【轉】ADROID 2.1 架構解析 7 鍵盤

原文出處： http://blog.csdn.net/skdev/archive/2010/03/08/5355542.aspx

 

 

7 鍵盤
系統在KeyInputQueue服務裏創建了一個線程，在這個線程裏不斷讀取輸入事件，然後對這個事件進行處理。

7.1 按鍵輸入隊列服務
按鍵輸入事件有多種方式，如：鍵盤敲擊、觸摸屏觸擊、鼠標點擊及多點觸摸，主要是按下和放開的事件。

7.1.1 輸入事件的數據結構
文件：frameworks/base/core/java/android/view/RawInputEvent.java

public class RawInputEvent { // Event class as defined by EventHub. ... public int deviceId; public int type; public int scancode; public int keycode; public int flags; public int value; public long when; }

7.1.2 輸入事件服務
文件：frameworks/base/services/java/com/android/server/KeyInputQueue.java

7.1.2.1 獲取事件
Thread mThread = new Thread("InputDeviceReader") { public void run() { if (DEBUG) Log.v(TAG, "InputDeviceReader.run()"); android.os.Process.setThreadPriority( android.os.Process.THREAD_PRIORITY_URGENT_DISPLAY); RawInputEvent ev = new RawInputEvent(); while (true) { try { ... // block, doesn't release the monitor readEvent(ev); ...

調用readEvent，將輸入事件讀取到ev類，即RawInputEvent的變量裏，readEvent對應jni的android_server_KeyInputQueue_readEvent

7.1.2.2 處理鍵盤事件
... public static KeyEvent newKeyEvent(InputDevice device, long downTime, long eventTime, boolean down, int keycode, int repeatCount, int scancode, int flags) { return new KeyEvent( downTime, eventTime, down ? KeyEvent.ACTION_DOWN : KeyEvent.ACTION_UP, keycode, repeatCount, device != null ? device.mMetaKeysState : 0, device != null ? device.id : -1, scancode, flags | KeyEvent.FLAG_FROM_SYSTEM); } Thread mThread = new Thread("InputDeviceReader") { public void run() { if (DEBUG) Log.v(TAG, "InputDeviceReader.run()"); android.os.Process.setThreadPriority( android.os.Process.THREAD_PRIORITY_URGENT_DISPLAY); RawInputEvent ev = new RawInputEvent(); while (true) { try { InputDevice di; // block, doesn't release the monitor readEvent(ev); ... final int scancode = ev.scancode; if (type == RawInputEvent.EV_KEY && (classes&RawInputEvent.CLASS_KEYBOARD) != 0 && (scancode < RawInputEvent.BTN_FIRST || scancode > RawInputEvent.BTN_LAST)) { boolean down; if (ev.value != 0) { down = true; di.mKeyDownTime = curTime; } else { down = false; } int keycode = rotateKeyCodeLocked(ev.keycode); addLocked(di, curTimeNano, ev.flags, RawInputEvent.CLASS_KEYBOARD, newKeyEvent(di, di.mKeyDownTime, curTime, down, keycode, 0, scancode, ((ev.flags & WindowManagerPolicy.FLAG_WOKE_HERE) != 0) ? KeyEvent.FLAG_WOKE_HERE : 0)); }

處理鍵盤事件，並將該事件加入事件隊列。

7.2硬件調用
文件：frameworks/base/services/jni/com_android_server_KeyInputQueue.cpp

int register_android_server_KeyInputQueue(JNIEnv* env) { ... jclass inputEvent = env->FindClass("android/view/RawInputEvent"); gInputOffsets.mDeviceId = env->GetFieldID(inputEvent, "deviceId", "I"); gInputOffsets.mType = env->GetFieldID(inputEvent, "type", "I"); gInputOffsets.mScancode = env->GetFieldID(inputEvent, "scancode", "I"); gInputOffsets.mKeycode = env->GetFieldID(inputEvent, "keycode", "I"); gInputOffsets.mFlags = env->GetFieldID(inputEvent, "flags", "I"); gInputOffsets.mValue = env->GetFieldID(inputEvent, "value", "I"); gInputOffsets.mWhen = env->GetFieldID(inputEvent, "when", "J"); ... } 獲取android/view/RawInputEvent類的變量。 static jboolean android_server_KeyInputQueue_readEvent(JNIEnv* env, jobject clazz, jobject event) { gLock.lock(); sp<EventHub> hub = gHub; if (hub == NULL) { hub = new EventHub; gHub = hub; } gLock.unlock(); int32_t deviceId; int32_t type; int32_t scancode, keycode; uint32_t flags; int32_t value; nsecs_t when; bool res = hub->getEvent(&deviceId, &type, &scancode, &keycode, &flags, &value, &when); env->SetIntField(event, gInputOffsets.mDeviceId, (jint)deviceId); env->SetIntField(event, gInputOffsets.mType, (jint)type); env->SetIntField(event, gInputOffsets.mScancode, (jint)scancode); env->SetIntField(event, gInputOffsets.mKeycode, (jint)keycode); env->SetIntField(event, gInputOffsets.mFlags, (jint)flags); env->SetIntField(event, gInputOffsets.mValue, value); env->SetLongField(event, gInputOffsets.mWhen, (jlong)(nanoseconds_to_milliseconds(when))); return res; }

將從eventhub讀到的變量存到android/view/RawInputEvent類對應的變量裏。

7.3 EventHub庫
文件：frameworks/base/libs/ui/EventHub.cpp

7.3.1 讀取輸入設備狀態
static const char *device_path = "/dev/input"; bool EventHub::getEvent(int32_t* outDeviceId, int32_t* outType, int32_t* outScancode, int32_t* outKeycode, uint32_t *outFlags, int32_t* outValue, nsecs_t* outWhen) { ... if (!mOpened) { mError = openPlatformInput() ? NO_ERROR : UNKNOWN_ERROR; mOpened = true; } ... while(1) { pollres = poll(mFDs, mFDCount, -1); // mFDs[0] is used for inotify, so process regular events starting at mFDs[1] for(i = 1; i < mFDCount; i++) { if(mFDs[i].revents) { LOGV("revents for %d = 0x%08x", i, mFDs[i].revents); if(mFDs[i].revents & POLLIN) { res = read(mFDs[i].fd, &iev, sizeof(iev)); if (res == sizeof(iev)) { *outDeviceId = mDevices[i]->id; if (*outDeviceId == mFirstKeyboardId) *outDeviceId = 0; *outType = iev.type; *outScancode = iev.code; if (iev.type == EV_KEY) { err = mDevices[i]->layoutMap->map(iev.code, outKeycode, outFlags); if (err != 0) { *outKeycode = 0; *outFlags = 0; } } else { *outKeycode = iev.code; } *outValue = iev.value; *outWhen = s2ns(iev.time.tv_sec) + us2ns(iev.time.tv_usec); return true; } else { if (res<0) { LOGW("could not get event (errno=%d)", errno); } else { LOGE("could not get event (wrong size: %d)", res); } continue; } } } } // read_notify() will modify mFDs and mFDCount, so this must be done after // processing all other events. if(mFDs[0].revents & POLLIN) { read_notify(mFDs[0].fd); } } }

openPlatformInput() 打開/dev/input/ 目錄下的所有輸入設備文件。

打開設備後，不斷輪循所有設備，直到讀取有POLLIN事件產生的設備的狀態。

7.3.2 導入鍵盤配置文件
int EventHub::open_device(const char *deviceName) { ... if(ioctl(fd, EVIOCGNAME(sizeof(name) - 1), &name) < 1) { //fprintf(stderr, "could not get device name for %s, %s/n", deviceName, strerror(errno)); name[0] = '/0'; } ... if ((device->classes&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; } device->layoutMap->load(keylayoutFilename); // tell the world about the devname (the descriptive name) int32_t publicID; if (!mHaveFirstKeyboard && !defaultKeymap) { publicID = 0; // the built-in keyboard has a well-known device ID of 0, // this device better not go away. mHaveFirstKeyboard = true; mFirstKeyboardId = device->id; } else { publicID = device->id; // ensure mFirstKeyboardId is set to -something-. if (mFirstKeyboardId == 0) { mFirstKeyboardId = device->id; } } char propName[100]; sprintf(propName, "hw.keyboards.%u.devname", publicID); property_set(propName, name); // 'Q' key support = cheap test of whether this is an alpha-capable kbd if (hasKeycode(device, kKeyCodeQ)) { device->classes |= CLASS_ALPHAKEY; } // See if this has a DPAD. if (hasKeycode(device, kKeyCodeDpadUp) && hasKeycode(device, kKeyCodeDpadDown) && hasKeycode(device, kKeyCodeDpadLeft) && hasKeycode(device, kKeyCodeDpadRight) && hasKeycode(device, kKeyCodeDpadCenter)) { device->classes |= CLASS_DPAD; } LOGI("New keyboard: publicID=%d device->id=0x%x devname='%s' propName='%s' keylayout='%s'/n", publicID, device->id, name, propName, keylayoutFilename); } ... }

由以上代碼可知，會優先加載/system/usr/keylayout/輸入設備名稱.kl

如: /sys/class/input/input1/name = keypad，則會加載/system/usr/keylayout/keypad.kl，如果該文件不存在，則加載默認文件/system/usr/keylayout/qwerty.kl，該文件的原型在：sdk/emulator/keymaps/qwerty.kl ，eclair以前的版本都是放在development/ emulator/keymaps/qwerty.kl

7.3.3 按鍵映射
如7.3.2所示代碼，先加載配置文件：

device->layoutMap->load(keylayoutFilename);

如7.3.1所示代碼，再將讀取到的按鍵碼進行轉換：

err = mDevices[i]->layoutMap->map(iev.code, outKeycode, outFlags);

文件：frameworks/base/libs/ui/KeyLayoutMap.cpp

status_t KeyLayoutMap::load(const char* filename) { int fd = open(filename, O_RDONLY); ... while (true) { String8 token = next_token(&p, &line); if (*p == '/0') { break; } switch (state) { case BEGIN: if (token == "key") { state = SCANCODE; } else { LOGE("%s:%d: expected key, got '%s'/n", filename, line, token.string()); err = BAD_VALUE; goto done; } break; case SCANCODE: scancode = strtol(token.string(), &end, 0); if (*end != '/0') { LOGE("%s:%d: expected scancode (a number), got '%s'/n", filename, line, token.string()); goto done; } //LOGI("%s:%d: got scancode %d/n", filename, line, scancode ); state = KEYCODE; break; case KEYCODE: keycode = token_to_value(token.string(), KEYCODES); //LOGI("%s:%d: got keycode %d for %s/n", filename, line, keycode, token.string() ); if (keycode == 0) { LOGE("%s:%d: expected keycode, got '%s'/n", filename, line, token.string()); goto done; } state = FLAG; break; case FLAG: if (token == "key") { if (scancode != -1) { //LOGI("got key decl scancode=%d keycode=%d" // " flags=0x%08x/n", scancode, keycode, flags); Key k = { keycode, flags }; m_keys.add(scancode, k); state = SCANCODE; scancode = -1; keycode = -1; flags = 0; break; } } tmp = token_to_value(token.string(), FLAGS); //LOGI("%s:%d: got flags %x for %s/n", filename, line, tmp, token.string() ); if (tmp == 0) { LOGE("%s:%d: expected flag, got '%s'/n", filename, line, token.string()); goto done; } flags |= tmp; break; } } ... }

由以上代碼可知，是以如下方式對配置文件進行解析的：

BEGIN: 如果第一個關鍵字是key，則轉入SCANCODE，否則退出。

SCANCODE: 將第二個關鍵字轉爲數字，即掃描碼scancode，轉向KEYCODE。

KEYCODE: 將第三個關鍵字與KEYCODES列表配對，找出關鍵碼keycode，轉向FLAG。

FLAG:如果第四個關鍵字是key，則保存剛掃描的鍵碼，然後轉向SCANCODE，否則將該關鍵字與FLAGS列表配對，找出flags值，然後轉向BEGIN。

 

注：KEYCODES列表和FLAGS列表的定義在：

frameworks/base/include/ui/KeycodeLabels.h

status_t KeyLayoutMap::map(int32_t scancode, int32_t *keycode, uint32_t *flags) const { if (m_status != NO_ERROR) { return m_status; } ssize_t index = m_keys.indexOfKey(scancode); if (index < 0) { //LOGW("couldn't map scancode=%d/n", scancode); return NAME_NOT_FOUND; } const Key& k = m_keys.valueAt(index); *keycode = k.keycode; *flags = k.flags; //LOGD("mapped scancode=%d to keycode=%d flags=0x%08x/n", scancode, // keycode, flags); return NO_ERROR; }   

Map的功能是根據scancode，找到對應的keycode.

 

qwerty.kl 的部分配置：

# scancode keycode flags key 399 GRAVE key 2 1 key 3 2 key 4 3 key 5 4 key 6 5 key 7 6 key 8 7 key 9 8 key 10 9 key 11 0 key 158 BACK WAKE_DROPPED key 230 SOFT_RIGHT WAKE key 60 SOFT_RIGHT WAKE

7.4 字符映射
7.4.1 加載字符配置表
文件：frameworks/base/core/java/android/view/KeyCharacterMap.java
public static KeyCharacterMap load(int keyboard) { ... result = new KeyCharacterMap(keyboard); ... } private KeyCharacterMap(int keyboardDevice) { mKeyboardDevice = keyboardDevice; mPointer = ctor_native(keyboardDevice); }

ctor_native 原型如下：

文件：frameworks/base/core/jni/android_text_KeyCharacterMap.cpp

static JNINativeMethod g_methods[] = { /* name, signature, funcPtr */ { "ctor_native", "(I)I", (void*)ctor }, ... }; static jint ctor(JNIEnv *env, jobject clazz, jint id) { return reinterpret_cast<int>(KeyCharacterMap::load(id)); }

KeyCharacterMap::load原型如下：

文件：frameworks/base/libs/ui/KeyCharacterMap.cpp

KeyCharacterMap* KeyCharacterMap::load(int id) { KeyCharacterMap* rv = NULL; char path[PATH_MAX]; char propName[100]; char dev[PROPERTY_VALUE_MAX]; char tmpfn[PROPERTY_VALUE_MAX]; int err; const char* root = getenv("ANDROID_ROOT"); sprintf(propName, "hw.keyboards.%u.devname", id); err = property_get(propName, dev, ""); if (err > 0) { // replace all the spaces with underscores strcpy(tmpfn, dev); for (char *p = strchr(tmpfn, ' '); p && *p; p = strchr(tmpfn, ' ')) *p = '_'; snprintf(path, sizeof(path), "%s/usr/keychars/%s.kcm.bin", root, tmpfn); //LOGD("load: dev='%s' path='%s'/n", dev, path); rv = try_file(path); if (rv != NULL) { return rv; } LOGW("Error loading keycharmap file '%s'. %s='%s'", path, propName, dev); } else { LOGW("No keyboard for id %d", id); } snprintf(path, sizeof(path), "%s/usr/keychars/qwerty.kcm.bin", root); rv = try_file(path); if (rv == NULL) { LOGE("Can't find any keycharmaps (also tried %s)", path); return NULL; } LOGW("Using default keymap: %s", path); return rv; }

以上所提及代碼要實現的功能是：先查看hw.keyboards.%u.devname的屬性，若存在則打開/system/usr/keychars/%s.kcm.bin文件，否則打開默認文件：/system/usr/keychars/qwerty.kcm.bin

 

文件：frameworks/base/libs/ui/EventHub.cpp

參考<<7.3.2 導入鍵盤配置文件>>裏的：

char propName[100]; sprintf(propName, "hw.keyboards.%u.devname", publicID); property_set(propName, name);

在代碼裏設置了KeyCharacterMap::load 中hw.keyboards.%u.devname所需要的值，即設備名稱，如: /sys/class/input/input1/name = keypad，則會加載/system/usr/keychars/keypad.kcm.bin

 

例：

/sys/class/input/input1/name = keypad

則要打開的文件路徑是：

/system/usr/keylayout/keypad.kl

/system/usr/keychars/keypad.kcm.bin

若以上文件不存在，則使用默認文件：

/system/usr/keylayout/qwerty.kl

/system/usr/keychars/qwerty.kcm.bin

7.4.2字符映射
文件：frameworks/base/core/java/android/view/KeyCharacterMap.java

public char getMatch(int keyCode, char[] chars) { return getMatch(keyCode, chars, 0); } public char getMatch(int keyCode, char[] chars, int modifiers) { if (chars == null) { // catch it here instead of in native throw new NullPointerException(); } return getMatch_native(mPointer, keyCode, chars, modifiers); }

getMatch_native 原型如下：

文件：frameworks/base/core/jni/android_text_KeyCharacterMap.cpp

static JNINativeMethod g_methods[] = { /* name, signature, funcPtr */ { "getMatch_native", "(II[CI)C", (void*)getMatch }, ... }; static jchar getMatch(JNIEnv *env, jobject clazz, jint ptr, jint keycode, jcharArray chars, jint modifiers) { jchar rv; jchar* ch = env->GetCharArrayElements(chars, NULL); jsize chsize = env->GetArrayLength(chars); rv = reinterpret_cast<KeyCharacterMap*>(ptr)->getMatch(keycode, ch, chsize, modifiers); env->ReleaseCharArrayElements(chars, ch, JNI_ABORT); return rv; }

getMatch的原型如下：

文件：frameworks/base/libs/ui/KeyCharacterMap.cpp

unsigned short KeyCharacterMap::getMatch(int keycode, const unsigned short* chars, int charsize, uint32_t modifiers) { Key* k = find_key(keycode); modifiers &= 3; // ignore the SYM key because we don't have keymap entries for it if (k != NULL) { const uint16_t* data = k->data; for (int j=0; j<charsize; j++) { uint16_t c = chars[j]; for (int i=0; i<(META_MASK + 1); i++) { if ((modifiers == 0) || ((modifiers & i) != 0)) { if (c == data[i]) { return c; } } } } } return 0; }

 qwerty.kcm的部分配置：

[type=QWERTY] # keycode display number base caps fn caps_fn A 'A' '2' 'a' 'A' '#' 0x00 B 'B' '2' 'b' 'B' '<' 0x00 C 'C' '2' 'c' 'C' '9' 0x00E7 D 'D' '3' 'd' 'D' '5' 0x00 E 'E' '3' 'e' 'E' '2' 0x0301 F 'F' '3' 'f' 'F' '6' 0x00A5 G 'G' '4' 'g' 'G' '-' '_' H 'H' '4' 'h' 'H' '[' '{' I 'I' '4' 'i' 'I' '$' 0x0302 J 'J' '5' 'j' 'J' ']' '}'

找到keyCode對應的所有字符，然後再根據modifiers選擇對應的字符

7.5 流程總結
當有按鍵響應時，內核傳給ANDROID的是scancode，ANDROID將scancode經配置表(如qwerty.kl)找到keycode標識符，然後由內部表KEYCODES列表找到keycode的數字值，再由keycode的數字值經字符配置表（如qwerty.kcm）找到對應的字符值。

 

本文來自CSDN博客，轉載請標明出處：http://blog.csdn.net/skdev/archive/2010/03/08/5355542.aspx