《学习OpenCV》第二章 课后题5

题目叙述：给程序加入滚动条，使得用户可以动态调节缩放比例，缩放比例的取值为2~8之间。可以跳过写入磁盘操作，但是必须将变换结果显示在窗口中。

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

int pos = 2 ;

// Convert a video to grayscale
// argv[1]: input video file
// argv[2]: name of new output file
//

//#define NOWRITE 1;   //Turn this on (removed the first comment out "//" if you can't write on linux

void ON_Change(int n)
{
//printf("d%",n);
pos = n;
}

void main(  ) {
cvNamedWindow( "Example2_10", CV_WINDOW_AUTOSIZE );
cvNamedWindow( "Log_Polar", CV_WINDOW_AUTOSIZE );
CvCapture* capture = cvCreateFileCapture("G:/数据/OpenCV数据/song.mp4" );
//if (!capture){
//    return -1;
//}
cvCreateTrackbar("scale","Example2_10",&pos,8,ON_Change);//创建滚动条
IplImage* bgr_frame;
double fps = cvGetCaptureProperty (
capture,
CV_CAP_PROP_FPS
);
printf("fps=%d\n",(int)fps);

CvSize size = cvSize(
(int)cvGetCaptureProperty( capture, CV_CAP_PROP_FRAME_WIDTH),
(int)cvGetCaptureProperty( capture, CV_CAP_PROP_FRAME_HEIGHT)
);

printf("frame (w, h) = (%d, %d)\n",size.width,size.height);
#ifndef NOWRITE
CvVideoWriter* writer = cvCreateVideoWriter(
"G:/数据/OpenCV数据/wind-img2.avi",
CV_FOURCC('M','J','P','G'),
fps,
size
);
#endif
IplImage* logpolar_frame = cvCreateImage(
size,
IPL_DEPTH_8U,
3
);

IplImage* gray_frame = cvCreateImage(
size,
IPL_DEPTH_8U,
1
);

while( (bgr_frame=cvQueryFrame(capture)) != NULL ) {
cvShowImage( "Example2_10", bgr_frame );
//We never make use of this gray image
cvConvertImage(
bgr_frame,
gray_frame,
CV_RGB2GRAY
);
//This is just a fun conversion the mimic's the human visual system
cvLogPolar( bgr_frame, logpolar_frame,
cvPoint2D32f(bgr_frame->width/2,
bgr_frame->height/2),
40,
CV_INTER_LINEAR+CV_WARP_FILL_OUTLIERS );
IplImage* img2 = cvCreateImage( cvSize( logpolar_frame->width/(pos+1),logpolar_frame->height/(pos+1)), logpolar_frame->depth, logpolar_frame->nChannels);
cvResize(logpolar_frame, img2, CV_INTER_LINEAR);
cvShowImage( "Log_Polar", img2 );

//Sigh, on linux, depending on your ffmpeg, this often won't work ...
//#ifndef NOWRITE
//       cvWriteToAVI( writer, img2 );
//#endif
char c = cvWaitKey(10);
if( c == 27 ) break;
}
#ifndef NOWRITE
cvReleaseVideoWriter( &writer );
#endif
cvReleaseImage( &gray_frame );
cvReleaseImage( &logpolar_frame );
cvReleaseCapture( &capture );
}

注：不要将滚动条放在缩放的窗口中，因为效果不好，喜欢的可以试试看！