Question

var canvas = document.getElementById('canvas'),
    ctx = canvas.getContext('2d'),
    rect = {
        x: 150,
        y: 100,
        w: 123,
        h: 58
    },
    handlesSize = 4,
    currentHandle = false,
    drag = false;

function init() {
    canvas.addEventListener('mousedown', mouseDown, false);
    canvas.addEventListener('mouseup', mouseUp, false);
    canvas.addEventListener('mousemove', mouseMove, false);
}

function point(x, y) {
    return {
        x: x,
        y: y
    };
}

function dist(p1, p2) {
    return Math.sqrt((p2.x - p1.x) * (p2.x - p1.x) + (p2.y - p1.y) * (p2.y - p1.y));
}

function getHandle(mouse) {
    if (dist(mouse, point(rect.x, rect.y)) <= handlesSize) return 'topleft';
    if (dist(mouse, point(rect.x + rect.w, rect.y)) <= handlesSize) return 'topright';
    if (dist(mouse, point(rect.x, rect.y + rect.h)) <= handlesSize) return 'bottomleft';
    if (dist(mouse, point(rect.x + rect.w, rect.y + rect.h)) <= handlesSize) return 'bottomright';
    if (dist(mouse, point(rect.x + rect.w / 2, rect.y)) <= handlesSize) return 'top';
    if (dist(mouse, point(rect.x, rect.y + rect.h / 2)) <= handlesSize) return 'left';
    if (dist(mouse, point(rect.x + rect.w / 2, rect.y + rect.h)) <= handlesSize) return 'bottom';
    if (dist(mouse, point(rect.x + rect.w, rect.y + rect.h / 2)) <= handlesSize) return 'right';
    return false;
}

function mouseDown(e) {
    if (currentHandle) drag = true;
    draw();
}

function mouseUp() {
    drag = false;
    currentHandle = false;
    draw();
}

function mouseMove(e) {
    var previousHandle = currentHandle;
    if (!drag) currentHandle = getHandle(point(e.pageX - this.offsetLeft, e.pageY - this.offsetTop));
    if (currentHandle && drag) {
        var mousePos = point(e.pageX - this.offsetLeft, e.pageY - this.offsetTop);
        switch (currentHandle) {
            case 'topleft':
                rect.w += rect.x - mousePos.x;
                rect.h += rect.y - mousePos.y;
                rect.x = mousePos.x;
                rect.y = mousePos.y;
                break;
            case 'topright':
                rect.w = mousePos.x - rect.x;
                rect.h += rect.y - mousePos.y;
                rect.y = mousePos.y;
                break;
            case 'bottomleft':
                rect.w += rect.x - mousePos.x;
                rect.x = mousePos.x;
                rect.h = mousePos.y - rect.y;
                break;
            case 'bottomright':
                rect.w = mousePos.x - rect.x;
                rect.h = mousePos.y - rect.y;
                break;

            case 'top':
                rect.h += rect.y - mousePos.y;
                rect.y = mousePos.y;
                break;

            case 'left':
                rect.w += rect.x - mousePos.x;
                rect.x = mousePos.x;
                break;

            case 'bottom':
                rect.h = mousePos.y - rect.y;
                break;

            case 'right':
                rect.w = mousePos.x - rect.x;
                break;
        }
    }
    if (drag || currentHandle != previousHandle) draw();
}

function draw() {
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    ctx.fillStyle = 'black';
    ctx.fillRect(rect.x, rect.y, rect.w, rect.h);
    if (currentHandle) {
        var posHandle = point(0, 0);
        switch (currentHandle) {
            case 'topleft':
                posHandle.x = rect.x;
                posHandle.y = rect.y;
                break;
            case 'topright':
                posHandle.x = rect.x + rect.w;
                posHandle.y = rect.y;
                break;
            case 'bottomleft':
                posHandle.x = rect.x;
                posHandle.y = rect.y + rect.h;
                break;
            case 'bottomright':
                posHandle.x = rect.x + rect.w;
                posHandle.y = rect.y + rect.h;
                break;
            case 'top':
                posHandle.x = rect.x + rect.w / 2;
                posHandle.y = rect.y;
                break;
            case 'left':
                posHandle.x = rect.x;
                posHandle.y = rect.y + rect.h / 2;
                break;
            case 'bottom':
                posHandle.x = rect.x + rect.w / 2;
                posHandle.y = rect.y + rect.h;
                break;
            case 'right':
                posHandle.x = rect.x + rect.w;
                posHandle.y = rect.y + rect.h / 2;
                break;
        }
        ctx.globalCompositeOperation = 'xor';
        ctx.beginPath();
        ctx.arc(posHandle.x, posHandle.y, handlesSize, 0, 2 * Math.PI);
        ctx.fill();
        ctx.globalCompositeOperation = 'source-over';
    }
}

init();
draw();

<canvas id="canvas" width="500" height="500"></canvas>

此链接包含我在结构js中需要的示例，用于调整具有固定角的矩形区域的大小，而不会以悬停为例。

Answer 1

你可以通过以下方式实现这一目标......

设置lockMovementX = true和lockMovementY = true以防止移动矩形对象
禁用角落控件以防止角落大小调整矩形对象（使其固定角落）

let canvas = new fabric.Canvas('canvas');
let rect = new fabric.Rect({
  left: 100,
  top: 100,
  fill: '#07C',
  width: 100,
  height: 100,
  hoverCursor: 'default'
});
canvas.add(rect);

// prevent movement
rect.lockMovementX = true;
rect.lockMovementY = true;

// prevent corner resizing
rect.setControlsVisibility({
  tl: false,
  tr: false,
  bl: false,
  br: false,
  mtr: false
});

canvas {
  border: 1px solid lightgrey;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/1.7.9/fabric.min.js"></script>
<canvas id="canvas" width="300" height="300"></canvas>

使用fabric js调整四个角的矩形

1 个答案: