Android12 双屏异显/异触流程分析

一、异显apk示例代码

安卓12系统源码的ApiDemo的示例代码：development/samples/ApiDemos/src/com/example/android/apis/app/PresentationActivity.java

该demo主要演示presentation的用法，presentation是一种特殊的对话框，主要用于在另外一块屏幕上显示内容。值得注意的是在创建presentation前必须把presentation与它的目标屏幕相关联，所以在使用它之前必须为它选择一个Display，选择display的方法主要有两种：
（1）利用MediaRouter

mMediaRouter = (MediaRouter)getSystemService(Context.MEDIA_ROUTER_SERVICE);
MediaRouter.RouteInfo route = mMediaRouter.getSelectedRoute(MediaRouter.ROUTE_TYPE_LIVE_VIDEO);
Display presentation = route != null ? route.getPresentationDisplay() :null;
presentation.show();
presentation.setOnDismissListener(mOnDismissListener);

（2）利用DisplayManager，也是ApiDemo的实现方式：

　　其中DisplayListAdapter 是 listView 的适配器，用于显示所有的屏幕信息，可获得对应DisplayId

/*
 * Copyright (C) 2012 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.
 */

package com.example.android.apis.app;

// Need the following import to get access to the app resources, since this
// class is in a sub-package.
import com.example.android.apis.R;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.Presentation;
import android.content.Context;
import android.content.DialogInterface;
import android.content.res.Resources;
import android.graphics.Point;
import android.graphics.drawable.GradientDrawable;
import android.hardware.display.DisplayManager;
import android.os.Bundle;
import android.os.Parcel;
import android.os.Parcelable;
import android.os.Parcelable.Creator;
import android.util.Log;
import android.util.SparseArray;
import android.view.Display;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.Spinner;
import android.widget.TextView;

//BEGIN_INCLUDE(activity)
/**
 * <h3>Presentation Activity</h3>
 *
 * <p>
 * This demonstrates how to create an activity that shows some content
 * on a secondary display using a {@link Presentation}.
 * </p><p>
 * The activity uses the {@link DisplayManager} API to enumerate displays.
 * When the user selects a display, the activity opens a {@link Presentation}
 * on that display.  We show a different photograph in each presentation
 * on a unique background along with a label describing the display.
 * We also write information about displays and display-related events to
 * the Android log which you can read using <code>adb logcat</code>.
 * </p><p>
 * You can try this out using an HDMI or Wifi display or by using the
 * "Simulate secondary displays" feature in Development Settings to create a few
 * simulated secondary displays.  Each display will appear in the list along with a
 * checkbox to show a presentation on that display.
 * </p><p>
 * See also the {@link PresentationWithMediaRouterActivity} sample which
 * uses the media router to automatically select a secondary display
 * on which to show content based on the currently selected route.
 * </p>
 */
public class PresentationActivity extends Activity
        implements OnCheckedChangeListener, OnClickListener, OnItemSelectedListener {
    private final String TAG = "PresentationActivity";

    // Key for storing saved instance state.
    private static final String PRESENTATION_KEY = "presentation";

    // The content that we want to show on the presentation.
    private static final int[] PHOTOS = new int[] {
        R.drawable.frantic,
        R.drawable.photo1, R.drawable.photo2, R.drawable.photo3,
        R.drawable.photo4, R.drawable.photo5, R.drawable.photo6,
        R.drawable.sample_4,
    };

    private DisplayManager mDisplayManager;
    private DisplayListAdapter mDisplayListAdapter;
    private CheckBox mShowAllDisplaysCheckbox;
    private ListView mListView;
    private int mNextImageNumber;

    // List of presentation contents indexed by displayId.
    // This state persists so that we can restore the old presentation
    // contents when the activity is paused or resumed.
    private SparseArray<DemoPresentationContents> mSavedPresentationContents;

    // List of all currently visible presentations indexed by display id.
    private final SparseArray<DemoPresentation> mActivePresentations =
            new SparseArray<DemoPresentation>();

    /**
     * Initialization of the Activity after it is first created.  Must at least
     * call {@link android.app.Activity#setContentView setContentView()} to
     * describe what is to be displayed in the screen.
     */
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // Be sure to call the super class.
        super.onCreate(savedInstanceState);

        // Restore saved instance state.
        if (savedInstanceState != null) {
            mSavedPresentationContents =
                    savedInstanceState.getSparseParcelableArray(PRESENTATION_KEY);
        } else {
            mSavedPresentationContents = new SparseArray<DemoPresentationContents>();
        }

        // Get the display manager service.
        mDisplayManager = (DisplayManager)getSystemService(Context.DISPLAY_SERVICE);

        // See assets/res/any/layout/presentation_activity.xml for this
        // view layout definition, which is being set here as
        // the content of our screen.
        setContentView(R.layout.presentation_activity);

        // Set up checkbox to toggle between showing all displays or only presentation displays.
        mShowAllDisplaysCheckbox = (CheckBox)findViewById(R.id.show_all_displays);
        mShowAllDisplaysCheckbox.setOnCheckedChangeListener(this);

        // Set up the list of displays.
        mDisplayListAdapter = new DisplayListAdapter(this);
        mListView = (ListView)findViewById(R.id.display_list);
        mListView.setAdapter(mDisplayListAdapter);
    }

    @Override
    protected void onResume() {
        // Be sure to call the super class.
        super.onResume();

        // Update our list of displays on resume.
        mDisplayListAdapter.updateContents();

        // Restore presentations from before the activity was paused.
        final int numDisplays = mDisplayListAdapter.getCount();
        for (int i = 0; i < numDisplays; i++) {
            final Display display = mDisplayListAdapter.getItem(i);
            final DemoPresentationContents contents =
                    mSavedPresentationContents.get(display.getDisplayId());
            if (contents != null) {
                showPresentation(display, contents);
            }
        }
        mSavedPresentationContents.clear();

        // Register to receive events from the display manager.
        mDisplayManager.registerDisplayListener(mDisplayListener, null);
    }

    @Override
    protected void onPause() {
        // Be sure to call the super class.
        super.onPause();

        // Unregister from the display manager.
        mDisplayManager.unregisterDisplayListener(mDisplayListener);

        // Dismiss all of our presentations but remember their contents.
        Log.d(TAG, "Activity is being paused.  Dismissing all active presentation.");
        for (int i = 0; i < mActivePresentations.size(); i++) {
            DemoPresentation presentation = mActivePresentations.valueAt(i);
            int displayId = mActivePresentations.keyAt(i);
            mSavedPresentationContents.put(displayId, presentation.mContents);
            presentation.dismiss();
        }
        mActivePresentations.clear();
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        // Be sure to call the super class.
        super.onSaveInstanceState(outState);
        outState.putSparseParcelableArray(PRESENTATION_KEY, mSavedPresentationContents);
    }

    /**
     * Shows a {@link Presentation} on the specified display.
     */
    private void showPresentation(Display display, DemoPresentationContents contents) {
        final int displayId = display.getDisplayId();
        if (mActivePresentations.get(displayId) != null) {
            return;
        }

        Log.d(TAG, "Showing presentation photo #" + contents.photo
                + " on display #" + displayId + ".");

        DemoPresentation presentation = new DemoPresentation(this, display, contents);
        presentation.show();
        presentation.setOnDismissListener(mOnDismissListener);
        mActivePresentations.put(displayId, presentation);
    }

    /**
     * Hides a {@link Presentation} on the specified display.
     */
    private void hidePresentation(Display display) {
        final int displayId = display.getDisplayId();
        DemoPresentation presentation = mActivePresentations.get(displayId);
        if (presentation == null) {
            return;
        }

        Log.d(TAG, "Dismissing presentation on display #" + displayId + ".");

        presentation.dismiss();
        mActivePresentations.delete(displayId);
    }

    /**
     * Sets the display mode of the {@link Presentation} on the specified display
     * if it is already shown.
     */
    private void setPresentationDisplayMode(Display display, int displayModeId) {
        final int displayId = display.getDisplayId();
        DemoPresentation presentation = mActivePresentations.get(displayId);
        if (presentation == null) {
            return;
        }

        presentation.setPreferredDisplayMode(displayModeId);
    }

    private int getNextPhoto() {
        final int photo = mNextImageNumber;
        mNextImageNumber = (mNextImageNumber + 1) % PHOTOS.length;
        return photo;
    }

    /**
     * Called when the show all displays checkbox is toggled or when
     * an item in the list of displays is checked or unchecked.
     */
    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
        if (buttonView == mShowAllDisplaysCheckbox) {
            // Show all displays checkbox was toggled.
            mDisplayListAdapter.updateContents();
        } else {
            // Display item checkbox was toggled.
            final Display display = (Display)buttonView.getTag();
            if (isChecked) {
                DemoPresentationContents contents = new DemoPresentationContents(getNextPhoto());
                showPresentation(display, contents);
            } else {
                hidePresentation(display);
            }
            mDisplayListAdapter.updateContents();
        }
    }

    /**
     * Called when the Info button next to a display is clicked to show information
     * about the display.
     */
    @Override
    public void onClick(View v) {
        Context context = v.getContext();
        AlertDialog.Builder builder = new AlertDialog.Builder(context);
        final Display display = (Display)v.getTag();
        Resources r = context.getResources();
        AlertDialog alert = builder
                .setTitle(r.getString(
                        R.string.presentation_alert_info_text, display.getDisplayId()))
                .setMessage(display.toString())
                .setNeutralButton(R.string.presentation_alert_dismiss_text,
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                dialog.dismiss();
                            }
                    })
                .create();
        alert.show();
    }

    /**
     * Called when a display mode has been selected.
     */
    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        final Display display = (Display)parent.getTag();
        final Display.Mode[] modes = display.getSupportedModes();
        setPresentationDisplayMode(display, position >= 1 && position <= modes.length ?
                modes[position - 1].getModeId() : 0);
    }

    /**
     * Called when a display mode has been unselected.
     */
    @Override
    public void onNothingSelected(AdapterView<?> parent) {
        final Display display = (Display)parent.getTag();
        setPresentationDisplayMode(display, 0);
    }

    /**
     * Listens for displays to be added, changed or removed.
     * We use it to update the list and show a new {@link Presentation} when a
     * display is connected.
     *
     * Note that we don't bother dismissing the {@link Presentation} when a
     * display is removed, although we could.  The presentation API takes care
     * of doing that automatically for us.
     */
    private final DisplayManager.DisplayListener mDisplayListener =
            new DisplayManager.DisplayListener() {
        @Override
        public void onDisplayAdded(int displayId) {
            Log.d(TAG, "Display #" + displayId + " added.");
            mDisplayListAdapter.updateContents();
        }

        @Override
        public void onDisplayChanged(int displayId) {
            Log.d(TAG, "Display #" + displayId + " changed.");
            mDisplayListAdapter.updateContents();
        }

        @Override
        public void onDisplayRemoved(int displayId) {
            Log.d(TAG, "Display #" + displayId + " removed.");
            mDisplayListAdapter.updateContents();
        }
    };

    /**
     * Listens for when presentations are dismissed.
     */
    private final DialogInterface.OnDismissListener mOnDismissListener =
            new DialogInterface.OnDismissListener() {
        @Override
        public void onDismiss(DialogInterface dialog) {
            DemoPresentation presentation = (DemoPresentation)dialog;
            int displayId = presentation.getDisplay().getDisplayId();
            Log.d(TAG, "Presentation on display #" + displayId + " was dismissed.");
            mActivePresentations.delete(displayId);
            mDisplayListAdapter.notifyDataSetChanged();
        }
    };

    /**
     * List adapter.
     * Shows information about all displays.
     */
    private final class DisplayListAdapter extends ArrayAdapter<Display> {
        final Context mContext;

        public DisplayListAdapter(Context context) {
            super(context, R.layout.presentation_list_item);
            mContext = context;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            final View v;
            if (convertView == null) {
                v = ((Activity) mContext).getLayoutInflater().inflate(
                        R.layout.presentation_list_item, null);
            } else {
                v = convertView;
            }

            final Display display = getItem(position);
            final int displayId = display.getDisplayId();

            DemoPresentation presentation = mActivePresentations.get(displayId);
            DemoPresentationContents contents = presentation != null ?
                    presentation.mContents : null;
            if (contents == null) {
                contents = mSavedPresentationContents.get(displayId);
            }

            CheckBox cb = (CheckBox)v.findViewById(R.id.checkbox_presentation);
            cb.setTag(display);
            cb.setOnCheckedChangeListener(PresentationActivity.this);
            cb.setChecked(contents != null);
            cb.setEnabled((display.getFlags() & Display.FLAG_PRESENTATION) != 0);

            TextView tv = (TextView)v.findViewById(R.id.display_id);
            tv.setText(v.getContext().getResources().getString(
                    R.string.presentation_display_id_text, displayId, display.getName()));

            Button b = (Button)v.findViewById(R.id.info);
            b.setTag(display);
            b.setOnClickListener(PresentationActivity.this);

            Spinner s = (Spinner)v.findViewById(R.id.modes);
            Display.Mode[] modes = display.getSupportedModes();
            if (contents == null || modes.length == 1) {
                s.setVisibility(View.GONE);
                s.setAdapter(null);
            } else {
                ArrayAdapter<String> modeAdapter = new ArrayAdapter<String>(mContext,
                        android.R.layout.simple_list_item_1);
                s.setVisibility(View.VISIBLE);
                s.setAdapter(modeAdapter);
                s.setTag(display);
                s.setOnItemSelectedListener(PresentationActivity.this);

                modeAdapter.add("<default mode>");

                for (Display.Mode mode : modes) {
                    modeAdapter.add(String.format("Mode %d: %dx%d/%.1ffps",
                            mode.getModeId(),
                            mode.getPhysicalWidth(), mode.getPhysicalHeight(),
                            mode.getRefreshRate()));
                    if (contents.displayModeId == mode.getModeId()) {
                        s.setSelection(modeAdapter.getCount() - 1);
                    }
                }
            }

            return v;
        }

        /**
         * Update the contents of the display list adapter to show
         * information about all current displays.
         */
        public void updateContents() {
            clear();

            String displayCategory = getDisplayCategory();
            Display[] displays = mDisplayManager.getDisplays(displayCategory);
            addAll(displays);

            Log.d(TAG, "There are currently " + displays.length + " displays connected.");
            for (Display display : displays) {
                Log.d(TAG, "  " + display);
            }
        }

        private String getDisplayCategory() {
            return mShowAllDisplaysCheckbox.isChecked() ? null :
                DisplayManager.DISPLAY_CATEGORY_PRESENTATION;
        }
    }

    /**
     * The presentation to show on the secondary display.
     *
     * Note that the presentation display may have different metrics from the display on which
     * the main activity is showing so we must be careful to use the presentation's
     * own {@link Context} whenever we load resources.
     */
    private final class DemoPresentation extends Presentation {

        final DemoPresentationContents mContents;

        public DemoPresentation(Context context, Display display,
                DemoPresentationContents contents) {
            super(context, display);
            mContents = contents;
        }

        /**
         * Sets the preferred display mode id for the presentation.
         */
        public void setPreferredDisplayMode(int modeId) {
            mContents.displayModeId = modeId;

            WindowManager.LayoutParams params = getWindow().getAttributes();
            params.preferredDisplayModeId = modeId;
            getWindow().setAttributes(params);
        }

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            // Be sure to call the super class.
            super.onCreate(savedInstanceState);

            // Get the resources for the context of the presentation.
            // Notice that we are getting the resources from the context of the presentation.
            Resources r = getContext().getResources();

            // Inflate the layout.
            setContentView(R.layout.presentation_content);

            final Display display = getDisplay();
            final int displayId = display.getDisplayId();
            final int photo = mContents.photo;

            // Show a caption to describe what's going on.
            TextView text = (TextView)findViewById(R.id.text);
            text.setText(r.getString(R.string.presentation_photo_text,
                    photo, displayId, display.getName()));

            // Show a n image for visual interest.
            ImageView image = (ImageView)findViewById(R.id.image);
            image.setImageDrawable(r.getDrawable(PHOTOS[photo]));

            GradientDrawable drawable = new GradientDrawable();
            drawable.setShape(GradientDrawable.RECTANGLE);
            drawable.setGradientType(GradientDrawable.RADIAL_GRADIENT);

            // Set the background to a random gradient.
            Point p = new Point();
            getDisplay().getSize(p);
            drawable.setGradientRadius(Math.max(p.x, p.y) / 2);
            drawable.setColors(mContents.colors);
            findViewById(android.R.id.content).setBackground(drawable);
        }
    }

    /**
     * Information about the content we want to show in the presentation.
     */
    private final static class DemoPresentationContents implements Parcelable {
        final int photo;
        final int[] colors;
        int displayModeId;

        public static final Creator<DemoPresentationContents> CREATOR =
                new Creator<DemoPresentationContents>() {
            @Override
            public DemoPresentationContents createFromParcel(Parcel in) {
                return new DemoPresentationContents(in);
            }

            @Override
            public DemoPresentationContents[] newArray(int size) {
                return new DemoPresentationContents[size];
            }
        };

        public DemoPresentationContents(int photo) {
            this.photo = photo;
            colors = new int[] {
                    ((int) (Math.random() * Integer.MAX_VALUE)) | 0xFF000000,
                    ((int) (Math.random() * Integer.MAX_VALUE)) | 0xFF000000 };
        }

        private DemoPresentationContents(Parcel in) {
            photo = in.readInt();
            colors = new int[] { in.readInt(), in.readInt() };
            displayModeId = in.readInt();
        }

        @Override
        public int describeContents() {
            return 0;
        }

        @Override
        public void writeToParcel(Parcel dest, int flags) {
            dest.writeInt(photo);
            dest.writeInt(colors[0]);
            dest.writeInt(colors[1]);
            dest.writeInt(displayModeId);
        }
    }
}
//END_INCLUDE(activity)

 

二、Framework层Presentation及show方法

1.Presenation类：public class Presentation extends Dialog 

    /**
     * Creates a new presentation that is attached to the specified display
     * using the optionally specified theme, and override the default window type for the
     * presentation.
     * @param outerContext The context of the application that is showing the presentation.
     * The presentation will create its own context (see {@link #getContext()}) based
     * on this context and information about the associated display.
     * From {@link android.os.Build.VERSION_CODES#S}, the presentation will create its own window
     * context based on this context, information about the associated display and the window type.
     * If the window type is not specified, the presentation will choose the default type for the
     * presentation.
     * @param display The display to which the presentation should be attached.
     * @param theme A style resource describing the theme to use for the window.
     * See <a href="{@docRoot}guide/topics/resources/available-resources.html#stylesandthemes">
     * Style and Theme Resources</a> for more information about defining and using
     * styles.  This theme is applied on top of the current theme in
     * <var>outerContext</var>.  If 0, the default presentation theme will be used.
     * @param type Window type.
     *
     * @hide
     */
    public Presentation(@NonNull Context outerContext, @NonNull Display display, int theme,
            @WindowType int type) {
        super(createPresentationContext(outerContext, display, theme, type), theme, false);

        mDisplay = display;
        mDisplayManager = getContext().getSystemService(DisplayManager.class);

        final Window w = getWindow();
        final WindowManager.LayoutParams attr = w.getAttributes();
        w.setAttributes(attr);
        w.setGravity(Gravity.FILL);
        w.setType(getWindowType(type, display));
        setCanceledOnTouchOutside(false);
    }

    private static Context createPresentationContext(
            Context outerContext, Display display, int theme, @WindowType int type) {
        if (outerContext == null) {
            throw new IllegalArgumentException("outerContext must not be null");
        }
        if (display == null) {
            throw new IllegalArgumentException("display must not be null");
        }

        Context windowContext = outerContext.createDisplayContext(display)
                .createWindowContext(getWindowType(type, display), null /* options */);
        if (theme == 0) {
            TypedValue outValue = new TypedValue();
            windowContext.getTheme().resolveAttribute(
                    com.android.internal.R.attr.presentationTheme, outValue, true);
            theme = outValue.resourceId;
        }
        return new ContextThemeWrapper(windowContext, theme);
    }

Presentation继承自Dialog，获取到Presentation要显示的设备后，就要将Activity的context对象和设备信息作为参数来创建Presentation对象，将设备记录在成员变量mDisplay中，将Presentation设置为不可在外部点击取消。

show流程图：

 创建ViewRoot并将view添加到链表上：

   /**
     * We have one child
     */
    public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView,
            int userId) {
        synchronized (this) {
            if (mView == null) {
                mView = view;

                ......try {
                    mOrigWindowType = mWindowAttributes.type;
                    mAttachInfo.mRecomputeGlobalAttributes = true;
                    collectViewAttributes();
                    adjustLayoutParamsForCompatibility(mWindowAttributes);
                    controlInsetsForCompatibility(mWindowAttributes);
                    res = mWindowSession.addToDisplayAsUser(mWindow, mWindowAttributes,
                            getHostVisibility(), mDisplay.getDisplayId(), userId,
                            mInsetsController.getRequestedVisibilities(), inputChannel, mTempInsets,
                            mTempControls);
                    if (mTranslator != null) {
                        mTranslator.translateInsetsStateInScreenToAppWindow(mTempInsets);
                        mTranslator.translateSourceControlsInScreenToAppWindow(mTempControls);
                    }
                } catch (RemoteException e) {
                    mAdded = false;
                    mView = null;
                    mAttachInfo.mRootView = null;
                    mFallbackEventHandler.setView(null);
                    unscheduleTraversals();
                    setAccessibilityFocus(null, null);
                    throw new RuntimeException("Adding window failed", e);
                } finally {
                    if (restore) {
                        attrs.restore();
                    }
                }
             　 ......

            }
        }
    }

setView的作用主要有两个：

（1）创建InputChannel来接受输入事件。

（2）将Window加入到WindowManager。

 

三、输入事件的传递

通过 frameworks/native/services/inputflinger/reader/mapper/ 下的mapper类可以看出，安卓将输入设备分为以下几种类型：

CursorInputMapper ：鼠标
ExternalStylusInputMapper ： 触控笔
JoystickInputMapper ：游戏杆
KeyboardInputMapper ：键盘
KeyMouseInputMapper ：通常由一个手持设备组成，具有键盘和触控板/鼠标的功能，适用于需要键盘输入和鼠标操作的情况，如在移动设备上进行文字输入和浏览。
RotaryEncoderInputMapper ：旋转编码器输入设备，一种用于测量旋转运动的设备。
SwitchInputMapper ： 开关
TouchInputMapper 、MultiTouchInputMapper、SingleTouchInputMapper：触摸屏
VibratorInputMapper ：震动器，严格意义上是输出设备

input设备不同初始化参数也不一样，如触摸设备的话可以配置displayId，Android12之前版本鼠标则只能输出到主显，而Android12可以通过 setprop sys.mouse.presentation 1 使能鼠标用于副屏，具体见CursorInputMapper.cpp的实现：

        char mMousePresentation[PROPERTY_VALUE_MAX] = {0};
        property_get("sys.mouse.presentation", mMousePresentation, "0");
        if (strcmp(mMousePresentation, "1") == 0) {
           //displayId = mDisplayId;
           float minX, minY, maxX, maxY;
           if (mPointerController->getBounds(&minX, &minY, &maxX, &maxY)) {
               if(xCursorPosition==minX||xCursorPosition==maxX||yCursorPosition==minY||yCursorPosition==maxY){
                   displayId=getPolicy()->notifyDisplayIdChanged();
                   //mDisplayId=displayId;
               }
           }
        }else{
           displayId = mPointerController->getDisplayId();
        }

    } else {
        // Pointer capture and navigation modes
        pointerCoords.setAxisValue(AMOTION_EVENT_AXIS_X, deltaX);
        pointerCoords.setAxisValue(AMOTION_EVENT_AXIS_Y, deltaY);
        pointerCoords.setAxisValue(AMOTION_EVENT_AXIS_RELATIVE_X, deltaX);
        pointerCoords.setAxisValue(AMOTION_EVENT_AXIS_RELATIVE_Y, deltaY);
    }

touch.displayId的配置流程：

void TouchInputMapper::configureParameters() {
    // Use the pointer presentation mode for devices that do not support distinct
    // multitouch.  The spot-based presentation relies on being able to accurately
    // locate two or more fingers on the touch pad.
    mParameters.gestureMode = getDeviceContext().hasInputProperty(INPUT_PROP_SEMI_MT)
            ? Parameters::GestureMode::SINGLE_TOUCH
            : Parameters::GestureMode::MULTI_TOUCH;

    ......

    mParameters.hasAssociatedDisplay = false;
    mParameters.associatedDisplayIsExternal = false;
    if (mParameters.orientationAware ||
        mParameters.deviceType == Parameters::DeviceType::TOUCH_SCREEN ||
        mParameters.deviceType == Parameters::DeviceType::POINTER) {
        mParameters.hasAssociatedDisplay = true;
        if (mParameters.deviceType == Parameters::DeviceType::TOUCH_SCREEN) {
            mParameters.associatedDisplayIsExternal = getDeviceContext().isExternal();
            String8 uniqueDisplayId;
            getDeviceContext().getConfiguration().tryGetProperty(String8("touch.displayId"),
                                                                 uniqueDisplayId);
            mParameters.uniqueDisplayId = uniqueDisplayId.c_str();
        }
    }
    if (getDeviceContext().getAssociatedDisplayPort()) {
        mParameters.hasAssociatedDisplay = true;
    }

    // Initial downs on external touch devices should wake the device.
    // Normally we don't do this for internal touch screens to prevent them from waking
    // up in your pocket but you can enable it using the input device configuration.
    mParameters.wake = getDeviceContext().isExternal();
    getDeviceContext().getConfiguration().tryGetProperty(String8("touch.wake"), mParameters.wake);
}

touch.displayId的传递流程：

void TouchInputMapper::dispatchMotion(nsecs_t when, nsecs_t readTime, uint32_t policyFlags,
                                      uint32_t source, int32_t action, int32_t actionButton,
                                      int32_t flags, int32_t metaState, int32_t buttonState,
                                      int32_t edgeFlags, const PointerProperties* properties,
                                      const PointerCoords* coords, const uint32_t* idToIndex,
                                      BitSet32 idBits, int32_t changedId, float xPrecision,
                                      float yPrecision, nsecs_t downTime) {
    PointerCoords pointerCoords[MAX_POINTERS];
    PointerProperties pointerProperties[MAX_POINTERS];
    uint32_t pointerCount = 0;

　　......

    float xCursorPosition = AMOTION_EVENT_INVALID_CURSOR_POSITION;
    float yCursorPosition = AMOTION_EVENT_INVALID_CURSOR_POSITION;
    if (mDeviceMode == DeviceMode::POINTER) {
        auto [x, y] = getMouseCursorPosition();
        xCursorPosition = x;
        yCursorPosition = y;
    }
    const int32_t displayId = getAssociatedDisplayId().value_or(ADISPLAY_ID_NONE);
    const int32_t deviceId = getDeviceId();
    std::vector<TouchVideoFrame> frames = getDeviceContext().getVideoFrames();
    std::for_each(frames.begin(), frames.end(),
                  [this](TouchVideoFrame& frame) { frame.rotate(this->mSurfaceOrientation); });
    NotifyMotionArgs args(getContext()->getNextId(), when, readTime, deviceId, source, displayId,
                          policyFlags, action, actionButton, flags, metaState, buttonState,
                          MotionClassification::NONE, edgeFlags, pointerCount, pointerProperties,
                          pointerCoords, xPrecision, yPrecision, xCursorPosition, yCursorPosition,
                          downTime, std::move(frames));
    getListener()->notifyMotion(&args);
}

将事件压入队列，具体实现见：frameworks/native/services/inputflinger/InputListener.cpp

void QueuedInputListener::notifyMotion(const NotifyMotionArgs* args) {
    traceEvent(__func__, args->id);
    mArgsQueue.push_back(new NotifyMotionArgs(*args));
}

然后在InputReader的loopOnce中会进行通知，具体实现见：frameworks/native/services/inputflinger/reader/InputReader.cpp

void InputReader::loopOnce() {
    int32_t oldGeneration;
    int32_t timeoutMillis;
    bool inputDevicesChanged = false;
    std::vector<InputDeviceInfo> inputDevices;
    { // acquire lock
        std::scoped_lock _l(mLock);

        oldGeneration = mGeneration;
        timeoutMillis = -1;

        uint32_t changes = mConfigurationChangesToRefresh;
        if (changes) {
            mConfigurationChangesToRefresh = 0;
            timeoutMillis = 0;
            refreshConfigurationLocked(changes);
        } else if (mNextTimeout != LLONG_MAX) {
            nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
            timeoutMillis = toMillisecondTimeoutDelay(now, mNextTimeout);
        }
    } // release lock

    size_t count = mEventHub->getEvents(timeoutMillis, mEventBuffer, EVENT_BUFFER_SIZE);

    { // acquire lock
        std::scoped_lock _l(mLock);
        mReaderIsAliveCondition.notify_all();

        if (count) {
            processEventsLocked(mEventBuffer, count);
        }

        if (mNextTimeout != LLONG_MAX) {
            nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
            if (now >= mNextTimeout) {
#if DEBUG_RAW_EVENTS
                ALOGD("Timeout expired, latency=%0.3fms", (now - mNextTimeout) * 0.000001f);
#endif
                mNextTimeout = LLONG_MAX;
                timeoutExpiredLocked(now);
            }
        }

        if (oldGeneration != mGeneration) {
            inputDevicesChanged = true;
            inputDevices = getInputDevicesLocked();
        }
    } // release lock

    // Send out a message that the describes the changed input devices.
    if (inputDevicesChanged) {
        mPolicy->notifyInputDevicesChanged(inputDevices);
    }

    // Flush queued events out to the listener.
    // This must happen outside of the lock because the listener could potentially call
    // back into the InputReader's methods, such as getScanCodeState, or become blocked
    // on another thread similarly waiting to acquire the InputReader lock thereby
    // resulting in a deadlock.  This situation is actually quite plausible because the
    // listener is actually the input dispatcher, which calls into the window manager,
    // which occasionally calls into the input reader.
    mQueuedListener->flush();
}

在InputDispatcher中同样是用的一个线程找到对应的窗口进行事件分发，具体实现见：frameworks/native/services/inputflinger/dispatcher/InputDispatcher.cpp

void InputDispatcher::dispatchOnce() {
    nsecs_t nextWakeupTime = LONG_LONG_MAX;
    { // acquire lock
        std::scoped_lock _l(mLock);
        mDispatcherIsAlive.notify_all();

        // Run a dispatch loop if there are no pending commands.
        // The dispatch loop might enqueue commands to run afterwards.
        if (!haveCommandsLocked()) {
            dispatchOnceInnerLocked(&nextWakeupTime);
        }

        // Run all pending commands if there are any.
        // If any commands were run then force the next poll to wake up immediately.
        if (runCommandsLockedInterruptible()) {
            nextWakeupTime = LONG_LONG_MIN;
        }

        // If we are still waiting for ack on some events,
        // we might have to wake up earlier to check if an app is anr'ing.
        const nsecs_t nextAnrCheck = processAnrsLocked();
        nextWakeupTime = std::min(nextWakeupTime, nextAnrCheck);

        // We are about to enter an infinitely long sleep, because we have no commands or
        // pending or queued events
        if (nextWakeupTime == LONG_LONG_MAX) {
            mDispatcherEnteredIdle.notify_all();
        }
    } // release lock

    // Wait for callback or timeout or wake.  (make sure we round up, not down)
    nsecs_t currentTime = now();
    int timeoutMillis = toMillisecondTimeoutDelay(currentTime, nextWakeupTime);
    mLooper->pollOnce(timeoutMillis);
}

对应EventEntry::Type::MOTION类型事件处理在 InputDispatcher::dispatchMotionLocked 方法中，根据entry->displayId决定分发到哪个屏幕：

bool InputDispatcher::dispatchMotionLocked(nsecs_t currentTime, std::shared_ptr<MotionEntry> entry,
                                           DropReason* dropReason, nsecs_t* nextWakeupTime) {
    ATRACE_CALL();
    // Preprocessing.
    if (!entry->dispatchInProgress) {
        entry->dispatchInProgress = true;

        logOutboundMotionDetails("dispatchMotion - ", *entry);
    }

    // Clean up if dropping the event.
    if (*dropReason != DropReason::NOT_DROPPED) {
        setInjectionResult(*entry,
                           *dropReason == DropReason::POLICY ? InputEventInjectionResult::SUCCEEDED
                                                             : InputEventInjectionResult::FAILED);
        return true;
    }

    bool isPointerEvent = entry->source & AINPUT_SOURCE_CLASS_POINTER;

    // Identify targets.
    std::vector<InputTarget> inputTargets;

    bool conflictingPointerActions = false;
    InputEventInjectionResult injectionResult;
    if (isPointerEvent) {
        // Pointer event.  (eg. touchscreen)
        injectionResult =
                findTouchedWindowTargetsLocked(currentTime, *entry, inputTargets, nextWakeupTime,
                                               &conflictingPointerActions);
    } else {
        // Non touch event.  (eg. trackball)
        injectionResult =
                findFocusedWindowTargetsLocked(currentTime, *entry, inputTargets, nextWakeupTime);
    }
    if (injectionResult == InputEventInjectionResult::PENDING) {
        return false;
    }

    setInjectionResult(*entry, injectionResult);
    if (injectionResult == InputEventInjectionResult::PERMISSION_DENIED) {
        ALOGW("Permission denied, dropping the motion (isPointer=%s)", toString(isPointerEvent));
        return true;
    }
    if (injectionResult != InputEventInjectionResult::SUCCEEDED) {
        CancelationOptions::Mode mode(isPointerEvent
                                              ? CancelationOptions::CANCEL_POINTER_EVENTS
                                              : CancelationOptions::CANCEL_NON_POINTER_EVENTS);
        CancelationOptions options(mode, "input event injection failed");
        synthesizeCancelationEventsForMonitorsLocked(options);
        return true;
    }

    // Add monitor channels from event's or focused display.
    addGlobalMonitoringTargetsLocked(inputTargets, getTargetDisplayId(*entry));

    if (isPointerEvent) {
        std::unordered_map<int32_t, TouchState>::iterator it =
                mTouchStatesByDisplay.find(entry->displayId);
        if (it != mTouchStatesByDisplay.end()) {
            const TouchState& state = it->second;
            if (!state.portalWindows.empty()) {
                // The event has gone through these portal windows, so we add monitoring targets of
                // the corresponding displays as well.
                for (size_t i = 0; i < state.portalWindows.size(); i++) {
                    const WindowInfo* windowInfo = state.portalWindows[i]->getInfo();
                    addGlobalMonitoringTargetsLocked(inputTargets, windowInfo->portalToDisplayId,
                                                     -windowInfo->frameLeft, -windowInfo->frameTop);
                }
            }
        }
    }

    // Dispatch the motion.
    if (conflictingPointerActions) {
        CancelationOptions options(CancelationOptions::CANCEL_POINTER_EVENTS,
                                   "conflicting pointer actions");
        synthesizeCancelationEventsForAllConnectionsLocked(options);
    }
    dispatchEventLocked(currentTime, entry, inputTargets);
    return true;
}

Motion事件分发过程，简化为下图：

 

从软件流程分析，touchScreen类型可以通过配置device.internal来配置TP事件输出到辅显，而Pointer类型的话则是通过displayId去设置输出的方向。

idc（Input Device Configuration）为输入设备配置文件，包含设备具体的配置属性，这些属性影响输入设备的行为，常见的配置有:

device.internal 指定输入设备属于内置组件；还是外部链接（很可能拆卸）的外围设备；0表示外部，1表示内部
touch.deviceType   touchScreen(与显示屏相关的触摸屏),touchPad（不与显示相关连的触摸板）,touchNavigation,pointer（类似于鼠标）,default(系统根据分类算法自动检测设备类型)
touch.orientationAware  等于1时表示触摸会随着显示屏方向更改，为0则表示不受显示屏方向更改的影响
touch.gestureMode single-touch multi-touch default
touch.wake   tp是否需要唤醒系统，一般希望外部设备才有这种能力，如果是内部的设备需要唤醒系统，也可以进行配置
...

另外google也有使用xml指定哪些输入设备属于哪些屏幕，这种关联由端口号完成，其中端口是指与屏幕连接的物理端口。
例如，如果 Android 设备有两个标记为 hdmi1 和 hdmi2 的 HDMI 端口，则屏幕端口值可以为 1 和 2。即使将不同的屏幕（例如不同的屏幕型号或制造商）连接到同一物理 HDMI 端口，端口值也保持不变。这样一来，设备制造商就能够提供组装和升级屏幕的说明。
这种关联在 /vendor/etc/input-port-associations.xml 中配置。例如：

<ports>
    <port display="0" input="usb-xhci-hcd.0.auto-1.1/input0" />
    <port display="1" input="usb-xhci-hcd.0.auto-1.2/input0" />
</ports>

在上面的示例中，display="0" 指定与屏幕连接的端口。input="usb-xhci-hcd.0.auto-1.1/input0" 指定与输入设备连接的端口。如需确定与特定设备关联的端口，请使用 dumpsys input 命令 ，然后在 Event Hub 状态中查看这些设备的 location 属性。或者使用 dumpsys SurfaceFlinger --display-id 转储所有已连接屏幕的标识信息。

详细参考：
https://source.android.google.cn/docs/core/display/multi_display/displays?hl=zh-cn
https://source.android.google.cn/docs/core/display/multi_display/input-routing?hl=zh-cn