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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
              h1 Paint
p.legend Draw me like one of your french girl in the box below
canvas#paint(width=270)(height=150)
button#clear clear
h2 Painted base64
textarea#data-paint.data
            
          
!
            
              body {  
  font-family: Arial;
}
#paint {
  border: 1px solid #333;
  display: block;
  margin: 20px 0;
}
#clear {
  margin: 8px 0;
  padding: 4px 8px;
  font-size: 1rem;
}
.data {
  width: 266px;
  height: 150px;
  margin: 5px 0;
}
.legend {
  font-style: italic;
  color: grey;
}
            
          
!
            
              /*
* This method returns the relative offset x/y for a mouse cursor position in an element such as canvas
* @param {object} e  - the event object</param>
* @param {string} id - the id of the element in which the mouse is positioned
*/
function getMouseOffset (_e, _el) {  
  let xpos, ypos;
  if (typeof _e.offsetX === 'undefined') { // ff hack
    // dans ce cas, jQuery facilite l'appel d'offset
    xpos = _e.pageX - $(_el).offset().left; 
    ypos = _e.pageY - $(_el).offset().top;
  } else {
    xpos = _e.offsetX;
    ypos = _e.offsetY;
  }
  const pointerPos = { x: xpos, y: ypos };
  console.log(pointerPos);
  return pointerPos;
}

/**
* Extends Canvas element to use it as a paint element
*/
var extendCanvas = function (canvas) {
  if (typeof canvas === 'string') {
    canvas = document.getElementById(canvas);
  }
  try {
    canvas.ctx = canvas.getContext('2d');
    canvas.ctx.strokeStyle = "black";
    canvas.ctx.lineWidth = 2;
    canvas.lineJoin = "round";
    canvas.ctx.scale(1, 1);
    canvas.isLocked = false;
    canvas.hasDrawn = false;

    canvas.disableSave = true;
    canvas.pixels = [];
    canvas.cpixels = [];
    canvas.xyLast = {};
    canvas.xyAddLast = {};
    canvas.calculate = false;

    //start drawing a stroke from a position
    canvas.draw = function (x, y) {
      this.ctx.lineTo(x, y);
      this.ctx.stroke();
    };
    //Get the mouse position in the canvas
    canvas.getCursorCoords = function (e) {
      return getMouseOffset(e, this);
    };
    //Clear the content of the canvas element
    canvas.clear = function () {
      if (!this.isLocked) {
        this.ctx.clearRect(0, 0, this.width, this.height);
        this.emptyRelatedField();
        this.isModified(false);
      }
    };
    //Lock the canvas element
    canvas.lock = function (shouldLock) {
      this.isLocked = shouldLock;
      if (shouldLock) {
        $(this).addClass('disabled');
      } else {
        $(this).removeClass('disabled');
      }
    };
    canvas.isModified = function (wasModified) {
      if (wasModified) {
        this.fillRelatedField();
        $(this).addClass('modified');
      } else {
        this.emptyRelatedField();
        $(this).removeClass('modified');
      }
    };
    //Empty the field that contains the base64 string
    canvas.emptyRelatedField = function () {
      var relatedField = document.getElementById('data-' + this.id);
      if (relatedField) {
        relatedField.value = "";
      }
    };
    //Fill the filed that contains the base64 string
    canvas.fillRelatedField = function () {
      document.getElementById('data-' + this.id).value = this.toDataURL();
    };
    //Load a passed image
    canvas.loadImage = function (base64Img) {
      //if (!canvas.isLocked) {
      var image = new Image();
      var thisCanvas = this;
      if (base64Img.indexOf("data:image/png;base64,") === -1) {
        base64Img = "data:image/png;base64," + base64Img;
      }
      image.src = base64Img;
      image.onload = function () {
        var offset = { x: 0, y: 0 };
        //center the image in the canvas
        try {
          offset.x = ((thisCanvas.width / 2) - (image.width / 2));
          offset.y = ((thisCanvas.height / 2) - (image.height / 2));
          if (offset.x < 0 || offset.y < 0) {
            throw {
              name: "Painting error",
              message: "Image has a negativ offset.", 
              toString: function () { return this.name + ": " + this.message; }
            };
          }
        } catch (err) {
          offset = { x: 0, y: 0 };
        }
        thisCanvas.ctx.drawImage(image, offset.x, offset.y);
      };      
    };

    /**
            * This method remove the event by default, to load them only when clicking in the canvas
            */
    function remove_event_listeners() {
      canvas.removeEventListener('mouseup', on_mouseup, false);
      canvas.removeEventListener('touchend', on_mouseup, false);
      canvas.removeEventListener('pointerup', on_mouseup, false);
      canvas.removeEventListener('mousemove', on_mousemove, false);
      canvas.removeEventListener('pointermove', on_mousemove, false);
      document.body.removeEventListener('mouseup', on_mouseup, false);
      document.body.removeEventListener('touchend', on_mouseup, false);
      document.body.removeEventListener('pointerup', on_mouseup, false);
    };
    //Event when the mouse is clicked
    function on_mousedown(e) {
      console.log('mousedown');
      if (!canvas.isLocked) {
        e.preventDefault();
        e.stopPropagation();

        canvas.hasDrawn = false;
        //we activate the mouse and touch events
        canvas.addEventListener('mouseup', on_mouseup, false);
        canvas.addEventListener('touchend', on_mouseup, false);
        canvas.addEventListener('pointerup', on_mouseup, false);
        canvas.addEventListener('mousemove', on_mousemove, false);
        canvas.addEventListener('pointermove', on_mousemove, false);
        document.body.addEventListener('mouseup', on_mouseup, false);
        document.body.addEventListener('touchend', on_mouseup, false);
        document.body.addEventListener('pointerup', on_mouseup, false);

        var xy = canvas.getCursorCoords(e);
        canvas.ctx.beginPath();
        canvas.pixels.push('moveStart');
        canvas.ctx.moveTo(xy.x, xy.y);
        canvas.pixels.push(xy.x, xy.y);
        canvas.xyLast = xy;
      }
    };
    //Event when the mouse is moving.
    function on_mousemove(e, finish) {
      if (!canvas.isLocked) {
        e.preventDefault();
        e.stopPropagation();

        canvas.hasDrawn = true;
        var xy = canvas.getCursorCoords(e);
        var xyAdd = {
          x: (canvas.xyLast.x + xy.x) / 2,
          y: (canvas.xyLast.y + xy.y) / 2
        };
        if (canvas.calculate) {
          var xLast = (canvas.xyAddLast.x + canvas.xyLast.x + xyAdd.x) / 3;
          var yLast = (canvas.xyAddLast.y + canvas.xyLast.y + xyAdd.y) / 3;
          canvas.pixels.push(xLast, yLast);
        } else {
          canvas.calculate = true;
        }
        canvas.ctx.quadraticCurveTo(canvas.xyLast.x, canvas.xyLast.y, xyAdd.x, xyAdd.y);
        canvas.pixels.push(xyAdd.x, xyAdd.y);
        canvas.ctx.stroke();
        canvas.ctx.beginPath();
        canvas.ctx.moveTo(xyAdd.x, xyAdd.y);
        canvas.xyAddLast = xyAdd;
        canvas.xyLast = xy;
      }
    };
    //Event when the click is released
    function on_mouseup(e) {
      console.log('mouseup');
      if (!canvas.isLocked) {
        if (!canvas.hasDrawn) {//If there was no move, draw a single point            
          var pos = canvas.getCursorCoords(e);
          canvas.ctx.rect(pos.x, pos.y, 1, 1);
        }
        remove_event_listeners();
        canvas.disableSave = false;
        canvas.ctx.stroke();
        canvas.pixels.push('e');
        canvas.calculate = false;
        canvas.isModified(true);
        canvas.hasDrawn = false;
      }
    };
    //We activate only the click or touch event.
    // ReSharper disable once Html.EventNotResolved correspond à un événement de toucher sur écran tactile
    canvas.addEventListener('mousedown', on_mousedown, false);
    canvas.addEventListener('touchstart', on_mousedown, false);
    canvas.addEventListener('pointerdown', on_mousedown, false);

  } catch (err) {
    //If someting went wrong, notify the user.
    console.error("Canvas not initialized. Painting is not activated.");
  }
  
  return canvas;
};


var myC = extendCanvas('paint');
$('#clear').on('click', (e) => {
  myC.clear();
  myC.emptyRelatedField();
});
            
          
!
999px
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