Block touches when stylus is down
Since we haven't yet added simultaneous touch and stylus support, let's
improve the user experience by blocking all touch when the stylus is
down.
Bug: 210159205
Test: atest inputflinger_tests
Change-Id: Id6a6467d7feb7c7d91770ddbd63b92583832d504
diff --git a/services/inputflinger/PreferStylusOverTouchBlocker.cpp b/services/inputflinger/PreferStylusOverTouchBlocker.cpp
new file mode 100644
index 0000000..ad639b4
--- /dev/null
+++ b/services/inputflinger/PreferStylusOverTouchBlocker.cpp
@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2022 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 "PreferStylusOverTouchBlocker.h"
+
+#include <android-base/stringprintf.h>
+
+using android::base::StringPrintf;
+
+static const char* toString(bool value) {
+ return value ? "true" : "false";
+}
+
+namespace android {
+
+ftl::StaticVector<NotifyMotionArgs, 2> PreferStylusOverTouchBlocker::processMotion(
+ const NotifyMotionArgs& args) {
+ const bool isStylusEvent = isFromSource(args.source, AINPUT_SOURCE_STYLUS);
+ if (isStylusEvent) {
+ for (size_t i = 0; i < args.pointerCount; i++) {
+ // Make sure we are canceling stylus pointers
+ const int32_t toolType = args.pointerProperties[i].toolType;
+ LOG_ALWAYS_FATAL_IF(toolType != AMOTION_EVENT_TOOL_TYPE_STYLUS &&
+ toolType != AMOTION_EVENT_TOOL_TYPE_ERASER,
+ "The pointer %zu has toolType=%i, but the source is STYLUS. If "
+ "simultaneous touch and stylus is supported, "
+ "'PreferStylusOverTouchBlocker' should be disabled.",
+ i, toolType);
+ }
+ }
+ const bool isDown = args.action == AMOTION_EVENT_ACTION_DOWN;
+ const bool isUpOrCancel =
+ args.action == AMOTION_EVENT_ACTION_UP || args.action == AMOTION_EVENT_ACTION_CANCEL;
+ if (isStylusEvent) {
+ if (isDown) {
+ // Reject all touch while stylus is down
+ mIsStylusDown = true;
+ if (mIsTouchDown && !mCurrentTouchIsCanceled) {
+ // Cancel touch!
+ mCurrentTouchIsCanceled = true;
+ mLastTouchEvent.action = AMOTION_EVENT_ACTION_CANCEL;
+ mLastTouchEvent.flags |= AMOTION_EVENT_FLAG_CANCELED;
+ mLastTouchEvent.eventTime = systemTime(SYSTEM_TIME_MONOTONIC);
+ return {mLastTouchEvent, args};
+ }
+ }
+ if (isUpOrCancel) {
+ mIsStylusDown = false;
+ }
+ // Never drop stylus events
+ return {args};
+ }
+
+ const bool isTouchEvent =
+ isFromSource(args.source, AINPUT_SOURCE_TOUCHSCREEN) && !isStylusEvent;
+ if (isTouchEvent) {
+ if (mIsStylusDown) {
+ mCurrentTouchIsCanceled = true;
+ }
+ // If we already canceled the current gesture, then continue to drop events from it, even if
+ // the stylus has been lifted.
+ if (mCurrentTouchIsCanceled) {
+ if (isUpOrCancel) {
+ mCurrentTouchIsCanceled = false;
+ }
+ return {};
+ }
+
+ // Update state
+ mLastTouchEvent = args;
+ if (isDown) {
+ mIsTouchDown = true;
+ }
+ if (isUpOrCancel) {
+ mIsTouchDown = false;
+ mCurrentTouchIsCanceled = false;
+ }
+ return {args};
+ }
+
+ // Not a touch or stylus event
+ return {args};
+}
+
+std::string PreferStylusOverTouchBlocker::dump() {
+ std::string out;
+ out += StringPrintf("mIsTouchDown: %s\n", toString(mIsTouchDown));
+ out += StringPrintf("mIsStylusDown: %s\n", toString(mIsStylusDown));
+ out += StringPrintf("mLastTouchEvent: %s\n", mLastTouchEvent.dump().c_str());
+ out += StringPrintf("mCurrentTouchIsCanceled: %s\n", toString(mCurrentTouchIsCanceled));
+ return out;
+}
+
+} // namespace android