Android 增加对鼠标的支持

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我是靠谱客的博主如意玉米，最近开发中收集的这篇文章主要介绍Android 增加对鼠标的支持，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

Android系统对鼠标的支持并不好，因为Android系统原本是为手机量身定做的，手机系统基本上是不需要鼠标的。但是随着Android系统移植到其他领域，对鼠标的支持也越来越有意义。
在android中鼠标的绘制代码在：
frameworksbaseservicesjavacomandroidserverWindowManagerService.java ,
   在performLayoutAndPlaceSurfacesLockedInner方法中：
   if (mMouseSurface == null)
   {
   int mMx, mMy, mMw, mMh;
   Canvas mCanvas;
   Path mPath = new Path();
   mMw = 13;
   mMh = 22;
   mMx = (mDisplay.getWidth() - mMw) / 2;
   mMy = (mDisplay.getHeight() - mMh) / 2;
   try
   {
   /*
   * First Mouse event, create Surface
   */
   mMouseSurface =
   new Surface(mFxSession,
   0, -1, mMw, mMh,
   PixelFormat.TRANSPARENT,
   Surface.FX_SURFACE_NORMAL);
   mCanvas = mMouseSurface.lockCanvas(null);
   Paint tPaint = new Paint();
   tPaint.setStyle(Paint.Style.STROKE);
   tPaint.setStrokeWidth(2);
   tPaint.setColor(0xffffffff);
   mPath.moveTo(0.0f, 0.0f);
   mPath.lineTo(12.0f, 12.0f);
   mPath.lineTo(7.0f, 12.0f);
   mPath.lineTo(11.0f, 20.0f);
   mPath.lineTo(8.0f, 21.0f);
   mPath.lineTo(4.0f, 13.0f);
   mPath.lineTo(0.0f, 17.0f);
   mPath.close();
   mCanvas.clipPath(mPath);
   mCanvas.drawColor(0xff000000);
   mCanvas.drawPath(mPath, tPaint);

   mMouseSurface.unlockCanvasAndPost(mCanvas);
   mMouseSurface.openTransaction();
   mMouseSurface.setSize(mMw, mMh);
   mMouseSurface.closeTransaction();
   }
   catch (Exception e)
   {
   Slog.e(TAG, "Exception creating mouse surface",e);
   }
   mMlx = mMx;
   mMly = mMy;
   mMlw = mMw;
   mMlh = mMh;
   }
   直接利用Surface绘制鼠标光标的形状，一般情况下都是利用bitmap位图资源进行绘制，这里简化了。
对于android2.3版本来说，发布的arm/sh4版本没有提供鼠标功能，直到前几天才发现mips社区已经将这块代码加入进去了，之间我在arm上搞这个功能时，重新进行实现，不过增加了一点功能，比如可以通过java 更换鼠标光标，并编写了一个服务用于光标隐藏的方法等。
   接口函数如下：
int cursor_util_initialize();
int cursor_util_finalize();
int cursor_util_start();
   int cursor_util_stop();
   int cursor_util_locate(int x,int y);
   int cursor_util_move(int dx,int dy);
   int cursor_util_get_location(int *x,int *y);
   int cursor_util_set_timeout(int timeout);
   int cursor_util_get_timeout(int *timeout);
   int cursor_util_set_bitmap(const char*buf,int w,int h);
由于代码涉及到版权问题，这里就将mips做的改动介绍一下吧：

1、首先在eventhub.cpp中增加鼠标的支持：
   代码路径： frameworksbaselibsuiEventHub.cpp
   /* The input device has mouse. */
   INPUT_DEVICE_CLASS_MOUSE = 0x00000100,
   if (test_bit(BTN_MOUSE, key_bitmask)) {
   uint8_t rel_bitmask[sizeof_bit_array(REL_MAX + 1)];
   memset(rel_bitmask, 0, sizeof(rel_bitmask));
   LOGV("Getting relative controllers...");
   if (ioctl(fd, EVIOCGBIT(EV_REL, sizeof(rel_bitmask)), rel_bitmask) >= 0) {
   if (test_bit(REL_X, rel_bitmask) && test_bit(REL_Y, rel_bitmask)) {
   /* 增加鼠标类的事件处理流程 */
   if (test_bit(BTN_LEFT, key_bitmask) && test_bit(BTN_RIGHT, key_bitmask))
device->classes |= INPUT_DEVICE_CLASS_MOUSE;
   else
   device->classes |= INPUT_DEVICE_CLASS_TRACKBALL;
   }
   }
   }

   2、inputreader中增加mousemapper的处理代码：
   代码路径： frameworksbaselibsuiInputReader.cpp
   重点就是下面两个函数：（注意鼠标传上来的值是相对坐标，如果需要处理绝对坐标，在process函数进行转换即可，比较简单）
   void MouseInputMapper::process(const RawEvent* rawEvent) {
   switch (rawEvent->type)
   {
   case EV_KEY:
   switch (rawEvent->scanCode)
   {
   case BTN_MOUSE:
   mAccumulator.fields |= Accumulator::FIELD_BTN_MOUSE;
   mAccumulator.btnMouse = rawEvent->value != 0;
   sync(rawEvent->when);
   break;
   case BTN_RIGHT:
   mAccumulator.fields |= Accumulator::FIELD_BTN_RIGHT;
   mAccumulator.btnRight = rawEvent->value != 0;
   sync(rawEvent->when);
   break;
   case BTN_MIDDLE:
   mAccumulator.fields |= Accumulator::FIELD_BTN_MIDDLE;
   mAccumulator.btnMiddle = rawEvent->value != 0;
   sync(rawEvent->when);
   break;
   }
   break;

   case EV_REL:
   switch (rawEvent->scanCode)
   {
   case REL_X:
   mAccumulator.fields |= Accumulator::FIELD_REL_X;
   mAccumulator.relX = rawEvent->value;
   break;
   case REL_Y:
   mAccumulator.fields |= Accumulator::FIELD_REL_Y;
   mAccumulator.relY = rawEvent->value;
   break;
   }
   break;

   case EV_SYN:
   switch (rawEvent->scanCode)
   {
   case SYN_REPORT:
   sync(rawEvent->when);
   break;
   }
   break;
   }
}

void MouseInputMapper::sync(nsecs_t when)
{
   uint32_t fields = mAccumulator.fields;
   if (fields == 0)
   {
   return; // no new state changes, so nothing to do
   }

   int motionEventAction;
   PointerCoords pointerCoords;
   nsecs_t downTime;
   { // acquire lock
   AutoMutex _l(mLock);

   if (fields & Accumulator::FIELD_BTN_RIGHT)
   {
   getDispatcher()->notifyKey(when, getDeviceId(), AINPUT_SOURCE_DPAD, 0,
   mAccumulator.btnRight ? AKEY_EVENT_ACTION_DOWN : AKEY_EVENT_ACTION_UP,
   AKEY_EVENT_FLAG_FROM_SYSTEM, 0x4 /*Keycode for back key*/,
   0x18 /*Scancode*/, mContext->getGlobalMetaState(), when);
   }

   if (fields & Accumulator::FIELD_BTN_MIDDLE)
   {
   getDispatcher()->notifyKey(when, getDeviceId(),AINPUT_SOURCE_DPAD, 0,
   mAccumulator.btnMiddle ? AKEY_EVENT_ACTION_DOWN : AKEY_EVENT_ACTION_UP,
   AKEY_EVENT_FLAG_FROM_SYSTEM, 0x52 /*Keycode for menu key*/,
   0x19 /*Scancode*/, mContext->getGlobalMetaState(), when);
   }

   bool downChanged = fields & Accumulator::FIELD_BTN_MOUSE;
   if (downChanged)
   {
   if (mAccumulator.btnMouse)
   {
   mLocked.down = true;
   mLocked.downTime = when;
   }
   else
   {
   mLocked.down = false;
   }
   motionEventAction = mLocked.down ? AMOTION_EVENT_ACTION_DOWN : AMOTION_EVENT_ACTION_UP;
   }
   else
   {
   motionEventAction = AMOTION_EVENT_ACTION_MOVE;
   }

   downTime = mLocked.downTime;

   float x = fields & Accumulator::FIELD_REL_X ? mAccumulator.relX : 0.0f;
   float y = fields & Accumulator::FIELD_REL_Y ? mAccumulator.relY : 0.0f;

   int32_t screenWidth;
   int32_t screenHeight;
   int32_t orientation;

   if (mAssociatedDisplayId < 0 || ! getPolicy()->getDisplayInfo(mAssociatedDisplayId, &screenWidth, &screenHeight, &orientation))
   {
   return;
   }

   float temp;
   switch (orientation)
   {
   case InputReaderPolicyInterface::ROTATION_90:
   {
   temp = x;
   x = y;
   y = - temp;
   temp = screenHeight;
   screenHeight = screenWidth;
   screenWidth = temp;
   break;
   }
   case InputReaderPolicyInterface::ROTATION_180:
   {
   x = - x;
   y = - y;
   break;
   }
   case InputReaderPolicyInterface::ROTATION_270:
   {
   temp = x;
   x = - y;
   y = temp;
   temp = screenHeight;
   screenHeight = screenWidth;
   screenWidth = temp;
   break;
   }
   }

   mAccumulator.absX =
   (mAccumulator.absX + x) > screenWidth ? screenWidth -1 :
   ((mAccumulator.absX + x) < 0 ? 0 : mAccumulator.absX + x);
   mAccumulator.absY = (mAccumulator.absY + y) > screenHeight ? screenHeight -1 :
   ((mAccumulator.absY + y) < 0 ? 0 : mAccumulator.absY + y);
   pointerCoords.x = mAccumulator.absX;
   pointerCoords.y = mAccumulator.absY;
   pointerCoords.pressure = mLocked.down ? 1.0f : 0.0f;
   pointerCoords.size = 0;
   pointerCoords.touchMajor = 0;
   pointerCoords.touchMinor = 0;
   pointerCoords.toolMajor = 0;
   pointerCoords.toolMinor = 0;
   pointerCoords.orientation = 0;

   } // release lock

   int32_t metaState = mContext->getGlobalMetaState();
   int32_t pointerId = 0;
   getDispatcher()->notifyMotion(when, getDeviceId(), AINPUT_SOURCE_MOUSE, 0,
   motionEventAction, 0, metaState, AMOTION_EVENT_EDGE_FLAG_NONE,
   1, &pointerId, &pointerCoords, 1, 1, downTime);
   mAccumulator.clear();
}
   3、事件分发InputDispatcher.cpp 函数修改
   bool isPointerEvent = entry->source & AINPUT_SOURCE_CLASS_POINTER;
   bool isMouseEvent = entry->source & (AINPUT_SOURCE_MOUSE & ~AINPUT_SOURCE_CLASS_POINTER);
   bool isTouchEvent = entry->source & (AINPUT_SOURCE_TOUCHSCREEN & ~AINPUT_SOURCE_CLASS_POINTER);
   bool isDownEvent = (entry->action & AMOTION_EVENT_ACTION_MASK) == AMOTION_EVENT_ACTION_DOWN;

   // Identify targets.
   if (! mCurrentInputTargetsValid) {
   int32_t injectionResult;
   if ( isPointerEvent && (isTouchEvent || (isMouseEvent && (isDownEvent || mTouchState.down))))
   {
   // Touch-like event. (eg. touchscreen or mouse drag-n-drop )
   injectionResult = findTouchedWindowTargetsLocked(currentTime, entry, nextWakeupTime);
   }
   else
   {
   // Non touch event. (eg. trackball or mouse simple move)
   injectionResult = findFocusedWindowTargetsLocked(currentTime, entry, nextWakeupTime);
   }

   4、java 处理鼠标事件
   private void dispatchMotion(MotionEvent event, boolean sendDone) {
   int source = event.getSource();
   if ((source & (InputDevice.SOURCE_MOUSE & ~InputDevice.SOURCE_CLASS_POINTER)) != 0) {
   try{
   wm.moveMouseSurface((int)event.getX() - (int)event.getXOffset(),
   (int)event.getY() - (int)event.getYOffset());
   }catch (RemoteException e){
   Log.e(TAG,"RemoteException thrown in moveMouseSurface");
   }
   dispatchPointer(event, sendDone);
   } else if ((source & InputDevice.SOURCE_CLASS_POINTER) != 0) {
   dispatchPointer(event, sendDone);
   } else if ((source & InputDevice.SOURCE_CLASS_TRACKBALL) != 0) {
   dispatchTrackball(event, sendDone);
   } else {
   // TODO
   Log.v(TAG, "Dropping unsupported motion event (unimplemented): " + event);
   if (sendDone) {
   finishInputEvent();
   }
   }
   }

   5、利用binder传递到WindowManagerService.java 中
   代码路径： frameworksbaseservicesjavaandroidserverWindowManagerService.java
   如果没有硬件光标层，可能就需要在此进行修改.
   /* 移动光标，如果有硬件光标层，直接利用jni调用即可 */
   public boolean moveMouseSurface(int x, int y)
{
if (mMouseSurface != null && (x != 0 || y != 0))
{
synchronized(mWindowMap)
{
Surface.openTransaction();
WindowState top =
(WindowState)mWindows.get(mWindows.size() - 1);
try
{
int mDisplayWidth = mDisplay.getWidth();
mMlx = x;
mMly = y;
mMouseSurface.setPosition(mMlx, mMly);
mMouseSurface.setLayer(top.mAnimLayer + 1);
if (!mMouseDisplayed)
{
mMouseSurface.show();
mMouseDisplayed = !mMouseDisplayed;
}
}
catch ( RuntimeException e)
{
Slog.e(TAG, "Failure showing mouse surface",e);
}

Surface.closeTransaction();
}
}

return true;
}

   /* 绘制光标图形 */
private final void performLayoutAndPlaceSurfacesLockedInner(
boolean recoveringMemory) {
...
if (mMouseSurface == null)
{
int mMx, mMy, mMw, mMh;
Canvas mCanvas;
Path mPath = new Path();
mMw = 13;
mMh = 22;
mMx = (mDisplay.getWidth() - mMw) / 2;
mMy = (mDisplay.getHeight() - mMh) / 2;
try
{
/*
* First Mouse event, create Surface
*/
mMouseSurface =
new Surface(mFxSession,
0, -1, mMw, mMh,
PixelFormat.TRANSPARENT,
Surface.FX_SURFACE_NORMAL);
mCanvas = mMouseSurface.lockCanvas(null);
Paint tPaint = new Paint();
tPaint.setStyle(Paint.Style.STROKE);
tPaint.setStrokeWidth(2);
tPaint.setColor(0xffffffff);
mPath.moveTo(0.0f, 0.0f);
mPath.lineTo(12.0f, 12.0f);
mPath.lineTo(7.0f, 12.0f);
mPath.lineTo(11.0f, 20.0f);
mPath.lineTo(8.0f, 21.0f);
mPath.lineTo(4.0f, 13.0f);
mPath.lineTo(0.0f, 17.0f);
mPath.close();
mCanvas.clipPath(mPath);
mCanvas.drawColor(0xff000000);
mCanvas.drawPath(mPath, tPaint);

mMouseSurface.unlockCanvasAndPost(mCanvas);
mMouseSurface.openTransaction();
mMouseSurface.setSize(mMw, mMh);
mMouseSurface.closeTransaction();

}
catch (Exception e)
{
Slog.e(TAG, "Exception creating mouse surface",e);
}
mMlx = mMx;
mMly = mMy;
mMlw = mMw;
mMlh = mMh;
}

...
｝

   6、直接利用jni实现硬件光标层
   frameworksbaseservicesjnicom_android_server_WindowManagerService.cpp

   ok,基本上的工作已经完成，此时鼠标将可以正常工作。可以看出Android系统鼠标光标的定制不是非常容易，需要修改不少的代码。不过mips社区已经将功能完成了90%了，仅需要简单与光标层对接一下接口即可。