[dasher: 128/217] win32 - prevent dasher from starting when obscured by other window.

[Patrick Welche <pwelche src gnome org>]

commit 51978d3d0660f324b38fd3d3c030ffe8c22b3f01
Author: ipomoena <amajorek google com>
Date:   Wed Nov 18 17:18:21 2015 -0800

    win32 - prevent dasher from starting when obscured by other window.
    
    Fixes https://github.com/ipomoena/dasher/issues/57

 Src/DasherCore/CircleStartHandler.cpp |    4 ++--
 Src/DasherCore/DasherScreen.h         |    3 +++
 Src/Gtk2/Canvas.h                     |    2 ++
 Src/Win32/Widgets/Screen.cpp          |   21 ++++++---------------
 Src/Win32/Widgets/Screen.h            |   11 ++---------
 5 files changed, 15 insertions(+), 26 deletions(-)
---
diff --git a/Src/DasherCore/CircleStartHandler.cpp b/Src/DasherCore/CircleStartHandler.cpp
index b5edc5a..85d68b1 100644
--- a/Src/DasherCore/CircleStartHandler.cpp
+++ b/Src/DasherCore/CircleStartHandler.cpp
@@ -81,8 +81,8 @@ void CCircleStartHandler::Timer(unsigned long iTime, dasherint mouseX, dasherint
   CDasherScreen::point ctr = CircleCenter(pView);
   screenint x,y;
   pView->Dasher2Screen(mouseX, mouseY, x, y);
-  x-=ctr.x; y-=ctr.y;
-  const bool inCircleNow = x*x + y*y <= (m_iScreenRadius * m_iScreenRadius);
+  int dx=x-ctr.x, dy=y-ctr.y;
+  const bool inCircleNow = dx*dx + dy*dy <= (m_iScreenRadius * m_iScreenRadius) && 
pView->Screen()->IsPointVisible(x,y);
 
   if (inCircleNow) {
     if (m_bInCircle) {
diff --git a/Src/DasherCore/DasherScreen.h b/Src/DasherCore/DasherScreen.h
index 48e7ae0..edb9b62 100644
--- a/Src/DasherCore/DasherScreen.h
+++ b/Src/DasherCore/DasherScreen.h
@@ -170,6 +170,9 @@ public:
   /// \param pColourScheme A colour scheme that should be used
   virtual void SetColourScheme(const Dasher::CColourIO::ColourInfo *pColourScheme) = 0;
   
+  // Returns true if point on screen is not obscured by another window
+  virtual bool IsPointVisible(screenint x, screenint y) = 0;
+
 private:
   //! Width and height of the screen
   screenint m_iWidth, m_iHeight;
diff --git a/Src/Gtk2/Canvas.h b/Src/Gtk2/Canvas.h
index 05217c7..e505640 100644
--- a/Src/Gtk2/Canvas.h
+++ b/Src/Gtk2/Canvas.h
@@ -185,6 +185,8 @@ public:
 
   // Redeclare to make public and adjust cairo/gdk surface sizes
   void resize(screenint w,screenint h);
+  // Returns true if point on screen is not obscured by another window
+  bool IsPointVisible(screenint x, screenint y) override { return true; }
 
 private:
 
diff --git a/Src/Win32/Widgets/Screen.cpp b/Src/Win32/Widgets/Screen.cpp
index 4379efe..6c34d3e 100644
--- a/Src/Win32/Widgets/Screen.cpp
+++ b/Src/Win32/Widgets/Screen.cpp
@@ -29,19 +29,9 @@ static char THIS_FILE[] = __FILE__;
 
 CScreen::CScreen(HDC hdc, HWND hWnd, Dasher::screenint iWidth, Dasher::screenint iHeight)
 :CLabelListScreen(iWidth, iHeight), m_hdc(hdc) {
-  // set up the off-screen buffers
-  // HDC hdc = GetDC(mainwindow);
-
   m_hWnd = hWnd;
 
   CreateBuffers();
-
-  CodePage = GetUserCodePage();
-
-//      m_hDCScreen = ::GetDC(m_hwnd);
-//      TCHAR debug[256];
-//      _stprintf(debug, TEXT("GetDC: hwnd %x hdc %x\n"), m_hwnd, m_hDCScreen);
-//      OutputDebugString(debug); 
 }
 
 void CScreen::CreateBuffers() {
@@ -205,11 +195,6 @@ pair<screenint,screenint> CScreen::TextSize_Impl(CScreen::Label *label, unsigned
 }
 
 /////////////////////////////////////////////////////////////////////////////
-
-/*void CScreen::Polygon(point *Points, int Number, int iColour) {
-  CScreen::Polygon( Points, Number, iColour, 1);
-}*/
-
 void CScreen::Polygon(point *Points, int Number, int fillColour, int outlineColour, int iWidth) {
   HGDIOBJ hpOld;
   hpOld = (HPEN) SelectObject(m_hDCBuffer, CScreen::GetPen(fillColour, iWidth));
@@ -224,3 +209,9 @@ void CScreen::Polygon(point *Points, int Number, int fillColour, int outlineColo
 }
 
 /////////////////////////////////////////////////////////////////////////////
+bool CScreen::IsPointVisible(screenint x, screenint y) {
+  POINT pt = { x, y };
+  ClientToScreen(m_hWnd, &pt);
+  HWND h = WindowFromPoint(pt);
+  return h == m_hWnd;
+}
diff --git a/Src/Win32/Widgets/Screen.h b/Src/Win32/Widgets/Screen.h
index f9a0673..e563057 100644
--- a/Src/Win32/Widgets/Screen.h
+++ b/Src/Win32/Widgets/Screen.h
@@ -38,8 +38,6 @@ public:
 
   void SetFont(const std::string &strFont);
 
-  void DrawMousePosBox(int which, int iMousePosDist,int layer=0);
-
   /// Make label from UTF8-encoded string
   /// \param iWrapSize 0 => single-line label (for nodes); any other value => wrapped to screen width
   /// (we wrap the text in whatever fontsize it's DrawString/TextSize'd in, even tho we don't have to)
@@ -54,12 +52,6 @@ public:
 
   void CScreen::DrawCircle(screenint iCX, screenint iCY, screenint iR, int iFillColour, int iLineColour, int 
iThickness);
 
-  // Draw a line of fixed colour (usually black). Intended for static UI elements such as a cross-hair
-  //! Draw a line between each of the points in the array
-  //
-  //! \param Number the number of points in the array
-  //void Polyline(point * Points, int Number, int iWidth);
-
   // Draw a line of arbitrary colour.
   //! Draw a line between each of the points in the array
   //
@@ -90,6 +82,8 @@ public:
   void SendMarker(int iMarker);
 
   void resize(screenint w,screenint h);
+  // Returns true if point on screen is not obscured by another window
+  bool IsPointVisible(screenint x, screenint y) override;
 private:
   const void point2POINT(const point * In, POINT * Out, int Number);
 
@@ -105,7 +99,6 @@ private:
   HBITMAP m_hbmBitDecorations;  // Offscreen buffer for decorations
   HGDIOBJ m_prevhbmBitBackground;
   HGDIOBJ m_prevhbmBitDecorations;
-  UINT CodePage;
 
   const Dasher::CColourIO::ColourInfo *m_pColours;