Android应用程序键盘（Keyboard）消息处理机制分析（6）

Step 21.EventHub.openDevice
这个函数定义在frameworks/base/libs/ui/EventHub.cpp文件中：
                    intEventHub::openDevice(constchar*deviceName){
            intversion;
            intfd;
            structpollfd*new_mFDs;
            device_t**new_devices;
            char**new_device_names;
            charname[80];
            charlocation[80];
            charidstr[80];
            structinput_idid;
            
            LOGV("Openingdevice:%s",deviceName);
            
            AutoMutex_l(mLock);
            
            fd=open(deviceName,O_RDWR);
            if(fd<0){
            LOGE("couldnotopen%s,%s\n",deviceName,strerror(errno));
            return-1;
            }
            
            ......
            
            intdevid=0;
            while(devid<mNumDevicesById){
            if(mDevicesById[devid].device==NULL){
            break;
            }
            devid++;
            }
            
            ......
            
            mDevicesById[devid].seq=(mDevicesById[devid].seq+(1<<SEQ_SHIFT))&SEQ_MASK;
            if(mDevicesById[devid].seq==0){
            mDevicesById[devid].seq=1<<SEQ_SHIFT;
            }
            
            new_mFDs=(pollfd*)realloc(mFDs,sizeof(mFDs[0])*(mFDCount+1));
            new_devices=(device_t**)realloc(mDevices,sizeof(mDevices[0])*(mFDCount+1));
            if(new_mFDs==NULL||new_devices==NULL){
            LOGE("outofmemory");
            return-1;
            }
            mFDs=new_mFDs;
            mDevices=new_devices;
            
            ......
            
            device_t*device=newdevice_t(devid|mDevicesById[devid].seq,deviceName,name);
            if(device==NULL){
            LOGE("outofmemory");
            return-1;
            }
            
            device->fd=fd;
            mFDs[mFDCount].fd=fd;
            mFDs[mFDCount].events=POLLIN;
            mFDs[mFDCount].revents=0;
            
            //Figureoutthekindsofeventsthedevicereports.
            
            uint8_tkey_bitmask[sizeof_bit_array(KEY_MAX+1)];
            memset(key_bitmask,0,sizeof(key_bitmask));
            
            LOGV("Gettingkeys...");
            if(ioctl(fd,EVIOCGBIT(EV_KEY,sizeof(key_bitmask)),key_bitmask)>=0){
            //Seeifthisisakeyboard.Ignoreeverythinginthebuttonrangeexceptfor
            //gamepadswhicharealsoconsideredkeyboards.
            if(containsNonZeroByte(key_bitmask,0,sizeof_bit_array(BTN_MISC))
            ||containsNonZeroByte(key_bitmask,sizeof_bit_array(BTN_GAMEPAD),
            sizeof_bit_array(BTN_DIGI))
            ||containsNonZeroByte(key_bitmask,sizeof_bit_array(KEY_OK),
            sizeof_bit_array(KEY_MAX+1))){
            device->classes|=INPUT_DEVICE_CLASS_KEYBOARD;
            
            device->keyBitmask=newuint8_t[sizeof(key_bitmask)];
            if(device->keyBitmask!=NULL){
            memcpy(device->keyBitmask,key_bitmask,sizeof(key_bitmask));
            }else{
            deletedevice;
            LOGE("outofmemoryallocatingkeybitmask");
            return-1;
            }
            }
            }
            
            ......
            
            if((device->classes&INPUT_DEVICE_CLASS_KEYBOARD)!=0){
            chartmpfn[sizeof(name)];
            charkeylayoutFilename[300];
            
            //amoredescriptivename
            device->name=name;
            
            //replaceallthespaceswithunderscores
            strcpy(tmpfn,name);
            for(char*p=strchr(tmpfn,'');p&&*p;p=strchr(tmpfn,''))
            *p='_';
            
            //findthe.klfileweneedforthisdevice
            constchar*root=getenv("ANDROID_ROOT");
            snprintf(keylayoutFilename,sizeof(keylayoutFilename),
            "%s/usr/keylayout/%s.kl",root,tmpfn);
            booldefaultKeymap=false;
            if(access(keylayoutFilename,R_OK)){
            snprintf(keylayoutFilename,sizeof(keylayoutFilename),
            "%s/usr/keylayout/%s",root,"qwerty.kl");
            defaultKeymap=true;
            }
            status_tstatus=device->layoutMap->load(keylayoutFilename);
            if(status){
            LOGE("Error%dloadingkeylayout.",status);
            }
            
            //telltheworldaboutthedevname(thedescriptivename)
            if(!mHaveFirstKeyboard&&!defaultKeymap&&strstr(name,"-keypad")){
            //thebuilt-inkeyboardhasawell-knowndeviceIDof0,
            //thisdevicebetternotgoaway.
            mHaveFirstKeyboard=true;
            mFirstKeyboardId=device->id;
            property_set("hw.keyboards.0.devname",name);
            }else{
            //ensuremFirstKeyboardIdissetto-something-.
            if(mFirstKeyboardId==0){
            mFirstKeyboardId=device->id;
            }
            }
            charpropName[100];
            sprintf(propName,"hw.keyboards.%u.devname",device->id);
            property_set(propName,name);
            
            //'Q'keysupport=cheaptestofwhetherthisisanalpha-capablekbd
            if(hasKeycodeLocked(device,AKEYCODE_Q)){
            device->classes|=INPUT_DEVICE_CLASS_ALPHAKEY;
            }
            
            //SeeifthisdevicehasaDPAD.
            if(hasKeycodeLocked(device,AKEYCODE_DPAD_UP)&&
            hasKeycodeLocked(device,AKEYCODE_DPAD_DOWN)&&
            hasKeycodeLocked(device,AKEYCODE_DPAD_LEFT)&&
            hasKeycodeLocked(device,AKEYCODE_DPAD_RIGHT)&&
            hasKeycodeLocked(device,AKEYCODE_DPAD_CENTER)){
            device->classes|=INPUT_DEVICE_CLASS_DPAD;
            }
            
            //Seeifthisdevicehasagamepad.
            for(size_ti=0;i<sizeof(GAMEPAD_KEYCODES)/sizeof(GAMEPAD_KEYCODES[0]);i++){
            if(hasKeycodeLocked(device,GAMEPAD_KEYCODES[i])){
            device->classes|=INPUT_DEVICE_CLASS_GAMEPAD;
            break;
            }
            }
            
            LOGI("Newkeyboard:device->id=0x%xdevname='%s'propName='%s'keylayout='%s'\n",
            device->id,name,propName,keylayoutFilename);
            }
            
            ......
            
            mDevicesById[devid].device=device;
            device->next=mOpeningDevices;
            mOpeningDevices=device;
            mDevices[mFDCount]=device;
            
            mFDCount++;
            return0;
            }
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