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package sun.java2d.pipe;
The API for an object that generates alpha coverage tiles for a given path. The 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: 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();
The bounding box for the iteration will be returned by the RenderingEngine via an argument to the getAATileGenerator() method. /**
* 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.
Returns: the width of the standard alpha tile
/**
* 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.
Returns: the height of the standard alpha tile
/**
* 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.
Returns: 0x00 for no coverage, 0xff for total coverage, or any other
value for partial coverage of the tile
/**
* 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.
/**
* 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.
/**
* 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.
/**
* Disposes this tile generator.
* No further calls will be made on this instance.
*/
public void dispose();
}