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/*
* Copyright (C) 2021 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 <stdint.h>
#include <optional>
#include <unordered_map>
#include <android/FocusRequest.h>
#include <binder/Binder.h>
#include <input/InputWindow.h>
namespace android::inputdispatcher {
// Keeps track of the focused window per display. The class listens to updates from input dispatcher
// and provides focus changes.
//
// Focus Policy
// Window focusabilty - A window token can be focused if there is at least one window handle that
// is visible with the same token and all window handles with the same token are focusable.
// See FocusResolver::isTokenFocusable
//
// Focus request - Request will be granted if the window is focusable. If it's not
// focusable, then the request is persisted and granted when it becomes focusable. The currently
// focused window will lose focus and any pending keys will be added to a queue so it can be sent
// to the window when it gets focus.
//
// Condition focus request - Request with a focus token specified. Request will be granted if the
// window is focusable and the focus token is the currently focused. Otherwise, the request is
// dropped. Conditional focus requests are not persisted. The window will lose focus and go back
// to the focus token if it becomes not focusable.
//
// Window handle updates - Focus is lost when the currently focused window becomes not focusable.
// If the previous focus request is focusable, then we will try to grant that window focus.
class FocusResolver {
public:
// Returns the focused window token on the specified display.
sp<IBinder> getFocusedWindowToken(int32_t displayId) const;
struct FocusChanges {
sp<IBinder> oldFocus;
sp<IBinder> newFocus;
int32_t displayId;
std::string reason;
};
std::optional<FocusResolver::FocusChanges> setInputWindows(
int32_t displayId, const std::vector<sp<InputWindowHandle>>& windows);
std::optional<FocusResolver::FocusChanges> setFocusedWindow(
const FocusRequest& request, const std::vector<sp<InputWindowHandle>>& windows);
// Display has been removed from the system, clean up old references.
void displayRemoved(int32_t displayId);
// exposed for debugging
bool hasFocusedWindowTokens() const { return !mFocusedWindowTokenByDisplay.empty(); }
std::string dumpFocusedWindows() const;
std::string dump() const;
private:
enum class Focusability {
OK,
NO_WINDOW,
NOT_FOCUSABLE,
NOT_VISIBLE,
};
// Checks if the window token can be focused on a display. The token can be focused if there is
// at least one window handle that is visible with the same token and all window handles with
// the same token are focusable.
//
// In the case of mirroring, two windows may share the same window token and their visibility
// might be different. Example, the mirrored window can cover the window its mirroring. However,
// we expect the focusability of the windows to match since its hard to reason why one window
// can receive focus events and the other cannot when both are backed by the same input channel.
//
static Focusability isTokenFocusable(const sp<IBinder>& token,
const std::vector<sp<InputWindowHandle>>& windows);
// Focus tracking for keys, trackball, etc. A window token can be associated with one or
// more InputWindowHandles. If a window is mirrored, the window and its mirror will share
// the same token. Focus is tracked by the token per display and the events are dispatched
// to the channel associated by this token.
typedef std::pair<std::string /* name */, sp<IBinder>> NamedToken;
std::unordered_map<int32_t /* displayId */, NamedToken> mFocusedWindowTokenByDisplay;
// This map will store the focus request per display. When the input window handles are updated,
// the current request will be checked to see if it can be processed at that time.
std::unordered_map<int32_t /* displayId */, FocusRequest> mFocusRequestByDisplay;
// Last reason for not granting a focus request. This is used to add more debug information
// in the event logs.
std::unordered_map<int32_t /* displayId */, Focusability> mLastFocusResultByDisplay;
std::optional<FocusResolver::FocusChanges> updateFocusedWindow(
int32_t displayId, const std::string& reason, const sp<IBinder>& token,
const std::string& tokenName = "");
std::optional<FocusRequest> getFocusRequest(int32_t displayId);
};
} // namespace android::inputdispatcher
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