index.js
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import { VantComponent } from '../common/component';
import { isObj } from '../common/utils';
import { BLUE, WHITE } from '../common/color';
function format(rate) {
return Math.min(Math.max(rate, 0), 100);
}
const PERIMETER = 2 * Math.PI;
const BEGIN_ANGLE = -Math.PI / 2;
const STEP = 1;
VantComponent({
props: {
text: String,
lineCap: {
type: String,
value: 'round'
},
value: {
type: Number,
value: 0,
observer: 'reRender'
},
speed: {
type: Number,
value: 50
},
size: {
type: Number,
value: 100,
observer: 'setStyle'
},
fill: String,
layerColor: {
type: String,
value: WHITE
},
color: {
type: [String, Object],
value: BLUE,
observer: 'setHoverColor'
},
strokeWidth: {
type: Number,
value: 4
},
clockwise: {
type: Boolean,
value: true
}
},
data: {
style: 'width: 100px; height: 100px;',
hoverColor: BLUE
},
methods: {
getContext() {
if (!this.ctx) {
this.ctx = wx.createCanvasContext('van-circle', this);
}
return this.ctx;
},
setHoverColor() {
const context = this.getContext();
const { color, size } = this.data;
let hoverColor = color;
if (isObj(color)) {
const LinearColor = context.createLinearGradient(size, 0, 0, 0);
Object.keys(color)
.sort((a, b) => parseFloat(a) - parseFloat(b))
.map(key => LinearColor.addColorStop(parseFloat(key) / 100, color[key]));
hoverColor = LinearColor;
}
this.setData({ hoverColor });
},
setStyle() {
const { size } = this.data;
const style = `width: ${size}px; height: ${size}px;`;
this.setData({ style });
},
presetCanvas(context, strokeStyle, beginAngle, endAngle, fill) {
const { strokeWidth, lineCap, clockwise, size } = this.data;
const position = size / 2;
const radius = position - strokeWidth / 2;
context.setStrokeStyle(strokeStyle);
context.setLineWidth(strokeWidth);
context.setLineCap(lineCap);
context.beginPath();
context.arc(position, position, radius, beginAngle, endAngle, !clockwise);
context.stroke();
if (fill) {
context.setFillStyle(fill);
context.fill();
}
},
renderLayerCircle(context) {
const { layerColor, fill } = this.data;
this.presetCanvas(context, layerColor, 0, PERIMETER, fill);
},
renderHoverCircle(context, formatValue) {
const { clockwise, hoverColor } = this.data;
// 结束角度
const progress = PERIMETER * (formatValue / 100);
const endAngle = clockwise
? BEGIN_ANGLE + progress
: 3 * Math.PI - (BEGIN_ANGLE + progress);
this.presetCanvas(context, hoverColor, BEGIN_ANGLE, endAngle);
},
drawCircle(currentValue) {
const context = this.getContext();
const { size } = this.data;
context.clearRect(0, 0, size, size);
this.renderLayerCircle(context);
const formatValue = format(currentValue);
if (formatValue !== 0) {
this.renderHoverCircle(context, formatValue);
}
context.draw();
},
reRender() {
// tofector 动画暂时没有想到好的解决方案
const { value, speed } = this.data;
if (speed <= 0 || speed > 1000) {
this.drawCircle(value);
return;
}
this.clearInterval();
this.currentValue = this.currentValue || 0;
this.interval = setInterval(() => {
if (this.currentValue !== value) {
if (this.currentValue < value) {
this.currentValue += STEP;
}
else {
this.currentValue -= STEP;
}
this.drawCircle(this.currentValue);
}
else {
this.clearInterval();
}
}, 1000 / speed);
},
clearInterval() {
if (this.interval) {
clearInterval(this.interval);
this.interval = null;
}
}
},
created() {
const { value } = this.data;
this.currentValue = value;
this.drawCircle(value);
},
destroyed() {
this.ctx = null;
this.clearInterval();
}
});