From ea481beda699165a7050ddcc37b10841d33ed9e6 Mon Sep 17 00:00:00 2001
From: Prashant Malani <pmalani@google.com>
Date: Wed, 7 Jan 2015 18:30:27 -0800
Subject: [PATCH] Improve the circularMask for round displays

The mask was earlier drawn as a thin ring at the display periphery.
This had undesirable effects when screenshots were taken, as the ring
was seen, as well as display content beyond it.

This patch modifies the mask to be a black canvas with portions erased
to improve the screenshot image.

Bug: 18772987
Change-Id: I25ef6387879613354308e015446fe325ed8c4515
---
 .../com/android/server/wm/CircularDisplayMask.java   | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/services/core/java/com/android/server/wm/CircularDisplayMask.java b/services/core/java/com/android/server/wm/CircularDisplayMask.java
index a7d41faecec47..9fdfc47dfede8 100644
--- a/services/core/java/com/android/server/wm/CircularDisplayMask.java
+++ b/services/core/java/com/android/server/wm/CircularDisplayMask.java
@@ -24,6 +24,7 @@ import android.graphics.Paint;
 import android.graphics.PixelFormat;
 import android.graphics.Point;
 import android.graphics.PorterDuff;
+import android.graphics.PorterDuffXfermode;
 import android.graphics.Rect;
 import android.view.Display;
 import android.view.Surface;
@@ -35,7 +36,6 @@ import android.util.Slog;
 class CircularDisplayMask {
     private static final String TAG = "CircularDisplayMask";
 
-    private static final int STROKE_WIDTH = 2;
     // size of the chin
     private int mScreenOffset = 0;
     // Display dimensions
@@ -82,9 +82,7 @@ class CircularDisplayMask {
         mDrawNeeded = true;
         mPaint = new Paint();
         mPaint.setAntiAlias(true);
-        mPaint.setStyle(Paint.Style.STROKE);
-        mPaint.setColor(Color.BLACK);
-        mPaint.setStrokeWidth(STROKE_WIDTH);
+        mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
         mScreenOffset = screenOffset;
     }
 
@@ -104,7 +102,6 @@ class CircularDisplayMask {
         if (c == null) {
             return;
         }
-        c.drawColor(Color.TRANSPARENT, PorterDuff.Mode.SRC);
         switch (mRotation) {
         case Surface.ROTATION_0:
         case Surface.ROTATION_90:
@@ -122,7 +119,10 @@ class CircularDisplayMask {
         }
 
         int circleRadius = mScreenSize.x / 2;
-        c.drawCircle(circleRadius, circleRadius, circleRadius, mPaint);
+        c.drawColor(Color.BLACK);
+
+        // The radius is reduced by 1 to provide an anti aliasing effect on the display edges.
+        c.drawCircle(circleRadius, circleRadius, circleRadius - 1, mPaint);
         mSurface.unlockCanvasAndPost(c);
     }