Merge #454: Add QRImageProvider

154c8e6 qml: Use QRImage in RequestPayment (goqusan)
c46517b qml: Add QRImage control (goqusan)
9e1f8a0 qml: Add QRImageProvider (goqusan)

Pull request description:

  The `QRImageProvider` can be used to display QR codes in QML `Image`.

  The new control `QRImage` wraps the new provider in a convenient way.

  The `RequestPayment` page is updated to showcase `QRImage` usage.

ACKs for top commit:
  johnny9:
    tACK 154c8e6

Tree-SHA512: eb4b57245943ca34495e10de6a2bc8e28a6d1148f5aa99d7150d48c2a49e9049c2c4d3b3a481780c9e55efa07c3caed45f18bb2f8aaa1c5bdb621cadadaa82df

Author: hebasto

qml/bitcoin.cpp

@@ -35,6 +35,7 @@
 #include <qml/models/walletlistmodel.h>
 #include <qml/models/walletqmlmodel.h>
 #include <qml/models/walletqmlmodeltransaction.h>
+#include <qml/qrimageprovider.h>
 #include <qml/util.h>
 #include <qml/walletqmlcontroller.h>
 #include <qt/guiutil.h>
@@ -313,6 +314,7 @@ int QmlGuiMain(int argc, char* argv[])
     QScopedPointer<const NetworkStyle> network_style{NetworkStyle::instantiate(Params().GetChainType())};
     assert(!network_style.isNull());
     engine.addImageProvider(QStringLiteral("images"), new ImageProvider{network_style.data()});
+    engine.addImageProvider(QStringLiteral("qr"), new QRImageProvider);
 
     engine.rootContext()->setContextProperty("networkTrafficTower", &network_traffic_tower);
     engine.rootContext()->setContextProperty("nodeModel", &node_model);

qml/bitcoin_qml.qrc

@@ -47,6 +47,7 @@
         <file>controls/PageIndicator.qml</file>
         <file>controls/PageStack.qml</file>
         <file>controls/ProgressIndicator.qml</file>
+        <file>controls/QRImage.qml</file>
         <file>controls/qmldir</file>
         <file>controls/SendOptionsPopup.qml</file>
         <file>controls/Setting.qml</file>

qml/controls/QRImage.qml

@@ -0,0 +1,17 @@
+// Copyright (c) 2025 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+import QtQuick 2.15
+
+Image {
+    id: root
+
+    property string code: ""
+    property color backgroundColor: Qt.black
+    property color foregroundColor: Qt.white
+
+    fillMode: Image.PreserveAspectFit
+    smooth: false
+    source: `image://qr/${encodeURIComponent(root.code)}?&fg=${encodeURIComponent(root.foregroundColor)}&bg=${encodeURIComponent(root.backgroundColor)}`
+}

qml/pages/wallet/RequestPayment.qml

@@ -199,6 +199,7 @@ Page {
                             clearRequest.visible = true
                             title.text = qsTr("Payment request #" + requestCounter)
                             address.text = "bc1q f5xe y2tf 89k9 zy6k gnru wszy 5fsa truy 9te1 bu"
+                            qrImage.code = "bc1qf5xey2tf89k9zy6kgnruwszy5fsatruy9te1bu"
                             continueButton.text = qsTr("Copy payment request")
                         }
                     }
@@ -220,19 +221,26 @@ Page {
                         clearRequest.visible = false
                         title.text = qsTr("Request a payment")
                         address.text = ""
+                        qrImage.code = ""
                         continueButton.text = qsTr("Create bitcoin address")
                     }
                 }
             }
 
-            Rectangle {
-                id: qrPlaceholder
+            Pane {
                 Layout.alignment: Qt.AlignTop
                 Layout.minimumWidth: 150
-                Layout.maximumWidth: 150
-                color: Theme.color.neutral2
-                width: 150
-                height: 150
+                Layout.minimumHeight: 150
+                padding: 0
+                background: Rectangle {
+                    color: Theme.color.neutral2
+                    visible: qrImage.code === ""
+                }
+                contentItem: QRImage {
+                    id: qrImage
+                    backgroundColor: "transparent"
+                    foregroundColor: Theme.color.neutral9
+                }
             }
         }
     }

qml/qrimageprovider.cpp

@@ -0,0 +1,56 @@
+// Copyright (c) 2025 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <qml/qrimageprovider.h>
+
+#if defined(HAVE_CONFIG_H)
+#include <config/bitcoin-config.h> /* for USE_QRCODE */
+#endif
+
+#ifdef USE_QRCODE
+#include <qrencode.h>
+#endif
+
+#include <QImage>
+#include <QQuickImageProvider>
+#include <QSize>
+#include <QString>
+#include <QUrl>
+#include <QUrlQuery>
+
+QRImageProvider::QRImageProvider()
+    : QQuickImageProvider{QQuickImageProvider::Image}
+{
+}
+
+QImage QRImageProvider::requestImage(const QString& id, QSize* size, const QSize& requested_size)
+{
+#ifdef USE_QRCODE
+    const QUrl url{"image:///" + id};
+    const QUrlQuery query{url};
+    const QString data{url.path().mid(1)};
+    const QColor fg{query.queryItemValue("fg")};
+    const QColor bg{query.queryItemValue("bg")};
+
+    QRcode* code = QRcode_encodeString(data.toUtf8().constData(), 0, QR_ECLEVEL_L, QR_MODE_8, 1);
+
+    if (code) {
+        QImage image{code->width, code->width, QImage::Format_ARGB32};
+        unsigned char* p = code->data;
+        for (int y = 0; y < code->width; ++y) {
+            for (int x = 0; x < code->width; ++x) {
+                image.setPixelColor(x, y, (*p & 1) ? fg : bg);
+                ++p;
+            }
+        }
+        *size = QSize(code->width, code->width);
+        QRcode_free(code);
+        return image;
+    }
+#endif // USE_QRCODE
+    QImage pixel{1, 1, QImage::Format_ARGB32};
+    pixel.setPixelColor(0, 0, QColorConstants::Transparent);
+    *size = QSize(1, 1);
+    return pixel;
+}

qml/qrimageprovider.h

@@ -0,0 +1,24 @@
+// Copyright (c) 2025 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_QML_QRIMAGEPROVIDER_H
+#define BITCOIN_QML_QRIMAGEPROVIDER_H
+
+#include <QQuickImageProvider>
+
+QT_BEGIN_NAMESPACE
+class QImage;
+class QSize;
+class QString;
+QT_END_NAMESPACE
+
+class QRImageProvider : public QQuickImageProvider
+{
+public:
+    explicit QRImageProvider();
+
+    QImage requestImage(const QString& id, QSize* size, const QSize& requested_size) override;
+};
+
+#endif // BITCOIN_QML_QRIMAGEPROVIDER_H