LOAndroid3: Prevent crash when opening a nonexistent file

Change-Id: Ic0fbe955dfdb8f044d7bf0f45215a632a111eae2

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

@@ -86,22 +86,24 @@ public class LOKitThread extends Thread {
         return true;
     }
 
-    private void initialize() {
+    private boolean initialize() {
         mApplication = LibreOfficeMainActivity.mAppContext;
         mTileProvider = new LOKitTileProvider(mApplication.getLayerController(), mInputFile);
+        return mTileProvider.isReady();
     }
 
     public void run() {
-        initialize();
-        try {
-            boolean drawn = false;
-            while (true) {
-                if (!mEvents.isEmpty()) {
-                    processEvent(mEvents.poll());
+        if (initialize()) {
+            try {
+                boolean drawn = false;
+                while (true) {
+                    if (!mEvents.isEmpty()) {
+                        processEvent(mEvents.poll());
+                    }
+                    Thread.sleep(100L);
                 }
-                Thread.sleep(100L);
+            } catch (InterruptedException ex) {
             }
-        } catch (InterruptedException ex) {
         }
     }
 

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

@@ -56,6 +56,11 @@ public class LOKitTileProvider implements TileProvider {
         return (int) twipToPixel(mDocument.getDocumentHeight(), mDPI);
     }
 
+    @Override
+    public boolean isReady() {
+        return mDocument != null;
+    }
+
     public SubTile createTile(int x, int y) {
         ByteBuffer buffer = ByteBuffer.allocateDirect(TILE_SIZE * TILE_SIZE * 4);
         Bitmap bitmap = Bitmap.createBitmap(TILE_SIZE, TILE_SIZE, Bitmap.Config.ARGB_8888);

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

@@ -25,6 +25,11 @@ public class MockTileProvider implements TileProvider {
         return 630*5;
     }
 
+    @Override
+    public boolean isReady() {
+        return true;
+    }
+
     @Override
     public SubTile createTile(int x, int y) {
         int tiles = (getPageWidth() / TILE_SIZE) + 1;

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

@@ -7,5 +7,7 @@ public interface TileProvider {
     int getPageWidth();
     int getPageHeight();
 
+    boolean isReady();
+
     SubTile createTile(int x, int y);
 }