somee refinements to chapter 9

Author: garybradski

example_09-01.cpp

@@ -2,11 +2,22 @@
 // Example 9-1. Creating a window and displaying an image in that window
 //
 #include <opencv2/opencv.hpp>
+#include <iostream>
 
 using namespace std;
 
 
+void help(char** argv ) {
+	cout << "\n"
+		<< "Create a window and display an image\nCall:\n"
+		<< argv[0] <<" image\n"
+		<< endl;
+}
+
 int main(int argc, char** argv) {
+	// Document the interface
+	help(argv);
+	if(argc != 2) { cout << "You need to supply an image path/name" << endl;; exit(0);}
 
   // Create a named window with the name of the file
   //
@@ -22,9 +33,7 @@ int main(int argc, char** argv) {
 
   // Idle until the user hits the Esc key
   //
-  while( true ) {
-    if( cv::waitKey( 100 /* milliseconds */ ) == 27 ) break;
-  }
+  cv::waitKey(); //Any key will end the program
 
   // Clean up and don't be piggies
   //

example_09-02.cpp

@@ -23,12 +23,12 @@ void draw_box( cv::Mat& img, cv::Rect box ) {
     cv::Scalar(0x00,0x00,0xff)    /* red */
   );
 }
-void help() {
-  std::cout << "Call: ./ch4_ex4_1\n" <<
-    " shows how to use a mouse to draw regions in an image." << std::endl;
+void help(char** argv) {
+  std::cout << "Call: " << argv[0] <<
+    " shows how to use a mouse to draw regions in an image. Esc to quit" << std::endl;
 }
 int main( int argc, char** argv ) {
-  help();
+  help(argv);
   box = cv::Rect(-1,-1,0,0);
   cv::Mat image(200, 200, CV_8UC3), temp;
   image.copyTo(temp);

example_09-03.cpp

@@ -26,8 +26,9 @@ void switch_callback( int position, void* ) {
 
 void help(char ** argv) {
     cout << "Call: " << argv[0] << " <my.avi>" << endl;
-    cout << "Shows putting a pause button in a video." << endl;
+    cout << "Shows putting a pause button in a video; Esc to quit" << endl;
 }
+
 int main( int argc, char** argv ) {
   cv::Mat frame; // To hold movie images
   cv::VideoCapture g_capture;