Added QRCode generation functions via libqrencode. Switch on with USE_QRENCODE=1.

Amended build docs for Linux and OSX, and OSX makefile.
Added package 'qrencode' to gitian.yml

src/qt/qrcodedialog.cpp

@@ -0,0 +1,106 @@
+#include "qrcodedialog.h"
+#include "ui_qrcodedialog.h"
+#include <QPixmap>
+#include <QUrl>
+#include <QFileDialog>
+#include <QDesktopServices>
+#include <QDebug>
+
+#include <qrencode.h>
+
+#define EXPORT_IMAGE_SIZE   256
+
+QRCodeDialog::QRCodeDialog(const QString &title, const QString &addr, const QString &label, bool enableReq, QWidget *parent) :
+    QDialog(parent),
+    ui(new Ui::QRCodeDialog),
+    address(addr)
+{
+    ui->setupUi(this);
+    setWindowTitle(title);
+    setAttribute(Qt::WA_DeleteOnClose);
+
+    ui->chkReq->setVisible(enableReq);
+    ui->lnReqAmount->setVisible(enableReq);
+    ui->lblAm1->setVisible(enableReq);
+    ui->lblAm2->setVisible(enableReq);
+
+    ui->lnLabel->setText(label);
+
+    genCode();
+}
+
+QRCodeDialog::~QRCodeDialog()
+{
+    delete ui;
+}
+
+void QRCodeDialog::genCode() {
+
+    QString uri = getURI();
+    //qDebug() << "Encoding:" << uri.toUtf8().constData();
+    QRcode *code = QRcode_encodeString(uri.toUtf8().constData(), 0, QR_ECLEVEL_L, QR_MODE_8, 1);
+    myImage = QImage(code->width + 8, code->width + 8, QImage::Format_RGB32);
+    myImage.fill(0xffffff);
+    unsigned char *p = code->data;
+    for(int y = 0; y < code->width; y++) {
+        for(int x = 0; x < code->width; x++) {
+            myImage.setPixel(x + 4, y + 4, ((*p & 1) ? 0x0 : 0xffffff));
+            p++;
+        }
+    }
+    QRcode_free(code);
+    ui->lblQRCode->setPixmap(QPixmap::fromImage(myImage).scaled(300, 300));
+}
+
+QString QRCodeDialog::getURI() {
+    QString ret = QString("bitcoin:%1").arg(address);
+
+    int paramCount = 0;
+    if(ui->chkReq->isChecked() && ui->lnReqAmount->text().isEmpty() == false) {
+        bool ok= false;
+        double amount = ui->lnReqAmount->text().toDouble(&ok);
+        if(ok) {
+            ret += QString("?amount=%1X8").arg(ui->lnReqAmount->text());
+            paramCount++;
+        }
+    }
+
+    if(ui->lnLabel->text().isEmpty() == false) {
+        QString lbl(QUrl::toPercentEncoding(ui->lnLabel->text()));
+        ret += QString("%1label=%2").arg(paramCount == 0 ? "?" : "&").arg(lbl);
+        paramCount++;
+    }
+
+    if(ui->lnMessage->text().isEmpty() == false) {
+        QString msg(QUrl::toPercentEncoding(ui->lnMessage->text()));
+        ret += QString("%1message=%2").arg(paramCount == 0 ? "?" : "&").arg(msg);
+        paramCount++;
+    }
+
+    return ret;
+}
+
+void QRCodeDialog::on_lnReqAmount_textChanged(const QString &) {
+    genCode();
+}
+
+void QRCodeDialog::on_lnLabel_textChanged(const QString &) {
+    genCode();
+}
+
+void QRCodeDialog::on_lnMessage_textChanged(const QString &) {
+    genCode();
+}
+
+void QRCodeDialog::on_btnSaveAs_clicked()
+{
+    QString fn = QFileDialog::getSaveFileName(this, "Save Image...", QDesktopServices::storageLocation(QDesktopServices::DocumentsLocation), "Images (*.png)");
+    if(!fn.isEmpty()) {
+        myImage.scaled(EXPORT_IMAGE_SIZE, EXPORT_IMAGE_SIZE).save(fn);
+    }
+}
+
+void QRCodeDialog::on_chkReq_toggled(bool)
+{
+    genCode();
+}