Drawing Shapes on an Image with a Mouse

In Photoshop, we crop an image by drawing a shape on it. We can’t always rely on drawing shapes automatically using code. We may want to work on the image manually to add the personal touch. In those cases, we can use our mouse to draw shapes. OpenCV provides us the feature to detect various mouse operations, such as left-click and right-click.

We start by declaring variables and reading the image. Then we need to create the ttemp image that we’ll use later for clearing the image after drawing shapes on it.

Create a temp image

To create a temp image, we need to use the clone() function. We use the namedWindow() function to create a window. We need to provide only one parameter to this function. It’s the name that we want to give to that window.

cv::Mat temp = image.clone();
cv::namedWindow("Window");

Function to draw rectangle

First, we need to detect touch on a mouse. We use the setMouseCallback() function, to ...