From 1db47a7b305624eda9af6375a09550c474d5d74b Mon Sep 17 00:00:00 2001
From: Stanislaw Halik <sthalik@misaki.pl>
Date: Wed, 24 Apr 2013 17:58:25 +0200
Subject: Prevent a crash from happening, apply defensive coding against races
 with camera start

---
 ftnoir_tracker_pt/video_widget.cpp | 53 +++++++++++++++++++-------------------
 ftnoir_tracker_pt/video_widget.h   |  4 +--
 2 files changed, 29 insertions(+), 28 deletions(-)

(limited to 'ftnoir_tracker_pt')

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
-- 
cgit v1.2.3