Ensure Bitmap.getDefaultDensity() matches DENSITY_DEVICE

Otherwise bitmaps constructed without a target display are incorrectly
scaled by a factor of (DENSITY_DEVICE / DENSITY_DEFAULT) when rendered
to a Canvas whose density has been specified correctly.

Bug: 26817900
Change-Id: I45edfc7c0cbdf84a267d5bedacb0548659ede301

1 files changed, 6 insertions, 8 deletions

diff --git a/core/java/android/app/ActivityThread.java b/core/java/android/app/ActivityThread.java
index 805b2034ff05..6424520df3ec 100644
--- a/core/java/android/app/ActivityThread.java
+++ b/core/java/android/app/ActivityThread.java
@@ -4822,14 +4822,12 @@ public final class ActivityThread {
     }
 
     private void updateDefaultDensity() {
-        if (mCurDefaultDisplayDpi != Configuration.DENSITY_DPI_UNDEFINED
-                && mCurDefaultDisplayDpi != DisplayMetrics.DENSITY_DEVICE
-                && !mDensityCompatMode) {
-            Slog.i(TAG, "Switching default density from "
-                    + DisplayMetrics.DENSITY_DEVICE + " to "
-                    + mCurDefaultDisplayDpi);
-            DisplayMetrics.DENSITY_DEVICE = mCurDefaultDisplayDpi;
-            Bitmap.setDefaultDensity(DisplayMetrics.DENSITY_DEFAULT);
+        final int densityDpi = mCurDefaultDisplayDpi;
+        if (!mDensityCompatMode
+                && densityDpi != Configuration.DENSITY_DPI_UNDEFINED
+                && densityDpi != DisplayMetrics.DENSITY_DEVICE) {
+            DisplayMetrics.DENSITY_DEVICE = densityDpi;
+            Bitmap.setDefaultDensity(densityDpi);
         }
     }