printf

cvui::printf() renders a piece of text that can be formatted using C printf() style. The signature of the function is:

void printf(cv::Mat& theWhere, int theX, int theY, const char *theFmt, ...);

where theWhere is the image/frame where the image will be rendered, theX is the position X, theY is the position Y, theFmt is the formating string as it would be supplied for stdio's printf(), e.g. "Text: %d and %f", 7, 3.1415.

cvui::printf() is used pretty much as C’s printf() function. Below is an example of the component, whose result on the screen is shown in Figure 1.

double value = 3.14;
cvui::printf(frame, 90, 50, "value = %.2f", value);

Figure 1: printf component.

Text size and color

It is possible to customize the size and color of the text produced by cvui::printf(). The following function signature can be used in that case:

void printf (
    cv::Mat& theWhere,
    int theX,
    int theY,
    double theFontScale,
    unsigned int theColor,
    const char *theFmt,
    ...
);

where theWhere is the image/frame where the image will be rendered, theX is the position X, theY is the position Y, theFontScale is the size of the text, theColor is the color of the text in the format 0xRRGGBB, e.g. 0xff0000 for red, and theFmt is the formating string as it would be supplied for stdio's printf(), e.g. "Text: %d and %f", 7, 3.1415.

Below is an example of a text with customized size and color. Result on the screen is shown in Figure 2.

double value = 3.14;
cvui::printf(frame, 90, 50, 0.8, 0x00ff00, "value = %.2f", value);

Figure 2: text with customized size and color.

Learn more

Check the main-app example for more information about cvui::printf().