RESTRICT AUTOMERGE: Backport When an opaque window has alpha < 0.5, don't let it receive touches.

When a window is declared as opaque but the alpha is low, it's likely a fadeout animation or other visual change that should not affect touch handling.

Bug: 266433089
Test: inputflinger_tests
Flag: EXEMPT BUGFIX
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:61b3b73116cb7fc760683db1d02e6466522aacbf
Merged-In: I9ba48365d0ea080a4e68c8c497049225b759df79
Change-Id: I9ba48365d0ea080a4e68c8c497049225b759df79

services/inputflinger/dispatcher/InputDispatcher.cpp

diff --git a/services/inputflinger/dispatcher/InputDispatcher.cpp b/services/inputflinger/dispatcher/InputDispatcher.cpp
index 2908c61..62b78fd 100644
--- a/services/inputflinger/dispatcher/InputDispatcher.cpp
+++ b/services/inputflinger/dispatcher/InputDispatcher.cpp
@@ -5343,6 +5343,12 @@
         const android::inputdispatcher::MotionEntry& motionEntry) const {
     const WindowInfo& info = *window->getInfo();
 
+    if (info.touchOcclusionMode == TouchOcclusionMode::USE_OPACITY && info.alpha < 0.5f) {
+        LOG(INFO) << "Not sending motion to " << window->getName() << ", window opacity="
+            << info.alpha << " is below the threshold";
+        return false;
+    }
+
     // Skip spy window targets that are not valid for targeted injection.
     if (const auto err = verifyTargetedInjection(window, motionEntry); err) {
         return false;

services/inputflinger/tests/InputDispatcher_test.cpp

diff --git a/services/inputflinger/tests/InputDispatcher_test.cpp b/services/inputflinger/tests/InputDispatcher_test.cpp
index 298ba42..82622fb 100644
--- a/services/inputflinger/tests/InputDispatcher_test.cpp
+++ b/services/inputflinger/tests/InputDispatcher_test.cpp
@@ -12219,11 +12219,14 @@
     static constexpr gui::Uid TOUCHED_APP_UID{10001};
     static constexpr gui::Uid APP_B_UID{10002};
     static constexpr gui::Uid APP_C_UID{10003};
+    static constexpr gui::Uid BOTTOM_APP_UID{10004};
 
     sp<FakeWindowHandle> mTouchWindow;
+    sp<FakeWindowHandle> mBottomWindow;
 
     virtual void SetUp() override {
         InputDispatcherTest::SetUp();
+        mBottomWindow = getWindow(BOTTOM_APP_UID, "Bottom");
         mTouchWindow = getWindow(TOUCHED_APP_UID, "Touched");
         mDispatcher->setMaximumObscuringOpacityForTouch(MAXIMUM_OBSCURING_OPACITY);
     }
@@ -12606,6 +12609,70 @@
     mTouchWindow->consumeAnyMotionDown();
 }
 
+/**
+ * If the touch window USE_OPACITY and it is translucent (alpha < 0.5), do not let it receive
+ * the touch event. The window below it also does not receive the touch event.
+ */
+TEST_F(InputDispatcherUntrustedTouchesTest, UseOpacity_BlocksWhenAlphaIsLow) {
+    mTouchWindow->editInfo()->touchOcclusionMode = TouchOcclusionMode::USE_OPACITY;
+    mTouchWindow->editInfo()->alpha = 0.4f; // Less than 0.5
+    mDispatcher->onWindowInfosChanged(
+            {{*mTouchWindow->getInfo(), *mBottomWindow->getInfo()}, {}, 0, 0});
+
+    touch();
+
+    mTouchWindow->assertNoEvents();
+    mBottomWindow->assertNoEvents();
+}
+
+/**
+ * If the touch window USE_OPACITY and it is visible (alpha > 0.5), it should receive
+ * the touch event. The window below it still does not receive the touch event.
+ */
+TEST_F(InputDispatcherUntrustedTouchesTest, UseOpacity_AllowsWhenAlphaIsSufficient) {
+    mTouchWindow->editInfo()->touchOcclusionMode = TouchOcclusionMode::USE_OPACITY;
+    mTouchWindow->editInfo()->alpha = 0.6f; // Greater than 0.5
+    mDispatcher->onWindowInfosChanged(
+            {{*mTouchWindow->getInfo(), *mBottomWindow->getInfo()}, {}, 0, 0});
+
+    touch();
+
+    mTouchWindow->consumeMotionDown();
+    mBottomWindow->assertNoEvents();
+}
+
+/**
+ * If the touch window USE_OPACITY and it is translucent at the threshold (alpha = 0.5),
+ * do not let it receive the touch event. The window below it also does not receive the touch event.
+ */
+TEST_F(InputDispatcherUntrustedTouchesTest, UseOpacity_AllowsWhenAlphaIsAtThreshold) {
+    mTouchWindow->editInfo()->touchOcclusionMode = TouchOcclusionMode::USE_OPACITY;
+    mTouchWindow->editInfo()->alpha = 0.5f; // Exactly at the threshold
+    mDispatcher->onWindowInfosChanged(
+            {{*mTouchWindow->getInfo(), *mBottomWindow->getInfo()}, {}, 0, 0});
+
+    touch();
+
+    mTouchWindow->consumeMotionDown();
+    mBottomWindow->assertNoEvents();
+}
+
+/**
+ * If the touch window does not USE_OPACITY and it is translucent (alpha < 0.4), let it receive
+ * the touch event. The window below it also does not receive the touch event.
+ */
+TEST_F(InputDispatcherUntrustedTouchesTest, OtherOcclusionMode_AllowsWhenAlphaIsLow) {
+    mTouchWindow->editInfo()->touchOcclusionMode = TouchOcclusionMode::BLOCK_UNTRUSTED;
+    mTouchWindow->editInfo()->alpha = 0.4f; // Less than 0.5, but mode is not USE_OPACITY
+    mDispatcher->onWindowInfosChanged(
+            {{*mTouchWindow->getInfo(), *mBottomWindow->getInfo()}, {}, 0, 0});
+
+    touch();
+
+    mTouchWindow->consumeMotionDown();
+    mBottomWindow->assertNoEvents();
+}
+
 class InputDispatcherDragTests : public InputDispatcherTest {
 protected:
     std::shared_ptr<FakeApplicationHandle> mApp;