drag-canvas.ts
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import {G6} from "@/g6/g6";
const Util = G6.Util
const abs = Math.abs;
const DRAG_OFFSET = 10;
const body = document.body;
const ALLOW_EVENTS = [16, 17, 18];
export function dragCanvas(G6) {
G6.registerBehavior('drag-canvas', {
getDefaultCfg() {
return {
direction: 'both'
};
},
getEvents() {
return {
'canvas:mousedown': 'onMouseDown',
'canvas:mousemove': 'onMouseMove',
'canvas:mouseup': 'onMouseUp',
'canvas:click': 'onMouseUp',
'canvas:mouseleave': 'onOutOfRange',
keyup: 'onKeyUp',
keydown: 'onKeyDown'
};
},
updateViewport(e) {
const origin = this.origin;
const clientX = +e.clientX;
const clientY = +e.clientY;
if (isNaN(clientX) || isNaN(clientY)) {
return;
}
let dx = clientX - origin.x;
let dy = clientY - origin.y;
if (this.get('direction') === 'x') {
dy = 0;
} else if (this.get('direction') === 'y') {
dx = 0;
}
this.origin = {
x: clientX,
y: clientY
};
this.graph.translate(dx, dy);
this.graph.paint();
},
onMouseDown(e) {
if (e.event.button === 2) {
return;
}
if (this.keydown) {
return;
}
this.origin = {x: e.clientX, y: e.clientY};
this.dragging = false;
},
onMouseMove(e) {
if (this.keydown) {
return;
}
e = Util.cloneEvent(e);
const graph = this.graph;
if (!this.origin) { return; }
if (this.origin && !this.dragging) {
if (abs(this.origin.x - e.clientX) + abs(this.origin.y - e.clientY) < DRAG_OFFSET) {
return;
}
if (this.shouldBegin.call(this, e)) {
e.type = 'dragstart';
graph.emit('canvas:dragstart', e);
this.dragging = true;
}
}
if (this.dragging) {
e.type = 'drag';
graph.emit('canvas:drag', e);
}
if (this.shouldUpdate.call(this, e)) {
this.updateViewport(e);
}
},
onMouseUp(e) {
if (this.keydown) {
return;
}
if (!this.dragging) {
this.origin = null;
return;
}
e = Util.cloneEvent(e);
const graph = this.graph;
if (this.shouldEnd.call(this, e)) {
this.updateViewport(e);
}
e.type = 'dragend';
graph.emit('canvas:dragend', e);
this.endDrag();
},
endDrag() {
if (this.dragging) {
this.origin = null;
this.dragging = false;
// 终止时需要判断此时是否在监听画布外的 mouseup 事件，若有则解绑
const fn = this.fn;
if (fn) {
body.removeEventListener('mouseup', fn, false);
this.fn = null;
}
}
},
// 若在拖拽时，鼠标移出画布区域，此时放开鼠标无法终止 drag 行为。在画布外监听 mouseup 事件，放开则终止
onOutOfRange(e) {
if (this.dragging) {
const self = this;
const canvasElement = self.graph.get('canvas').get('el');
const fn = ev => {
if (ev.target !== canvasElement) {
self.onMouseUp(e);
}
};
this.fn = fn;
body.addEventListener('mouseup', fn, false);
}
},
onKeyDown(e) {
const code = e.keyCode || e.which;
if (ALLOW_EVENTS.indexOf(code) > -1) {
this.keydown = true;
} else {
this.keydown = false;
}
},
onKeyUp() {
this.keydown = false;
}
})
}