使 interact.js 可调整大小的像素完美

Question

在这个jsFiddle 中，我有一个可以使用interact.js 调整大小的SVG 矩形。还有一个 10 像素 x 10 像素的网格，.resizable 函数包含一个 10 像素 x 10 像素的快照。目标是调整矩形的大小并让边缘准确地捕捉到网格上。

在大多数情况下，它可以正常工作，但很多时候情况并非如此，如下图所示。也许需要在 resizeend 上手动进行调整？如何解决这个问题？

Answer 1

正如埃里克所说：

有了这个target.setAttribute(attr/a, Math.round(v/10)*10)，它似乎工作了：

  .on('resizemove', function(event) {
    // Resize the rect, not the group, it will resize automatically
    const target = event.target.querySelector('rect');

    for (const attr of ['width', 'height']) {
      let v = Number(target.getAttribute(attr));
      v += event.deltaRect[attr];
      target.setAttribute(attr, Math.round(v/10)*10);
    }

    for (const attr of ['top', 'left']) {
      const a = attr == 'left' ? 'x' : 'y';
      let v = Number(target.getAttribute(a));
      v += event.deltaRect[attr];
      target.setAttribute(a, Math.round(v/10)*10);
    }

    findLocations(rect, handles);
  });

完整演示在这里 - https://jsfiddle.net/alexander_L/1mzs36qL/3/ 及以下：

const svg = document.getElementById('mysvg');
const rect = document.createElementNS("http://www.w3.org/2000/svg", "rect");
const group = document.createElementNS("http://www.w3.org/2000/svg", "g");


// draw vertical lines
var gridSize = 10;
for (var i=0;i < 100;i++){
  var line = document.createElementNS("http://www.w3.org/2000/svg", "line");    
  svg.appendChild(line);
  line.setAttribute("x1", (i + 1) * gridSize)
  line.setAttribute("y1", 0)
  line.setAttribute("x2", (i + 1) * gridSize)
  line.setAttribute("y2", 500)
  line.setAttribute("stroke-width", 1)
  line.setAttribute("stroke", 'gray');
}
        
// draw horizontal lines
for (var i=0;i < 100;i++){
  var line = document.createElementNS("http://www.w3.org/2000/svg", "line");    
  svg.appendChild(line);
  line.setAttribute("x1", 0)
  line.setAttribute("y1", (i + 1) * gridSize)
  line.setAttribute("x2", 2000)
  line.setAttribute("y2", (i + 1) * gridSize)
  line.setAttribute("stroke-width", 1)
  line.setAttribute("stroke", 'gray');
}


svg.appendChild(group);
group.appendChild(rect);
group.setAttribute('class', 'resize-me');

rect.setAttribute('x', 100);
rect.setAttribute('y', 100);
rect.setAttribute('width', 100);
rect.setAttribute('height', 100);
rect.setAttribute('stroke-width', 1);
rect.setAttribute('stroke', 'white');
rect.setAttribute('fill', 'grey');

// Create the handles
const handles = [];
for (let i = 0; i < 8; i++) {
  const handle = document.createElementNS("http://www.w3.org/2000/svg", "rect");

  handle.setAttribute('width', 8);
  handle.setAttribute('height', 8);
  handle.setAttribute('stroke-width', 1);
  handle.setAttribute('stroke', 'white');
  handle.setAttribute('fill', 'black');

  handles.push(handle);
  group.appendChild(handle);
}

// Manually assign them their resize duties (R->L, T->B)
handles[0].classList.add('resize-top', 'resize-left');
handles[1].classList.add('resize-top');
handles[2].classList.add('resize-top', 'resize-right');
handles[3].classList.add('resize-left');
handles[4].classList.add('resize-right');
handles[5].classList.add('resize-bottom', 'resize-left');
handles[6].classList.add('resize-bottom');
handles[7].classList.add('resize-bottom', 'resize-right');



// This function takes the rect and the list of handles and positions
// the handles accordingly
const findLocations = (r, h) => {
  const x = Number(r.getAttribute('x'));
  const y = Number(r.getAttribute('y'));
  const width = Number(r.getAttribute('width'));
  const height = Number(r.getAttribute('height'));

  // Important these are in the same order as the classes above
  let locations = [
    [0, 0],
    [width / 2, 0],
    [width, 0],
    [0, height / 2],
    [width, height / 2],
    [0, height],
    [width / 2, height],
    [width, height]
  ];

  // Move each location such that it's relative to the (x,y) of the rect,
  // and also subtract half the width of the handles to make up for their
  // own size.
  locations = locations.map(subarr => [
    subarr[0] + x - 4,
    subarr[1] + y - 4
  ]);

  for (let i = 0; i < locations.length; i++) {
    h[i].setAttribute('x', locations[i][0]);
    h[i].setAttribute('y', locations[i][1]);
  }
}

interact('.resize-me')
  .resizable({
    edges: {
      left: '.resize-left',
      right: '.resize-right',
      bottom: '.resize-bottom',
      top: '.resize-top'
    },
    modifiers: [
      interact.modifiers.snap({
          targets: [
            interact.snappers.grid({
              x: 10,
              y: 10,
            })
          ]
        })
     ]
  })
  .on('resizemove', function(event) {
    // Resize the rect, not the group, it will resize automatically
    const target = event.target.querySelector('rect');

    for (const attr of ['width', 'height']) {
      let v = Number(target.getAttribute(attr));
      v += event.deltaRect[attr];
      target.setAttribute(attr, Math.round(v/10)*10);
    }

    for (const attr of ['top', 'left']) {
      const a = attr == 'left' ? 'x' : 'y';
      let v = Number(target.getAttribute(a));
      v += event.deltaRect[attr];
      target.setAttribute(a, Math.round(v/10)*10);
    }

    findLocations(rect, handles);
  });

findLocations(rect, handles);

svg {
  width: 100%;
  height: 240px;
  background-color: #2e9;
  
  -ms-touch-action: none;
      touch-action: none;
}
body { margin: 0; }

<script src="https://cdn.jsdelivr.net/npm/interactjs@latest/dist/interact.min.js"></script>

<svg id="mysvg"></svg>