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A fork of https://github.com/crosspoint-reader/crosspoint-reader
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2.3 kB · 66 lines
C++
12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667#include "QrUtils.h"
#include <Utf8.h>#include <qrcode.h>
#include <algorithm>#include <memory>
#include "Logging.h"
void QrUtils::drawQrCode(const GfxRenderer& renderer, const Rect& bounds, const std::string& textPayload) { // Dynamically calculate the QR code version based on text length // Version 4 holds ~114 bytes, Version 10 ~395, Version 20 ~1066, up to 40 // qrcode.h max version is 40. // Formula: approx version = size / 26 + 1 (very rough estimate, better to find best fit) size_t len = textPayload.length();
// Truncate to max QR capacity at a UTF-8 safe boundary to avoid splitting multi-byte sequences static constexpr size_t MAX_QR_CAPACITY = 2953; // Version 40, ECC_LOW, byte mode std::string truncated; const char* payload = textPayload.c_str(); if (len > MAX_QR_CAPACITY) { len = utf8SafeTruncateBuffer(textPayload.c_str(), static_cast<int>(MAX_QR_CAPACITY)); truncated = textPayload.substr(0, len); payload = truncated.c_str(); }
int version = 4; if (len > 114) version = 10; if (len > 395) version = 20; if (len > 1066) version = 30; if (len > 2110) version = 40;
// Make sure we have a large enough buffer on the heap to avoid blowing the stack uint32_t bufferSize = qrcode_getBufferSize(version); auto qrcodeBytes = std::make_unique<uint8_t[]>(bufferSize);
QRCode qrcode; // Initialize the QR code. We use ECC_LOW for max capacity. int8_t res = qrcode_initText(&qrcode, qrcodeBytes.get(), version, ECC_LOW, payload);
if (res == 0) { // Determine the optimal pixel size. const int maxDim = std::min(bounds.width, bounds.height);
int px = maxDim / qrcode.size; if (px < 1) px = 1;
// Calculate centering X and Y const int qrDisplaySize = qrcode.size * px; const int xOff = bounds.x + (bounds.width - qrDisplaySize) / 2; const int yOff = bounds.y + (bounds.height - qrDisplaySize) / 2;
// Draw the QR Code for (uint8_t cy = 0; cy < qrcode.size; cy++) { for (uint8_t cx = 0; cx < qrcode.size; cx++) { if (qrcode_getModule(&qrcode, cx, cy)) { renderer.fillRect(xOff + px * cx, yOff + px * cy, px, px, true); } } } } else { // If it fails (e.g. text too large), log an error LOG_ERR("QR", "Text too large for QR Code version %d", version); }}