Recalculate Transform type after obtaining an inverse Transform

When getting the inverse of a Transform, the type can change. For
example, the inverse of a ROT_90 transform is a ROT_270 transform. We
need to recalculate the type of the inverse Transform.

Bug: 200794735
Bug: 179274888
Test: atest Transform_test
Change-Id: I10c8613e34edf8e76a5692c01bc58ce7e498cf4b

3 files changed, 103 insertions, 10 deletions

diff --git a/libs/ui/Transform.cpp b/libs/ui/Transform.cpp
index cd68c1c0ec..b34d90699f 100644
--- a/libs/ui/Transform.cpp
+++ b/libs/ui/Transform.cpp
@@ -396,6 +396,11 @@ Transform Transform::inverse() const {
         result.mMatrix[1][0] = -b*idet;
         result.mMatrix[1][1] =  a*idet;
         result.mType = mType;
+        if (getOrientation() & ROT_90) {
+            // Recalculate the type if there is a 90-degree rotation component, since the inverse
+            // of ROT_90 is ROT_270 and vice versa.
+            result.mType |= UNKNOWN_TYPE;
+        }
 
         vec2 T(-x, -y);
         T = result.transform(T);
diff --git a/libs/ui/tests/Android.bp b/libs/ui/tests/Android.bp
index a87740aeca..0ee15f26cf 100644
--- a/libs/ui/tests/Android.bp
+++ b/libs/ui/tests/Android.bp
@@ -27,28 +27,40 @@ cc_test {
     name: "Region_test",
     shared_libs: ["libui"],
     srcs: ["Region_test.cpp"],
-    cflags: ["-Wall", "-Werror"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
 }
 
 cc_test {
     name: "colorspace_test",
     shared_libs: ["libui"],
     srcs: ["colorspace_test.cpp"],
-    cflags: ["-Wall", "-Werror"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
 }
 
 cc_test {
     name: "DisplayId_test",
     shared_libs: ["libui"],
     srcs: ["DisplayId_test.cpp"],
-    cflags: ["-Wall", "-Werror"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
 }
 
 cc_test {
     name: "FlattenableHelpers_test",
     shared_libs: ["libui"],
     srcs: ["FlattenableHelpers_test.cpp"],
-    cflags: ["-Wall", "-Werror"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
 }
 
 cc_test {
@@ -68,7 +80,10 @@ cc_test {
         "GraphicBufferAllocator_test.cpp",
         "mock/MockGrallocAllocator.cpp",
     ],
-    cflags: ["-Wall", "-Werror"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
 }
 
 cc_test {
@@ -83,14 +98,20 @@ cc_test {
         "libutils",
     ],
     srcs: ["GraphicBuffer_test.cpp"],
-    cflags: ["-Wall", "-Werror"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
 }
 
 // This test has a main method, and requires a separate binary to be built.
 cc_test {
     name: "GraphicBufferOverBinder_test",
     srcs: ["GraphicBufferOverBinder_test.cpp"],
-    cflags: ["-Wall", "-Werror"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
     shared_libs: [
         "libbinder",
         "libgui",
@@ -105,7 +126,10 @@ cc_test {
     test_suites: ["device-tests"],
     shared_libs: ["libui"],
     srcs: ["Rect_test.cpp"],
-    cflags: ["-Wall", "-Werror"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
 }
 
 cc_test {
@@ -113,7 +137,10 @@ cc_test {
     test_suites: ["device-tests"],
     shared_libs: ["libui"],
     srcs: ["Size_test.cpp"],
-    cflags: ["-Wall", "-Werror"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
 }
 
 cc_test {
@@ -121,6 +148,18 @@ cc_test {
     shared_libs: ["libui"],
     static_libs: ["libgmock"],
     srcs: ["MockFence_test.cpp"],
-    cflags: ["-Wall", "-Werror"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
 }
 
+cc_test {
+    name: "Transform_test",
+    shared_libs: ["libui"],
+    srcs: ["Transform_test.cpp"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
+}
diff --git a/libs/ui/tests/Transform_test.cpp b/libs/ui/tests/Transform_test.cpp
new file mode 100644
index 0000000000..6964284eaa
--- /dev/null
+++ b/libs/ui/tests/Transform_test.cpp
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <ui/Transform.h>
+
+#include <gtest/gtest.h>
+
+namespace android::ui {
+
+TEST(TransformTest, inverseRotation_hasCorrectType) {
+    const auto testRotationFlagsForInverse = [](Transform::RotationFlags rotation,
+                                                Transform::RotationFlags expectedInverse,
+                                                bool isRotation) {
+        const Transform t(rotation, 0, 0);
+        EXPECT_EQ(t.getOrientation(), rotation);
+        const Transform inverse = t.inverse();
+        EXPECT_EQ(inverse.getOrientation(), expectedInverse);
+
+        if (isRotation) {
+            EXPECT_TRUE(t.getType() & Transform::ROTATE);
+            EXPECT_TRUE(inverse.getType() & Transform::ROTATE);
+        } else {
+            EXPECT_FALSE(t.getType() & Transform::ROTATE);
+            EXPECT_FALSE(inverse.getType() & Transform::ROTATE);
+        }
+    };
+
+    testRotationFlagsForInverse(Transform::ROT_0, Transform::ROT_0, false);
+    testRotationFlagsForInverse(Transform::ROT_90, Transform::ROT_270, true);
+    testRotationFlagsForInverse(Transform::ROT_180, Transform::ROT_180, true);
+    testRotationFlagsForInverse(Transform::ROT_270, Transform::ROT_90, true);
+    testRotationFlagsForInverse(Transform::FLIP_H, Transform::FLIP_H, false);
+    testRotationFlagsForInverse(Transform::FLIP_V, Transform::FLIP_V, false);
+}
+
+} // namespace android::ui