Merge pull request #2122 from adishavit:feature-HandleMouseWheel

modules/highgui/doc/user_interface.rst

@@ -208,6 +208,26 @@ Sets mouse handler for the specified window
     :param userdata: The optional parameter passed to the callback.
 
 
+getMouseWheelDelta
+------------------
+Gets the mouse-wheel motion delta, when handling mouse-wheel events EVENT_MOUSEWHEEL and EVENT_MOUSEHWHEEL.
+
+.. ocv:function:: int getMouseWheelDelta(int flags)
+
+    :param flags: The mouse callback flags parameter.
+
+For regular mice with a scroll-wheel, delta will be a multiple of 120. The value 120 corresponds to a one notch rotation of the wheel or the threshold for action to be taken and one such action should occur for each delta.
+Some high-precision mice with higher-resolution freely-rotating wheels may generate smaller values.
+
+For EVENT_MOUSEWHEEL positive and negative values mean forward and backward scrolling, respectively.
+For EVENT_MOUSEHWHEEL, where available, positive and negative values mean right and left scrolling, respectively.
+
+With the C API, the macro CV_GET_WHEEL_DELTA(flags) can be used alternatively.
+
+.. note::
+
+    Mouse-wheel events are currently supported only on Windows.
+
 setTrackbarPos
 ------------------
 Sets the trackbar position.

modules/highgui/include/opencv2/highgui.hpp

@@ -76,7 +76,9 @@ enum { EVENT_MOUSEMOVE      = 0,
        EVENT_MBUTTONUP      = 6,
        EVENT_LBUTTONDBLCLK  = 7,
        EVENT_RBUTTONDBLCLK  = 8,
-       EVENT_MBUTTONDBLCLK  = 9
+       EVENT_MBUTTONDBLCLK  = 9,
+       EVENT_MOUSEWHEEL     = 10,
+       EVENT_MOUSEHWHEEL    = 11
      };
 
 enum { EVENT_FLAG_LBUTTON   = 1,
@@ -137,6 +139,8 @@ CV_EXPORTS_W double getWindowProperty(const String& winname, int prop_id);
 //! assigns callback for mouse events
 CV_EXPORTS void setMouseCallback(const String& winname, MouseCallback onMouse, void* userdata = 0);
 
+CV_EXPORTS int getMouseWheelDelta(int flags);
+
 CV_EXPORTS int createTrackbar(const String& trackbarname, const String& winname,
                               int* value, int count,
                               TrackbarCallback onChange = 0,

modules/highgui/include/opencv2/highgui/highgui_c.h

@@ -170,7 +170,9 @@ enum
     CV_EVENT_MBUTTONUP      =6,
     CV_EVENT_LBUTTONDBLCLK  =7,
     CV_EVENT_RBUTTONDBLCLK  =8,
-    CV_EVENT_MBUTTONDBLCLK  =9
+    CV_EVENT_MBUTTONDBLCLK  =9,
+    CV_EVENT_MOUSEWHEEL     =10,
+    CV_EVENT_MOUSEHWHEEL    =11
 };
 
 enum
@@ -183,6 +185,9 @@ enum
     CV_EVENT_FLAG_ALTKEY    =32
 };
 
+
+#define CV_GET_WHEEL_DELTA(flags) ((short)((flags >> 16) & 0xffff)) // upper 16 bits
+
 typedef void (CV_CDECL *CvMouseCallback )(int event, int x, int y, int flags, void* param);
 
 /* assign callback for mouse events */

modules/highgui/src/window.cpp

@@ -216,6 +216,11 @@ void cv::setMouseCallback( const String& windowName, MouseCallback onMouse, void
     cvSetMouseCallback(windowName.c_str(), onMouse, param);
 }
 
+int cv::getMouseWheelDelta( int flags )
+{
+    return CV_GET_WHEEL_DELTA(flags);
+}
+
 int cv::startWindowThread()
 {
     return cvStartWindowThread();

modules/highgui/src/window_w32.cpp

@@ -40,6 +40,7 @@
 //M*/
 
 #include "precomp.hpp"
+#include <windowsx.h> // required for GET_X_LPARAM() and GET_Y_LPARAM() macros
 
 #if defined WIN32 || defined _WIN32
 
@@ -1377,6 +1378,39 @@ MainWindowProc( HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam )
             SetFocus(window->hwnd);
         break;
 
+    case WM_MOUSEWHEEL:
+    case WM_MOUSEHWHEEL:
+       if( window->on_mouse )
+       {
+          int flags = (wParam & MK_LBUTTON      ? CV_EVENT_FLAG_LBUTTON  : 0)|
+                      (wParam & MK_RBUTTON      ? CV_EVENT_FLAG_RBUTTON  : 0)|
+                      (wParam & MK_MBUTTON      ? CV_EVENT_FLAG_MBUTTON  : 0)|
+                      (wParam & MK_CONTROL      ? CV_EVENT_FLAG_CTRLKEY  : 0)|
+                      (wParam & MK_SHIFT        ? CV_EVENT_FLAG_SHIFTKEY : 0)|
+                      (GetKeyState(VK_MENU) < 0 ? CV_EVENT_FLAG_ALTKEY   : 0);
+          int event = (uMsg == WM_MOUSEWHEEL    ? CV_EVENT_MOUSEWHEEL    : CV_EVENT_MOUSEHWHEEL);
+
+          // Set the wheel delta of mouse wheel to be in the upper word of 'event'
+          int delta = GET_WHEEL_DELTA_WPARAM(wParam);
+          flags |= (delta << 16);
+
+          POINT pt;
+          pt.x = GET_X_LPARAM( lParam );
+          pt.y = GET_Y_LPARAM( lParam );
+          ::ScreenToClient(hwnd, &pt); // Convert screen coordinates to client coordinates.
+
+          RECT rect;
+          GetClientRect( window->hwnd, &rect );
+
+          SIZE size = {0,0};
+          icvGetBitmapData( window, &size, 0, 0 );
+
+          window->on_mouse( event, pt.x*size.cx/MAX(rect.right - rect.left,1),
+                                   pt.y*size.cy/MAX(rect.bottom - rect.top,1), flags,
+                                   window->on_mouse_param );
+       }
+       break;
+
     case WM_ERASEBKGND:
         {
             RECT cr, tr, wrc;
@@ -1474,8 +1508,8 @@ static LRESULT CALLBACK HighGUIProc( HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM
             if( uMsg == WM_LBUTTONUP || uMsg == WM_RBUTTONUP || uMsg == WM_MBUTTONUP )
                 ReleaseCapture();
 
-            pt.x = LOWORD( lParam );
-            pt.y = HIWORD( lParam );
+            pt.x = GET_X_LPARAM( lParam );
+            pt.y = GET_Y_LPARAM( lParam );
 
             GetClientRect( window->hwnd, &rect );
             icvGetBitmapData( window, &size, 0, 0 );