如何将矩形添加到缩放的画布区域？

Question

我正在使用 Fabric JS。每次我按下Add Door 按钮时，它都会在左上角创建。我给了矩形中的值（左：40，上：40，）。 但是，当我在我缩放的区域上按下按钮时，我希望它将它添加到我缩放的区域。我看了几个例子，但找不到我想要的。我该怎么做？

Video

var canvas = new fabric.Canvas('c');
canvas.setBackgroundImage('https://i.hizliresim.com/0pIPiv.jpg', canvas.renderAll.bind(canvas));
var uniqids = 0;
$("#door").on("click", function(e) {
  rect = new fabric.Rect({
    id:uniqid,
    left: 40,
    top: 40,
    width: 35,
    height: 50,      
    fill: 'blue',
    stroke: 'blue',
    strokeWidth: 5,
    strokeUniform: false,
    hasControls : true,
  });  

  var uniqid = uniqids.toString(); 

  var text = new fabric.Text(uniqid, {
    fontSize: 30,
    originX: 'center',
    originY: 'right'
  });

  var group = new fabric.Group([ rect, text ], {
    left: 0,
    top: 100,
  });

  canvas.add(group);
  uniqids++;

  canvas.on('selection:cleared', c => {
    console.log("empty");
  });
  canvas.selection = false;

});
//*****************************
// canvas.on('mouse:wheel', function(opt) {
//   var delta = opt.e.deltaY;
//   var zoom = canvas.getZoom();
//   zoom *= 0.999 ** delta;
//   if (zoom > 20) zoom = 20;
//   if (zoom < 0.01) zoom = 0.01;
//   canvas.setZoom(zoom);
//   opt.e.preventDefault();
//   opt.e.stopPropagation();

// })

$('#getid').click(function() {
  var activeObject = canvas.getActiveObjects();
  alert(canvas.getActiveObject().id); 
});



//***************************************

$("#save").on("click", function(e) {
  $(".save").html(canvas.toSVG());
});

$('#delete').click(function() {
  var activeObject = canvas.getActiveObjects(); 
  canvas.discardActiveObject();
  canvas.remove(...activeObject); 
});


$("#btnResetZoom").on("click", function(e) {
  canvas.setViewportTransform([1,0,0,1,0,0]);
});

canvas.on('mouse:wheel', function(opt) {
    var delta = opt.e.deltaY;
    var zoom = canvas.getZoom();
    zoom *= 0.999 ** delta;
    if (zoom > 20) zoom = 20;
    if (zoom < 1) zoom = 1;
    canvas.zoomToPoint({x: opt.e.offsetX, y: opt.e.offsetY}, zoom);
    opt.e.preventDefault();
    opt.e.stopPropagation();
});
var shiftKeyDown = true;
var mouseDownPoint = null;
canvas.on('mouse:move', function(options) {
  if (shiftKeyDown && mouseDownPoint) {
    var pointer = canvas.getPointer(options.e, true);
    var mouseMovePoint = new fabric.Point(pointer.x, pointer.y);
    canvas.relativePan(mouseMovePoint.subtract(mouseDownPoint));
    mouseDownPoint = mouseMovePoint;
    keepPositionInBounds(canvas);
  }
});




var Direction = {
  LEFT: 0,
  UP: 1,
  RIGHT: 2,
  DOWN: 3
};

var zoomLevel = 0;
var zoomLevelMin = 0;
var zoomLevelMax = 3;

var shiftKeyDown = false;
var mouseDownPoint = null;

canvas.on('mouse:down', function(options) {
  var pointer = canvas.getPointer(options.e, true);
  mouseDownPoint = new fabric.Point(pointer.x, pointer.y);
});
canvas.on('mouse:up', function(options) {
  mouseDownPoint = null;
});
canvas.on('mouse:move', function(options) {
  if (shiftKeyDown && mouseDownPoint) {
    var pointer = canvas.getPointer(options.e, true);
    var mouseMovePoint = new fabric.Point(pointer.x, pointer.y);
    canvas.relativePan(mouseMovePoint.subtract(mouseDownPoint));
    mouseDownPoint = mouseMovePoint;
    keepPositionInBounds(canvas);
  }
});
fabric.util.addListener(document.body, 'keydown', function(options) {
  if (options.repeat) {
    return;
  }
  var key = options.which || options.keyCode; // key detection
  if (key == 16) { // handle Shift key
    canvas.defaultCursor = 'move';
    canvas.selection = false;
    shiftKeyDown = true;
  } else if (key === 37) { // handle Left key
    move(Direction.LEFT);
  } else if (key === 38) { // handle Up key
    move(Direction.UP);
  } else if (key === 39) { // handle Right key
    move(Direction.RIGHT);
  } else if (key === 40) { // handle Down key
    move(Direction.DOWN);
  }
});
fabric.util.addListener(document.body, 'keyup', function(options) {
  var key = options.which || options.keyCode; // key detection
  if (key == 16) { // handle Shift key
    canvas.defaultCursor = 'default';
    canvas.selection = true;
    shiftKeyDown = false;
  }
});
// jQuery('.canvas-container').on('mousewheel', function(options) {
//   var delta = options.originalEvent.wheelDelta;
//   if (delta != 0) {
//     var pointer = canvas.getPointer(options.e, true);
//     var point = new fabric.Point(pointer.x, pointer.y);
//     if (delta > 0) {
//       zoomIn(point);
//     } else if (delta < 0) {
//       zoomOut(point);
//     }
//   }
// });

function move(direction) {
  switch (direction) {
    case Direction.LEFT:
      canvas.relativePan(new fabric.Point(-10 * canvas.getZoom(), 0));
      break;
    case Direction.UP:
      canvas.relativePan(new fabric.Point(0, -10 * canvas.getZoom()));
      break;
    case Direction.RIGHT:
      canvas.relativePan(new fabric.Point(10 * canvas.getZoom(), 0));
      break;
    case Direction.DOWN:
      canvas.relativePan(new fabric.Point(0, 10 * canvas.getZoom()));
      break;
  }
  keepPositionInBounds(canvas);
}


// function zoomIn(point) {
//   if (zoomLevel < zoomLevelMax) {
//     zoomLevel++;
//     canvas.zoomToPoint(point, Math.pow(2, zoomLevel));
//     keepPositionInBounds(canvas);
//   }
// }

// function zoomOut(point) {
//   console.log(zoomLevel, zoomLevelMin);
//   if (zoomLevel > zoomLevelMin) {
//     zoomLevel--;
//     canvas.zoomToPoint(point, Math.pow(2, zoomLevel));
//     keepPositionInBounds(canvas);
//   }
// }

function keepPositionInBounds() {
  var zoom = canvas.getZoom();
  var xMin = (2 - zoom) * canvas.getWidth() / 2;
  var xMax = zoom * canvas.getWidth() / 2;
  var yMin = (2 - zoom) * canvas.getHeight() / 2;
  var yMax = zoom * canvas.getHeight() / 2;

  var point = new fabric.Point(canvas.getWidth() / 2, canvas.getHeight() / 2);
  var center = fabric.util.transformPoint(point, canvas.viewportTransform);

  var clampedCenterX = clamp(center.x, xMin, xMax);
  var clampedCenterY = clamp(center.y, yMin, yMax);

  var diffX = clampedCenterX - center.x;
  var diffY = clampedCenterY - center.y;

  if (diffX != 0 || diffY != 0) {
    canvas.relativePan(new fabric.Point(diffX, diffY));
  }
}

function clamp(value, min, max) {
  return Math.max(min, Math.min(value, max));
}

#c {
  background-color: grey;
  margin-top: 10px;
}

button {
  padding: 10px 20px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/3.1.0/fabric.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<button id="door">Door</button>
<button id="delete">Delete Door</button>
<button id="save">Save</button>
<button id="getid">GET ID</button>
<button id="btnResetZoom">Reset Zoom</button>

<canvas id="c" width="800" height="800"></canvas>
<br>  
<p class="save">
</p>

Answer 1

我认为你应该使用transformPoint方法来翻译位置

    $("#door").on("click", function (e) {
    const points = {};
    const iVpt = fabric.util.invertTransform(canvas.viewportTransform);
    points.tl = fabric.util.transformPoint({x: 40, y: 40}, iVpt);
    rect = new fabric.Rect({
        id: uniqid,
        left: points.tl.x,
        top: points.tl.y,
        width: 35,
        height: 50,
        fill: "blue",
        stroke: "blue",
        strokeWidth: 5,
        strokeUniform: false,
        hasControls: true,
    });