recovery: Implement sysbar

Add a system bar (navigation bar) similar to the main Android system
with back and home buttons.  This makes it easier for users to figure
out how to go back on devices that lack hardware buttons, and also
provides a quick way to get back to the main menu.

Note only buttons that do not have a hardware equivalent are shown, in
order to prevent redundancy and confusion.

Change-Id: I7538749978837571a8c250c3c8e54ac127b39d84

1 files changed, 9 insertions, 0 deletions

diff --git a/ui.h b/ui.h
index abe4bca..e71dbe2 100644
--- a/ui.h
+++ b/ui.h
@@ -162,6 +162,9 @@ class RecoveryUI {
     // of phones and tablets, false otherwise.
     virtual bool HasThreeButtons();
 
+    virtual bool HasBackKey() const { return has_back_key; }
+    virtual bool HasHomeKey() const { return has_home_key; }
+
     // Erase any queued-up keys.
     virtual void FlushKeys();
 
@@ -191,6 +194,10 @@ class RecoveryUI {
     virtual int MenuItemStart() const = 0;
     virtual int MenuItemHeight() const = 0;
 
+    virtual int  GetSysbarHeight() = 0;
+    virtual int  GetSysbarState() = 0;
+    virtual void SetSysbarState(int state) = 0;
+
     // Display some header text followed by a menu of items, which appears
     // at the top of the screen (in place of any scrolling ui_print()
     // output, if necessary).
@@ -230,6 +237,8 @@ private:
     bool has_power_key;
     bool has_up_key;
     bool has_down_key;
+    bool has_back_key;
+    bool has_home_key;
 
     input_device input_devices[MAX_NR_INPUT_DEVICES];