Add android:angle on <gradient> for min sdk <= Q

The default orientation of gradients in android Q is different than
previous android versions. Set the android:angle attribute to "0"
to ensure that the default gradient orientation will remain
left-to-right in android Q.

Bug: 139883313
Test: aapt2_tests
Change-Id: I82e222f635858ed3ecf4a3f3761503d857adb93b
diff --git a/tools/aapt2/link/XmlReferenceLinker.cpp b/tools/aapt2/link/XmlReferenceLinker.cpp
index f3be483..c3c16b9 100644
--- a/tools/aapt2/link/XmlReferenceLinker.cpp
+++ b/tools/aapt2/link/XmlReferenceLinker.cpp
@@ -83,6 +83,15 @@
     Attribute default_attribute(android::ResTable_map::TYPE_ANY);
     default_attribute.SetWeak(true);
 
+    // The default orientation of gradients in android Q is different than previous android
+    // versions. Set the android:angle attribute to "0" to ensure that the default gradient
+    // orientation will remain left-to-right in android Q.
+    if (el->name == "gradient" && context_->GetMinSdkVersion() <= SDK_Q) {
+      if (!el->FindAttribute(xml::kSchemaAndroid, "angle")) {
+        el->attributes.push_back(xml::Attribute{xml::kSchemaAndroid, "angle", "0"});
+      }
+    }
+
     const Source source = source_.WithLine(el->line_number);
     for (xml::Attribute& attr : el->attributes) {
       // If the attribute has no namespace, interpret values as if
diff --git a/tools/aapt2/link/XmlReferenceLinker_test.cpp b/tools/aapt2/link/XmlReferenceLinker_test.cpp
index ef99355..0ce2e50 100644
--- a/tools/aapt2/link/XmlReferenceLinker_test.cpp
+++ b/tools/aapt2/link/XmlReferenceLinker_test.cpp
@@ -47,6 +47,8 @@
                                             test::AttributeBuilder()
                                                 .SetTypeMask(android::ResTable_map::TYPE_STRING)
                                                 .Build())
+                           .AddPublicSymbol("android:attr/angle", ResourceId(0x01010004),
+                                            test::AttributeBuilder().Build())
 
                            // Add one real symbol that was introduces in v21
                            .AddPublicSymbol("android:attr/colorAccent", ResourceId(0x01010435),
@@ -75,7 +77,7 @@
   }
 
  protected:
-  std::unique_ptr<IAaptContext> context_;
+  std::unique_ptr<test::Context> context_;
 };
 
 TEST_F(XmlReferenceLinkerTest, LinkBasicAttributes) {
@@ -254,4 +256,63 @@
   EXPECT_EQ(make_value(ResourceId(0x7f030000)), ref->id);
 }
 
+
+TEST_F(XmlReferenceLinkerTest, AddAngleOnGradientForAndroidQ) {
+  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"(
+    <gradient />)");
+
+  XmlReferenceLinker linker;
+  ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
+
+  xml::Element* gradient_el = doc->root.get();
+  ASSERT_THAT(gradient_el, NotNull());
+
+  xml::Attribute* xml_attr = gradient_el->FindAttribute(xml::kSchemaAndroid, "angle");
+  ASSERT_THAT(xml_attr, NotNull());
+  ASSERT_TRUE(xml_attr->compiled_attribute);
+  EXPECT_EQ(make_value(ResourceId(0x01010004)), xml_attr->compiled_attribute.value().id);
+
+  BinaryPrimitive* value = ValueCast<BinaryPrimitive>(xml_attr->compiled_value.get());
+  ASSERT_THAT(value, NotNull());
+  EXPECT_EQ(value->value.dataType, android::Res_value::TYPE_INT_DEC);
+  EXPECT_EQ(value->value.data, 0U);
+}
+
+TEST_F(XmlReferenceLinkerTest, DoNotOverwriteAngleOnGradientForAndroidQ) {
+  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"(
+  <gradient xmlns:android="http://schemas.android.com/apk/res/android"
+      android:angle="90"/>)");
+
+  XmlReferenceLinker linker;
+  ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
+
+  xml::Element* gradient_el = doc->root.get();
+  ASSERT_THAT(gradient_el, NotNull());
+
+  xml::Attribute* xml_attr = gradient_el->FindAttribute(xml::kSchemaAndroid, "angle");
+  ASSERT_THAT(xml_attr, NotNull());
+  ASSERT_TRUE(xml_attr->compiled_attribute);
+  EXPECT_EQ(make_value(ResourceId(0x01010004)), xml_attr->compiled_attribute.value().id);
+
+  BinaryPrimitive* value = ValueCast<BinaryPrimitive>(xml_attr->compiled_value.get());
+  ASSERT_THAT(value, NotNull());
+  EXPECT_EQ(value->value.dataType, android::Res_value::TYPE_INT_DEC);
+  EXPECT_EQ(value->value.data, 90U);
+}
+
+TEST_F(XmlReferenceLinkerTest, DoNotOverwriteAngleOnGradientForPostAndroidQ) {
+  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"(
+  <gradient xmlns:android="http://schemas.android.com/apk/res/android" />)");
+  context_->SetMinSdkVersion(30);
+
+  XmlReferenceLinker linker;
+  ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
+
+  xml::Element* gradient_el = doc->root.get();
+  ASSERT_THAT(gradient_el, NotNull());
+
+  xml::Attribute* xml_attr = gradient_el->FindAttribute(xml::kSchemaAndroid, "angle");
+  ASSERT_THAT(xml_attr, IsNull());
+}
+
 }  // namespace aapt
diff --git a/tools/aapt2/test/Context.h b/tools/aapt2/test/Context.h
index 7e10a59..553c43e 100644
--- a/tools/aapt2/test/Context.h
+++ b/tools/aapt2/test/Context.h
@@ -81,6 +81,10 @@
     return min_sdk_version_;
   }
 
+  void SetMinSdkVersion(int min_sdk_version) {
+    min_sdk_version_ = min_sdk_version;
+  }
+
  const std::set<std::string>& GetSplitNameDependencies() override {
     return split_name_dependencies_;
   }