From 12a05922687cddcef06ed84e15ad43683fba5b7f Mon Sep 17 00:00:00 2001
From: Daria Volvenkova <d.volvenkova@corp.mail.ru>
Date: Fri, 25 Nov 2016 16:09:55 +0300
Subject: [PATCH] Show the ruler only during scaling.

---
 drape_frontend/gui/ruler.cpp        |  2 +-
 drape_frontend/gui/ruler_helper.cpp | 14 +++++++++++++-
 drape_frontend/gui/ruler_helper.hpp |  4 ++++
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/drape_frontend/gui/ruler.cpp b/drape_frontend/gui/ruler.cpp
index 541ccb8733..e24bfd5cdb 100644
--- a/drape_frontend/gui/ruler.cpp
+++ b/drape_frontend/gui/ruler.cpp
@@ -51,7 +51,7 @@ public:
     : TBase(id, anchor, pivot)
     , m_isAppearing(isAppearing)
     , m_isVisibleAtEnd(true)
-    , m_animation(false, 0.4)
+    , m_animation(false, 0.2)
   {
   }
 
diff --git a/drape_frontend/gui/ruler_helper.cpp b/drape_frontend/gui/ruler_helper.cpp
index e3bdbe0b54..e60a50fe9c 100644
--- a/drape_frontend/gui/ruler_helper.cpp
+++ b/drape_frontend/gui/ruler_helper.cpp
@@ -29,6 +29,8 @@ static int const MinUnitValue = -1;
 static int const MaxUnitValue = numeric_limits<int>::max() - 1;
 static int const InvalidUnitValue = MaxUnitValue + 1;
 
+static double const kHideDelaySeconds = 1.0;
+
 struct UnitValue
 {
   char const * m_s;
@@ -113,6 +115,14 @@ RulerHelper::RulerHelper()
 
 void RulerHelper::Update(ScreenBase const & screen)
 {
+  if (m_lastScale != screen.GetScale())
+  {
+    if (!IsVisible(screen))
+      SetTextDirty();
+    m_lastScale = screen.GetScale();
+    m_hideTimer.Reset();
+  }
+
   m2::PointD pivot = screen.PixelRect().Center();
   int const minPxWidth = my::rounds(MinPixelWidth * df::VisualParams::Instance().GetVisualScale());
   m2::PointD pt1 = screen.PtoG(pivot);
@@ -150,7 +160,9 @@ void RulerHelper::Update(ScreenBase const & screen)
 bool RulerHelper::IsVisible(ScreenBase const & screen) const
 {
   DrapeGui & gui = DrapeGui::Instance();
-  return !gui.IsCopyrightActive() && df::GetDrawTileScale(screen) >= VISIBLE_RULER_BOTTOM_SCALE;
+  return !gui.IsCopyrightActive() &&
+      (df::GetDrawTileScale(screen) >= VISIBLE_RULER_BOTTOM_SCALE) &&
+      (m_hideTimer.ElapsedSeconds() < kHideDelaySeconds);
 }
 
 void RulerHelper::Invalidate()
diff --git a/drape_frontend/gui/ruler_helper.hpp b/drape_frontend/gui/ruler_helper.hpp
index 5ed7fa2111..a30d6f0db6 100644
--- a/drape_frontend/gui/ruler_helper.hpp
+++ b/drape_frontend/gui/ruler_helper.hpp
@@ -2,6 +2,8 @@
 
 #include "drape_frontend/animation/show_hide_animation.hpp"
 
+#include "base/timer.hpp"
+
 #include "std/string.hpp"
 
 class ScreenBase;
@@ -38,6 +40,8 @@ private:
   bool m_isTextDirty;
   mutable bool m_dirtyTextRequested;
   int m_currentDrawScale = 0;
+  my::Timer m_hideTimer;
+  double m_lastScale = 0.0;
 };
 
 }