/*
* Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* 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).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package sun.java2d.pipe;
/**
* The API for an object that generates alpha coverage tiles for a given
* path.
* The {@link RenderingEngine} will be consulted as a factory to return
* one of these objects for a given Shape and a given set of rendering
* attributes.
* This object will iterate through the bounds of the rendering primitive
* and return tiles of a constant size as specified by the getTileWidth()
* and getTileHeight() parameters.
* The iteration order of the tiles will be as specified by the pseudo-code:
* <pre>
* int bbox[] = {left, top, right, bottom};
* AATileGenerator aatg = renderengine.getAATileGenerator(..., bbox);
* int tw = aatg.getTileWidth();
* int th = aatg.getTileHeight();
* byte tile[] = new byte[tw * th];
* for (y = top; y < bottom; y += th) {
* for (x = left; x < right; x += tw) {
* int a = aatg.getTypicalAlpha();
* int w = Math.min(tw, right-x);
* int h = Math.min(th, bottom-y);
* if (a == 0x00) {
* // can skip this tile...
* aatg.nextTile();
* } else if (a == 0xff) {
* // can treat this tile like a fillRect
* aatg.nextTile();
* doFill(x, y, w, h);
* } else {
* aatg.getAlpha(tile, 0, tw);
* handleAlpha(tile, x, y, w, h);
* }
* }
* }
* aatg.dispose();
* </pre>
* The bounding box for the iteration will be returned by the
* {@code RenderingEngine} via an argument to the getAATileGenerator() method.
*/
public interface AATileGenerator {
/**
* Gets the width of the tiles that the generator batches output into.
* @return the width of the standard alpha tile
*/
public int getTileWidth();
/**
* Gets the height of the tiles that the generator batches output into.
* @return the height of the standard alpha tile
*/
public int getTileHeight();
/**
* Gets the typical alpha value that will characterize the current
* tile.
* The answer may be 0x00 to indicate that the current tile has
* no coverage in any of its pixels, or it may be 0xff to indicate
* that the current tile is completely covered by the path, or any
* other value to indicate non-trivial coverage cases.
* @return 0x00 for no coverage, 0xff for total coverage, or any other
* value for partial coverage of the tile
*/
public int getTypicalAlpha();
/**
* Skips the current tile and moves on to the next tile.
* Either this method, or the getAlpha() method should be called
* once per tile, but not both.
*/
public void nextTile();
/**
* Gets the alpha coverage values for the current tile.
* Either this method, or the nextTile() method should be called
* once per tile, but not both.
*/
public void getAlpha(byte tile[], int offset, int rowstride);
/**
* Disposes this tile generator.
* No further calls will be made on this instance.
*/
public void dispose();
}