From 932970c6963d51deaf8e4c4f4e99ec517b3ebcec Mon Sep 17 00:00:00 2001
From: Chuck Liao <chuckliao@google.com>
Date: Thu, 21 Oct 2021 01:41:19 +0000
Subject: [PATCH] Revert "Always select the next higher density bucket when
 picking resources"

This reverts commit 49243877490fa1a0e7b0f9041e4505468c3a81b0.

Reason for revert: DroidMonitor-triggered revert due to breakage https://android-build.googleplex.com/builds/tests/hub?tab=clusterView&clusterId=7006296665623803063, bug b/203718917

Change-Id: I4ac8d8fb9b4b39fe677fb3b2eac809f3443ed0fa
---
 libs/androidfw/ResourceTypes.cpp     | 17 +++++++++++++----
 libs/androidfw/tests/Config_test.cpp | 15 ++++-----------
 2 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/libs/androidfw/ResourceTypes.cpp b/libs/androidfw/ResourceTypes.cpp
index 50117ce9e69bd..cae2d0bc16b3f 100644
--- a/libs/androidfw/ResourceTypes.cpp
+++ b/libs/androidfw/ResourceTypes.cpp
@@ -2677,21 +2677,30 @@ bool ResTable_config::isBetterThan(const ResTable_config& o,
                 // DENSITY_ANY is now dealt with. We should look to
                 // pick a density bucket and potentially scale it.
                 // Any density is potentially useful
-                // because the system will scale it.  Always prefer
-                // scaling down.
+                // because the system will scale it.  Scaling down
+                // is generally better than scaling up.
                 int h = thisDensity;
                 int l = otherDensity;
                 bool bImBigger = true;
                 if (l > h) {
-                    std::swap(l, h);
+                    int t = h;
+                    h = l;
+                    l = t;
                     bImBigger = false;
                 }
 
+                if (requestedDensity >= h) {
+                    // requested value higher than both l and h, give h
+                    return bImBigger;
+                }
                 if (l >= requestedDensity) {
                     // requested value lower than both l and h, give l
                     return !bImBigger;
+                }
+                // saying that scaling down is 2x better than up
+                if (((2 * l) - requestedDensity) * h > requestedDensity * requestedDensity) {
+                    return !bImBigger;
                 } else {
-                    // otherwise give h
                     return bImBigger;
                 }
             }
diff --git a/libs/androidfw/tests/Config_test.cpp b/libs/androidfw/tests/Config_test.cpp
index f5fd0f20d5808..b54915f03c299 100644
--- a/libs/androidfw/tests/Config_test.cpp
+++ b/libs/androidfw/tests/Config_test.cpp
@@ -27,19 +27,15 @@ namespace android {
 
 static ResTable_config selectBest(const ResTable_config& target,
                                   const Vector<ResTable_config>& configs) {
-  Vector<ResTable_config> matchedConfigs;
+  ResTable_config bestConfig;
+  memset(&bestConfig, 0, sizeof(bestConfig));
   const size_t configCount = configs.size();
   for (size_t i = 0; i < configCount; i++) {
     const ResTable_config& thisConfig = configs[i];
-    if (thisConfig.match(target)) {
-      matchedConfigs.add(thisConfig);
+    if (!thisConfig.match(target)) {
+      continue;
     }
-  }
 
-  ResTable_config bestConfig = matchedConfigs[0];
-  const size_t matchingConfigCount = matchedConfigs.size();
-  for (size_t i = 1; i < matchingConfigCount; i++) {
-    const ResTable_config& thisConfig = configs[i];
     if (thisConfig.isBetterThan(bestConfig, &target)) {
       bestConfig = thisConfig;
     }
@@ -79,9 +75,6 @@ TEST(ConfigTest, shouldSelectBestDensity) {
   configs.add(buildDensityConfig(int(ResTable_config::DENSITY_HIGH) + 20));
   ASSERT_EQ(expectedBest, selectBest(deviceConfig, configs));
 
-  configs.add(buildDensityConfig(int(ResTable_config::DENSITY_XHIGH) - 1));
-  ASSERT_EQ(expectedBest, selectBest(deviceConfig, configs));
-
   expectedBest = buildDensityConfig(ResTable_config::DENSITY_XHIGH);
   configs.add(expectedBest);
   ASSERT_EQ(expectedBest, selectBest(deviceConfig, configs));