学习OpenCV第四章第四题答案

// learningOpenCV_4_4.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include<highgui.h>
#include<cv.h>

CvCapture* g_capture=NULL;
int g_frame_count=0;
int g_slider_pos=0;
int g_slider_pos1=0;
bool t=true;
void on_TrackbarSlider(int pos)
{
	cvSetCaptureProperty(g_capture,CV_CAP_PROP_POS_FRAMES,pos);
	g_frame_count=pos;
}
void switch_callback(int position)
{
	if(position==0)
		t=false;
	else 
		t=true;
}


int _tmain(int argc, _TCHAR* argv[])
{
	cvNamedWindow("show");
	g_capture=cvCreateFileCapture("E:\数字信号处理\1离散时间信号与系统.flv");
	int frames=0;
    frames=(int)cvGetCaptureProperty(g_capture,CV_CAP_PROP_FRAME_COUNT);
	if(frames!=0)
	{
		cvCreateTrackbar("trackbar","show",&g_slider_pos,frames,on_TrackbarSlider);
		cvCreateTrackbar("trackbar1","show",&g_slider_pos1,1,switch_callback);
	}
	cvSetTrackbarPos("trackbar","show",1);
	cvSetTrackbarPos("trackbar1","show",1);
	IplImage* frame;
	while(1)
	{
		frame=cvQueryFrame(g_capture);
		if(frame==0)
			break;
		char c=cvWaitKey(33);
		if(c==27)
			break;
		
		if(t)
		{
			cvShowImage("show",frame);
			cvSetTrackbarPos("trackbar","show",g_frame_count);
			g_frame_count++;
		}
		else
		{
			cvSetCaptureProperty(g_capture,CV_CAP_PROP_POS_FRAMES,g_frame_count);
		}
		
	}

	cvReleaseCapture(&g_capture);
	cvDestroyAllWindows();

	return 0;
}// learningOpenCV_4_4.cpp : 定义控制台应用程序的入口点。
//