Update the AppBannerView appearance

chrome/android/java/src/org/chromium/chrome/browser/banners/RatingView.java

Index: chrome/android/java/src/org/chromium/chrome/browser/banners/RatingView.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/banners/RatingView.java b/chrome/android/java/src/org/chromium/chrome/browser/banners/RatingView.java
new file mode 100644
index 0000000000000000000000000000000000000000..536ad4ed6a3a74292a9c4b2810da1befbb3ac486
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/banners/RatingView.java
@@ -0,0 +1,99 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.banners;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
+import android.graphics.Canvas;
+import android.graphics.Matrix;
+import android.graphics.Rect;
+import android.util.AttributeSet;
+import android.view.View;
+
+import org.chromium.chrome.R;
+import org.chromium.ui.base.LocalizationUtils;
+
+/**
+ * Displays a set of stars representing a rating for an app.

[newt (away), 2014/02/19 21:52:49]

Yay! Class-level JavaDoc!

+ */
+public class RatingView extends View {
+    private static final int MAX_INCREMENT = 10;
+
+    // Bitmaps shared across all RatingViews.
+    private static Bitmap sStarFull;

[newt (away), 2014/02/19 21:52:49]

advantage of statics: If many RatingViews exist simultaneously, they can use the
same Bitmaps and hence save memory and decoding time.

disadvantage of statics: We'll keep this memory around forever, even (in the
common case) where no more app banners will ever be shown. Plus, findbugs may
chastise you for thread safety issues here, though that's not an issue IMO.

I'd lean towards making these member variables instead of statics.

[gone, 2014/02/19 23:31:43]

Done.

+    private static Bitmap sStarHalf;
+    private static Bitmap sStarEmpty;

[David Trainor- moved to gerrit, 2014/02/20 01:22:27]

Ah I knew it!

+
+    /** Stores whether or not the layout is left-to-right. */
+    private final boolean mIsLayoutLTR;
+
+    /** Variables used for drawing. */
+    private final Rect mDrawingRect;
+
+    /** Each increment represents 0.5 stars. */
+    private int mIncrements;
+
+    public RatingView(Context context, AttributeSet params) {
+        super(context, params);
+        mIsLayoutLTR = !LocalizationUtils.isSystemLayoutDirectionRtl();
+        mDrawingRect = new Rect();
+    }
+
+    /**
+     * Initializes the RatingView.
+     * @param rating How many stars to display.
+     */
+    void initialize(float rating) {
+        // Ratings are rounded to the nearest 0.5 increment, like in the Play Store.
+        mIncrements = Math.round(rating * 2);
+
+        // Cache the Bitmaps for any future banners that appear.
+        if (sStarFull == null) {
+            Resources res = getContext().getResources();

[newt (away), 2014/02/19 21:52:49]

Simpler:

    Resources res = getResources();

[gone, 2014/02/19 23:31:43]

Done.

+
+            Bitmap starHalf = BitmapFactory.decodeResource(res, R.drawable.btn_star_mini_half);

[newt (away), 2014/02/19 21:52:49]

suggestion for simplifying this a bit:

    sStarHalf = BitmapFactory.decodeResource(res,
R.drawable.btn_star_mini_half);
    if (!mIsLayoutLTR) {
        ...
        sStartHalf = Bitmap.createBitmap(sStarHalf, 0, 0, width, height, m,
false);
    }

[gone, 2014/02/19 23:31:43]

Problem is then you can't mark the bitmap as final.  Changed it up a bit.

+            if (mIsLayoutLTR) {
+                sStarHalf = starHalf;
+            } else {
+                // RTL mode requires flipping the Bitmap.
+                int width = starHalf.getWidth();
+                int height = starHalf.getHeight();
+                Matrix m = new Matrix();
+                m.preScale(-1, 1);
+                sStarHalf = Bitmap.createBitmap(starHalf, 0, 0, width, height, m, false);
+            }
+
+            sStarFull = BitmapFactory.decodeResource(res, R.drawable.btn_star_mini_full);
+            sStarEmpty = BitmapFactory.decodeResource(res, R.drawable.btn_star_mini_empty);
+        }
+    }
+
+    @Override
+    public void onDraw(Canvas canvas) {
+        int starDimension = canvas.getHeight();

[newt (away), 2014/02/19 21:52:49]

Is this the 5th dimension?? Just an opinion, but, "starSize" makes more sense to
me.

[gone, 2014/02/19 23:31:43]

Yep, shot right past the 4th.

+
+        // Start off on the left for LTR mode, on the right for RTL.
+        mDrawingRect.top = 0;
+        mDrawingRect.bottom = starDimension;
+        mDrawingRect.left = mIsLayoutLTR ? 0 : (canvas.getWidth() - starDimension);
+        mDrawingRect.right = mDrawingRect.left + starDimension;
+
+        // Draw all the stars.
+        for (int i = 0; i < MAX_INCREMENT; i += 2) {
+            Bitmap toShow = sStarEmpty;
+            if (i < mIncrements) {
+                boolean isFullStar = (mIncrements - i) >= 2;
+                toShow = isFullStar ? sStarFull : sStarHalf;
+            }
+            canvas.drawBitmap(toShow, null, mDrawingRect, null);
+
+            // Scooch over to show the next star.
+            mDrawingRect.left += (mIsLayoutLTR ? 1 : -1) * starDimension;
+            mDrawingRect.right = mDrawingRect.left + starDimension;
+        }
+    }
+}