Merge #15928: GUI: Move QRImageWidget to its own file-pair

fc929842c20ac81869a33edce765e389a46e6c0c GUI: Move QRImageWidget to its own file-pair (Luke Dashjr)
77851ab682bf94f78874a245919bcc4b79dc054e GUI: Refactor actual QR code rendering into new QRImageWidget::setQR (Luke Dashjr)

Pull request description:

  For at least QR-code based pairing of mobile wallets with nodes, it will be desirable to render QR codes even without wallet support.

  Therefore, this prepares by moving the QRImageWidget out of a wallet-specific file into its own `qrencoder` file-pair.

ACKs for commit fc9298:
  laanwj:
    utACK fc929842c20ac81869a33edce765e389a46e6c0c
  jonasschnelli:
    utACK fc929842c20ac81869a33edce765e389a46e6c0c

Tree-SHA512: 95529a38c0573a4b3f1253fb5f11ca07a5b3a9840ec24acc7d87270212f3c9f7c5b186d9274d297517a3b80494f38a57574fb9730b1574db01688539b987bd91

1 files changed, 45 insertions, 0 deletions

diff --git a/src/qt/qrimagewidget.h b/src/qt/qrimagewidget.h
new file mode 100644
index 0000000000..2a219ac101
--- /dev/null
+++ b/src/qt/qrimagewidget.h
@@ -0,0 +1,45 @@
+// Copyright (c) 2011-2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_QT_QRIMAGEWIDGET_H
+#define BITCOIN_QT_QRIMAGEWIDGET_H
+
+#include <QImage>
+#include <QLabel>
+
+/* Maximum allowed URI length */
+static const int MAX_URI_LENGTH = 255;
+
+/* Size of exported QR Code image */
+static const int QR_IMAGE_SIZE = 300;
+
+QT_BEGIN_NAMESPACE
+class QMenu;
+QT_END_NAMESPACE
+
+/* Label widget for QR code. This image can be dragged, dropped, copied and saved
+ * to disk.
+ */
+class QRImageWidget : public QLabel
+{
+    Q_OBJECT
+
+public:
+    explicit QRImageWidget(QWidget *parent = nullptr);
+    bool setQR(const QString& data, const QString& text = "");
+    QImage exportImage();
+
+public Q_SLOTS:
+    void saveImage();
+    void copyImage();
+
+protected:
+    virtual void mousePressEvent(QMouseEvent *event);
+    virtual void contextMenuEvent(QContextMenuEvent *event);
+
+private:
+    QMenu *contextMenu;
+};
+
+#endif // BITCOIN_QT_QRIMAGEWIDGET_H