add NextCheckKeyIsLong() and EnqueueKey() methods

NextCheckKeyIsLong() is called right before each call to CheckKey() to
tell the implementation if the key is a long-press or not.  (To be
used on devices with few buttons.)  It's done as a separate method
(rather than a parameter to CheckKey) to not break existing recovery
UI implementations.

EnqueueKey() can be called from CheckKey() to put arbitrary code codes
in the synchronous queue (to be processed by HandleMenuKey).

Change-Id: If8a83d66efe0bbc9e2dc178e5ebe12acd216324b
diff --git a/ui.cpp b/ui.cpp
index bd0fcae..65f4028 100644
--- a/ui.cpp
+++ b/ui.cpp
@@ -45,7 +45,8 @@
 
 RecoveryUI::RecoveryUI() :
     key_queue_len(0),
-    key_last_down(-1) {
+    key_last_down(-1),
+    key_down_time(0) {
     pthread_mutex_init(&key_queue_mutex, NULL);
     pthread_cond_init(&key_queue_cond, NULL);
     self = this;
@@ -109,19 +110,29 @@
 // updown == 1 for key down events; 0 for key up events
 void RecoveryUI::process_key(int key_code, int updown) {
     bool register_key = false;
+    bool long_press = false;
+
+    const long long_threshold = CLOCKS_PER_SEC * 750 / 1000;
 
     pthread_mutex_lock(&key_queue_mutex);
     key_pressed[key_code] = updown;
     if (updown) {
         key_last_down = key_code;
+        key_down_time = clock();
     } else {
-        if (key_last_down == key_code)
+        if (key_last_down == key_code) {
+            long duration = clock() - key_down_time;
+            if (duration > long_threshold) {
+                long_press = true;
+            }
             register_key = true;
+        }
         key_last_down = -1;
     }
     pthread_mutex_unlock(&key_queue_mutex);
 
     if (register_key) {
+        NextCheckKeyIsLong(long_press);
         switch (CheckKey(key_code)) {
           case RecoveryUI::IGNORE:
             break;
@@ -135,18 +146,23 @@
             break;
 
           case RecoveryUI::ENQUEUE:
-            pthread_mutex_lock(&key_queue_mutex);
-            const int queue_max = sizeof(key_queue) / sizeof(key_queue[0]);
-            if (key_queue_len < queue_max) {
-                key_queue[key_queue_len++] = key_code;
-                pthread_cond_signal(&key_queue_cond);
-            }
-            pthread_mutex_unlock(&key_queue_mutex);
+            EnqueueKey(key_code);
             break;
         }
     }
 }
 
+void RecoveryUI::EnqueueKey(int key_code) {
+    pthread_mutex_lock(&key_queue_mutex);
+    const int queue_max = sizeof(key_queue) / sizeof(key_queue[0]);
+    if (key_queue_len < queue_max) {
+        key_queue[key_queue_len++] = key_code;
+        pthread_cond_signal(&key_queue_cond);
+    }
+    pthread_mutex_unlock(&key_queue_mutex);
+}
+
+
 // Reads input events, handles special hot keys, and adds to the key queue.
 void* RecoveryUI::input_thread(void *cookie)
 {
@@ -223,3 +239,6 @@
 RecoveryUI::KeyAction RecoveryUI::CheckKey(int key) {
     return RecoveryUI::ENQUEUE;
 }
+
+void RecoveryUI::NextCheckKeyIsLong(bool is_long_press) {
+}
diff --git a/ui.h b/ui.h
index acb5766..aca7b7b 100644
--- a/ui.h
+++ b/ui.h
@@ -19,6 +19,7 @@
 
 #include <linux/input.h>
 #include <pthread.h>
+#include <time.h>
 
 // Abstract class for controlling the user interface during recovery.
 class RecoveryUI {
@@ -79,6 +80,8 @@
     enum KeyAction { ENQUEUE, TOGGLE, REBOOT, IGNORE };
     virtual KeyAction CheckKey(int key);
 
+    virtual void NextCheckKeyIsLong(bool is_long_press);
+
     // --- menu display ---
 
     // Display some header text followed by a menu of items, which appears
@@ -95,6 +98,9 @@
     // statements will be displayed.
     virtual void EndMenu() = 0;
 
+protected:
+    void EnqueueKey(int key_code);
+
 private:
     // Key event input queue
     pthread_mutex_t key_queue_mutex;
@@ -102,6 +108,7 @@
     int key_queue[256], key_queue_len;
     char key_pressed[KEY_MAX + 1];     // under key_queue_mutex
     int key_last_down;                 // under key_queue_mutex
+    clock_t key_down_time;             // under key_queue_mutex
     int rel_sum;
 
     pthread_t input_t;