JavaScript html5 canvas implements drawing hyperlinks on pictures-JS Tutorial-php.cn

JavaScript html5 canvas implements drawing hyperlinks on pictures

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Release： 2017-12-09 14:42:23

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This article mainly introduces JavaScript html5 canvas to realize drawing hyperlinks on pictures in detail. It has certain reference value. Interested friends can refer to it. I hope it can help everyone.

The example in this article shares the specific code for drawing hyperlinks on pictures using html5 canvas for your reference. The specific content is as follows

1. html

<canvas id="canvasFile" style="margin-top:15px;" width="500" height="400"></canvas> 
<input type="button" id="btnRedo" value="Re-Draw" class="btn btn-warning"/>

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2. javascript

var photoW = 400; 
    var photoH = 300; 
    var photo; 
     
     
    // logic load image into canvas 
    // ... 
    // e.g.  
    // photo = new Image(); 
    // photo.onload = function() { 
    // draw photo into canvas when ready 
    // ctx.drawImage(photo, 0, 0, photoW, photoH); 
    // }; 
    // load photo into canvas 
    // photo.src = picURL; 
   
     
 // canvas highlight 
    var canvas = document.getElementById(&#39;canvasFile&#39;), 
      ctx = canvas.getContext(&#39;2d&#39;), 
      img = new Image; 
    var btnDone = document.getElementById(&#39;btnDone&#39;); 
    var btnRedo = document.getElementById(&#39;btnRedo&#39;); 
 
 
    ctx.strokeStyle = &#39;#FF0000&#39;; 
 
    function DrawDot(x, y) { 
      var centerX = x; 
      var centerY = y; 
      var radius = 2; 
 
 
      ctx.beginPath(); 
      ctx.arc(centerX, centerY, radius, 0, 2 * Math.PI, false); 
      ctx.fillStyle = &#39;red&#39;; 
      ctx.fill(); 
      ctx.lineWidth = 2; 
      ctx.strokeStyle = &#39;#FF0000&#39;; 
      ctx.stroke(); 
    } 
 
 
    function startDrawing() { 
      ctx.drawImage(img, 0, 0, photoW, photoH); 
      canvas.onmousemove = mousemoving; 
      canvas.onmousedown = mousedownhandle; 
      canvas.onmouseup = mouseuphandle; 
      // ## mobile events 
      //touchstart – to toggle drawing mode “on” 
      //touchend – to toggle drawing mode “off” 
      //touchmove – to track finger position, used in drawing 
      canvas.addEventListener(&#39;touchmove&#39;, touchmove, false); 
      canvas.addEventListener(&#39;touchend&#39;, mouseuphandle, false); 
 
 
      btnRedo.onclick = function (e) { 
        ctx.clearRect(0, 0, ctx.width, ctx.height); 
        ctx.drawImage(photo, 0, 0, photoW, photoH); 
        savedrawing(); 
      } 
    } 
    function savedrawing(e) { 
      var image = document.getElementById(&#39;canvasFile&#39;).toDataURL("image/jpeg"); 
      image = image.replace(&#39;data:image/jpeg;base64,&#39;, &#39;&#39;); 
      $("#imgNric1").val(image); 
    }; 
 

    function mousemoving(e) { 
      if (drawing) { 
        mousedownhandle(e); 
      } 
    } 
 
 
    var drawing = false; 
 
 
    function mousedownhandle(e) { 
      drawing = true; 
      var r = canvas.getBoundingClientRect(), 
        x = e.clientX - r.left, 
        y = e.clientY - r.top; 
 
 
      DrawDot(x, y); 
    }  
 
    function mouseuphandle(e) { 
      savedrawing(); 
      e.preventDefault(); 
      drawing = false; 
       
    } 
  
 
    //// mobile touch events 
    function touchmove(e) { 
      if (e.clientX > 800) { 
        mousedownhandle(e); 
        return; 
      } 
 
      var r = canvas.getBoundingClientRect(), 
        //event.changedTouches[0].pageX + ":" + event.changedTouches[0].pageY; 
        x = e.changedTouches[0].pageX - r.left, 
        y = e.changedTouches[0].pageY - r.top; 
 
 
      DrawDot(x, y); 
      e.preventDefault(); 
    }

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