深入理解input命令只支持单指，是否可以修改实现多指？-千里马android framework实战开发

背景：

经常使用的input命令如下：
在这里插入图片描述
正常情况下一般要模拟一个触摸点击事件一般用如下命令
input tap 200 300
执行完成后手机画面一般就会响应一个click事件，这里发现一般都是一个手指，一直寻找看看input命令是否可以支持多个手指通过命令同时按下操作的情况，发现并没有这种多指的触摸的命令。难道确实是不支持吗？

input只支持单指源码分析

源码路径
frameworks/base/cmds/input/src/com/android/commands/input/Input.java

public static void main(String[] args) {
        (new Input()).run(args);
    }

    private void run(String[] args) {
        if (args.length < 1) {
            showUsage();
            return;
        }

        int index = 0;
        String command = args[index];
        int inputSource = InputDevice.SOURCE_UNKNOWN;
        if (SOURCES.containsKey(command)) {
            inputSource = SOURCES.get(command);
            index++;
            command = args[index];
        }
        final int length = args.length - index;

        try {
            if (command.equals("text")) {
                if (length == 2) {
                    inputSource = getSource(inputSource, InputDevice.SOURCE_KEYBOARD);
                    sendText(inputSource, args[index+1]);
                    return;
                }
            } else if (command.equals("keyevent")) {
                if (length >= 2) {
                    final boolean longpress = "--longpress".equals(args[index + 1]);
                    final int start = longpress ? index + 2 : index + 1;
                    inputSource = getSource(inputSource, InputDevice.SOURCE_KEYBOARD);
                    if (length > start) {
                        for (int i = start; i < length; i++) {
                            int keyCode = KeyEvent.keyCodeFromString(args[i]);
                            if (keyCode == KeyEvent.KEYCODE_UNKNOWN) {
                                keyCode = KeyEvent.keyCodeFromString("KEYCODE_" + args[i]);
                            }
                            sendKeyEvent(inputSource, keyCode, longpress);
                        }
                        return;
                    }
                }
            } else if (command.equals("tap")) {//可以看到这里input tap走的是这里
                if (length == 3) {
                    inputSource = getSource(inputSource, InputDevice.SOURCE_TOUCHSCREEN);
                    sendTap(inputSource, Float.parseFloat(args[index+1]),
                            Float.parseFloat(args[index+2]));
                    return;
                }
            } else if (command.equals("swipe")) {
                int duration = -1;
                inputSource = getSource(inputSource, InputDevice.SOURCE_TOUCHSCREEN);
                switch (length) {
                    case 6:
                        duration = Integer.parseInt(args[index+5]);
                    case 5:
                        sendSwipe(inputSource,
                                Float.parseFloat(args[index+1]), Float.parseFloat(args[index+2]),
                                Float.parseFloat(args[index+3]), Float.parseFloat(args[index+4]),
                                duration);
                        return;
                }
            } else if (command.equals("draganddrop")) {
                int duration = -1;
                inputSource = getSource(inputSource, InputDevice.SOURCE_TOUCHSCREEN);
                switch (length) {
                    case 6:
                        duration = Integer.parseInt(args[index+5]);
                    case 5:
                        sendDragAndDrop(inputSource,
                                Float.parseFloat(args[index+1]), Float.parseFloat(args[index+2]),
                                Float.parseFloat(args[index+3]), Float.parseFloat(args[index+4]),
                                duration);
                        return;
                }
            } else if (command.equals("press")) {
                inputSource = getSource(inputSource, InputDevice.SOURCE_TRACKBALL);
                if (length == 1) {
                    sendTap(inputSource, 0.0f, 0.0f);
                    return;
                }
            } else if (command.equals("roll")) {
                inputSource = getSource(inputSource, InputDevice.SOURCE_TRACKBALL);
                if (length == 3) {
                    sendMove(inputSource, Float.parseFloat(args[index+1]),
                            Float.parseFloat(args[index+2]));
                    return;
                }
            } else {
                System.err.println("Error: Unknown command: " + command);
                showUsage();
                return;
            }
        } catch (NumberFormatException ex) {
        }
        System.err.println(INVALID_ARGUMENTS + command);
        showUsage();
    }

上面代码可以看到最后input tap这个命令最后走入是sendTap方法：

看看这里sendTap

//注意这里传递的参数只有坐标x,y,和一个inputsource，根本没有看到有多个手指的id传入，基本就可以确定这里其实是不支持多指的
   private void sendTap(int inputSource, float x, float y) {
        long now = SystemClock.uptimeMillis();
        injectMotionEvent(inputSource, MotionEvent.ACTION_DOWN, now, x, y, 1.0f);
        injectMotionEvent(inputSource, MotionEvent.ACTION_UP, now, x, y, 0.0f);
    }

明显可以看到其实tap就是注入了2个触摸事件，一个是ACTION_DOWN一个是ACTION_UP，按下抬起就是tap也就是常说的click事件。
在看看injectMotionEvent方法：

   private void injectMotionEvent(int inputSource, int action, long when, float x, float y, float pressure) {
        final float DEFAULT_SIZE = 1.0f;
        final int DEFAULT_META_STATE = 0;
        final float DEFAULT_PRECISION_X = 1.0f;
        final float DEFAULT_PRECISION_Y = 1.0f;
        final int DEFAULT_EDGE_FLAGS = 0;
        //构建出对应的MotionEvent对象
        MotionEvent event = MotionEvent.obtain(when, when, action, x, y, pressure, DEFAULT_SIZE,
                DEFAULT_META_STATE, DEFAULT_PRECISION_X, DEFAULT_PRECISION_Y,
                getInputDeviceId(inputSource), DEFAULT_EDGE_FLAGS);
        event.setSource(inputSource);
        Log.i(TAG, "injectMotionEvent: " + event);
        //然后在通过inputmanager的相关方法注入这个motionevent
        InputManager.getInstance().injectInputEvent(event,
                InputManager.INJECT_INPUT_EVENT_MODE_WAIT_FOR_FINISH);
    }