使用 KonvaJS 绘制和旋转图像
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【中文标题】使用 KonvaJS 绘制和旋转图像【英文标题】：Drawing and rotated images using KonvaJS 【发布时间】：2020-07-01 17:26:40 【问题描述】：所以我一直在尝试使用 Konva 来绘制图像、文本和形状的数量，一切都很好，直到我尝试在混合中添加旋转。我知道 Konva 使用原点（默认情况下可以通过偏移移动的左上角）来旋转图像，但我需要位置始终位于左上角。
所以我试图计算、旋转重新定位对象以模仿我想要的东西，但这总是导致图像位置与我的初始状态不同，这是一种不需要的行为。
所以我的问题是，Konva 可以从中心旋转图像，同时在旋转后保持原点位置在左上角吗？
*使用代码示例编辑： 绿色框/文本旋转但位置全错。我需要在左边的位置。
const stage = new Konva.Stage(
container: 'container',
width: window.innerWidth,
height: window.innerHeight
);
const layer = new Konva.Layer();
stage.add(layer);
const rotatePoint= (x, y , rad)=>
const rcos = Math.cos(rad);
const rsin = Math.sin(rad);
return
x: x * rcos - y * rsin,
y: y * rcos + x * rsin
const rotateAroundCenter = (node, rotation) =>
const topLeft = x: -node.width() / 2, y: -node.height() / 2 ;
const current = rotatePoint(topLeft.x, topLeft.y, Konva.getAngle(node.rotation()));
const rotated = rotatePoint(topLeft.x, topLeft.y, Konva.getAngle(rotation));
const dx = rotated.x - current.x,
dy = rotated.y - current.y;
node.rotation(rotation);
node.x(node.x() + dx);
node.y(node.y() + dy);
return node;
let x = 100,
y = 50,
width = 50,
height = 50;
const rotation = 90;
const text = width, height, fontSize: 15, fontFamily: 'Calibri', text: 'Simple Text', opacity: 0.5 ;
const rect = width, height, strokeWidth: 2
let pos = x, y;
layer.add(new Konva.Circle( ...pos, radius:5, fill: 'black' ));
layer.add(new Konva.Text( ...pos, ...text, fill: 'black' ));
layer.add(new Konva.Rect( ...pos, ...rect, stroke: 'purple' ));
layer.add(new Konva.Text( ...pos, ...text, fill: 'purple', rotation: rotation ));
layer.add(new Konva.Rect( ...pos, ...rect, stroke: 'purple', rotation: rotation ));
pos = x, y:150;
layer.add(new Konva.Circle( ...pos, radius:5, fill: 'black' ));
layer.add(rotateAroundCenter(new Konva.Text( ...pos, ...text, fill: 'green' ), rotation));
layer.add(rotateAroundCenter(new Konva.Rect( ...pos, ...rect, stroke: 'green' ), rotation));
layer.draw();<!DOCTYPE html>
<html>
<head>
<meta name="description" content="KonvaJS Template">
<script src="https://cdnjs.cloudflare.com/ajax/libs/konva/4.2.0/konva.min.js"></script>
<meta charset="utf-8">
</head>
<body>
<div id="container"></div>
</body>
</html>【问题讨论】：
请提供您的一些代码或您的问题的最小表示 您可以手动将节点的位置移动到所需的数量，以将节点保持在屏幕的预期位置。 【参考方案1】：好吧，基本上必须按照 lavrton 说的做，将形状放在一个组中（位置正确），然后在组内旋转和偏移形状。
const stage = new Konva.Stage(
container: 'container',
width: 300,
height: 700
);
const layer = new Konva.Layer();
stage.add(layer);
const rotatePoint = ( x, y , rad) =>
const rcos = Math.cos(rad);
const rsin = Math.sin(rad);
return x: x * rcos - y * rsin, y: y * rcos + x * rsin ;
// will work for shapes with top-left origin, like rectangle
const rotateAroundCenter = (node, rotation) =>
//current rotation origin (0, 0) relative to desired origin - center (node.width()/2, node.height()/2)
const topLeft = x: -node.width() / 2, y: -node.height() / 2 ;
const current = rotatePoint(topLeft, Konva.getAngle(node.rotation()));
const rotated = rotatePoint(topLeft, Konva.getAngle(rotation));
const dx = rotated.x - current.x,
dy = rotated.y - current.y;
const r = Math.floor(rotation / 90) % 4;
switch(r)
case 1:
case 3:
node.x(node.x() + dx + node.height()/2);
node.y(node.y() + dy + node.width()/2);
break;
case 2:
default:
node.x(node.x() + dx + node.width()/2);
node.y(node.y() + dy + node.height()/2);
break;
node.rotation(rotation);
return node;
let x = 200, y = 250, width = 30, height = 75, text = "? ? ? ? ?", opacity = 0.4;
drawShapes = (x, y, width, height, rotation) =>
layer.add(new Konva.Text(x:0, y, fill: 'black', text: (rotation+"°").padStart(5,"_")));
layer.add(new Konva.Rect(x, y, width, height, fill: 'black', rotation));
layer.add(new Konva.Text(x, y, width, height, fill: 'white', rotation, text));
const group = new Konva.Group( x, y,/* clip:x:0,y:0,width:200,height:200*/)
group.add(rotateAroundCenter(new Konva.Rect(x:-width/2,y:-height/2, width, height,fill: 'grey', opacity), rotation));
group.add(rotateAroundCenter(new Konva.Text(x:-width/2,y:-height/2, width, height,fill: 'black', text), rotation));
layer.add(group, new Konva.Circle(x, y, radius: 2, fill: 'black'));
drawShapes(x, 50, width, height, 0);
drawShapes(x, 200, width, height, 90);
drawShapes(x, 350, width, height, 180);
drawShapes(x, 500, width, height, 270);
layer.draw();<!DOCTYPE html>
<html>
<head>
<meta name="description" content="KonvaJS Template">
<script src="https://cdnjs.cloudflare.com/ajax/libs/konva/4.2.0/konva.min.js"></script>
<meta charset="utf-8">
</head>
<body>
<div id="container" style="height:700px"></div>
</body>
</html>【讨论】：
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