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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
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*
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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package sun.font;
import java.awt.geom.GeneralPath;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.lang.ref.WeakReference;
import sun.java2d.DisposerRecord;
/* FontScaler is "internal interface" to font rasterizer library.
*
* Access to native rasterizers without going through this interface is
* strongly discouraged. In particular, this is important because native
* data could be disposed due to runtime font processing error at any time.
*
* FontScaler represents combination of particular rasterizer implementation
* and particular font. It does not include rasterization attributes such as
* transform. These attributes are part of native scalerContext object.
* This approach allows to share same scaler for different requests related
* to the same font file.
*
* Note that scaler may throw FontScalerException on any operation.
* Generally this means that runtime error had happened and scaler is not
* usable. Subsequent calls to this scaler should not cause crash but will
* likely cause exceptions to be thrown again.
*
* It is recommended that callee should replace its reference to the scaler
* with something else. For instance it could be FontManager.getNullScaler().
* Note that NullScaler is trivial and will not actually rasterize anything.
*
* Alternatively, callee can use more sophisticated error recovery strategies
* and for instance try to substitute failed scaler with new scaler instance
* using another font.
*
* Note that in case of error there is no need to call dispose(). Moreover,
* dispose() generally is called by Disposer thread and explicit calls to
* dispose might have unexpected sideeffects because scaler can be shared.
*
* Current disposing logic is the following:
* - scaler is registered in the Disposer by the FontManager (on creation)
* - scalers are disposed when associated Font2D object (e.g. TruetypeFont)
* is garbage collected. That's why this object implements DisposerRecord
* interface directly (as it is not used as indicator when it is safe
* to release native state) and that's why we have to use WeakReference
* to Font internally.
* - Majority of Font2D objects are linked from various mapping arrays
* (e.g. FontManager.localeFullNamesToFont). So, they are not collected.
* This logic only works for fonts created with Font.createFont()
*
* Notes:
* - Eventually we may consider releasing some of the scaler resources if
* it was not used for a while but we do not want to be too aggressive on
* this (and this is probably more important for Type1 fonts).
*/
public abstract class FontScaler implements DisposerRecord {
protected WeakReference<Font2D> font = null;
protected long nativeScaler = 0; //used by decendants
//that have native state
protected boolean disposed = false;
abstract StrikeMetrics getFontMetrics(long pScalerContext)
throws FontScalerException;
abstract float getGlyphAdvance(long pScalerContext, int glyphCode)
throws FontScalerException;
abstract void getGlyphMetrics(long pScalerContext, int glyphCode,
Point2D.Float metrics)
throws FontScalerException;
/*
* Returns pointer to native GlyphInfo object.
* Callee is responsible for freeing this memory.
*
* Note:
* currently this method has to return not 0L but pointer to valid
* GlyphInfo object. Because Strike and drawing releated logic does
* expect that.
* In the future we may want to rework this to allow 0L here.
*/
abstract long getGlyphImage(long pScalerContext, int glyphCode)
throws FontScalerException;
abstract Rectangle2D.Float getGlyphOutlineBounds(long pContext,
int glyphCode)
throws FontScalerException;
abstract GeneralPath getGlyphOutline(long pScalerContext, int glyphCode,
float x, float y)
throws FontScalerException;
abstract GeneralPath getGlyphVectorOutline(long pScalerContext, int[] glyphs,
int numGlyphs, float x, float y)
throws FontScalerException;
/* Used by Java2D disposer to ensure native resources are released.
Note: this method does not release any of created
scaler context objects! */
public void dispose() {}
/* At the moment these 3 methods are needed for Type1 fonts only.
* For Truetype fonts we extract required info outside of scaler
* on java layer.
*/
abstract int getNumGlyphs() throws FontScalerException;
abstract int getMissingGlyphCode() throws FontScalerException;
abstract int getGlyphCode(char charCode) throws FontScalerException;
/* This method returns table cache used by native layout engine.
* This cache is essentially just small collection of
* pointers to various truetype tables. See definition of TTLayoutTableCache
* in the fontscalerdefs.h for more details.
*
* Note that tables themselves have same format as defined in the truetype
* specification, i.e. font scaler do not need to perform any preprocessing.
*
* Probably it is better to have API to request pointers to each table
* separately instead of requesting pointer to some native structure.
* (then there is not need to share its definition by different
* implementations of scaler).
* However, this means multiple JNI calls and potential impact on performance.
*
* Note: return value 0 is legal.
* This means tables are not available (e.g. type1 font).
*/
abstract long getLayoutTableCache() throws FontScalerException;
/* Used by the OpenType engine for mark positioning. */
abstract Point2D.Float getGlyphPoint(long pScalerContext,
int glyphCode, int ptNumber)
throws FontScalerException;
abstract long getUnitsPerEm();
/* Returns pointer to native structure describing rasterization attributes.
Format of this structure is scaler-specific.
Callee is responsible for freeing scaler context (using free()).
Note:
Context is tightly associated with strike and it is actually
freed when corresponding strike is being released.
*/
abstract long createScalerContext(double[] matrix,
boolean fontType,
int aa, int fm,
float boldness, float italic);
/* Marks context as invalid because native scaler is invalid.
Notes:
- pointer itself is still valid and has to be released
- if pointer to native scaler was cached it
should not be neither disposed nor used.
it is very likely it is already disposed by this moment. */
abstract void invalidateScalerContext(long ppScalerContext);
}