JavaScript Canvas Mousemove

JavaScript Canvas Mousemove is a technique used to track the movement of a mouse over a canvas element using JavaScript. This technique is useful in creating interactive and dynamic web applications.

Basic Syntax

To track the movement of the mouse over the canvas element, we need to add an event listener for "mousemove" event. Here's the basic syntax for adding an event listener for "mousemove" event:

canvas.addEventListener("mousemove", function(event){
    // code to track mouse movement
});

Getting the Mouse Coordinates

To get the position of the mouse on the canvas, we can use the "offsetX" and "offsetY" properties of the "event" object passed to the event listener. Here's how we can get the position of the mouse on the canvas:

canvas.addEventListener("mousemove", function(event){
    var mouseX = event.offsetX;
    var mouseY = event.offsetY;
    // code to use mouseX and mouseY coordinates
});

Updating Canvas on Mousemove

We can use the "mousemove" event listener to update the canvas in real-time based on the position of the mouse on the canvas. Here's a basic example of how we can update the canvas on mousemove:

canvas.addEventListener("mousemove", function(event){
    var mouseX = event.offsetX;
    var mouseY = event.offsetY;

    // update canvas based on mouseX and mouseY coordinates
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    ctx.beginPath();
    ctx.arc(mouseX, mouseY, 10, 0, 2*Math.PI);
    ctx.fillStyle = "red";
    ctx.fill();
});

In this example, we are updating the canvas with a red circle that follows the movement of the mouse over the canvas.

Conclusion

JavaScript Canvas Mousemove is a useful technique for creating interactive and dynamic web applications. By tracking the movement of the mouse over a canvas element, we can create a variety of interactive effects and animations.