Android 8.0 的长按Home事件位置

1. SystemUI 的虚拟导航栏按键事件

本身View事件可以监听home，同时事件会下发到Framwork层

注意：不同系统版本下源码位置是变化的

package com.android.systemui.statusbar.phone;

/**
 * Fragment containing the NavigationBarFragment. Contains logic for what happens
 * on clicks and view states of the nav bar.
 */
public class NavigationBarFragment extends Fragment implements Callbacks {

    private void prepareNavigationBarView() {
        mNavigationBarView.reorient();

        ButtonDispatcher recentsButton = mNavigationBarView.getRecentsButton();
        recentsButton.setOnClickListener(this::onRecentsClick);
        recentsButton.setOnTouchListener(this::onRecentsTouch);
        recentsButton.setLongClickable(true);
        recentsButton.setOnLongClickListener(this::onLongPressBackRecents);

        ButtonDispatcher backButton = mNavigationBarView.getBackButton();
        backButton.setLongClickable(true);
        backButton.setOnLongClickListener(this::onLongPressBackRecents);

        ButtonDispatcher homeButton = mNavigationBarView.getHomeButton();
        homeButton.setOnTouchListener(this::onHomeTouch);
        homeButton.setOnLongClickListener(this::onHomeLongClick);

        ButtonDispatcher accessibilityButton = mNavigationBarView.getAccessibilityButton();
        accessibilityButton.setOnClickListener(this::onAccessibilityClick);
        accessibilityButton.setOnLongClickListener(this::onAccessibilityLongClick);
        updateAccessibilityServicesState(mAccessibilityManager);
    }


    @VisibleForTesting
    boolean onHomeLongClick(View v) {
        if (shouldDisableNavbarGestures()) {
            return false;
        }
        MetricsLogger.action(getContext(), MetricsEvent.ACTION_ASSIST_LONG_PRESS);
        mAssistManager.startAssist(new Bundle() /* args */);
        mStatusBar.awakenDreams();
        if (mNavigationBarView != null) {
            mNavigationBarView.abortCurrentGesture();
        }
        return true;
    }

2. Framework 层的Home事件，这里偏向实体按键

package com.android.server.policy;

public class PhoneWindowManager implements WindowManagerPolicy {

        /** {@inheritDoc} */
    @Override
    public long interceptKeyBeforeDispatching(WindowState win, KeyEvent event, int policyFlags) {

    // First we always handle the home key here, so applications
        // can never break it, although if keyguard is on, we do let
        // it handle it, because that gives us the correct 5 second
        // timeout.
        if (keyCode == KeyEvent.KEYCODE_HOME) {
            // If we have released the home key, and didn't do anything else
            // while it was pressed, then it is time to go home!
            if (!down) {
                cancelPreloadRecentApps();

                mHomePressed = false;
                if (mHomeConsumed) {
                    mHomeConsumed = false;
                    return -1;
                }

                if (canceled) {
                    Log.i(TAG, "Ignoring HOME; event canceled.");
                    return -1;
                }

                // Delay handling home if a double-tap is possible.
                if (mDoubleTapOnHomeBehavior != DOUBLE_TAP_HOME_NOTHING) {
                    mHandler.removeCallbacks(mHomeDoubleTapTimeoutRunnable); // just in case
                    mHomeDoubleTapPending = true;
                    mHandler.postDelayed(mHomeDoubleTapTimeoutRunnable,
                            ViewConfiguration.getDoubleTapTimeout());
                    return -1;
                }

                handleShortPressOnHome();
                return -1;
            }

            // If a system window has focus, then it doesn't make sense
            // right now to interact with applications.
            WindowManager.LayoutParams attrs = win != null ? win.getAttrs() : null;
            if (attrs != null) {
                final int type = attrs.type;
                if (type == TYPE_KEYGUARD_DIALOG
                        || (attrs.privateFlags & PRIVATE_FLAG_KEYGUARD) != 0) {
                    // the "app" is keyguard, so give it the key
                    return 0;
                }
                final int typeCount = WINDOW_TYPES_WHERE_HOME_DOESNT_WORK.length;
                for (int i=0; iif (type == WINDOW_TYPES_WHERE_HOME_DOESNT_WORK[i]) {
                        // don't do anything, but also don't pass it to the app
                        return -1;
                    }
                }
            }

            // Remember that home is pressed and handle special actions.
            if (repeatCount == 0) {

                mHomePressed = true;
                if (mHomeDoubleTapPending) {
                    mHomeDoubleTapPending = false;
                    mHandler.removeCallbacks(mHomeDoubleTapTimeoutRunnable);
                    handleDoubleTapOnHome();
                } else if (mDoubleTapOnHomeBehavior == DOUBLE_TAP_HOME_RECENT_SYSTEM_UI) {
                    preloadRecentApps();
                }
            } else if ((event.getFlags() & KeyEvent.FLAG_LONG_PRESS) != 0) {
                if (!keyguardOn) {
                    handleLongPressOnHome(event.getDeviceId());
                }

            }
            return -1;