services/inputflinger/dispatcher/InputTarget.h

/*
 * Copyright (C) 2019 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.
 */

#pragma once

#include <ftl/flags.h>
#include <gui/WindowInfo.h>
#include <gui/constants.h>
#include <input/InputTransport.h>
#include <ui/Transform.h>
#include <utils/BitSet.h>
#include <bitset>

namespace android::inputdispatcher {

/*
 * An input target specifies how an input event is to be dispatched to a particular window
 * including the window's input channel, control flags, a timeout, and an X / Y offset to
 * be added to input event coordinates to compensate for the absolute position of the
 * window area.
 */
struct InputTarget {
    enum class Flags : uint32_t {
        /* This flag indicates that the event is being delivered to a foreground application. */
        FOREGROUND = 1 << 0,

        /* This flag indicates that the MotionEvent falls within the area of the target
         * obscured by another visible window above it.  The motion event should be
         * delivered with flag AMOTION_EVENT_FLAG_WINDOW_IS_OBSCURED. */
        WINDOW_IS_OBSCURED = 1 << 1,

        /* This flag indicates that a motion event is being split across multiple windows. */
        SPLIT = 1 << 2,

        /* This flag indicates that the pointer coordinates dispatched to the application
         * will be zeroed out to avoid revealing information to an application. This is
         * used in conjunction with FLAG_DISPATCH_AS_OUTSIDE to prevent apps not sharing
         * the same UID from watching all touches. */
        ZERO_COORDS = 1 << 3,

        /* This flag indicates that the target of a MotionEvent is partly or wholly
         * obscured by another visible window above it.  The motion event should be
         * delivered with flag AMOTION_EVENT_FLAG_WINDOW_IS_PARTIALLY_OBSCURED. */
        WINDOW_IS_PARTIALLY_OBSCURED = 1 << 14,
    };

    enum class DispatchMode {
        /* This flag indicates that the event should be sent as is.
         * Should always be set unless the event is to be transmuted. */
        AS_IS,
        /* This flag indicates that a MotionEvent with AMOTION_EVENT_ACTION_DOWN falls outside
         * of the area of this target and so should instead be delivered as an
         * AMOTION_EVENT_ACTION_OUTSIDE to this target. */
        OUTSIDE,
        /* This flag indicates that a hover sequence is starting in the given window.
         * The event is transmuted into ACTION_HOVER_ENTER. */
        HOVER_ENTER,
        /* This flag indicates that a hover event happened outside of a window which handled
         * previous hover events, signifying the end of the current hover sequence for that
         * window.
         * The event is transmuted into ACTION_HOVER_ENTER. */
        HOVER_EXIT,
        /* This flag indicates that the event should be canceled.
         * It is used to transmute ACTION_MOVE into ACTION_CANCEL when a touch slips
         * outside of a window. */
        SLIPPERY_EXIT,
        /* This flag indicates that the event should be dispatched as an initial down.
         * It is used to transmute ACTION_MOVE into ACTION_DOWN when a touch slips
         * into a new window. */
        SLIPPERY_ENTER,

        ftl_last = SLIPPERY_ENTER,
    };

    // The input channel to be targeted.
    std::shared_ptr<InputChannel> inputChannel;

    // Flags for the input target.
    ftl::Flags<Flags> flags;

    // The dispatch mode that should be used for this target.
    DispatchMode dispatchMode = DispatchMode::AS_IS;

    // Scaling factor to apply to MotionEvent as it is delivered.
    // (ignored for KeyEvents)
    float globalScaleFactor = 1.0f;

    // Current display transform. Used for compatibility for raw coordinates.
    ui::Transform displayTransform;

    // The subset of pointer ids to include in motion events dispatched to this input target
    // if FLAG_SPLIT is set.
    std::bitset<MAX_POINTER_ID + 1> pointerIds;
    // Event time for the first motion event (ACTION_DOWN) dispatched to this input target if
    // FLAG_SPLIT is set.
    std::optional<nsecs_t> firstDownTimeInTarget;
    // The data is stored by the pointerId. Use the bit position of pointerIds to look up
    // Transform per pointerId.
    ui::Transform pointerTransforms[MAX_POINTERS];

    // The window that this input target is being dispatched to. It is possible for this to be
    // null for cases like global monitors.
    sp<gui::WindowInfoHandle> windowHandle;

    void addPointers(std::bitset<MAX_POINTER_ID + 1> pointerIds, const ui::Transform& transform);
    void setDefaultPointerTransform(const ui::Transform& transform);

    /**
     * Returns whether the default pointer information should be used. This will be true when the
     * InputTarget doesn't have any bits set in the pointerIds bitset. This can happen for monitors
     * and non splittable windows since we want all pointers for the EventEntry to go to this
     * target.
     */
    bool useDefaultPointerTransform() const;

    /**
     * Returns the default Transform object. This should be used when useDefaultPointerTransform is
     * true.
     */
    const ui::Transform& getDefaultPointerTransform() const;

    std::string getPointerInfoString() const;
};

std::ostream& operator<<(std::ostream& out, const InputTarget& target);

} // namespace android::inputdispatcher