Android 输入事件流程
2010-05-24 21:08:00 来源:WEB开发网EventHubEventHub对输入设备进行了封装。输入设备驱动程序对用户空间应用程序提供一些设备文件,这些设备文件放在/dev/input里面。
EventHub扫描/dev/input下所有设备文件,并打开它们。
bool EventHub::openPlatformInput(void)
{
...
mFDCount = 1;
mFDs = (pollfd *)calloc(1, sizeof(mFDs[0]));
mDevices = (device_t **)calloc(1, sizeof(mDevices[0]));
mFDs[0].events = POLLIN;
mDevices[0] = NULL;
res = scan_dir(device_path);
...
return true;
}
EventHub对外提供了一个函数用于从输入设备文件中读取数据。
bool EventHub::getEvent(int32_t* outDeviceId, int32_t* outType,
int32_t* outScancode, int32_t* outKeycode, uint32_t *outFlags,
int32_t* outValue, nsecs_t* outWhen)
{
...
while(1) {
// First, report any devices that had last been added/removed.
if (mClosingDevices != NULL) {
device_t* device = mClosingDevices;
LOGV("Reporting device closed: id=0x%x, name=%s ",
device->id, device->path.string());
mClosingDevices = device->next;
*outDeviceId = device->id;
if (*outDeviceId == mFirstKeyboardId) *outDeviceId = 0;
*outType = DEVICE_REMOVED;
delete device;
return true;
}
if (mOpeningDevices != NULL) {
device_t* device = mOpeningDevices;
LOGV("Reporting device opened: id=0x%x, name=%s ",
device->id, device->path.string());
mOpeningDevices = device->next;
*outDeviceId = device->id;
if (*outDeviceId == mFirstKeyboardId) *outDeviceId = 0;
*outType = DEVICE_ADDED;
return true;
}
release_wake_lock(WAKE_LOCK_ID);
pollres = poll(mFDs, mFDCount, -1);
acquire_wake_lock(PARTIAL_WAKE_LOCK, WAKE_LOCK_ID);
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