import { toCanvas } from 'qrcode';
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import type { QRCodeRenderersOptions } from 'qrcode';
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import { RenderQrCodeParams, ContentType } from './typing';
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export const renderQrCode = ({ canvas, content, width = 0, options = {} }: RenderQrCodeParams) => {
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// 容错率，默认对内容少的二维码采用高容错率，内容多的二维码采用低容错率
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options.errorCorrectionLevel = options.errorCorrectionLevel || getErrorCorrectionLevel(content);
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return getOriginWidth(content, options).then((_width: number) => {
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options.scale = width === 0 ? undefined : (width / _width) * 4;
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return toCanvas(canvas, content, options);
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});
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};
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// 得到原QrCode的大小，以便缩放得到正确的QrCode大小
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function getOriginWidth(content: ContentType, options: QRCodeRenderersOptions) {
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const _canvas = document.createElement('canvas');
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return toCanvas(_canvas, content, options).then(() => _canvas.width);
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}
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// 对于内容少的QrCode，增大容错率
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function getErrorCorrectionLevel(content: ContentType) {
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if (content.length > 36) {
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return 'M';
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} else if (content.length > 16) {
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return 'Q';
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} else {
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return 'H';
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}
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}
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