qrimagewidget.cpp raw

   1  // Copyright (c) 2011-present The Bitcoin Core developers
   2  // Distributed under the MIT software license, see the accompanying
   3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   4  
   5  #include <qt/qrimagewidget.h>
   6  
   7  #include <qt/guiutil.h>
   8  
   9  #include <QApplication>
  10  #include <QClipboard>
  11  #include <QDrag>
  12  #include <QFontDatabase>
  13  #include <QMenu>
  14  #include <QMimeData>
  15  #include <QMouseEvent>
  16  #include <QPainter>
  17  
  18  #include <bitcoin-build-config.h> // IWYU pragma: keep
  19  
  20  #ifdef USE_QRCODE
  21  #include <qrencode.h>
  22  #endif
  23  
  24  QRImageWidget::QRImageWidget(QWidget* parent)
  25      : QLabel(parent)
  26  {
  27      contextMenu = new QMenu(this);
  28      contextMenu->addAction(tr("&Save Image…"), this, &QRImageWidget::saveImage);
  29      contextMenu->addAction(tr("&Copy Image"), this, &QRImageWidget::copyImage);
  30  }
  31  
  32  bool QRImageWidget::setQR(const QString& data, const QString& text)
  33  {
  34  #ifdef USE_QRCODE
  35      setText("");
  36      if (data.isEmpty()) return false;
  37  
  38      // limit length
  39      if (data.length() > MAX_URI_LENGTH) {
  40          setText(tr("Resulting URI too long, try to reduce the text for label / message."));
  41          return false;
  42      }
  43  
  44      QRcode *code = QRcode_encodeString(data.toUtf8().constData(), 0, QR_ECLEVEL_L, QR_MODE_8, 1);
  45  
  46      if (!code) {
  47          setText(tr("Error encoding URI into QR Code."));
  48          return false;
  49      }
  50  
  51      QImage qrImage = QImage(code->width + 8, code->width + 8, QImage::Format_RGB32);
  52      qrImage.fill(0xffffff);
  53      unsigned char *p = code->data;
  54      for (int y = 0; y < code->width; ++y) {
  55          for (int x = 0; x < code->width; ++x) {
  56              qrImage.setPixel(x + 4, y + 4, ((*p & 1) ? 0x0 : 0xffffff));
  57              ++p;
  58          }
  59      }
  60      QRcode_free(code);
  61  
  62      const int qr_image_size = QR_IMAGE_SIZE + (text.isEmpty() ? 0 : 2 * QR_IMAGE_MARGIN);
  63      QImage qrAddrImage(qr_image_size, qr_image_size, QImage::Format_RGB32);
  64      qrAddrImage.fill(0xffffff);
  65      {
  66          QPainter painter(&qrAddrImage);
  67          painter.drawImage(QR_IMAGE_MARGIN, 0, qrImage.scaled(QR_IMAGE_SIZE, QR_IMAGE_SIZE));
  68  
  69          if (!text.isEmpty()) {
  70              QRect paddedRect = qrAddrImage.rect();
  71              paddedRect.setHeight(QR_IMAGE_SIZE + QR_IMAGE_TEXT_MARGIN);
  72  
  73              QFont font = GUIUtil::fixedPitchFont();
  74              font.setStretch(QFont::SemiCondensed);
  75              font.setLetterSpacing(QFont::AbsoluteSpacing, 1);
  76              const qreal font_size = GUIUtil::calculateIdealFontSize(paddedRect.width() - 2 * QR_IMAGE_TEXT_MARGIN, text, font);
  77              font.setPointSizeF(font_size);
  78  
  79              painter.setFont(font);
  80              painter.drawText(paddedRect, Qt::AlignBottom | Qt::AlignCenter, text);
  81          }
  82      }
  83  
  84      setPixmap(QPixmap::fromImage(qrAddrImage));
  85  
  86      return true;
  87  #else
  88      setText(tr("QR code support not available."));
  89      return false;
  90  #endif
  91  }
  92  
  93  QImage QRImageWidget::exportImage()
  94  {
  95      if (!GUIUtil::HasPixmap(this)) {
  96          return QImage();
  97      }
  98  
  99      return this->pixmap(Qt::ReturnByValue).toImage();
 100  }
 101  
 102  void QRImageWidget::mousePressEvent(QMouseEvent *event)
 103  {
 104      if (event->button() == Qt::LeftButton && GUIUtil::HasPixmap(this)) {
 105          event->accept();
 106          QMimeData *mimeData = new QMimeData;
 107          mimeData->setImageData(exportImage());
 108  
 109          QDrag *drag = new QDrag(this);
 110          drag->setMimeData(mimeData);
 111          drag->exec();
 112      } else {
 113          QLabel::mousePressEvent(event);
 114      }
 115  }
 116  
 117  void QRImageWidget::saveImage()
 118  {
 119      if (!GUIUtil::HasPixmap(this))
 120          return;
 121      QString fn = GUIUtil::getSaveFileName(
 122          this, tr("Save QR Code"), QString(),
 123          /*: Expanded name of the PNG file format.
 124              See: https://en.wikipedia.org/wiki/Portable_Network_Graphics. */
 125          tr("PNG Image") + QLatin1String(" (*.png)"), nullptr);
 126      if (!fn.isEmpty())
 127      {
 128          exportImage().save(fn);
 129      }
 130  }
 131  
 132  void QRImageWidget::copyImage()
 133  {
 134      if (!GUIUtil::HasPixmap(this))
 135          return;
 136      QApplication::clipboard()->setImage(exportImage());
 137  }
 138  
 139  void QRImageWidget::contextMenuEvent(QContextMenuEvent *event)
 140  {
 141      if (!GUIUtil::HasPixmap(this))
 142          return;
 143      contextMenu->exec(event->globalPos());
 144  }
 145