Custom qrcode renderer to allow smooth resizing

src/mainwindow.cpp

@@ -701,38 +701,7 @@ void MainWindow::setupRecieveTab() {
         }
 
         ui->txtRecieve->setPlainText(addr);       
-        
-        QSize sz = ui->qrcodeDisplay->size();
-
-        QPixmap pm(sz);
-        pm.fill(Qt::white);
-        QPainter painter(&pm);
-        
-        // NOTE: At this point you will use the API to get the encoding and format you want, instead of my hardcoded stuff:
-        qrcodegen::QrCode qr = qrcodegen::QrCode::encodeText(addr.toUtf8().constData(), qrcodegen::QrCode::Ecc::LOW);
-        const int    s      = qr.getSize()>0?qr.getSize():1;
-        const double w      = sz.width();
-        const double h      = sz.height();
-        const double aspect = w/h;
-        const double size   = ((aspect>1.0)?h:w);
-        const double scale  = size/(s+2);
-		const double offset = (w - size) > 0 ? (w - size) / 2 : 0;
-        // NOTE: For performance reasons my implementation only draws the foreground parts in supplied color.
-        // It expects background to be prepared already (in white or whatever is preferred).
-        painter.setPen(Qt::NoPen);
-        painter.setBrush(QColor(Qt::black));
-        for(int y=0; y<s; y++) {
-            for(int x=0; x<s; x++) {
-                const int color=qr.getModule(x, y);  // 0 for white, 1 for black
-                if(0!=color) {
-                    const double rx1=(x+1)*scale+ offset, ry1=(y+1)*scale;
-                    QRectF r(rx1, ry1, scale, scale);
-                    painter.drawRects(&r,1);
-                }
-            }
-        }
-        
-        ui->qrcodeDisplay->setPixmap(pm);
+        ui->qrcodeDisplay->setAddress(addr);
     });    
 
 }

src/mainwindow.ui

@@ -22,7 +22,7 @@
     <item row="0" column="0">
      <widget class="QTabWidget" name="tabWidget">
       <property name="currentIndex">
-       <number>3</number>
+       <number>2</number>
       </property>
       <widget class="QWidget" name="tab">
        <attribute name="title">
@@ -316,8 +316,8 @@
                <rect>
                 <x>0</x>
                 <y>0</y>
-                <width>849</width>
-                <height>369</height>
+                <width>841</width>
+                <height>321</height>
                </rect>
               </property>
               <layout class="QVBoxLayout" name="sendToLayout">
@@ -670,7 +670,7 @@
              </widget>
             </item>
             <item>
-             <widget class="QLabel" name="qrcodeDisplay">
+             <widget class="QRCodeLabel" name="qrcodeDisplay">
               <property name="sizePolicy">
                <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
                 <horstretch>0</horstretch>
@@ -718,7 +718,7 @@
      <x>0</x>
      <y>0</y>
      <width>889</width>
-     <height>19</height>
+     <height>22</height>
     </rect>
    </property>
    <widget class="QMenu" name="menuFile">
@@ -783,6 +783,13 @@
   </action>
  </widget>
  <layoutdefault spacing="6" margin="11"/>
+ <customwidgets>
+  <customwidget>
+   <class>QRCodeLabel</class>
+   <extends>QLabel</extends>
+   <header>qrcodelabel.h</header>
+  </customwidget>
+ </customwidgets>
  <tabstops>
   <tabstop>tabWidget</tabstop>
   <tabstop>inputsCombo</tabstop>

src/qrcodelabel.cpp

@@ -0,0 +1,56 @@
+#include "qrcodelabel.h"
+
+QRCodeLabel::QRCodeLabel(QWidget *parent) :
+    QLabel(parent)
+{
+    this->setMinimumSize(1,1);
+    setScaledContents(false);
+}
+
+QSize QRCodeLabel::sizeHint() const
+{
+    int w = this->width();
+    return QSize(w, w);   // 1:1 
+}
+
+void QRCodeLabel::resizeEvent(QResizeEvent * e)
+{
+    if(!address.isEmpty())
+        QLabel::setPixmap(scaledPixmap());
+}
+
+QPixmap QRCodeLabel::scaledPixmap() const {
+    QPixmap pm(size());
+    pm.fill(Qt::white);
+    QPainter painter(&pm);
+    
+    qrcodegen::QrCode qr = qrcodegen::QrCode::encodeText(address.toUtf8().constData(), qrcodegen::QrCode::Ecc::LOW);
+    const int    s      = qr.getSize()>0?qr.getSize():1;
+    const double w      = pm.width();
+    const double h      = pm.height();
+    const double aspect = w/h;
+    const double size   = ((aspect>1.0)?h:w);
+    const double scale  = size/(s+2);
+    const double offset = (w - size) > 0 ? (w - size) / 2 : 0;
+    
+    // NOTE: For performance reasons my implementation only draws the foreground parts    
+    painter.setPen(Qt::NoPen);
+    painter.setBrush(QColor(Qt::black));
+    for(int y=0; y<s; y++) {
+        for(int x=0; x<s; x++) {
+            const int color=qr.getModule(x, y);  // 0 for white, 1 for black
+            if(0!=color) {
+                const double rx1=(x+1)*scale+ offset, ry1=(y+1)*scale;
+                QRectF r(rx1, ry1, scale, scale);
+                painter.drawRects(&r,1);
+            }
+        }
+    }
+    
+    return pm;
+}
+
+void QRCodeLabel::setAddress(QString addr) {
+    address = addr;
+    QLabel::setPixmap(scaledPixmap());
+}

src/qrcodelabel.h

@@ -0,0 +1,23 @@
+#ifndef QRCODELABEL_H
+#define QRCODELABEL_H
+
+#include "precompiled.h"
+
+class QRCodeLabel : public QLabel
+{
+    Q_OBJECT
+public:
+    explicit        QRCodeLabel(QWidget *parent = 0);
+    virtual QSize   sizeHint() const;
+    
+    void            setAddress(QString address);
+    QPixmap         scaledPixmap() const;
+public slots:    
+    void resizeEvent(QResizeEvent *);
+
+private:
+    QString address;
+};
+
+
+#endif // QRCODELABEL_H

zec-qt-wallet.pro

@@ -51,7 +51,8 @@ SOURCES += \
     src/senttxstore.cpp \
     src/txtablemodel.cpp \
 	src/turnstile.cpp \
-    src/utils.cpp
+    src/utils.cpp \
+    src/qrcodelabel.cpp
 
 HEADERS += \
     src/mainwindow.h \
@@ -67,7 +68,8 @@ HEADERS += \
     src/txtablemodel.h \
     src/senttxstore.h \
 	src/turnstile.h \
-    src/utils.h
+    src/utils.h \
+    src/qrcodelabel.h
 
 FORMS += \
     src/mainwindow.ui \