Resizeable QrCode

src/widgets/QrCodeWidget.cpp

@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: BSD-3-Clause
+// Copyright (c) 2020-2021, The Monero Project.
+
+#include "QrCodeWidget.h"
+
+#include <QColor>
+#include <QPainter>
+#include <QPen>
+
+QrCodeWidget::QrCodeWidget(QWidget *parent) : QWidget(parent)
+{
+}
+
+void QrCodeWidget::setQrCode(QrCode *qrCode) {
+    m_qrcode = qrCode;
+
+    int k = m_qrcode->width();
+    this->setMinimumSize(k*5, k*5);
+
+    this->update();
+}
+
+void QrCodeWidget::paintEvent(QPaintEvent *event) {
+    // Implementation adapted from Electrum: qrcodewidget.py
+    if (!m_qrcode) {
+        return;
+    }
+
+    QColor black{0, 0, 0, 255};
+    QColor white{255, 255, 255, 255};
+    QPen blackPen{black};
+    blackPen.setJoinStyle(Qt::MiterJoin);
+
+    QPainter painter(this);
+
+    auto r = painter.viewport();
+    int k = m_qrcode->width();
+    int margin = 10;
+    int framesize = std::min(r.width(), r.height());
+    int boxsize = int((framesize - (2*margin)) / k);
+    int size = k*boxsize;
+    int left = (framesize - size)/2;
+    int top = (framesize - size)/2;
+
+    painter.setBrush(white);
+    painter.setPen(white);
+    painter.drawRect(0, 0, framesize, framesize);
+
+    painter.setBrush(black);
+    painter.setPen(blackPen);
+
+    unsigned char* dot = m_qrcode->data();
+    for (int row = 0; row < k; row++) {
+        for (int column = 0; column < k; column++) {
+            if (quint8(0x01) == (static_cast<quint8>(*dot++) & quint8(0x01))) {
+                painter.drawRect(int(left+(column*boxsize)), int(top+(row*boxsize)), boxsize - 1, boxsize - 1);
+            }
+        }
+    }
+}