HTML5 Canvas moving object to mouse click position

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Basically I want to move an object from point A ( 10x,10y ) to a position on the canvas where the mouse has been clicked ( 255x,34y ).

I\'m currently using a method

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2020-12-10 19:59

When you “move” an object, what you really need to do is erase the object and redraw it

First code a function that will redraw the rect at a specified x,y

function draw(x,y){
    ctx.clearRect(0,0,canvas.width,canvas.height);
    ctx.beginPath();
    ctx.fillStyle="skyblue";
    ctx.strokeStyle="gray";
    ctx.rect(x,y,30,20);
    ctx.fill();
    ctx.stroke();
}

Then handle mousedown events and call the draw function

This example uses jquery for cross-browser compatibility, but you can always recode using native javascript.

// listen for all mousedown events on the canvas
$("#canvas").mousedown(function(e){handleMouseDown(e);});


// handle the mousedown event
function handleMouseDown(e){
  mouseX=parseInt(e.clientX-offsetX);
  mouseY=parseInt(e.clientY-offsetY);
  $("#downlog").html("Down: "+ mouseX + " / " + mouseY);

  // Put your mousedown stuff here
  draw(mouseX,mouseY);
}

Here is code and a Fiddle: http://jsfiddle.net/m1erickson/GHSG4/

<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>

<style>
    body{ background-color: ivory; }
    canvas{border:1px solid red;}
</style>

<script>
$(function(){

    var canvas=document.getElementById("canvas");
    var ctx=canvas.getContext("2d");

    var canvasOffset=$("#canvas").offset();
    var offsetX=canvasOffset.left;
    var offsetY=canvasOffset.top;

    function draw(x,y){
        ctx.clearRect(0,0,canvas.width,canvas.height);
        ctx.beginPath();
        ctx.fillStyle="skyblue";
        ctx.strokeStyle="gray";
        ctx.rect(x,y,30,20);
        ctx.fill();
        ctx.stroke();
    }

    function handleMouseDown(e){
      mouseX=parseInt(e.clientX-offsetX);
      mouseY=parseInt(e.clientY-offsetY);
      $("#downlog").html("Down: "+ mouseX + " / " + mouseY);

      // Put your mousedown stuff here
      draw(mouseX,mouseY);

    }

    $("#canvas").mousedown(function(e){handleMouseDown(e);});

    // start the rect at [10,10]
    draw(10,10);


}); // end $(function(){});
</script>

</head>

<body>
    <p>Click to redraw the rect at the mouse position</p>
    <p id="downlog">Down</p>
    <canvas id="canvas" width=300 height=300></canvas>

</body>
</html>

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