Android应用程序键盘（Keyboard）消息处理机制分析（6）

int EventHub::openDevice(const char *deviceName) {
int version;
int fd;
struct pollfd *new_mFDs;
device_t **new_devices;
char **new_device_names;
char name[80];
char location[80];
char idstr[80];
struct input_id id;

LOGV("Opening device: %s", deviceName);

AutoMutex _l(mLock);

fd = open(deviceName, O_RDWR);
if(fd < 0) {
LOGE("could not open %s, %s\n", deviceName, strerror(errno));
return -1;
}

......

int devid = 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("out of memory");
return -1;
}
mFDs = new_mFDs;
mDevices = new_devices;

......

device_t* device = new device_t(devid|mDevicesById[devid].seq, deviceName, name);
if (device == NULL) {
LOGE("out of memory");
return -1;
}

device->fd = fd;
mFDs[mFDCount].fd = fd;
mFDs[mFDCount].events = POLLIN;
mFDs[mFDCount].revents = 0;

// Figure out the kinds of events the device reports.

uint8_t key_bitmask[sizeof_bit_array(KEY_MAX + 1)];
memset(key_bitmask, 0, sizeof(key_bitmask));

LOGV("Getting keys...");
if (ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(key_bitmask)), key_bitmask) >= 0) {
// See if this is a keyboard.  Ignore everything in the button range except for
// gamepads which are also considered keyboards.
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 = new uint8_t[sizeof(key_bitmask)];
if (device->keyBitmask != NULL) {
memcpy(device->keyBitmask, key_bitmask, sizeof(key_bitmask));
} else {
delete device;
LOGE("out of memory allocating key bitmask");
return -1;
}
}
}

......

if ((device->classes & INPUT_DEVICE_CLASS_KEYBOARD) != 0) {
char tmpfn[sizeof(name)];
char keylayoutFilename[300];

// a more descriptive name
device->name = name;

// replace all the spaces with underscores
strcpy(tmpfn, name);
for (char *p = strchr(tmpfn, ' '); p && *p; p = strchr(tmpfn, ' '))
*p = '_';

// find the .kl file we need for this device
const char* root = getenv("ANDROID_ROOT");
snprintf(keylayoutFilename, sizeof(keylayoutFilename),
"%s/usr/keylayout/%s.kl", root, tmpfn);
bool defaultKeymap = false;
if (access(keylayoutFilename, R_OK)) {
snprintf(keylayoutFilename, sizeof(keylayoutFilename),
"%s/usr/keylayout/%s", root, "qwerty.kl");
defaultKeymap = true;
}
status_t status = device->layoutMap->load(keylayoutFilename);
if (status) {
LOGE("Error %d loading key layout.", status);
}

// tell the world about the devname (the descriptive name)
if (!mHaveFirstKeyboard && !defaultKeymap && strstr(name, "-keypad")) {
// the built-in keyboard has a well-known device ID of 0,
// this device better not go away.
mHaveFirstKeyboard = true;
mFirstKeyboardId = device->id;
property_set("hw.keyboards.0.devname", name);
} else {
// ensure mFirstKeyboardId is set to -something-.
if (mFirstKeyboardId == 0) {
mFirstKeyboardId = device->id;
}
}
char propName[100];
sprintf(propName, "hw.keyboards.%u.devname", device->id);
property_set(propName, name);

// 'Q' key support = cheap test of whether this is an alpha-capable kbd
if (hasKeycodeLocked(device, AKEYCODE_Q)) {
device->classes |= INPUT_DEVICE_CLASS_ALPHAKEY;
}

// See if this device has a DPAD.
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;
}

// See if this device has a gamepad.
for (size_t i = 0; i < sizeof(GAMEPAD_KEYCODES)/sizeof(GAMEPAD_KEYCODES[0]); i++) {
if (hasKeycodeLocked(device, GAMEPAD_KEYCODES[i])) {
device->classes |= INPUT_DEVICE_CLASS_GAMEPAD;
break;
}
}

LOGI("New keyboard: device->id=0x%x devname='%s' propName='%s' keylayout='%s'\n",
device->id, name, propName, keylayoutFilename);
}

......

mDevicesById[devid].device = device;
device->next = mOpeningDevices;
mOpeningDevices = device;
mDevices[mFDCount] = device;

mFDCount++;
return 0;
}