LOAndroid3: correctly calculate the tile view rect

Because the tile view rect wasn't correctly calculated, some tiles
were deleted and in the same call immediately created again. With
this fix the performance increases.
Additionally inflate tile view rect by one tile to minimize the
undrawn tiles when scrolling.

Change-Id: I4b5b2bb31dd4f55babf87503dd37e396f6a5e200

android/experimental/LOAndroid3/src/java/org/libreoffice/LOKitThread.java

@@ -21,6 +21,7 @@ public class LOKitThread extends Thread {
     private TileProvider mTileProvider;
     private ViewportMetrics mViewportMetrics;
     private String mInputFile;
+    private Rect mOldRect;
 
     LOKitThread(String inputFile) {
         mInputFile = inputFile;
@@ -40,7 +41,22 @@ public class LOKitThread extends Thread {
         return new Rect(minX, minY, maxX, maxY);
     }
 
+    Rect inflate(Rect rect, int inflateSize) {
+        Rect newRect = new Rect(rect);
+        newRect.left -= inflateSize;
+        newRect.left = newRect.left < 0 ? 0 : newRect.left;
+
+        newRect.top -= inflateSize;
+        newRect.top = newRect.top < 0 ? 0 : newRect.top;
+
+        newRect.right += inflateSize;
+        newRect.bottom += inflateSize;
+
+        return newRect;
+    }
+
     private boolean draw() throws InterruptedException {
+        Log.i(LOGTAG, "tilerender draw");
         int pageWidth = mTileProvider.getPageWidth();
         int pageHeight = mTileProvider.getPageHeight();
 
@@ -56,18 +72,25 @@ public class LOKitThread extends Thread {
 
         ViewportMetrics metrics = mApplication.getLayerController().getViewportMetrics();
         RectF viewport = normlizeRect(metrics);
-        Rect rect = roundToTileSize(viewport, TILE_SIZE);
+        Rect rect = inflate(roundToTileSize(viewport, TILE_SIZE), TILE_SIZE);
+
+        mOldRect = rect;
+
+        Log.i(LOGTAG, "tilerender rect: " + rect);
 
         ArrayList<SubTile> removeTiles = new ArrayList<SubTile>();
         for (SubTile tile : layerClient.getTiles()) {
-            if (!rect.intersects(tile.x, tile.y, tile.x + TILE_SIZE, tile.y + TILE_SIZE)) {
+            Rect tileRect = new Rect(tile.x, tile.y, tile.x + TILE_SIZE, tile.y + TILE_SIZE);
+            if (!Rect.intersects(rect, tileRect)) {
+                Log.i(LOGTAG, "tilerender delete " + tileRect);
                 removeTiles.add(tile);
             }
         }
+
         layerClient.getTiles().removeAll(removeTiles);
 
-        for (int y = rect.top; y <= rect.bottom; y += TILE_SIZE) {
-            for (int x = rect.left; x <= rect.right; x += TILE_SIZE) {
+        for (int y = rect.top; y < rect.bottom; y += TILE_SIZE) {
+            for (int x = rect.left; x < rect.right; x += TILE_SIZE) {
                 if (x > pageWidth) {
                     continue;
                 }
@@ -88,7 +111,7 @@ public class LOKitThread extends Thread {
         }
 
         layerClient.endDrawing();
-
+        Log.i(LOGTAG, "tilerender end draw");
         return true;
     }