使用fabric.js在画布上自由绘图

Question

我正在尝试使用fabric.js在画布上绘制一个免费的绘图，但我无法在我身边自由绘制像喷雾，圆圈，纹理模式我使用此代码只有铅笔模式绘图工作但是当我选择喷涂和模式绘制为铅笔的其他模式。

这是我的HTML Here is fiddle ink

            <label for="drawing-mode-selector">Mode:</label>
            <select id="drawing-mode-selector">
              <option>Pencil</option>
              <option>Circle</option>
              <option>Spray</option>
              <option>Pattern</option>

              <option>hline</option>
              <option>vline</option>
              <option>square</option>
              <option>diamond</option>
              <option>texture</option>
            </select><br>
            <label for="drawing-line-width">Line width:</label>
            <input type="range" value="30" min="0" max="150" id="drawing-            line-width"><br>
            <label for="drawing-color">Line color:</label>
            <input type="color" value="#005E7A" id="drawing-color"><br>
            <label for="drawing-shadow-width">Line shadow width:</label>
            <input type="range" value="0" min="0" max="50" id="drawing-shadow-width"><br>
          </div>
        </li>

这是我的脚本代码

     var canvas = new fabric.Canvas('canvas')
     var drawingModeEl = document.getElementById('drawing-mode'),
      drawingOptionsEl = document.getElementById('drawing-mode-options'),
      drawingColorEl = document.getElementById('drawing-color'),
      drawingLineWidthEl = document.getElementById('drawing-line-width'),
      drawingShadowWidth = document.getElementById('drawing-shadow-width');

     drawingModeEl.onclick = function() {
    canvas.isDrawingMode = !canvas.isDrawingMode;
    if (canvas.isDrawingMode) {
      drawingModeEl.innerHTML = 'Cancel drawing mode';
      drawingOptionsEl.style.display = '';
    }
    else {
      drawingModeEl.innerHTML = 'Enter drawing mode';
      drawingOptionsEl.style.display = 'none';
    }
  };

  canvas.on('path:created', function() {
    updateComplexity();
  });

  if (fabric.PatternBrush) {
    var vLinePatternBrush = new fabric.PatternBrush(canvas);
    vLinePatternBrush.getPatternSrc = function() {

      var patternCanvas = fabric.document.createElement('canvas');
      patternCanvas.width = patternCanvas.height = 10;
      var ctx = patternCanvas.getContext('2d');

      ctx.strokeStyle = this.color;
      ctx.lineWidth = 5;
      ctx.beginPath();
      ctx.moveTo(0, 5);
      ctx.lineTo(10, 5);
      ctx.closePath();
      ctx.stroke();

      return patternCanvas;
    };

    var hLinePatternBrush = new fabric.PatternBrush(canvas);
    hLinePatternBrush.getPatternSrc = function() {

      var patternCanvas = fabric.document.createElement('canvas');
      patternCanvas.width = patternCanvas.height = 10;
      var ctx = patternCanvas.getContext('2d');

      ctx.strokeStyle = this.color;
      ctx.lineWidth = 5;
      ctx.beginPath();
      ctx.moveTo(5, 0);
      ctx.lineTo(5, 10);
      ctx.closePath();
      ctx.stroke();

      return patternCanvas;
    };

    var squarePatternBrush = new fabric.PatternBrush(canvas);
    squarePatternBrush.getPatternSrc = function() {

      var squareWidth = 10, squareDistance = 2;

      var patternCanvas = fabric.document.createElement('canvas');
      patternCanvas.width = patternCanvas.height = squareWidth + squareDistance;
      var ctx = patternCanvas.getContext('2d');

      ctx.fillStyle = this.color;
      ctx.fillRect(0, 0, squareWidth, squareWidth);

      return patternCanvas;
    };

    var diamondPatternBrush = new fabric.PatternBrush(canvas);
    diamondPatternBrush.getPatternSrc = function() {

      var squareWidth = 10, squareDistance = 5;
      var patternCanvas = fabric.document.createElement('canvas');
      var rect = new fabric.Rect({
        width: squareWidth,
        height: squareWidth,
        angle: 45,
        fill: this.color
      });

      var canvasWidth = rect.getBoundingRectWidth();

      patternCanvas.width = patternCanvas.height = canvasWidth + squareDistance;
      rect.set({ left: canvasWidth / 2, top: canvasWidth / 2 });

      var ctx = patternCanvas.getContext('2d');
      rect.render(ctx);

      return patternCanvas;
    };

    var img = new Image();
    img.src = '../assets/honey_im_subtle.png';

    var texturePatternBrush = new fabric.PatternBrush(canvas);
    texturePatternBrush.source = img;
  }

  $('#drawing-mode-selector').on('change', function() {

    if (this.value === 'hline') {
      canvas.freeDrawingBrush = vLinePatternBrush;
    }
    else if (this.value === 'vline') {
      canvas.freeDrawingBrush = hLinePatternBrush;
    }
    else if (this.value === 'square') {
      canvas.freeDrawingBrush = squarePatternBrush;
    }
    else if (this.value === 'diamond') {
      canvas.freeDrawingBrush = diamondPatternBrush;
    }
    else if (this.value === 'texture') {
      canvas.freeDrawingBrush = texturePatternBrush;
    }
    else {
      canvas.freeDrawingBrush = new fabric[this.value + 'Brush'](canvas);
    }

    if (canvas.freeDrawingBrush) {
      canvas.freeDrawingBrush.color = drawingColorEl.value;
      canvas.freeDrawingBrush.width = parseInt(drawingLineWidthEl.value, 10) || 1;
      canvas.freeDrawingBrush.shadowBlur = parseInt(drawingShadowWidth.value, 10) || 0;
    }
  });

  drawingColorEl.onchange = function() {
    canvas.freeDrawingBrush.color = drawingColorEl.value;
  };
  drawingLineWidthEl.onchange = function() {
    canvas.freeDrawingBrush.width = parseInt(drawingLineWidthEl.value, 10) || 1;
  };
  drawingShadowWidth.onchange = function() {
    canvas.freeDrawingBrush.shadowBlur = parseInt(drawingShadowWidth.value, 10) || 0;
  };

  if (canvas.freeDrawingBrush) {
    canvas.freeDrawingBrush.color = drawingColorEl.value;
    canvas.freeDrawingBrush.width = parseInt(drawingLineWidthEl.value, 10) || 1;
    canvas.freeDrawingBrush.shadowBlur = 0;
  }

  var canvas = new fabric.Canvas('c');
document.getElementById('canvas-background-picker').onchange = function() {
    canvas.backgroundColor = this.value;
    canvas.renderAll();
  };
//end free drawing

在这里看到一个完整的屏幕截图，我选择了模式vline，但它绘制像简单的铅笔    

Answer 1

我已经更新了你的jsfiddle，现在它正常工作Demo。

在您的页面上出现问题 - 请查看您的开发控制台：

  $('#drawing-mode-selector').on('change', function() {
  //Uncaught TypeError: Object [object Object] has no method 'on'