fixing waitKey commands to be universal

apps/createsamples/utility.cpp

@@ -1270,7 +1270,7 @@ void cvCreateTrainingSamples( const char* filename,
                 if( showsamples )
                 {
                     cvShowImage( "Sample", &sample );
-                    if( cvWaitKey( 0 ) == 27 )
+                    if( (cvWaitKey( 0 ) & 0xFF) == 27 )
                     {
                         showsamples = 0;
                     }
@@ -1402,7 +1402,7 @@ void cvCreateTestSamples( const char* infoname,
                 if( showsamples )
                 {
                     cvShowImage( "Image", &cvbgreader->src );
-                    if( cvWaitKey( 0 ) == 27 )
+                    if( (cvWaitKey( 0 ) & 0xFF) == 27 )
                     {
                         showsamples = 0;
                     }
@@ -1525,7 +1525,7 @@ int cvCreateTrainingSamplesFromInfo( const char* infoname, const char* vecfilena
             if( showsamples )
             {
                 cvShowImage( "Sample", sample );
-                if( cvWaitKey( 0 ) == 27 )
+                if( (cvWaitKey( 0 ) & 0xFF) == 27 )
                 {
                     showsamples = 0;
                 }
@@ -1672,12 +1672,12 @@ void cvShowVecSamples( const char* filename, int winwidth, int winheight,
                 icvGetTraininDataFromVec( sample, &file );
                 if( scale != 1.0 ) cvResize( sample, scaled_sample, CV_INTER_LINEAR);
                 cvShowImage( "Sample", scaled_sample );
-                if( cvWaitKey( 0 ) == 27 ) break;
+                if( (cvWaitKey( 0 ) & 0xFF) == 27 ) break;
             }
             if( scaled_sample && scaled_sample != sample ) cvReleaseMat( &scaled_sample );
             cvReleaseMat( &sample );
             cvFree( &file.vector );
         }
         fclose( file.input );
     }
-}
+}

apps/interactive-calibration/calibPipeline.cpp

@@ -62,7 +62,7 @@ PipelineExitStatus CalibPipeline::start(std::vector<cv::Ptr<FrameProcessor> > pr
         for (std::vector<cv::Ptr<FrameProcessor> >::iterator it = processors.begin(); it != processors.end(); ++it)
             processedFrame = (*it)->processFrame(processedFrame);
         cv::imshow(mainWindowName, processedFrame);
-        int key = cv::waitKey(CAP_DELAY);
+        char key = cv::waitChar(CAP_DELAY);
 
         if(key == 27) // esc
             return Finished;

doc/tutorials/imgproc/imgtrans/remap/remap.markdown

@@ -85,9 +85,9 @@ Explanation
     while( true )
     {
       /// Each 1 sec. Press ESC to exit the program
-      int c = waitKey( 1000 );
+      char c = waitChar( 1000 );
 
-      if( (char)c == 27 )
+      if( c == 27 )
         { break; }
 
       /// Update map_x & map_y. Then apply remap

doc/tutorials/imgproc/pyramids/pyramids.markdown

@@ -93,6 +93,7 @@ Let's check the general structure of the program:
 
 -   Perform an infinite loop waiting for user input.
     @snippet cpp/tutorial_code/ImgProc/Pyramids.cpp infinite_loop
+
     Our program exits if the user presses *ESC*. Besides, it has two options:
 
     -   **Perform upsampling (after pressing 'u')**

modules/highgui/include/opencv2/highgui.hpp

@@ -109,7 +109,7 @@ It provides easy interface to:
 
             Mat img2,img3;
 
-            while( waitKey(33) != 27 )
+            while( waitChar(33) != 27 )
             {
                 img1.convertTo(img2,-1,1,value);
                 video >> img3;
@@ -338,6 +338,26 @@ If there are several HighGUI windows, any of them can be active.
  */
 CV_EXPORTS_W int waitKey(int delay = 0);
 
+/** @brief Waits for a pressed key and returns the corresponding char value (ASCII) assigned.
+
+The function waitChar waits for a key event infinitely (when \f$\texttt{delay}\leq 0\f$ ) or for delay
+milliseconds, when it is positive. It returns the ASCII code of the pressed key as a char value. If no key was pressed before
+the specified time has elapsed, -1 (most systems) or 255 (if char == unsigned char) is returned depending on the system available.
+
+@note
+
+There is a minor issue for `char == unsigned char systems`. Return value or timeout could be mixed up with value of valid `'\0xFF'` symbol.
+However this is an extremely rare usecase, and is thus ignored for the moment.
+
+@note
+
+The function only works if there is at least one HighGUI window created and the window is active.
+If there are several HighGUI windows, any of them can be active.
+
+@param delay Delay in milliseconds. 0 is the special value that means "forever".
+ */
+CV_EXPORTS_W char waitChar(int delay = 0);
+
 /** @brief Displays an image in the specified window.
 
 The function imshow displays an image in the specified window. If the window was created with the

modules/highgui/src/window.cpp

@@ -198,6 +198,15 @@ int cv::waitKey(int delay)
     return cvWaitKey(delay);
 }
 
+char cv::waitChar(int delay){
+#if CHAR_MIN==SCHAR_MIN
+    int intKey = cv::waitKey(delay) & 0xFF;
+    return (char)(intKey & 0x80 ? intKey - 0x100 : intKey);
+#else
+    return (char)(cv::waitKey(delay) & 0xff);
+#endif
+}
+
 int cv::createTrackbar(const String& trackbarName, const String& winName,
                    int* value, int count, TrackbarCallback callback,
                    void* userdata)

modules/python/src2/cv2.cpp

@@ -542,6 +542,12 @@ bool pyopencv_to(PyObject* obj, double& value, const char* name)
     return !PyErr_Occurred();
 }
 
+template<>
+PyObject* pyopencv_from(const char& value)
+{
+    return PyInt_FromLong(value);
+}
+
 template<>
 PyObject* pyopencv_from(const float& value)
 {

modules/python/test/tst_scene_render.py

@@ -113,7 +113,7 @@ def resetTime(self):
         img = render.getNextFrame()
         cv2.imshow('img', img)
 
-        ch = 0xFF & cv2.waitKey(3)
+        ch = cv2.waitChar(3)
         if  ch == 27:
             break
-    cv2.destroyAllWindows()
+    cv2.destroyAllWindows()

samples/cpp/3calibration.cpp

@@ -351,7 +351,7 @@ int main( int argc, char** argv )
         for( k = 0; k < small_canvas.rows; k += 16 )
             line(small_canvas, Point(0, k), Point(small_canvas.cols, k), Scalar(0,255,0), 1);
         imshow("rectified", small_canvas);
-        int c = waitKey(0);
+        char c = waitChar(0);
         if( c == 27 || c == 'q' || c == 'Q' )
             break;
     }

samples/cpp/autofocus.cpp

@@ -400,7 +400,7 @@ int main(int argc, char ** argv)
         }
 
         imshow(windowOriginal, frame);
-        switch (key = static_cast<char>(waitKey(30)))
+        switch (key = waitChar(30))
         {
             case 'k': // focus out
                 cap.set(CAP_PROP_ZOOM, 100);

samples/cpp/bgfg_segm.cpp

@@ -95,7 +95,7 @@ int main(int argc, const char** argv)
         if(!bgimg.empty())
           imshow("mean background image", bgimg );
 
-        char k = (char)waitKey(30);
+        char k = waitChar(30);
         if( k == 27 ) break;
         if( k == ' ' )
         {

samples/cpp/calibration.cpp

@@ -493,9 +493,9 @@ int main( int argc, char** argv )
         }
 
         imshow("Image View", view);
-        int key = 0xff & waitKey(capture.isOpened() ? 50 : 500);
+        char key = waitChar(capture.isOpened() ? 50 : 500);
 
-        if( (key & 255) == 27 )
+        if( key == 27 )
             break;
 
         if( key == 'u' && mode == CALIBRATED )
@@ -536,8 +536,8 @@ int main( int argc, char** argv )
             //undistort( view, rview, cameraMatrix, distCoeffs, cameraMatrix );
             remap(view, rview, map1, map2, INTER_LINEAR);
             imshow("Image View", rview);
-            int c = 0xff & waitKey();
-            if( (c & 255) == 27 || c == 'q' || c == 'Q' )
+            char c = waitChar();
+            if( c == 27 || c == 'q' || c == 'Q' )
                 break;
         }
     }

samples/cpp/camshiftdemo.cpp

@@ -188,7 +188,7 @@ int main( int argc, const char** argv )
         imshow( "CamShift Demo", image );
         imshow( "Histogram", histimg );
 
-        char c = (char)waitKey(10);
+        char c = waitChar(10);
         if( c == 27 )
             break;
         switch(c)

samples/cpp/cloning_gui.cpp

@@ -453,7 +453,7 @@ int main()
 
     for(;;)
     {
-        char key = (char) waitKey(0);
+        char key = waitChar(0);
 
         if(key == 'd' && flag3 == 0)
         {

samples/cpp/convexhull.cpp

@@ -25,7 +25,6 @@ int main( int argc, char** argv )
 
     for(;;)
     {
-        char key;
         int i, count = (unsigned)rng%100 + 1;
 
         vector<Point> points;
@@ -58,7 +57,7 @@ int main( int argc, char** argv )
 
         imshow("hull", img);
 
-        key = (char)waitKey();
+        char key = waitChar();
         if( key == 27 || key == 'q' || key == 'Q' ) // 'ESC'
             break;
     }

samples/cpp/detect_mser.cpp

@@ -277,8 +277,8 @@ static void DrawOpenGLMSER(Mat img, Mat result)
     for (;;)
         {
         updateWindow("OpenGL");
-        int key = waitKey(40);
-        if ((key & 0xff) == 27)
+        char key = waitChar(40);
+        if (key == 27)
             break;
         if (key == 0x20)
             rotateEnable = !rotateEnable;

samples/cpp/distrans.cpp

@@ -133,7 +133,7 @@ int main( int argc, const char** argv )
         // Call to update the view
         onTrackbar(0, 0);
 
-        int c = waitKey(0) & 255;
+        char c = waitChar(0);
 
         if( c == 27 )
             break;

samples/cpp/facedetect.cpp

@@ -72,9 +72,9 @@ int main( int argc, const char** argv )
     }
     if( inputName.empty() || (isdigit(inputName[0]) && inputName.size() == 1) )
     {
-        int c = inputName.empty() ? 0 : inputName[0] - '0';
-        if(!capture.open(c))
-            cout << "Capture from camera #" <<  c << " didn't work" << endl;
+        int camera = inputName.empty() ? 0 : inputName[0] - '0';
+        if(!capture.open(camera))
+            cout << "Capture from camera #" <<  camera << " didn't work" << endl;
     }
     else if( inputName.size() )
     {
@@ -104,7 +104,7 @@ int main( int argc, const char** argv )
             Mat frame1 = frame.clone();
             detectAndDraw( frame1, cascade, nestedCascade, scale, tryflip );
 
-            int c = waitKey(10);
+            char c = waitChar(10);
             if( c == 27 || c == 'q' || c == 'Q' )
                 break;
         }
@@ -127,7 +127,7 @@ int main( int argc, const char** argv )
                 char buf[1000+1];
                 while( fgets( buf, 1000, f ) )
                 {
-                    int len = (int)strlen(buf), c;
+                    int len = (int)strlen(buf);
                     while( len > 0 && isspace(buf[len-1]) )
                         len--;
                     buf[len] = '\0';
@@ -136,7 +136,7 @@ int main( int argc, const char** argv )
                     if( !image.empty() )
                     {
                         detectAndDraw( image, cascade, nestedCascade, scale, tryflip );
-                        c = waitKey(0);
+                        char c = waitChar(0);
                         if( c == 27 || c == 'q' || c == 'Q' )
                             break;
                     }

samples/cpp/ffilldemo.cpp

@@ -105,13 +105,13 @@ int main( int argc, char** argv )
     {
         imshow("image", isColor ? image : gray);
 
-        int c = waitKey(0);
-        if( (c & 255) == 27 )
+        char c = waitChar(0);
+        if( c == 27 )
         {
             cout << "Exiting ...\n";
             break;
         }
-        switch( (char)c )
+        switch( c )
         {
         case 'c':
             if( isColor )

samples/cpp/grabcut.cpp

@@ -306,8 +306,8 @@ int main( int argc, char** argv )
 
     for(;;)
     {
-        int c = waitKey(0);
-        switch( (char) c )
+        char c = waitChar(0);
+        switch( c )
         {
         case '\x1b':
             cout << "Exiting ..." << endl;

samples/cpp/image_sequence.cpp

@@ -57,7 +57,7 @@ int main(int argc, char** argv)
 
         imshow("Image sequence | press ESC to close", image);
 
-        if(waitKey(500) == 27)
+        if( waitChar(500) == 27)
             break;
     }
 

samples/cpp/inpaint.cpp

@@ -71,7 +71,7 @@ int main( int argc, char** argv )
 
     for(;;)
     {
-        char c = (char)waitKey();
+        char c = waitChar();
 
         if( c == 27 )
             break;

samples/cpp/kalman.cpp

@@ -35,7 +35,7 @@ int main(int, char**)
     Mat state(2, 1, CV_32F); /* (phi, delta_phi) */
     Mat processNoise(2, 1, CV_32F);
     Mat measurement = Mat::zeros(1, 1, CV_32F);
-    char code = (char)-1;
+    char code = 0;
 
     for(;;)
     {
@@ -89,7 +89,7 @@ int main(int, char**)
             state = KF.transitionMatrix*state + processNoise;
 
             imshow( "Kalman", img );
-            code = (char)waitKey(100);
+            code = waitChar(100);
 
             if( code > 0 )
                 break;

samples/cpp/kmeans.cpp

@@ -68,7 +68,7 @@ int main( int /*argc*/, char** /*argv*/ )
 
         imshow("clusters", img);
 
-        char key = (char)waitKey();
+        char key = waitChar();
         if( key == 27 || key == 'q' || key == 'Q' ) // 'ESC'
             break;
     }

samples/cpp/laplace.cpp

@@ -83,10 +83,10 @@ int main( int argc, char** argv )
         convertScaleAbs(laplace, result, (sigma+1)*0.25);
         imshow("Laplacian", result);
 
-        int c = waitKey(30);
+        char c = waitChar(30);
         if( c == ' ' )
             smoothType = smoothType == GAUSSIAN ? BLUR : smoothType == BLUR ? MEDIAN : GAUSSIAN;
-        if( c == 'q' || c == 'Q' || (c & 255) == 27 )
+        if( c == 'q' || c == 'Q' || c == 27 )
             break;
     }
 

samples/cpp/lkdemo.cpp

@@ -131,7 +131,7 @@ int main( int argc, char** argv )
         needToInit = false;
         imshow("LK Demo", image);
 
-        char c = (char)waitKey(10);
+        char c = waitChar(10);
         if( c == 27 )
             break;
         switch( c )

samples/cpp/minarea.cpp

@@ -72,7 +72,7 @@ int main( int /*argc*/, char** /*argv*/ )
 
         imshow( "Rectangle, triangle & circle", img );
 
-        char key = (char)waitKey();
+        char key = waitChar();
         if( key == 27 || key == 'q' || key == 'Q' ) // 'ESC'
             break;
     }