Added image_window::get_next_keypress()

dlib/gui_widgets/widgets.cpp

@@ -6480,6 +6480,51 @@ namespace dlib
         return base_window::CLOSE_WINDOW;
     }
 
+// ----------------------------------------------------------------------------------------
+
+    bool image_window::
+    get_next_keypress (
+        unsigned long& key,
+        bool& is_printable,
+        unsigned long& state
+    ) 
+    {
+        auto_mutex lock(wm);
+        while (have_last_keypress == false && !window_has_closed)
+        {
+            clicked_signaler.wait();
+        }
+
+        if (window_has_closed)
+            return false;
+
+        // Mark that we are taking the key click so the next call to get_next_keypress()
+        // will have to wait for another click.
+        have_last_keypress = false;
+        key = next_key;
+        is_printable = next_is_printable;
+        state = next_state;
+        return true;
+    }
+
+// ----------------------------------------------------------------------------------------
+
+    void image_window::
+    on_keydown (
+        unsigned long key,
+        bool is_printable,
+        unsigned long state
+    )
+    {
+        dlib::base_window::on_keydown(key,is_printable,state);
+
+        have_last_keypress = true;
+        next_key = key;
+        next_is_printable = is_printable;
+        next_state = state;
+        clicked_signaler.signal();
+    }
+
 // ----------------------------------------------------------------------------------------
 
     bool image_window::
@@ -6497,8 +6542,8 @@ namespace dlib
         if (window_has_closed)
             return false;
 
-        // Mark that we are taking the point click so the next call to get_next_click()
-        // will have to wait for another click.
+        // Mark that we are taking the point click so the next call to
+        // get_next_double_click() will have to wait for another click.
         have_last_click = false;
         mouse_button = mouse_btn;
         p = last_clicked_point;

dlib/gui_widgets/widgets.h

@@ -3564,7 +3564,8 @@ namespace dlib
             window_has_closed(false),
             have_last_click(false),
             mouse_btn(0),
-            clicked_signaler(this->wm) 
+            clicked_signaler(this->wm),
+            have_last_keypress(false)
         {  
             gui_img.set_image_clicked_handler(*this, &image_window::on_image_clicked);
             set_image(img); 
@@ -3580,7 +3581,8 @@ namespace dlib
             window_has_closed(false),
             have_last_click(false),
             mouse_btn(0),
-            clicked_signaler(this->wm) 
+            clicked_signaler(this->wm),
+            have_last_keypress(false)
         {  
             gui_img.set_image_clicked_handler(*this, &image_window::on_image_clicked);
             set_image(img); 
@@ -3758,6 +3760,21 @@ namespace dlib
             return get_next_double_click(p, mouse_button);
         }
 
+        bool get_next_keypress (
+            unsigned long& key,
+            bool& is_printable,
+            unsigned long& state
+        );
+
+        bool get_next_keypress (
+            unsigned long& key,
+            bool& is_printable
+        )
+        {
+            unsigned long state;
+            return get_next_keypress(key,is_printable,state);
+        }
+
     private:
 
         virtual base_window::on_close_return_code on_window_close(
@@ -3772,6 +3789,12 @@ namespace dlib
             unsigned long btn
         );
 
+        virtual void on_keydown (
+            unsigned long key,
+            bool is_printable,
+            unsigned long state
+        );
+
         // restricted functions
         image_window(image_window&);
         image_window& operator= (image_window&);
@@ -3784,6 +3807,11 @@ namespace dlib
         point last_clicked_point;
         unsigned long mouse_btn;
         rsignaler clicked_signaler;
+
+        bool have_last_keypress;
+        unsigned long next_key;
+        bool next_is_printable;
+        unsigned long next_state;
     };
 
 // ----------------------------------------------------------------------------------------

dlib/gui_widgets/widgets_abstract.h

@@ -3045,6 +3045,35 @@ namespace dlib
                       dlib::base_window::MIDDLE, or dlib::base_window::RIGHT
         !*/
 
+        bool get_next_keypress (
+            unsigned long& key,
+            bool& is_printable,
+            unsigned long& state
+        );
+        /*!
+            ensures
+                - This function blocks until the user presses a keyboard key or the
+                  window is closed by the user.
+                - if (this function returns true) then
+                    - The keyboard button press is recorded into #key, #is_printable, and
+                      #state.  In particular, these variables are populated with the three
+                      identically named arguments to the base_window::on_keydown(key,is_printable,state) 
+                      event.
+        !*/
+
+
+        bool get_next_keypress (
+            unsigned long& key,
+            bool& is_printable
+        );
+        /*!
+            ensures
+                - This function blocks until the user presses a keyboard key or the
+                  window is closed by the user.
+                - This function is the equivalent to calling get_next_keypress(key,is_printable,temp) 
+                  and then discarding temp.
+        !*/
+
     private:
 
         // restricted functions