Support high-resolution scroll
VirtualMouse currently supports -1f to 1f float scroll values,
but it worked for integer values only as input framework supported
only REL_HWHEEL and REL_WHEEL events. With the introduction of
high-res scroll event support (REL_HWHEEL_HI_RES and REL_WHEEL_HI_RES),
granular mouse scrolling can be done, and VirtualMouse scroll API
would work for all float values.
Flag: android.companion.virtualdevice.flags.high_resolution_scroll
Test: atest VirtualMouseTest
Bug: 335160780
Change-Id: I7b13ac1722b6fd31736fe1c0117d4de6e838261a
diff --git a/libs/input/VirtualInputDevice.cpp b/libs/input/VirtualInputDevice.cpp
index b73ee65..2e3e1a0 100644
--- a/libs/input/VirtualInputDevice.cpp
+++ b/libs/input/VirtualInputDevice.cpp
@@ -18,6 +18,7 @@
#include <android/input.h>
#include <android/keycodes.h>
+#include <android_companion_virtualdevice_flags.h>
#include <fcntl.h>
#include <input/Input.h>
#include <input/VirtualInputDevice.h>
@@ -40,6 +41,8 @@
namespace android {
+namespace vd_flags = android::companion::virtualdevice::flags;
+
VirtualInputDevice::VirtualInputDevice(unique_fd fd) : mFd(std::move(fd)) {}
VirtualInputDevice::~VirtualInputDevice() {
@@ -253,7 +256,10 @@
// clang-format on
};
-VirtualMouse::VirtualMouse(unique_fd fd) : VirtualInputDevice(std::move(fd)) {}
+VirtualMouse::VirtualMouse(unique_fd fd)
+ : VirtualInputDevice(std::move(fd)),
+ mAccumulatedHighResScrollX(0),
+ mAccumulatedHighResScrollY(0) {}
VirtualMouse::~VirtualMouse() {}
@@ -272,9 +278,43 @@
bool VirtualMouse::writeScrollEvent(float xAxisMovement, float yAxisMovement,
std::chrono::nanoseconds eventTime) {
- return writeInputEvent(EV_REL, REL_HWHEEL, xAxisMovement, eventTime) &&
- writeInputEvent(EV_REL, REL_WHEEL, yAxisMovement, eventTime) &&
- writeInputEvent(EV_SYN, SYN_REPORT, 0, eventTime);
+ if (!vd_flags::high_resolution_scroll()) {
+ return writeInputEvent(EV_REL, REL_HWHEEL, xAxisMovement, eventTime) &&
+ writeInputEvent(EV_REL, REL_WHEEL, yAxisMovement, eventTime) &&
+ writeInputEvent(EV_SYN, SYN_REPORT, 0, eventTime);
+ }
+
+ const int32_t highResScrollX = xAxisMovement * kEvdevMouseHighResScrollUnitsPerDetent;
+ const int32_t highResScrollY = yAxisMovement * kEvdevMouseHighResScrollUnitsPerDetent;
+ bool highResScrollResult =
+ writeInputEvent(EV_REL, REL_HWHEEL_HI_RES, highResScrollX, eventTime) &&
+ writeInputEvent(EV_REL, REL_WHEEL_HI_RES, highResScrollY, eventTime);
+ if (!highResScrollResult) {
+ return false;
+ }
+
+ // According to evdev spec, a high-resolution mouse needs to emit REL_WHEEL / REL_HWHEEL events
+ // in addition to high-res scroll events. Regular scroll events can approximate high-res scroll
+ // events, so we send a regular scroll event when the accumulated scroll motion reaches a detent
+ // (single mouse wheel click).
+ mAccumulatedHighResScrollX += highResScrollX;
+ mAccumulatedHighResScrollY += highResScrollY;
+ const int32_t scrollX = mAccumulatedHighResScrollX / kEvdevMouseHighResScrollUnitsPerDetent;
+ const int32_t scrollY = mAccumulatedHighResScrollY / kEvdevMouseHighResScrollUnitsPerDetent;
+ if (scrollX != 0) {
+ if (!writeInputEvent(EV_REL, REL_HWHEEL, scrollX, eventTime)) {
+ return false;
+ }
+ mAccumulatedHighResScrollX %= kEvdevMouseHighResScrollUnitsPerDetent;
+ }
+ if (scrollY != 0) {
+ if (!writeInputEvent(EV_REL, REL_WHEEL, scrollY, eventTime)) {
+ return false;
+ }
+ mAccumulatedHighResScrollY %= kEvdevMouseHighResScrollUnitsPerDetent;
+ }
+
+ return writeInputEvent(EV_SYN, SYN_REPORT, 0, eventTime);
}
// --- VirtualTouchscreen ---