Allow snap to grid (closes #14)

core/src/io/github/lonamiwebs/klooni/Klooni.java

@@ -50,6 +50,8 @@ public class Klooni extends Game {
         skin.add("share_texture", new Texture(Gdx.files.internal("ui/share.png")));
         skin.add("sound_on_texture", new Texture(Gdx.files.internal("ui/sound_on.png")));
         skin.add("sound_off_texture", new Texture(Gdx.files.internal("ui/sound_off.png")));
+        skin.add("snap_on_texture", new Texture(Gdx.files.internal("ui/snap_on.png")));
+        skin.add("snap_off_texture", new Texture(Gdx.files.internal("ui/snap_off.png")));
         skin.add("issues_texture", new Texture(Gdx.files.internal("ui/issues.png")));
         skin.add("credits_texture", new Texture(Gdx.files.internal("ui/credits.png")));
         skin.add("web_texture", new Texture(Gdx.files.internal("ui/web.png")));
@@ -121,6 +123,14 @@ public class Klooni extends Game {
         prefs.putBoolean("muteSound", soundsEnabled()).flush();
     }
 
+    public static boolean shouldSnapToGrid() {
+        return prefs.getBoolean("snapToGrid", false);
+    }
+
+    public static void toggleSnapToGrid() {
+        prefs.putBoolean("snapToGrid", !shouldSnapToGrid()).flush();
+    }
+
     public static boolean isThemeBought(Theme theme) {
         if (theme.getPrice() == 0)
             return true;

core/src/io/github/lonamiwebs/klooni/game/Board.java

@@ -121,6 +121,21 @@ public class Board implements BinSerializable {
         return putPiece(piece, x, y);
     }
 
+    Vector2 snapToGrid(final Piece piece, final Vector2 position) {
+        // Snaps the given position (e.g. mouse) to the grid,
+        // assuming piece wants to be put at the specified position.
+        // If the piece was not on the grid, the original position is returned
+        //
+        // Logic to determine the x and y is a copy-paste from putScreenPiece
+        final Vector2 local = position.cpy().sub(pos);
+        int x = MathUtils.round(local.x / piece.cellSize);
+        int y = MathUtils.round(local.y / piece.cellSize);
+        if (canPutPiece(piece, x, y))
+            return new Vector2(pos.x + x * piece.cellSize, pos.y + y * piece.cellSize);
+        else
+            return position;
+    }
+
     // This will clear both complete rows and columns, all at once.
     // The reason why we can't check first rows and then columns
     // (or vice versa) is because the following case (* filled, _ empty):

core/src/io/github/lonamiwebs/klooni/game/PieceHolder.java

@@ -209,7 +209,8 @@ public class PieceHolder implements BinSerializable {
     }
 
     // Updates the state of the piece holder (and the held piece)
-    public void update() {
+    // TODO Passing the board seems expensive… Should it rather be an attribute?
+    public void update(Board board) {
         Piece piece;
         if (heldPiece > -1) {
             piece = pieces[heldPiece];
@@ -227,6 +228,8 @@ public class PieceHolder implements BinSerializable {
                 // avoiding to cover it with the finger (issue on Android devices)
                 mouse.sub(piece.getRectangle().width * 0.5f, -pickedCellSize);
             }
+            if (Klooni.shouldSnapToGrid())
+                mouse.set(board.snapToGrid(piece, mouse));
 
             piece.pos.lerp(mouse, DRAG_SPEED);
             piece.cellSize = Interpolation.linear.apply(piece.cellSize, pickedCellSize, DRAG_SPEED);

core/src/io/github/lonamiwebs/klooni/screens/CustomizeScreen.java

@@ -80,6 +80,20 @@ class CustomizeScreen implements Screen {
         });
         optionsGroup.addActor(soundButton);
 
+        // Snap to grid on/off
+        final SoftButton snapButton = new SoftButton(
+                2, Klooni.shouldSnapToGrid() ? "snap_on_texture" : "snap_off_texture");
+
+        snapButton.addListener(new ChangeListener() {
+            @Override
+            public void changed(ChangeEvent event, Actor actor) {
+                Klooni.toggleSnapToGrid();
+                snapButton.image = CustomizeScreen.this.game.skin.getDrawable(
+                        Klooni.shouldSnapToGrid() ? "snap_on_texture" : "snap_off_texture");
+            }
+        });
+        optionsGroup.addActor(snapButton);
+
         // Issues
         final SoftButton issuesButton = new SoftButton(3, "issues_texture");
         issuesButton.addListener(new ChangeListener() {

core/src/io/github/lonamiwebs/klooni/screens/GameScreen.java

@@ -166,7 +166,7 @@ class GameScreen implements Screen, InputProcessor, BinSerializable {
 
         scorer.draw(batch);
         board.draw(batch);
-        holder.update();
+        holder.update(board);
         holder.draw(batch);
         bonusParticleHandler.run(batch);