public void coverWithTilesIfNeeded(BSTimerTask task) {
Rect visibleRect = visibleRect();
Rect rect = mapFromContents(mClient.tbsGetContentsRect());
boolean didChange =
!mTrajectoryVector.equals(mPendingTrajectoryVector)
|| !mVisibleRect.equals(visibleRect)
|| !mRect.equals(rect);
if (didChange || mPendingTileCreation) createTiles(task);
}
private boolean resizeEdgeTiles() {
boolean wasResized = false;
List<Coordinate> tilesToRemove = new ArrayList<Coordinate>();
Iterator<Entry<Coordinate, ITile>> it = mMainTiles.iterator();
while (it.hasNext()) {
Entry<Coordinate, ITile> entry = it.next();
Coordinate tileCoordinate = entry.getValue().coordinate();
Rect tileRect = entry.getValue().rect();
Rect expectedTileRect = tileRectForCoordinate(tileCoordinate);
if (expectedTileRect.isEmpty()) tilesToRemove.add(tileCoordinate);
else if (!expectedTileRect.equals(tileRect)) {
entry.getValue().resize(expectedTileRect.getWidth(), expectedTileRect.getHeight());
wasResized = true;
}
}
int removeCount = tilesToRemove.size();
for (int n = 0; n < removeCount; ++n) removeTile(tilesToRemove.get(n));
return wasResized;
}
private void createTiles(BSTimerTask task) {
// Guard here as as these can change before the timer fires.
if (isBackingStoreUpdatesSuspended()) return;
// Update our backing store geometry.
final Rect previousRect = mRect.clone();
mapFromContents(mClient.tbsGetContentsRect()).copyTo(mRect);
mPendingTrajectoryVector.copyTo(mTrajectoryVector);
visibleRect().copyTo(mVisibleRect);
if (mRect.isEmpty()) {
setCoverRect(new Rect());
setKeepRect(new Rect());
return;
}
/* We must compute cover and keep rects using the visibleRect, instead of the rect intersecting the visibleRect with m_rect,
* because TBS can be used as a backing store of GraphicsLayer and the visible rect usually does not intersect with m_rect.
* In the below case, the intersecting rect is an empty.
*
* +---------------+
* | |
* | m_rect |
* | +-------|-----------------------+
* | | HERE | cover or keep |
* +---------------+ rect |
* | +---------+ |
* | | visible | |
* | | rect | |
* | +---------+ |
* | |
* | |
* +-------------------------------+
*
* We must create or keep the tiles in the HERE region.
*/
Rect coverRect = new Rect();
Rect keepRect = new Rect();
computeCoverAndKeepRect(mVisibleRect, coverRect, keepRect);
setCoverRect(coverRect);
setKeepRect(keepRect);
if (coverRect.isEmpty()) return;
// Resize tiles at the edge in case the contents size has changed, but only do so
// after having dropped tiles outside the keep rect.
boolean didResizeTiles = false;
if (!previousRect.equals(mRect)) didResizeTiles = resizeEdgeTiles();
// Search for the tile position closest to the viewport center that does not yet contain a tile.
// Which position is considered the closest depends on the tileDistance function.
double shortestDistance = Double.POSITIVE_INFINITY;
List<Coordinate> tilesToCreate = new ArrayList<Coordinate>();
int requiredTileCount = 0;
// Cover areas (in tiles) with minimum distance from the visible rect. If the visible rect is
// not covered already it will be covered first in one go, due to the distance being 0 for tiles
// inside the visible rect.
Coordinate topLeft = tileCoordinateForPoint(coverRect.getLeft(), coverRect.getTop());
Coordinate bottomRight = tileCoordinateForPoint(coverRect.getRight(), coverRect.getBottom());
for (int yCoordinate = topLeft.getY(); yCoordinate <= bottomRight.getY(); ++yCoordinate) {
for (int xCoordinate = topLeft.getX(); xCoordinate <= bottomRight.getX(); ++xCoordinate) {
if (getTileAt(xCoordinate, yCoordinate) != null) continue;
++requiredTileCount;
double distance = tileDistance(mVisibleRect, xCoordinate, yCoordinate);
if (distance > shortestDistance) continue;
if (distance < shortestDistance) {
tilesToCreate.clear();
shortestDistance = distance;
}
tilesToCreate.add(new Coordinate(xCoordinate, yCoordinate));
}
}
// Now construct the tile(s) within the shortest distance.
int tilesToCreateCount = tilesToCreate.size();
for (int n = 0; n < tilesToCreateCount; ++n) {
Coordinate coordinate = tilesToCreate.get(n);
setTile(coordinate, mBackend.createTile(coordinate));
}
requiredTileCount -= tilesToCreateCount;
// Paint the content of the newly created tiles or resized tiles.
if (tilesToCreateCount != 0 || didResizeTiles) updateTileBuffers(task);
// Re-call createTiles on a timer to cover the visible area with the newest shortest distance.
mPendingTileCreation = requiredTileCount != 0;
if (mPendingTileCreation) {
if (!mCommitTileUpdatesOnIdleEventLoop) {
mClient.tbsHasPendingTileCreation();
return;
}
Log.d(
"tt",
"start BSUpdate scheduleTask in createTiles func scale "
+ mContentsScale
+ " pending scale "
+ mPendingScale);
if (task == null || !task.cancelled()) startBSUpdateTask(TILE_CREATION_DELAY_MS);
}
}