HTML 5 Canvas - Get real coordinate when zooming











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I finally achieved to implement a zoomable and panning canvas using this code as a base https://stackoverflow.com/a/3151987/5221943 .
Now I need to detect the real coordinate where the user clicked inside the canvas. I don't know how to convert the mouse page coordinate to the real world coordinate taking into account the user has already zoomed or panned the canvas. Any suggestion here?






javascript html5 canvas transform zoom







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    up vote
    0
    down vote

    favorite












    I finally achieved to implement a zoomable and panning canvas using this code as a base https://stackoverflow.com/a/3151987/5221943 .
    Now I need to detect the real coordinate where the user clicked inside the canvas. I don't know how to convert the mouse page coordinate to the real world coordinate taking into account the user has already zoomed or panned the canvas. Any suggestion here?






    javascript html5 canvas transform zoom







    share|improve this question
























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      I finally achieved to implement a zoomable and panning canvas using this code as a base https://stackoverflow.com/a/3151987/5221943 .
      Now I need to detect the real coordinate where the user clicked inside the canvas. I don't know how to convert the mouse page coordinate to the real world coordinate taking into account the user has already zoomed or panned the canvas. Any suggestion here?






      javascript html5 canvas transform zoom







      share|improve this question













      I finally achieved to implement a zoomable and panning canvas using this code as a base https://stackoverflow.com/a/3151987/5221943 .
      Now I need to detect the real coordinate where the user clicked inside the canvas. I don't know how to convert the mouse page coordinate to the real world coordinate taking into account the user has already zoomed or panned the canvas. Any suggestion here?






      javascript html5 canvas transform zoom




      javascript html5 canvas transform zoom






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          Here the code for gating the coordinates of the canvas






          Call the DumpInfo function in the html canvas tag like 
          
 <canvas id="canvas" width="600" height="200" onmousedown="DumpInfo(event)"></canvas>
          
Bellow two functions defined 
          
 <script type = "text/javascript" >
          
    function DumpInfo(event) {
          
        var info = document.getElementById("canvas");
          
    //info.innerHTML += event.type + ", ";
          
        var pos = getMousePos(info, event);
          
        alert(pos.x);
          
        alert(pos.y);
          
        }
          
        function getMousePos(canvas, evt) {
          
            var rect = canvas.getBoundingClientRect();
          
            return {
          
                x: evt.clientX - rect.left,
          
                y: evt.clientY - rect.top
          
            };
          
        }
          
    </script>








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            Here the code for gating the coordinates of the canvas






            Call the DumpInfo function in the html canvas tag like 
            
 <canvas id="canvas" width="600" height="200" onmousedown="DumpInfo(event)"></canvas>
            
Bellow two functions defined 
            
 <script type = "text/javascript" >
            
    function DumpInfo(event) {
            
        var info = document.getElementById("canvas");
            
    //info.innerHTML += event.type + ", ";
            
        var pos = getMousePos(info, event);
            
        alert(pos.x);
            
        alert(pos.y);
            
        }
            
        function getMousePos(canvas, evt) {
            
            var rect = canvas.getBoundingClientRect();
            
            return {
            
                x: evt.clientX - rect.left,
            
                y: evt.clientY - rect.top
            
            };
            
        }
            
    </script>








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              up vote
              0
              down vote













              Here the code for gating the coordinates of the canvas






              Call the DumpInfo function in the html canvas tag like 
              
 <canvas id="canvas" width="600" height="200" onmousedown="DumpInfo(event)"></canvas>
              
Bellow two functions defined 
              
 <script type = "text/javascript" >
              
    function DumpInfo(event) {
              
        var info = document.getElementById("canvas");
              
    //info.innerHTML += event.type + ", ";
              
        var pos = getMousePos(info, event);
              
        alert(pos.x);
              
        alert(pos.y);
              
        }
              
        function getMousePos(canvas, evt) {
              
            var rect = canvas.getBoundingClientRect();
              
            return {
              
                x: evt.clientX - rect.left,
              
                y: evt.clientY - rect.top
              
            };
              
        }
              
    </script>








              share|improve this answer























                up vote
                0
                down vote










                up vote
                0
                down vote









                Here the code for gating the coordinates of the canvas






                Call the DumpInfo function in the html canvas tag like 
                
 <canvas id="canvas" width="600" height="200" onmousedown="DumpInfo(event)"></canvas>
                
Bellow two functions defined 
                
 <script type = "text/javascript" >
                
    function DumpInfo(event) {
                
        var info = document.getElementById("canvas");
                
    //info.innerHTML += event.type + ", ";
                
        var pos = getMousePos(info, event);
                
        alert(pos.x);
                
        alert(pos.y);
                
        }
                
        function getMousePos(canvas, evt) {
                
            var rect = canvas.getBoundingClientRect();
                
            return {
                
                x: evt.clientX - rect.left,
                
                y: evt.clientY - rect.top
                
            };
                
        }
                
    </script>








                share|improve this answer












                Here the code for gating the coordinates of the canvas






                Call the DumpInfo function in the html canvas tag like 
                
 <canvas id="canvas" width="600" height="200" onmousedown="DumpInfo(event)"></canvas>
                
Bellow two functions defined 
                
 <script type = "text/javascript" >
                
    function DumpInfo(event) {
                
        var info = document.getElementById("canvas");
                
    //info.innerHTML += event.type + ", ";
                
        var pos = getMousePos(info, event);
                
        alert(pos.x);
                
        alert(pos.y);
                
        }
                
        function getMousePos(canvas, evt) {
                
            var rect = canvas.getBoundingClientRect();
                
            return {
                
                x: evt.clientX - rect.left,
                
                y: evt.clientY - rect.top
                
            };
                
        }
                
    </script>








                Call the DumpInfo function in the html canvas tag like 
                
 <canvas id="canvas" width="600" height="200" onmousedown="DumpInfo(event)"></canvas>
                
Bellow two functions defined 
                
 <script type = "text/javascript" >
                
    function DumpInfo(event) {
                
        var info = document.getElementById("canvas");
                
    //info.innerHTML += event.type + ", ";
                
        var pos = getMousePos(info, event);
                
        alert(pos.x);
                
        alert(pos.y);
                
        }
                
        function getMousePos(canvas, evt) {
                
            var rect = canvas.getBoundingClientRect();
                
            return {
                
                x: evt.clientX - rect.left,
                
                y: evt.clientY - rect.top
                
            };
                
        }
                
    </script>





                Call the DumpInfo function in the html canvas tag like 
                
 <canvas id="canvas" width="600" height="200" onmousedown="DumpInfo(event)"></canvas>
                
Bellow two functions defined 
                
 <script type = "text/javascript" >
                
    function DumpInfo(event) {
                
        var info = document.getElementById("canvas");
                
    //info.innerHTML += event.type + ", ";
                
        var pos = getMousePos(info, event);
                
        alert(pos.x);
                
        alert(pos.y);
                
        }
                
        function getMousePos(canvas, evt) {
                
            var rect = canvas.getBoundingClientRect();
                
            return {
                
                x: evt.clientX - rect.left,
                
                y: evt.clientY - rect.top
                
            };
                
        }
                
    </script>






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