fine work on examples

modules/viz2d/samples/cpp/font_rendering.cpp

@@ -21,7 +21,7 @@ int main(int argc, char** argv) {
 		fontFace("sans-bold");
 		fillColor(Scalar(255, 0, 0, 255));
 		textAlign(NVG_ALIGN_CENTER | NVG_ALIGN_TOP);
-		text(WIDTH / 2.0, HEIGHT / 2.0, hw.c_str(), hw.c_str() + hw.size());
+		text(sz.width / 2.0, sz.height / 2.0, hw.c_str(), hw.c_str() + hw.size());
 	});
 
     //Display the framebuffer in the native window in an endless loop

modules/viz2d/samples/cpp/font_with_gui.cpp

@@ -36,7 +36,7 @@ int main(int argc, char** argv) {
 			fontFace("sans-bold");
 			fillColor(Scalar(textColor.b() * 255, textColor.g() * 255, textColor.r() * 255, 255));
 			textAlign(NVG_ALIGN_CENTER | NVG_ALIGN_TOP);
-			text(WIDTH / 2.0, HEIGHT / 2.0, hw.c_str(), hw.c_str() + hw.size());
+			text(sz.width / 2.0, sz.height / 2.0, hw.c_str(), hw.c_str() + hw.size());
 		});
 		return v2d->display();
 	});

modules/viz2d/samples/cpp/vector_graphics.cpp

@@ -16,10 +16,10 @@ int main(int argc, char** argv) {
 		beginPath();
 		strokeWidth(3.0);
 		strokeColor(Scalar(0,0,255,255)); //BGRA
-		moveTo(WIDTH/2.0, 0);
-		lineTo(WIDTH/2.0, HEIGHT);
-		moveTo(0, HEIGHT/2.0);
-		lineTo(WIDTH, HEIGHT/2.0);
+		moveTo(sz.width/2.0, 0);
+		lineTo(sz.width/2.0, sz.height);
+		moveTo(0, sz.height/2.0);
+		lineTo(sz.width, sz.height/2.0);
 		stroke();
 	});
 

modules/viz2d/samples/cpp/vector_graphics_and_fb.cpp

@@ -16,10 +16,10 @@ int main(int argc, char** argv) {
 		beginPath();
 		strokeWidth(3.0);
 		strokeColor(Scalar(0,0,255,255)); //BGRA
-		moveTo(WIDTH/2.0, 0);
-		lineTo(WIDTH/2.0, HEIGHT);
-		moveTo(0, HEIGHT/2.0);
-		lineTo(WIDTH, HEIGHT/2.0);
+        moveTo(sz.width/2.0, 0);
+        lineTo(sz.width/2.0, sz.height);
+        moveTo(0, sz.height/2.0);
+        lineTo(sz.width, sz.height/2.0);
 		stroke();
 	});
 

modules/viz2d/samples/cpp/video_editing.cpp

@@ -21,7 +21,8 @@ int main(int argc, char** argv) {
 
 	v2d->run([=]() {
 		if(!v2d->capture())
-			return false;
+			return false; //end of input video
+
 		v2d->nvg([=](const Size& sz) {
 			using namespace cv::viz::nvg;
 
@@ -29,10 +30,10 @@ int main(int argc, char** argv) {
 			fontFace("sans-bold");
 			fillColor(Scalar(255, 0, 0, 255));
 			textAlign(NVG_ALIGN_CENTER | NVG_ALIGN_TOP);
-			text(WIDTH / 2.0, HEIGHT / 2.0, hv.c_str(), hv.c_str() + hv.size());
+			text(sz.width / 2.0, sz.height / 2.0, hv.c_str(), hv.c_str() + hv.size());
 		});
-		v2d->write();
-		return v2d->display();
+		v2d->write(); //write the output video
+		return v2d->display(); //display the framebuffer in the native window
 	});
 }