目标
- Use the Random Number generator class (cv::RNG ) and how to get a random number from a uniform distribution.
- Display text on an OpenCV window by using the function cv::putText
代码
int cv::waitKey ( int delay = 0 )： 返回按键值或者-1（时间走完仍没有按键）
if (waitKey(DELAY) >= 0)
{
return -1;
}
这样根据返回值，随时可以结束。
RNG rng( 0xFFFFFFFF )：RNG implements a random number generator. In this example, rng is a RNG element initialized with the value 0xFFFFFFFF
{
int lineType = 8;
for ( int i = 1; i < NUMBER; i++ )
{
Point org;
org.x = rng.uniform(x_1, x_2);
org.y = rng.uniform(y_1, y_2);
putText( image, "Testing text rendering", org, rng.uniform(0,8),
rng.uniform(0,100)*0.05+0.1, randomColor(rng), rng.uniform(1, 10), lineType);
imshow( window_name, image );
if( waitKey(DELAY) >= 0 )
{ return -1; }
}
return 0;
}
一个window可以持续写入多个imshow，仍是同一个Mat。
int Displaying_Big_End( Mat image, char* window_name, RNG rng )
{
Size textsize = getTextSize("OpenCV forever!", FONT_HERSHEY_COMPLEX, 3, 5, 0);
Point org((window_width - textsize.width)/2, (window_height - textsize.height)/2);
int lineType = 8;
Mat image2;
for( int i = 0; i < 255; i += 2 )
{
image2 = image - Scalar::all(i);
putText( image2, "OpenCV forever!", org, FONT_HERSHEY_COMPLEX, 3,
Scalar(i, i, 255), 5, lineType );
imshow( window_name, image2 );
if( waitKey(DELAY) >= 0 )
{ return -1; }
}
return 0;
}
Mat变了。
