by:
        getTableType in class GlyphSubtable
        Returns:
        this subtable's table type
      • getTypeName

        public java.lang.String getTypeName()
        Specified by:
        getTypeName in class GlyphSubtable
        Returns:
        this subtable's type name
      • isCompatible

        public boolean isCompatible​(GlyphSubtable subtable)
        Determine if a glyph subtable is compatible with this glyph subtable. Two glyph subtables are compatible if the both may appear in a single lookup table.
        Specified by:
        isCompatible in class GlyphSubtable
        Parameters:
        subtable - a glyph subtable to determine compatibility
        Returns:
        true if specified subtable is compatible with this glyph subtable, where by compatible is meant that they share the same lookup type
      • usesReverseScan

        public boolean usesReverseScan()
        Specified by:
        usesReverseScan in class GlyphSubtable
        Returns:
        true if subtable uses reverse scanning of glyph sequence, meaning from the last glyph in a glyph sequence to the first glyph
      • position

        public boolean position​(GlyphPositioningState ps)
        Perform glyph positioning at the current index, mutating the positioning state object as required. Only the context associated with the current index is processed.
        Specified by:
        position in interface GlyphPositioning
        Parameters:
        ps - glyph positioning state object
        Returns:
        true if the glyph subtable applies, meaning that the current context matches the associated input context glyph coverage table; note that returning true does not mean any position adjustment occurred; it only means that no further glyph subtables for the current lookup table should be applied.
      • position

        public static final boolean position​(GlyphPositioningState ps,
                                             GlyphPositioningSubtable[] sta,
                                             int sequenceIndex)
        Apply positioning using specified state and subtable array. For each position in input sequence, apply subtables in order until some subtable applies or none remain. If no subtable applied or no input was consumed for a given position, then apply default action (no adjustments and advance). If sequenceIndex is non-negative, then apply subtables only when current position matches sequenceIndex in relation to the starting position. Furthermore, upon successful application at sequenceIndex, then discontinue processing the remaining
        Parameters:
        ps - positioning state
        sta - array of subtables to apply
        sequenceIndex - if non negative, then apply subtables only at specified sequence index
        Returns:
        true if a non-zero adjustment occurred
      • position

        public static final boolean position​(GlyphSequence gs,
                                             java.lang.String script,
                                             java.lang.String language,
                                             java.lang.String feature,
                                             int fontSize,
                                             GlyphPositioningSubtable[] sta,
                                             int[] widths,
                                             int[][] adjustments,
                                             ScriptContextTester sct)
        Apply positioning.
        Parameters:
        gs - input glyph sequence
        script - tag
        language - tag
        feature - tag
        fontSize - the font size
        sta - subtable array
        widths - array
        adjustments - array (receives output adjustments)
        sct - script context tester
        Returns:
        true if a non-zero adjustment occurred