com.adobe.fontengine.font.Subset Maven / Gradle / Ivy
Show all versions of aem-sdk-api Show documentation
/*
*
* File: Subset.java
*
*
* ADOBE CONFIDENTIAL
* ___________________
*
* Copyright 2004-2005 Adobe Systems Incorporated
* All Rights Reserved.
*
* NOTICE: All information contained herein is, and remains the property of
* Adobe Systems Incorporated and its suppliers, if any. The intellectual
* and technical concepts contained herein are proprietary to Adobe Systems
* Incorporated and its suppliers and may be covered by U.S. and Foreign
* Patents, patents in process, and are protected by trade secret or
* copyright law. Dissemination of this information or reproduction of this
* material is strictly forbidden unless prior written permission is obtained
* from Adobe Systems Incorporated.
*
*/
package com.adobe.fontengine.font;
/**
* Represent a subset of a font.
*
*
* Implementations of this interface keeps track of the correspondance between
* gids in the original font and gids in the subsetted font, which can be
* accessed via getFullGID and getSubsetGID. The
* number of glyphs in the subset is accessed by getNumGlyphs.
* New glyphs are added to the subset as needed when getSubsetGID
* is called: if the glyph that is passed in is not yet in the subset, it is
* added.
*
*
* Initially, the subset contains only the glyphs needed for the
* integrity of the subset font (e.g. it contains the .notdef glyph if that is
* required by the font format). For TrueType fonts, the subset
* always includes the glyphs with glyphID 0, 1, 2, 3; the purpose of this is
* to preserve the recommendation on the first four glyphs, if it has been
* followed by the original font (and the cost is typically very small,
* even if the recommendation was not followed in the first place).
*
*
* Some fonts do not allow subsetting. The subset behaves as if it had been
* built with all the glyphs of the original font.
*
*
* Some font technologies have the notion of building glyphs using other glyphs.
* For example, a TrueType glyph outline can invoke other glyph outlines.
* Implementations of this inteface maintain the subset so that it is closed,
* i.e. if such a composite glyph is in the subset, then the component glyphs
* are also in the subset.
*
*
* There is no guarantee that the glyph ID in a subset be equal to the glyph ID
* in the full font, even that is possible. In particular, adding all the
* glyphs in a font to a subset may result in an arbitrary permutation of
* the glyph ids (except for glyphs with well-known gids, such as .notdef, if
* any).
*
*
Synchronization
*
*
* A Subset object implements enough synchronization to be called safely from
* multiple threads.
*
*
* As methods are called, glyphs are only added to the subset. In particular,
* getNumGlyphs never decreases over time; if
* getSubsetGid returns some value at some point it always
* returns that value afterward; if getFullGid returns some value
* at some point for a glyph in the subset, then it always returns that value
* afterwards. Thus, code of the form:
*
*
* if (k < getNumGlyphs ()) {
* getFullGid (k);
* }
*
*
* does not need to be synchronized; the precondition on getFullGid is
* guaranteed by the earlier test (since getNumGlyph cannot decrease).
*/
public interface Subset {
/** Return the number of glyphs in the subset. */
public int getNumGlyphs ();
/** Return the subset gid corresponding to a full gid.
* @param fullGid the full gid, must be a legal gid for the full font.
* */
public int getSubsetGid (int fullGid)
throws UnsupportedFontException, InvalidFontException;
/** Return the currently esisting subset gid corresponding to a full gid,
* if there is one, without generating a new one. Return -1 if the full gid is not in the subset.
* @param fullGid the full gid, must be a legal gid for the full font.
* */
public int getExistingSubsetGid (int fullGid)
throws UnsupportedFontException, InvalidFontException;
/** Return the full gid corresponding to a subset gid.
* @param subsetGid the subset gid, must be in the range
* [0..getNumGlyphs () [
*/
public int getFullGid (int subsetGid);
}