text: // Copyright (c) 2011-2020 The Beans Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include <qt/qrimagewidget.h>
  
  #include <qt/guiutil.h>
  
  #include <QApplication>
  #include <QClipboard>
  #include <QDrag>
  #include <QFontDatabase>
  #include <QMenu>
  #include <QMimeData>
  #include <QMouseEvent>
  #include <QPainter>
  
  #if defined(HAVE_CONFIG_H)
  #include <config/beans-config.h> /* for USE_QRCODE */
  #endif
  
  #ifdef USE_QRCODE
  #include <qrencode.h>
  #endif
  
  QRImageWidget::QRImageWidget(QWidget *parent):
      QLabel(parent), contextMenu(nullptr)
  {
      contextMenu = new QMenu(this);
      contextMenu->addAction(tr("Save Image…"), this, &QRImageWidget::saveImage);
      contextMenu->addAction(tr("Copy Image"), this, &QRImageWidget::copyImage);
  }
  
  bool QRImageWidget::setQR(const QString& data, const QString& text)
  {
  #ifdef USE_QRCODE
      setText("");
      if (data.isEmpty()) return false;
  
      // limit length
      if (data.length() > MAX_URI_LENGTH) {
          setText(tr("Resulting URI too long, try to reduce the text for label / message."));
          return false;
      }
  
      QRcode *code = QRcode_encodeString(data.toUtf8().constData(), 0, QR_ECLEVEL_L, QR_MODE_8, 1);
  
      if (!code) {
          setText(tr("Error encoding URI into QR Code."));
          return false;
      }
  
      QImage qrImage = QImage(code->width + 8, code->width + 8, QImage::Format_RGB32);
      qrImage.fill(0xffffff);
      unsigned char *p = code->data;
      for (int y = 0; y < code->width; ++y) {
          for (int x = 0; x < code->width; ++x) {
              qrImage.setPixel(x + 4, y + 4, ((*p & 1) ? 0x0 : 0xffffff));
              ++p;
          }
      }
      QRcode_free(code);
  
      const int qr_image_size = QR_IMAGE_SIZE + (text.isEmpty() ? 0 : 2 * QR_IMAGE_MARGIN);
      QImage qrAddrImage(qr_image_size, qr_image_size, QImage::Format_RGB32);
      qrAddrImage.fill(0xffffff);
      {
          QPainter painter(&qrAddrImage);
          painter.drawImage(QR_IMAGE_MARGIN, 0, qrImage.scaled(QR_IMAGE_SIZE, QR_IMAGE_SIZE));
  
          if (!text.isEmpty()) {
              QRect paddedRect = qrAddrImage.rect();
              paddedRect.setHeight(QR_IMAGE_SIZE + QR_IMAGE_TEXT_MARGIN);
  
              QFont font = GUIUtil::fixedPitchFont();
              font.setStretch(QFont::SemiCondensed);
              font.setLetterSpacing(QFont::AbsoluteSpacing, 1);
              const qreal font_size = GUIUtil::calculateIdealFontSize(paddedRect.width() - 2 * QR_IMAGE_TEXT_MARGIN, text, font);
              font.setPointSizeF(font_size);
  
              painter.setFont(font);
              painter.drawText(paddedRect, Qt::AlignBottom | Qt::AlignCenter, text);
          }
      }
  
      setPixmap(QPixmap::fromImage(qrAddrImage));
  
      return true;
  #else
      setText(tr("QR code support not available."));
      return false;
  #endif
  }
  
  QImage QRImageWidget::exportImage()
  {
      return GUIUtil::GetImage(this);
  }
  
  void QRImageWidget::mousePressEvent(QMouseEvent *event)
  {
      if (event->button() == Qt::LeftButton && GUIUtil::HasPixmap(this)) {
          event->accept();
          QMimeData *mimeData = new QMimeData;
          mimeData->setImageData(exportImage());
  
          QDrag *drag = new QDrag(this);
          drag->setMimeData(mimeData);
          drag->exec();
      } else {
          QLabel::mousePressEvent(event);
      }
  }
  
  void QRImageWidget::saveImage()
  {
      if (!GUIUtil::HasPixmap(this))
          return;
      QString fn = GUIUtil::getSaveFileName(
          this, tr("Save QR Code"), QString(),
          tr("PNG Image", "Name of PNG file format") + QLatin1String(" (*.png)"), nullptr);
      if (!fn.isEmpty())
      {
          exportImage().save(fn);
      }
  }
  
  void QRImageWidget::copyImage()
  {
      if (!GUIUtil::HasPixmap(this))
          return;
      QApplication::clipboard()->setImage(exportImage());
  }
  
  void QRImageWidget::contextMenuEvent(QContextMenuEvent *event)
  {
      if (!GUIUtil::HasPixmap(this))
          return;
      contextMenu->exec(event->globalPos());
  }
  