recovery: Show slot indicator for A/B devices

When running on an A/B device, split the top version line horizontally
to show the Android version on the left and the boot slot on the right.

When not running on A/B device, center the Android version.

Change-Id: Ica18af5e46dadf1088fdfd6d23d96db090195a6a

3 files changed, 22 insertions, 5 deletions

diff --git a/screen_ui.cpp b/screen_ui.cpp
index 9376bdd7..af20942a 100644
--- a/screen_ui.cpp
+++ b/screen_ui.cpp
@@ -715,12 +715,24 @@ void ScreenRecoveryUI::draw_screen_locked() {
     // Draw version info
     if (menu_is_main_) {
       int text_x, text_y;
-      text_x = kMarginWidth + (gr_fb_width() - (android_version_.size() * char_width_)) / 2;
-      text_y = gr_fb_height() - 2 * (char_height_ + 4);
       SetColor(MENU);
-      DrawTextLine(text_x, text_y, android_version_.c_str(), false);
-      text_x = kMarginWidth + (gr_fb_width() - (lineage_version_.size() * char_width_)) / 2;
-      text_y = gr_fb_height() - 1 * (char_height_ + 4);
+      text_y = gr_fb_height() - 2 * (char_height_ + 4);
+      if (boot_slot_.empty()) {
+        text_x = kMarginWidth + gr_fb_width() * 1 / 2 -
+                 (android_version_.size() * char_width_) / 2;
+        DrawTextLine(text_x, text_y, android_version_.c_str(), false);
+      }
+      else {
+          text_x = kMarginWidth + gr_fb_width() * 1 / 4 -
+                   (android_version_.size() * char_width_) / 2;
+          DrawTextLine(text_x, text_y, android_version_.c_str(), false);
+          text_x = kMarginWidth + gr_fb_width() * 3 / 4 -
+                   (boot_slot_.size() * char_width_) / 2;
+          DrawTextLine(text_x, text_y, boot_slot_.c_str(), false);
+      }
+      text_y += char_height_ + 4;
+      text_x = kMarginWidth + gr_fb_width() * 1 / 2 -
+               (lineage_version_.size() * char_width_) / 2;
       DrawTextLine(text_x, text_y, lineage_version_.c_str(), false);
     }
   } else {
diff --git a/ui.cpp b/ui.cpp
index 09b13779..126961c4 100644
--- a/ui.cpp
+++ b/ui.cpp
@@ -88,6 +88,10 @@ RecoveryUI::RecoveryUI()
   char propval[PROPERTY_VALUE_MAX];
   property_get("ro.build.version.release", propval, "(unknown)");
   android_version_ = std::string("Android ") + propval;
+  property_get("ro.boot.slot_suffix", propval, "");
+  if (propval[0] == '_') {
+      boot_slot_ = std::string("Slot ") + &propval[1];
+  }
   property_get("ro.lineage.version", propval, "(unknown)");
   lineage_version_ = std::string("LineageOS ") + propval;
 
diff --git a/ui.h b/ui.h
index 6356d387..6cac86c3 100644
--- a/ui.h
+++ b/ui.h
@@ -272,6 +272,7 @@ class RecoveryUI {
   void EnqueueTouch(const Point& pos);
 
   std::string android_version_;
+  std::string boot_slot_;
   std::string lineage_version_;
 
   // The normal and dimmed brightness percentages (default: 50 and 25, which means 50% and 25% of