commit 1b217913fbc80d3b8042a628d1a3eb7a3842e7ff
author Harry Cutts <hcutts@google.com> Tue Jan 03 17:13:19 2023 +0000
committer Harry Cutts <hcutts@google.com> Fri Jan 20 11:44:41 2023 +0000
tree 698672cc2bc37bce2f32bd604a8059e47e96c1c3
parent 808ff1d46d82b9585699251a9ff08e7c318ce952

TouchpadInputMapper: Add gesture property provider

Gesture properties are configurable parameters used by the gestures
library [0]. These will be used for per-device tuning and to implement
various touchpad settings. The property provider gives Android an
interface with which to get and set property values.

[0]: https://chromium.googlesource.com/chromiumos/platform/gestures/+/refs/heads/main/docs/gesture_properties.md

Bug: 251196347
Test: atest inputflinger_tests
Test: on device with some hacky test code
Change-Id: I7723dcbabf29e13c8ab0907c71e5dd1faa766b45

services/inputflinger/reader/mapper/TouchpadInputMapper.cpp

diff --git a/services/inputflinger/reader/mapper/TouchpadInputMapper.cpp b/services/inputflinger/reader/mapper/TouchpadInputMapper.cpp
index 3b51be8..89ba07e 100644
--- a/services/inputflinger/reader/mapper/TouchpadInputMapper.cpp
+++ b/services/inputflinger/reader/mapper/TouchpadInputMapper.cpp
@@ -96,11 +96,12 @@
     mGestureInterpreter->Initialize(GESTURES_DEVCLASS_TOUCHPAD);
     mGestureInterpreter->SetHardwareProperties(createHardwareProperties(deviceContext));
     // Even though we don't explicitly delete copy/move semantics, it's safe to
-    // give away a pointer to TouchpadInputMapper here because
+    // give away pointers to TouchpadInputMapper and its members here because
     // 1) mGestureInterpreter's lifecycle is determined by TouchpadInputMapper, and
     // 2) TouchpadInputMapper is stored as a unique_ptr and not moved.
+    mGestureInterpreter->SetPropProvider(const_cast<GesturesPropProvider*>(&gesturePropProvider),
+                                         &mPropertyProvider);
     mGestureInterpreter->SetCallback(gestureInterpreterCallback, this);
-    // TODO(b/251196347): set a property provider, so we can change gesture properties.
     // TODO(b/251196347): set a timer provider, so the library can use timers.
 }
 
@@ -108,6 +109,15 @@
     if (mPointerController != nullptr) {
         mPointerController->fade(PointerControllerInterface::Transition::IMMEDIATE);
     }
+
+    // The gesture interpreter's destructor will call its property provider's free function for all
+    // gesture properties, in this case calling PropertyProvider::freeProperty using a raw pointer
+    // to mPropertyProvider. Depending on the declaration order in TouchpadInputMapper.h, this may
+    // happen after mPropertyProvider has been destructed, causing allocation errors. Depending on
+    // declaration order to avoid crashes seems rather fragile, so explicitly clear the property
+    // provider here to ensure all the freeProperty calls happen before mPropertyProvider is
+    // destructed.
+    mGestureInterpreter->SetPropProvider(nullptr, nullptr);
 }
 
 uint32_t TouchpadInputMapper::getSources() const {