javascript - Fabric js : fabric js drawing mode and selection mode options

Question

我正在使用 Fabric js 开发一个应用程序，用于在一个 Canvas 上绘制线条、矩形和圆形。还有另一个功能可以将图像拖放到 Canvas 上。但是当我向应用程序添加拖放功能时，其他三个功能不起作用。我找到了这个article 。但我无法将它与我的集成。

function initCanvas() {
    $('.canvas-container').each(function (index) {

        var canvasContainer = $(this)[0];
        var canvasObject = $("canvas", this)[0];
        var url = $(this).data('floorplan');
        var canvas = window._canvas = new fabric.Canvas(canvasObject);

        canvas.setHeight(400);
        canvas.setWidth(500);
        canvas.setBackgroundImage(url, canvas.renderAll.bind(canvas));

        var imageOffsetX, imageOffsetY;

        function handleDragStart(e) {
            [].forEach.call(images, function (img) {
                img.classList.remove('img_dragging');
            });
            this.classList.add('img_dragging');


            var imageOffset = $(this).offset();
            imageOffsetX = e.clientX - imageOffset.left;
            imageOffsetY = e.clientY - imageOffset.top;
        }

        function handleDragOver(e) {
            if (e.preventDefault) {
                e.preventDefault();
            }
            e.dataTransfer.dropEffect = 'copy';
            return false;
        }

        function handleDragEnter(e) {
            this.classList.add('over');
        }

        function handleDragLeave(e) {
            this.classList.remove('over');
        }

        function handleDrop(e) {
            e = e || window.event;
            if (e.preventDefault) {
                e.preventDefault();
            }
            if (e.stopPropagation) {
                e.stopPropagation();
            }
            var img = document.querySelector('.furniture img.img_dragging');
            console.log('event: ', e);

            var offset = $(canvasObject).offset();
            var y = e.clientY - (offset.top + imageOffsetY);
            var x = e.clientX - (offset.left + imageOffsetX);

            var newImage = new fabric.Image(img, {
                width: img.width,
                height: img.height,
                left: x,
                top: y
            });
            canvas.add(newImage);
            return false;
        }

        function handleDragEnd(e) {
            [].forEach.call(images, function (img) {
                img.classList.remove('img_dragging');
            });
        }

        var images = document.querySelectorAll('.furniture img');
        [].forEach.call(images, function (img) {
            img.addEventListener('dragstart', handleDragStart, false);
            img.addEventListener('dragend', handleDragEnd, false);
        });
        canvasContainer.addEventListener('dragenter', handleDragEnter, false);
        canvasContainer.addEventListener('dragover', handleDragOver, false);
        canvasContainer.addEventListener('dragleave', handleDragLeave, false);
        canvasContainer.addEventListener('drop', handleDrop, false);
    });
}
initCanvas();

var canvas = new fabric.Canvas('canvas1', { selection: false });

var line, isDown;
function myFun() {
    removeEvents();    
    canvas.on('mouse:down', function (o) {
        isDown = true;
        var pointer = canvas.getPointer(o.e);
        var points = [pointer.x, pointer.y, pointer.x, pointer.y];
        line = new fabric.Line(points, {
            strokeWidth: 5,
            fill: '#07ff11a3',
            stroke: '#07ff11a3',
            originX: 'center',
            originY: 'center'
        });
        canvas.add(line);
    });
    canvas.on('mouse:move', function (o) {
        if (!isDown) return;
        var pointer = canvas.getPointer(o.e);
        line.set({ x2: pointer.x, y2: pointer.y });
        canvas.renderAll();
    });

    canvas.on('mouse:up', function (o) {
        isDown = false;
    });
    canvas.selection = false;

}

function drawrec() {
    var line, isDown, origX, origY;
    removeEvents();

    canvas.on('mouse:down', function (o) {
        isDown = true;
        var pointer = canvas.getPointer(o.e);
        origX = pointer.x;
        origY = pointer.y;
        var pointer = canvas.getPointer(o.e);
        line = new fabric.Rect({
            left: origX,
            top: origY,
            originX: 'left',
            originY: 'top',
            width: pointer.x - origX,
            height: pointer.y - origY,
            angle: 0,
            fill: '#07ff11a3',
            stroke: 'black',
            transparentCorners: false
        });
        canvas.add(line);
    });

    canvas.on('mouse:move', function (o) {
        if (!isDown) return;
        var pointer = canvas.getPointer(o.e);

        if (origX > pointer.x) {
            line.set({ left: Math.abs(pointer.x) });
        }
        if (origY > pointer.y) {
            line.set({ top: Math.abs(pointer.y) });
        }

        line.set({ width: Math.abs(origX - pointer.x) });
        line.set({ height: Math.abs(origY - pointer.y) });


        canvas.renderAll();
    });

    canvas.on('mouse:up', function (o) {
        isDown = false;
    });
}

function drawcle() {

    var circle, isDown, origX, origY;
    removeEvents();
    canvas.on('mouse:down', function (o) {
        isDown = true;
        var pointer = canvas.getPointer(o.e);
        origX = pointer.x;
        origY = pointer.y;
        circle = new fabric.Circle({
            left: pointer.x,
            top: pointer.y,
            radius: 1,
            strokeWidth: 1,
            fill: '#07ff11a3',
            stroke: 'black',
            selectable: false,
            originX: 'center', originY: 'center'
        });
        canvas.add(circle);
    });

    canvas.on('mouse:move', function (o) {
        if (!isDown) return;
        var pointer = canvas.getPointer(o.e);
        circle.set({ radius: Math.abs(origX - pointer.x) });
        canvas.renderAll();
    });

    canvas.on('mouse:up', function (o) {
        isDown = false;
    });

}

function removeEvents() {
    canvas.off('mouse:down');
    canvas.off('mouse:up');
    canvas.off('mouse:move');
}

<div class="fullpage">
  <div class="section">
  <a class="thmb" href="#" onclick="myFun()" style="padding: 0px 10px;margin:5px;border: 2px solid;">line</a>
  <a class="thmb" href="#" onclick="drawrec()" style="padding: 0px 10px;margin:5px;border: 2px solid;">Rectangle</a>
  <a class="thmb" href="#" onclick="drawcle()" style="padding: 0px 10px;margin:5px;border: 2px solid;">Circle</a>
    <div class="canvas-container">
      <canvas id="canvas1" style="border: 1px solid;width: 500px;height: 500px"></canvas>
    </div>
    <div class="furniture" style="padding: 20px;border: 1px solid;width: 460px">
      <h3>Drag the image to canvas</h3> 
      <img draggable="true" src="https://www.mve.com/media/Move_logo_-01.png" width="60">
    </div>
  </div>
</div>
<script src='https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.min.js'></script>

<script src='https://cdnjs.cloudflare.com/ajax/libs/fabric.js/1.7.6/fabric.min.js'></script>

  

Answer 1

var canvas = window._canvas = new fabric.Canvas(canvasObject);

在initCanvas()中，您再次创建织物 Canvas ，因此将其删除。要启用自由绘图，您需要执行 canvas.isDrawingMode = true

function initCanvas() {
  $('.canvas-container').each(function(index) {

    var canvasContainer = $(this)[0];
    var canvasObject = $("canvas", this)[0];

    var imageOffsetX, imageOffsetY;

    function handleDragStart(e) {
      [].forEach.call(images, function(img) {
        img.classList.remove('img_dragging');
      });
      this.classList.add('img_dragging');
      var imageOffset = $(this).offset();
      imageOffsetX = e.clientX - imageOffset.left;
      imageOffsetY = e.clientY - imageOffset.top;
    }

    function handleDragOver(e) {
      if (e.preventDefault) {
        e.preventDefault();
      }
      e.dataTransfer.dropEffect = 'copy';
      return false;
    }

    function handleDragEnter(e) {
      this.classList.add('over');
    }

    function handleDragLeave(e) {
      this.classList.remove('over');
    }

    function handleDrop(e) {
      e = e || window.event;
      if (e.preventDefault) {
        e.preventDefault();
      }
      if (e.stopPropagation) {
        e.stopPropagation();
      }
      var img = document.querySelector('.furniture img.img_dragging');
      console.log('event: ', e);

      var offset = $(canvasObject).offset();
      var y = e.clientY - (offset.top + imageOffsetY);
      var x = e.clientX - (offset.left + imageOffsetX);

      var newImage = new fabric.Image(img, {
        width: img.width,
        height: img.height,
        left: x,
        top: y
      });
      canvas.add(newImage);
      return false;
    }

    function handleDragEnd(e) {
      [].forEach.call(images, function(img) {
        img.classList.remove('img_dragging');
      });
    }

    var images = document.querySelectorAll('.furniture img');
    [].forEach.call(images, function(img) {
      img.addEventListener('dragstart', handleDragStart, false);
      img.addEventListener('dragend', handleDragEnd, false);
    });
    canvasContainer.addEventListener('dragenter', handleDragEnter, false);
    canvasContainer.addEventListener('dragover', handleDragOver, false);
    canvasContainer.addEventListener('dragleave', handleDragLeave, false);
    canvasContainer.addEventListener('drop', handleDrop, false);
  });
}
initCanvas();

var canvas = new fabric.Canvas('canvas1', {
  selection: false
});

var line, isDown;

function drawLine() {
  removeEvents();
  changeObjectSelection(false);
  canvas.on('mouse:down', function(o) {
    isDown = true;
    var pointer = canvas.getPointer(o.e);
    var points = [pointer.x, pointer.y, pointer.x, pointer.y];
    line = new fabric.Line(points, {
      strokeWidth: 5,
      fill: '#07ff11a3',
      stroke: '#07ff11a3',
      originX: 'center',
      originY: 'center',
      selectable: false
    });
    canvas.add(line);
  });
  canvas.on('mouse:move', function(o) {
    if (!isDown) return;
    var pointer = canvas.getPointer(o.e);
    line.set({
      x2: pointer.x,
      y2: pointer.y
    });
    canvas.renderAll();
  });

  canvas.on('mouse:up', function(o) {
    isDown = false;
    line.setCoords();
  });
}

function drawrec() {
  var rect, isDown, origX, origY;
  removeEvents();
  changeObjectSelection(false);

  canvas.on('mouse:down', function(o) {
    isDown = true;
    var pointer = canvas.getPointer(o.e);
    origX = pointer.x;
    origY = pointer.y;
    var pointer = canvas.getPointer(o.e);
    rect = new fabric.Rect({
      left: origX,
      top: origY,
      originX: 'left',
      originY: 'top',
      width: pointer.x - origX,
      height: pointer.y - origY,
      angle: 0,
      selectable:false,
      fill: '#07ff11a3',
      stroke: 'black',
      transparentCorners: false
    });
    canvas.add(rect);
  });

  canvas.on('mouse:move', function(o) {
    if (!isDown) return;
    var pointer = canvas.getPointer(o.e);

    if (origX > pointer.x) {
      rect.set({
        left: Math.abs(pointer.x)
      });
    }
    if (origY > pointer.y) {
      rect.set({
        top: Math.abs(pointer.y)
      });
    }

    rect.set({
      width: Math.abs(origX - pointer.x)
    });
    rect.set({
      height: Math.abs(origY - pointer.y)
    });


    canvas.renderAll();
  });
  
  canvas.on('mouse:up', function(o) {
    isDown = false;
    rect.setCoords();
  });
}

function drawcle() {
  var circle, isDown, origX, origY;
  removeEvents();
  changeObjectSelection(false);
  canvas.on('mouse:down', function(o) {
    isDown = true;
    var pointer = canvas.getPointer(o.e);
    origX = pointer.x;
    origY = pointer.y;
    circle = new fabric.Circle({
      left: pointer.x,
      top: pointer.y,
      radius: 1,
      strokeWidth: 1,
      fill: '#07ff11a3',
      stroke: 'black',
      selectable: false,
      originX: 'center',
      originY: 'center'
    });
    canvas.add(circle);
  });

  canvas.on('mouse:move', function(o) {
    if (!isDown) return;
    var pointer = canvas.getPointer(o.e);
    circle.set({
      radius: Math.abs(origX - pointer.x)
    });
    canvas.renderAll();
  });

  canvas.on('mouse:up', function(o) {
    isDown = false;
    circle.setCoords();
  });

}

function enableFreeDrawing(){
  removeEvents();
  canvas.isDrawingMode = true;
}

function enableSelection() {
  removeEvents();
  changeObjectSelection(true);
  canvas.selection = true;
}

function changeObjectSelection(value) {
  canvas.forEachObject(function (obj) {
    obj.selectable = value;
  });
  canvas.renderAll();
}

function removeEvents() {
  canvas.isDrawingMode = false;
  canvas.selection = false;
  canvas.off('mouse:down');
  canvas.off('mouse:up');
  canvas.off('mouse:move');
}

<div class="fullpage">
  <div class="section">
  <a class="thmb" href="#" onclick="drawLine()" style="padding: 0px 10px;margin:5px;border: 2px solid;">line</a>
  <a class="thmb" href="#" onclick="drawrec()" style="padding: 0px 10px;margin:5px;border: 2px solid;">Rectangle</a>
  <a class="thmb" href="#" onclick="drawcle()" style="padding: 0px 10px;margin:5px;border: 2px solid;">Circle</a>
  <a class="thmb" href="#" onclick="enableFreeDrawing()" style="padding: 0px 10px;margin:5px;border: 2px solid;">Drawing</a>
  <a class="thmb" href="#" onclick="enableSelection()" style="padding: 0px 10px;margin:5px;border: 2px solid;">Selection</a>
    <div class="canvas-container">
      <canvas id="canvas1" style="border: 1px solid;width: 500px;height: 500px"></canvas>
    </div>
    <div class="furniture" style="padding: 20px;border: 1px solid;width: 460px">
      <h3>Drag the image to canvas</h3> 
      <img draggable="true" src="https://www.mve.com/media/Move_logo_-01.png" width="60">
    </div>
  </div>
</div>
<script src='https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.min.js'></script>

<script src='https://cdnjs.cloudflare.com/ajax/libs/fabric.js/1.7.6/fabric.min.js'></script>