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Dessinez sur une toile HTML5 à l'aide d'une souris

Je veux dessiner sur un canevas HTML à l'aide d'une souris (ex: dessiner une signature, dessiner un nom, ...)

S'il vous plaît, aidez-moi, comment puis-je faire? S'il vous plaît donner un code source. Je vous remercie

html5canvasgesture-recognitiongestures
87
MartinJoo

Voici un exemple de travail.

 <html>
    <script type="text/javascript">
    var canvas, ctx, flag = false,
        prevX = 0,
        currX = 0,
        prevY = 0,
        currY = 0,
        dot_flag = false;

    var x = "black",
        y = 2;
    
    function init() {
        canvas = document.getElementById('can');
        ctx = canvas.getContext("2d");
        w = canvas.width;
        h = canvas.height;
    
        canvas.addEventListener("mousemove", function (e) {
            findxy('move', e)
        }, false);
        canvas.addEventListener("mousedown", function (e) {
            findxy('down', e)
        }, false);
        canvas.addEventListener("mouseup", function (e) {
            findxy('up', e)
        }, false);
        canvas.addEventListener("mouseout", function (e) {
            findxy('out', e)
        }, false);
    }
    
    function color(obj) {
        switch (obj.id) {
            case "green":
                x = "green";
                break;
            case "blue":
                x = "blue";
                break;
            case "red":
                x = "red";
                break;
            case "yellow":
                x = "yellow";
                break;
            case "orange":
                x = "orange";
                break;
            case "black":
                x = "black";
                break;
            case "white":
                x = "white";
                break;
        }
        if (x == "white") y = 14;
        else y = 2;
    
    }
    
    function draw() {
        ctx.beginPath();
        ctx.moveTo(prevX, prevY);
        ctx.lineTo(currX, currY);
        ctx.strokeStyle = x;
        ctx.lineWidth = y;
        ctx.stroke();
        ctx.closePath();
    }
    
    function erase() {
        var m = confirm("Want to clear");
        if (m) {
            ctx.clearRect(0, 0, w, h);
            document.getElementById("canvasimg").style.display = "none";
        }
    }
    
    function save() {
        document.getElementById("canvasimg").style.border = "2px solid";
        var dataURL = canvas.toDataURL();
        document.getElementById("canvasimg").src = dataURL;
        document.getElementById("canvasimg").style.display = "inline";
    }
    
    function findxy(res, e) {
        if (res == 'down') {
            prevX = currX;
            prevY = currY;
            currX = e.clientX - canvas.offsetLeft;
            currY = e.clientY - canvas.offsetTop;
    
            flag = true;
            dot_flag = true;
            if (dot_flag) {
                ctx.beginPath();
                ctx.fillStyle = x;
                ctx.fillRect(currX, currY, 2, 2);
                ctx.closePath();
                dot_flag = false;
            }
        }
        if (res == 'up' || res == "out") {
            flag = false;
        }
        if (res == 'move') {
            if (flag) {
                prevX = currX;
                prevY = currY;
                currX = e.clientX - canvas.offsetLeft;
                currY = e.clientY - canvas.offsetTop;
                draw();
            }
        }
    }
    </script>
    <body onload="init()">
        <canvas id="can" width="400" height="400" style="position:absolute;top:10%;left:10%;border:2px solid;"></canvas>
        <div style="position:absolute;top:12%;left:43%;">Choose Color</div>
        <div style="position:absolute;top:15%;left:45%;width:10px;height:10px;background:green;" id="green" onclick="color(this)"></div>
        <div style="position:absolute;top:15%;left:46%;width:10px;height:10px;background:blue;" id="blue" onclick="color(this)"></div>
        <div style="position:absolute;top:15%;left:47%;width:10px;height:10px;background:red;" id="red" onclick="color(this)"></div>
        <div style="position:absolute;top:17%;left:45%;width:10px;height:10px;background:yellow;" id="yellow" onclick="color(this)"></div>
        <div style="position:absolute;top:17%;left:46%;width:10px;height:10px;background:orange;" id="orange" onclick="color(this)"></div>
        <div style="position:absolute;top:17%;left:47%;width:10px;height:10px;background:black;" id="black" onclick="color(this)"></div>
        <div style="position:absolute;top:20%;left:43%;">Eraser</div>
        <div style="position:absolute;top:22%;left:45%;width:15px;height:15px;background:white;border:2px solid;" id="white" onclick="color(this)"></div>
        <img id="canvasimg" style="position:absolute;top:10%;left:52%;" style="display:none;">
        <input type="button" value="save" id="btn" size="30" onclick="save()" style="position:absolute;top:55%;left:10%;">
        <input type="button" value="clear" id="clr" size="23" onclick="erase()" style="position:absolute;top:55%;left:15%;">
    </body>
    </html>
182
user1083202

Voici le moyen le plus simple de créer une application de dessin avec canvas:

  1. Attachez un écouteur d'événement mousedown, mousemove et mouseup au DOM de la zone de dessin.
  2. sur mousedown, obtenez les coordonnées de la souris et utilisez la méthode moveTo() pour positionner votre curseur de dessin et la méthode beginPath() pour commencer un nouveau chemin de dessin.
  3. sur mousemove, ajoutez en permanence un nouveau point au chemin avec lineTo() et colorez le dernier segment avec stroke().
  4. sur mouseup, définissez un indicateur pour désactiver le dessin.

À partir de là, vous pouvez ajouter toutes sortes d'autres fonctionnalités, telles que donner à l'utilisateur la possibilité de choisir une épaisseur de trait, une couleur, des coups de pinceau et même des calques.

32
Eric Rowell

Googlé ceci ("programme de peinture de toile html5"). On dirait ce dont vous avez besoin.

http://dev.opera.com/articles/view/html5-canvas-painting/

24
Mike Robinson

Je pense que d’autres exemples ici sont trop compliqués. Celui-ci est plus simple et JS seulement ...

// create canvas element and append it to document body
var canvas = document.createElement('canvas');
document.body.appendChild(canvas);

// some hotfixes... ( ≖_≖)
document.body.style.margin = 0;
canvas.style.position = 'fixed';

// get canvas 2D context and set him correct size
var ctx = canvas.getContext('2d');
resize();

// last known position
var pos = { x: 0, y: 0 };

window.addEventListener('resize', resize);
document.addEventListener('mousemove', draw);
document.addEventListener('mousedown', setPosition);
document.addEventListener('mouseenter', setPosition);

// new position from mouse event
function setPosition(e) {
  pos.x = e.clientX;
  pos.y = e.clientY;
}

// resize canvas
function resize() {
  ctx.canvas.width = window.innerWidth;
  ctx.canvas.height = window.innerHeight;
}

function draw(e) {
  // mouse left button must be pressed
  if (e.buttons !== 1) return;

  ctx.beginPath(); // begin

  ctx.lineWidth = 5;
  ctx.lineCap = 'round';
  ctx.strokeStyle = '#c0392b';

  ctx.moveTo(pos.x, pos.y); // from
  setPosition(e);
  ctx.lineTo(pos.x, pos.y); // to

  ctx.stroke(); // draw it!
}
18
Matěj Pokorný

vérifiez ceci http://jsfiddle.net/ArtBIT/kneDX/ . Cela devrait vous diriger dans la bonne direction

16
Shadrack B. Orina

Je cherchais également à utiliser cette méthode pour les signatures. J'ai trouvé un échantillon sur http://codetheory.in/ .

J'ai ajouté le code ci-dessous à un jsfiddle

Html:

<div id="sketch">
    <canvas id="Paint"></canvas>
</div>

Javascript:

 (function() {
    var canvas = document.querySelector('#Paint');
    var ctx = canvas.getContext('2d');

    var sketch = document.querySelector('#sketch');
    var sketch_style = getComputedStyle(sketch);
    canvas.width = parseInt(sketch_style.getPropertyValue('width'));
    canvas.height = parseInt(sketch_style.getPropertyValue('height'));

    var mouse = {x: 0, y: 0};
    var last_mouse = {x: 0, y: 0};

    /* Mouse Capturing Work */
    canvas.addEventListener('mousemove', function(e) {
        last_mouse.x = mouse.x;
        last_mouse.y = mouse.y;

        mouse.x = e.pageX - this.offsetLeft;
        mouse.y = e.pageY - this.offsetTop;
    }, false);


    /* Drawing on Paint App */
    ctx.lineWidth = 5;
    ctx.lineJoin = 'round';
    ctx.lineCap = 'round';
    ctx.strokeStyle = 'blue';

    canvas.addEventListener('mousedown', function(e) {
        canvas.addEventListener('mousemove', onPaint, false);
    }, false);

    canvas.addEventListener('mouseup', function() {
        canvas.removeEventListener('mousemove', onPaint, false);
    }, false);

    var onPaint = function() {
        ctx.beginPath();
        ctx.moveTo(last_mouse.x, last_mouse.y);
        ctx.lineTo(mouse.x, mouse.y);
        ctx.closePath();
        ctx.stroke();
    };

}());
10
Sam Jones

Voici mon travail de travail de dessin très simple et effacer.

https://jsfiddle.net/richardcwc/d2gxjdva/

//Canvas
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
//Variables
var canvasx = $(canvas).offset().left;
var canvasy = $(canvas).offset().top;
var last_mousex = last_mousey = 0;
var mousex = mousey = 0;
var mousedown = false;
var tooltype = 'draw';

//Mousedown
$(canvas).on('mousedown', function(e) {
    last_mousex = mousex = parseInt(e.clientX-canvasx);
        last_mousey = mousey = parseInt(e.clientY-canvasy);
    mousedown = true;
});

//Mouseup
$(canvas).on('mouseup', function(e) {
    mousedown = false;
});

//Mousemove
$(canvas).on('mousemove', function(e) {
    mousex = parseInt(e.clientX-canvasx);
    mousey = parseInt(e.clientY-canvasy);
    if(mousedown) {
        ctx.beginPath();
        if(tooltype=='draw') {
            ctx.globalCompositeOperation = 'source-over';
            ctx.strokeStyle = 'black';
            ctx.lineWidth = 3;
        } else {
            ctx.globalCompositeOperation = 'destination-out';
            ctx.lineWidth = 10;
        }
        ctx.moveTo(last_mousex,last_mousey);
        ctx.lineTo(mousex,mousey);
        ctx.lineJoin = ctx.lineCap = 'round';
        ctx.stroke();
    }
    last_mousex = mousex;
    last_mousey = mousey;
    //Output
    $('#output').html('current: '+mousex+', '+mousey+'<br/>last: '+last_mousex+', '+last_mousey+'<br/>mousedown: '+mousedown);
});

//Use draw|erase
use_tool = function(tool) {
    tooltype = tool; //update
}
canvas {
    cursor: crosshair;
    border: 1px solid #000000;
}
<canvas id="canvas" width="800" height="500"></canvas>
<input type="button" value="draw" onclick="use_tool('draw');" />
<input type="button" value="erase" onclick="use_tool('erase');" />
<div id="output"></div>
5
Richard

Alco vérifie celui-ci:
Exemple:
https://github.com/williammalone/Simple-HTML5-Drawing-App

Documentation:
http://www.williammalone.com/articles/create-html5-canvas-javascript-drawing-app/

Ce document comprend les codes suivants: -

HTML:

<canvas id="canvas" width="490" height="220"></canvas>

JS:

context = document.getElementById('canvas').getContext("2d");

$('#canvas').mousedown(function(e){
  var mouseX = e.pageX - this.offsetLeft;
  var mouseY = e.pageY - this.offsetTop;

  Paint = true;
  addClick(e.pageX - this.offsetLeft, e.pageY - this.offsetTop);
  redraw();
});

$('#canvas').mouseup(function(e){
  Paint = false;
});

$('#canvas').mouseleave(function(e){
  Paint = false;
});

var clickX = new Array();
var clickY = new Array();
var clickDrag = new Array();
var Paint;

function addClick(x, y, dragging)
{
  clickX.Push(x);
  clickY.Push(y);
  clickDrag.Push(dragging);
}

//Also redraw
function redraw(){
  context.clearRect(0, 0, context.canvas.width, context.canvas.height); // Clears the canvas

  context.strokeStyle = "#df4b26";
  context.lineJoin = "round";
  context.lineWidth = 5;

  for(var i=0; i < clickX.length; i++) {        
    context.beginPath();
    if(clickDrag[i] && i){
      context.moveTo(clickX[i-1], clickY[i-1]);
     }else{
       context.moveTo(clickX[i]-1, clickY[i]);
     }
     context.lineTo(clickX[i], clickY[i]);
     context.closePath();
     context.stroke();
  }
}

Et un autre exemple génial
http://perfectionkills.com/exploring-canvas-drawing-techniques/

4
vusan

Je devais donner un exemple simple pour ce sujet, je vais donc le partager ici:

http://jsfiddle.net/Haelle/v6tfp2e1

class SignTool {
  constructor() {
    this.initVars()
    this.initEvents()
  }

  initVars() {
    this.canvas = $('#canvas')[0]
    this.ctx = this.canvas.getContext("2d")
    this.isMouseClicked = false
    this.isMouseInCanvas = false
    this.prevX = 0
    this.currX = 0
    this.prevY = 0
    this.currY = 0
  }

  initEvents() {
    $('#canvas').on("mousemove", (e) => this.onMouseMove(e))
    $('#canvas').on("mousedown", (e) => this.onMouseDown(e))
    $('#canvas').on("mouseup", () => this.onMouseUp())
    $('#canvas').on("mouseout", () => this.onMouseOut())
    $('#canvas').on("mouseenter", (e) => this.onMouseEnter(e))
  }
  
  onMouseDown(e) {
        this.isMouseClicked = true
    this.updateCurrentPosition(e)
  }
  
  onMouseUp() {
        this.isMouseClicked = false
  }
  
  onMouseEnter(e) {
        this.isMouseInCanvas = true
    this.updateCurrentPosition(e)
  }
  
  onMouseOut() {
        this.isMouseInCanvas = false
  }

  onMouseMove(e) {
    if (this.isMouseClicked && this.isMouseInCanvas) {
        this.updateCurrentPosition(e)
      this.draw()
    }
  }
  
  updateCurrentPosition(e) {
      this.prevX = this.currX
      this.prevY = this.currY
      this.currX = e.clientX - this.canvas.offsetLeft
      this.currY = e.clientY - this.canvas.offsetTop
  }
  
  draw() {
    this.ctx.beginPath()
    this.ctx.moveTo(this.prevX, this.prevY)
    this.ctx.lineTo(this.currX, this.currY)
    this.ctx.strokeStyle = "black"
    this.ctx.lineWidth = 2
    this.ctx.stroke()
    this.ctx.closePath()
  }
}

var canvas = new SignTool()
canvas {
  position: absolute;
  border: 2px solid;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<canvas id="canvas" width="500" height="300"></canvas>
4
Haelle

Faites-moi savoir si vous avez du mal à mettre cela en œuvre. Il utilise processing.js et a des fonctionnalités pour changer les couleurs et rendre le point de dessin plus grand et plus petit.

<html>
<head>
<!--script librarires-->
<script type="text/javascript" src="processing.js"></script>
<script type="text/javascript" src="init.js"></script>

<!--styles -->
<style type="text/css" src="stylesheet.css">
</style> 
</head>
<body>
<!--toolbox -->
<div id="draggable toolbox"></div>
<script type="application/processing">
// new script
int prevx, prevy;
int newx, newy;
boolean cliked;
color c1 = #000000;
int largeur=2;
int ps = 20;
int px = 50;
int py = 50;

void setup() {
size(500,500);
frameRate(25);
background(50);

 prevx = mouseX;
 prevy = mouseY;
 cliked = false;
 }

void draw() {
 //couleur
 noStroke(0);
 fill(#FFFFFF);//blanc
rect(px, py, ps, ps);
 fill(#000000);
 rect(px, py+(ps), ps, ps);
 fill(#FF0000);
 rect(px, py+(ps*2), ps, ps);
 fill(#00FF00);
 rect(px, py+(ps*3), ps, ps);
 fill(#FFFF00);
 rect(px, py+(ps*4), ps, ps);
 fill(#0000FF);
 rect(px, py+(ps*5), ps, ps);
 //largeur
 fill(#FFFFFF);
 rect(px, py+(ps*7), ps, ps);
  fill(#FFFFFF);
 rect(px, py+(ps*8), ps, ps);
 stroke(#000000);
 line(px+2, py+(ps*7)+(ps/2), px+(ps-2), py+(ps*7)+(ps/2));
 line(px+(ps/2), py+(ps*7)+1, px+(ps/2), py+(ps*8)-1);
 line(px+2, py+(ps*8)+(ps/2), px+(ps-2), py+(ps*8)+(ps/2));

 if(cliked==false){
  prevx = mouseX;
 prevy = mouseY;  
 }
 if(mousePressed) { 
  cliked = true;
 newx = mouseX;
  newy = mouseY;
  strokeWeight(largeur);
  stroke(c1);
  line(prevx, prevy, newx, newy);
  prevx = newx;
 prevy = newy;
 }else{
  cliked= false;
  }
}
void mouseClicked() {
 if (mouseX>=px && mouseX<=(px+ps)){
  //couleur
  if (mouseY>=py && mouseY<=py+(ps*6)){ 
   c1 = get(mouseX, mouseY);
  }
   //largeur
  if (mouseY>=py+(ps*7) && mouseY<=py+(ps*8)){ 
   largeur += 2;
  }
 if (mouseY>=py+(ps*8) && mouseY<=py+(ps*9)){ 
   if (largeur>2){
    largeur -= 2;
   }
  }
 }
}
</script><canvas></canvas>
</body>
</html>
2
expiredninja

si vous avez une image d’arrière-plan pour votre toile, vous devrez faire quelques ajustements pour que cela fonctionne correctement, car une astuce d’effacement des blancs masquera l’arrière-plan.

voici un Gist avec le code.

<html>
    <script type="text/javascript">
    var canvas, canvasimg, backgroundImage, finalImg;
    var mouseClicked = false;
    var prevX = 0;
    var currX = 0;
    var prevY = 0;
    var currY = 0;
    var fillStyle = "black";
    var globalCompositeOperation = "source-over";
    var lineWidth = 2;

    function init() {
      var imageSrc = '/abstract-geometric-pattern_23-2147508597.jpg'
      backgroundImage = new Image();
      backgroundImage.src = imageSrc;
      canvas = document.getElementById('can');
      finalImg = document.getElementById('finalImg');
      canvasimg = document.getElementById('canvasimg');
      canvas.style.backgroundImage = "url('" + imageSrc + "')";
      canvas.addEventListener("mousemove", handleMouseEvent);
      canvas.addEventListener("mousedown", handleMouseEvent);
      canvas.addEventListener("mouseup", handleMouseEvent);
      canvas.addEventListener("mouseout", handleMouseEvent);
    }

    function getColor(btn) {
      globalCompositeOperation = 'source-over';
      lineWidth = 2;
      switch (btn.getAttribute('data-color')) {
        case "green":
        fillStyle = "green";
        break;
        case "blue":
        fillStyle = "blue";
        break;
        case "red":
        fillStyle = "red";
        break;
        case "yellow":
        fillStyle = "yellow";
        break;
        case "orange":
        fillStyle = "orange";
        break;
        case "black":
        fillStyle = "black";
        break;
        case "eraser":
        globalCompositeOperation = 'destination-out';
        fillStyle = "rgba(0,0,0,1)";
        lineWidth = 14;
        break;
      }

    }

    function draw(dot) {
      var ctx = canvas.getContext("2d");
      ctx.beginPath();
      ctx.globalCompositeOperation = globalCompositeOperation;
      if(dot){
        ctx.fillStyle = fillStyle;
        ctx.fillRect(currX, currY, 2, 2);
      } else {
        ctx.beginPath();
        ctx.moveTo(prevX, prevY);
        ctx.lineTo(currX, currY);
        ctx.strokeStyle = fillStyle;
        ctx.lineWidth = lineWidth;
        ctx.stroke();
      }
      ctx.closePath();
    }

    function erase() {
      if (confirm("Want to clear")) {
        var ctx = canvas.getContext("2d");
        ctx.clearRect(0, 0, canvas.width, canvas.height);
        document.getElementById("canvasimg").style.display = "none";
      }
    }

    function save() {
      canvas.style.border = "2px solid";
      canvasimg.width = canvas.width;
      canvasimg.height = canvas.height;
      var ctx2 = canvasimg.getContext("2d");
      // comment next line to save the draw only
      ctx2.drawImage(backgroundImage, 0, 0);
      ctx2.drawImage(canvas, 0, 0);
      finalImg.src = canvasimg.toDataURL();
      finalImg.style.display = "inline";
    }

    function handleMouseEvent(e) {
      if (e.type === 'mousedown') {
        prevX = currX;
        prevY = currY;
        currX = e.offsetX;
        currY = e.offsetY;
        mouseClicked = true;
        draw(true);
      }
      if (e.type === 'mouseup' || e.type === "mouseout") {
        mouseClicked = false;
      }
      if (e.type === 'mousemove') {
        if (mouseClicked) {
          prevX = currX;
          prevY = currY;
          currX = e.offsetX;
          currY = e.offsetY;
          draw();
        }
      }
    }
    </script>
    <body onload="init()">
      <canvas id="can" width="400" height="400" style="position:absolute;top:10%;left:10%;border:2px solid;">
      </canvas>
      <div style="position:absolute;top:12%;left:43%;">Choose Color</div>
      <div style="position:absolute;top:15%;left:45%;width:10px;height:10px;background:green;" data-color="green" onclick="getColor(this)"></div>
      <div style="position:absolute;top:15%;left:46%;width:10px;height:10px;background:blue;" data-color="blue" onclick="getColor(this)"></div>
      <div style="position:absolute;top:15%;left:47%;width:10px;height:10px;background:red;" data-color="red" onclick="getColor(this)"></div>
      <div style="position:absolute;top:17%;left:45%;width:10px;height:10px;background:yellow;" data-color="yellow" onclick="getColor(this)"></div>
      <div style="position:absolute;top:17%;left:46%;width:10px;height:10px;background:orange;" data-color="orange" onclick="getColor(this)"></div>
      <div style="position:absolute;top:17%;left:47%;width:10px;height:10px;background:black;" data-color="black" onclick="getColor(this)"></div>
      <div style="position:absolute;top:20%;left:43%;">Eraser</div>
      <div style="position:absolute;top:22%;left:45%;width:15px;height:15px;background:white;border:2px solid;" data-color="eraser" onclick="getColor(this)"></div>
      <canvas id="canvasimg" style="display:none;" ></canvas>
      <img id="finalImg" style="position:absolute;top:10%;left:52%;display:none;" >
      <input type="button" value="save" id="btn" size="30" onclick="save()" style="position:absolute;top:55%;left:10%;">
      <input type="button" value="clear" id="clr" size="23" onclick="erase()" style="position:absolute;top:55%;left:15%;">
    </body>
    </html>
0
Mohammed Essehemy

Cela fait des années que la question a été posée et a reçu une réponse.

Pour ceux qui recherchent un canevas de dessin simple (par exemple, pour prendre la signature de l'utilisateur/client), je poste ici une version simplifiée de la réponse actuellement acceptée.

$(document).ready(function() {
  var flag, dot_flag = false,
        prevX, prevY, currX, currY = 0,
        color = 'black', thickness = 2;
  var $canvas = $('#canvas');
  var ctx = $canvas[0].getContext('2d');

  $canvas.on('mousemove mousedown mouseup mouseout', function(e) {
    prevX = currX;
    prevY = currY;
    currX = e.clientX - $canvas.offset().left;
    currY = e.clientY - $canvas.offset().top;
    if (e.type == 'mousedown') {
      flag = true;
    }
    if (e.type == 'mouseup' || e.type == 'mouseout') {
      flag = false;
    }
    if (e.type == 'mousemove') {
      if (flag) {
        ctx.beginPath();
        ctx.moveTo(prevX, prevY);
        ctx.lineTo(currX, currY);
        ctx.strokeStyle = color;
        ctx.lineWidth = thickness;
        ctx.stroke();
        ctx.closePath();
      }
    }
  });

  $('.canvas-clear').on('click', function(e) {
    c_width = $canvas.width();
    c_height = $canvas.height();
    ctx.clearRect(0, 0, c_width, c_height);
    $('#canvasimg').hide();
  });
});
<html>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.0/jquery.min.js"></script>
  <body>
    <canvas id="canvas" width="400" height="400" style="position:absolute;top:10%;left:10%;border:2px solid;"></canvas>
    <input type="button" value="Clear" class="canvas-clear" />
  </body>
</html>
0
Munawir