55 lines
1.8 KiB
C++
55 lines
1.8 KiB
C++
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#include "QrUtils.h"
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#include <qrcode.h>
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#include <algorithm>
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#include <memory>
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#include "Logging.h"
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void QrUtils::drawQrCode(const GfxRenderer& renderer, const Rect& bounds, const std::string& textPayload) {
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// Dynamically calculate the QR code version based on text length
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// Version 4 holds ~114 bytes, Version 10 ~395, Version 20 ~1066, up to 40
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// qrcode.h max version is 40.
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// Formula: approx version = size / 26 + 1 (very rough estimate, better to find best fit)
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const size_t len = textPayload.length();
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int version = 4;
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if (len > 114) version = 10;
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if (len > 395) version = 20;
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if (len > 1066) version = 30;
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if (len > 2110) version = 40;
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// Make sure we have a large enough buffer on the heap to avoid blowing the stack
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uint32_t bufferSize = qrcode_getBufferSize(version);
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auto qrcodeBytes = std::make_unique<uint8_t[]>(bufferSize);
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QRCode qrcode;
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// Initialize the QR code. We use ECC_LOW for max capacity.
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int8_t res = qrcode_initText(&qrcode, qrcodeBytes.get(), version, ECC_LOW, textPayload.c_str());
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if (res == 0) {
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// Determine the optimal pixel size.
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const int maxDim = std::min(bounds.width, bounds.height);
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int px = maxDim / qrcode.size;
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if (px < 1) px = 1;
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// Calculate centering X and Y
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const int qrDisplaySize = qrcode.size * px;
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const int xOff = bounds.x + (bounds.width - qrDisplaySize) / 2;
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const int yOff = bounds.y + (bounds.height - qrDisplaySize) / 2;
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// Draw the QR Code
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for (uint8_t cy = 0; cy < qrcode.size; cy++) {
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for (uint8_t cx = 0; cx < qrcode.size; cx++) {
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if (qrcode_getModule(&qrcode, cx, cy)) {
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renderer.fillRect(xOff + px * cx, yOff + px * cy, px, px, true);
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}
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}
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}
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} else {
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// If it fails (e.g. text too large), log an error
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LOG_ERR("QR", "Text too large for QR Code version %d", version);
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}
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}
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