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Merge pull request #239 from binbat/feat/web-qrcode-stream-timestamp
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feat(web): add human readable timestamp to QRCode stream
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a-wing authored Oct 20, 2024
2 parents 697286e + f972977 commit 1552bf5
Showing 1 changed file with 43 additions and 1 deletion.
44 changes: 43 additions & 1 deletion web/shared/qrcode-stream.ts
Original file line number Diff line number Diff line change
@@ -1,10 +1,23 @@
import { Encoder, Numeric, binarize, Decoder, Detector, grayscale } from '@nuintun/qrcode';
import { TypedEventTarget } from "typescript-event-target";
import { TypedEventTarget } from 'typescript-event-target';

function timestamp(value: number) {
const date = new Date(value);
const s = date.toLocaleString('zh-CN', {
hour: '2-digit',
minute: '2-digit',
second: '2-digit',
hourCycle: 'h23'
});
const ms = date.getMilliseconds().toString().padStart(3, '0');
return `${s}.${ms}`;
}

export class QRCodeStream {

static White = '#fff';
static Black = '#000';
static TimestampTextSample = '12:34:56.789';

private encoder: Encoder;
private width: number;
Expand All @@ -13,6 +26,8 @@ export class QRCodeStream {
private qrSize: number;
private qrMarginX: number;
private qrMarginY: number;
private textOriginX: number;
private textOriginY: number;

private scheduled = false;
private frameRequestCallback: FrameRequestCallback;
Expand All @@ -29,6 +44,32 @@ export class QRCodeStream {
this.qrMarginX = (width - this.qrSize) / 2;
this.qrMarginY = (height - this.qrSize) / 2;
this.frameRequestCallback = this.frameRequestCallback_unbound.bind(this);
// try fit timestamp text beside QR code
const textMarginX = Math.max(4, width * 0.01);
const textMarginY = Math.max(4, height * 0.01);
let fontSize = 1000;
this.ctx.font = `bold ${fontSize}px monospace`;
const metrics = this.ctx.measureText(QRCodeStream.TimestampTextSample);
const textWidth = metrics.width;
const textHeight = metrics.actualBoundingBoxAscent + metrics.actualBoundingBoxDescent;
if (this.qrMarginX > 0) {
if (textWidth > this.qrMarginX) {
fontSize *= (this.qrMarginX - textMarginX * 2) / textWidth;
}
} else if (this.qrMarginY > 0) {
let scale = 1;
if (textWidth > this.width) {
scale = Math.min(scale, (this.width - textMarginX * 2) / textWidth);
}
if (textHeight > this.qrMarginY) {
scale = Math.min(scale, (this.qrMarginY - textMarginY * 2) / textHeight);
}
fontSize *= scale;
}
this.ctx.font = `bold ${fontSize}px monospace`;
this.textOriginX = textMarginX;
const realMetrics = this.ctx.measureText(QRCodeStream.TimestampTextSample);
this.textOriginY = textMarginY + realMetrics.actualBoundingBoxAscent + realMetrics.actualBoundingBoxDescent;;
}

private doFrame(now: number) {
Expand All @@ -50,6 +91,7 @@ export class QRCodeStream {
}
}
}
this.ctx.fillText(timestamp(now), this.textOriginX, this.textOriginY);
}

private frameRequestCallback_unbound(_time: DOMHighResTimeStamp) {
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