Prevent a crash from happening, apply defensive coding against races with camera start

2 files changed, 29 insertions, 28 deletions

diff --git a/ftnoir_tracker_pt/video_widget.cpp b/ftnoir_tracker_pt/video_widget.cpp
index c297c455..1b8b4a7a 100644
--- a/ftnoir_tracker_pt/video_widget.cpp
+++ b/ftnoir_tracker_pt/video_widget.cpp
@@ -39,33 +39,34 @@ void VideoWidget::resizeGL(int w, int h)
 

 void VideoWidget::paintGL()

 {

-    QMutexLocker lck(&mtx);

+    QMutexLocker((QMutex*)&mtx);

     if (resized_qframe.size() == size() || (resized_qframe.width() <= width() && resized_qframe.height() <= height())) {

         glDrawPixels(resized_qframe.width(), resized_qframe.height(), GL_RGB, GL_UNSIGNED_BYTE, resized_qframe.bits());

-		

-		const int crosshair_radius = 10;

-		const int crosshair_thickness = 1;

-

-		glColor3f(1.0, 0.0, 0.0);

-		glLineWidth(crosshair_thickness);

-		int x,y;

-		for (vector<Vec2f>::iterator iter = points->begin();

-			 iter != points->end();

-			 ++iter)

-		{

-			x = (*iter)[0] * resized_qframe.width() + resized_qframe.width()/2.0  + 0.5;

-			y = (*iter)[1] * resized_qframe.width() + resized_qframe.height()/2.0 + 0.5;

-			

-			glBegin(GL_LINES);

-			glVertex2i(x-crosshair_radius, y);

-			glVertex2i(x+crosshair_radius, y);

-			glEnd();

-			glBegin(GL_LINES);

-			glVertex2i(x, y-crosshair_radius);

-			glVertex2i(x, y+crosshair_radius);

-			glEnd();

-		}

-

+        if (points.get() != NULL)

+        {

+            const int crosshair_radius = 10;

+            const int crosshair_thickness = 1;

+            

+            glColor3f(1.0, 0.0, 0.0);

+            glLineWidth(crosshair_thickness);

+            int x,y;

+            for (vector<Vec2f>::iterator iter = points->begin();

+                 iter != points->end();

+                 ++iter)

+            {

+                x = (*iter)[0] * resized_qframe.width() + resized_qframe.width()/2.0  + 0.5;

+                y = (*iter)[1] * resized_qframe.width() + resized_qframe.height()/2.0 + 0.5;

+                

+                glBegin(GL_LINES);

+                glVertex2i(x-crosshair_radius, y);

+                glVertex2i(x+crosshair_radius, y);

+                glEnd();

+                glBegin(GL_LINES);

+                glVertex2i(x, y-crosshair_radius);

+                glVertex2i(x, y+crosshair_radius);

+                glEnd();

+            }

+        }

     } else {

         glClear(GL_DEPTH_BUFFER_BIT);

     }

@@ -75,7 +76,6 @@ void VideoWidget::paintGL()
 

 void VideoWidget::resize_frame()

 {

-    QMutexLocker lck(&mtx);

 #ifdef _WIN32

     if (qframe.size() == size() || (qframe.width() <= width() && qframe.height() <= height()))

         resized_qframe = qframe.mirrored();

@@ -96,6 +96,7 @@ void VideoWidget::update()
 

 void VideoWidget::update_image(Mat frame, std::auto_ptr< vector<Vec2f> > points)

 {

+    QMutexLocker((QMutex*)&mtx);

 	this->frame = frame;

 	this->points = points;

 

diff --git a/ftnoir_tracker_pt/video_widget.h b/ftnoir_tracker_pt/video_widget.h
index 2425603b..bb567478 100644
--- a/ftnoir_tracker_pt/video_widget.h
+++ b/ftnoir_tracker_pt/video_widget.h
@@ -22,7 +22,7 @@ class VideoWidget : public QGLWidget
 	Q_OBJECT

 

 public:

-    VideoWidget(QWidget *parent) : QGLWidget(parent) {

+    VideoWidget(QWidget *parent) : QGLWidget(parent), mtx() {

 #if !defined(_WIN32)

         setAttribute(Qt::WA_NativeWindow, true);

 #endif

@@ -41,9 +41,9 @@ private:
 	cv::Mat frame;

 	QImage qframe;

 	QImage resized_qframe;

+    QMutex mtx;

 

     std::auto_ptr< std::vector<cv::Vec2f> > points;

-    QMutex mtx;

 };

 

 #endif // VIDEOWIDGET_H