// ************************* 程序 8-6 ****************************
/*** 程序功能：
    使用鼠標在圖像上繪制線段

// ***************************************************************/

//
/*

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


IplImage *img0 = 0, *img = 0;
CvPoint prev_pt =
{
    -1, -1
};

void on_mouse ( int event, int x, int y, int flags, void * )
{
    if ( !img )
    {
        return;
    }

    if ( event == CV_EVENT_LBUTTONUP || ( !flags ) )
        // LBUTTONUP表示從放開鼠標左鍵 !flags表示鼠標左鍵未按下
    {
        prev_pt = cvPoint ( -1, -1 );
        printf ( "%d %d %d\n", flags, prev_pt.x, prev_pt.y );
        // 當鼠標沒有按下時取消prev_pt
    }
    else if ( event == CV_EVENT_LBUTTONDOWN )
    {
        prev_pt = cvPoint ( x, y );
        printf ( "%d %d %d\n", flags, prev_pt.x, prev_pt.y );
        // 初始化直線起點
    }
    else if ( event == CV_EVENT_MOUSEMOVE && ( flags & CV_EVENT_FLAG_LBUTTON ) )
        // 按下鼠標左鍵并且移動
    {
        CvPoint pt = cvPoint ( x, y );
        printf ( "%d %d %d\n", flags, pt.x, pt.y );
        // 可以清楚看到CV_EVENT_MOUSEMOVE的運作
        if ( prev_pt.x < 0 )
        {
            prev_pt = pt;
        }

        cvLine ( img, prev_pt, pt, cvScalarAll ( 255 ), 3, 8, 0 );
        // 在鼠標經過的上一個坐標點和當前坐標點之間畫一條白色線段
        prev_pt = pt;
        cvShowImage ( "image", img );
    }
}

int main ()
{
    char *filename = "1.jpg";

    if ( ( img0 = cvLoadImage ( filename, -1 ) ) == 0 )
    {
        return 0;
    }

    printf ( "Hot keys: \n" "\tESC - quit the program\n" "\tr - restore the original image\n" );

    cvNamedWindow ( "image", 1 );

    img = cvCloneImage ( img0 );
    // 存儲原圖img圖像

    cvShowImage ( "image", img );
    cvSetMouseCallback ( "image", on_mouse, 0 );
    // 調用on_mouse

    while ( true )
    {
        int c = cvWaitKey ( 0 );

        if ( ( char ) c == 27 )
        {
            break;
        }

        if ( ( char ) c == 'r' )
        {
            cvCopy ( img0, img );
            cvShowImage ( "image", img );
            // 恢復原圖圖像
        }
    }

    return 0;
}

//*/