previewform.cpp Example File

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 #include <QtWidgets>

 #include "previewform.h"

 // Helpers for creating hex dumps
 static void indent(QTextStream &str, int indent)
 {
     for (int i = 0; i < indent; ++i)
         str << ' ';
 }

 static void formatHex(QTextStream &str, const QByteArray &data)
 {
     const int fieldWidth = str.fieldWidth();
     const QTextStream::FieldAlignment alignment = str.fieldAlignment();
     const int base = str.integerBase();
     const QChar padChar = str.padChar();
     str.setIntegerBase(16);
     str.setPadChar(QLatin1Char('0'));
     str.setFieldAlignment(QTextStream::AlignRight);

     const unsigned char *p = reinterpret_cast<const unsigned char *>(data.constBegin());
     for (const unsigned char *end = p + data.size(); p < end; ++p) {
         str << ' ';
         str.setFieldWidth(2);
         str << unsigned(*p);
         str.setFieldWidth(fieldWidth);
     }
     str.setFieldAlignment(alignment);
     str.setPadChar(padChar);
     str.setIntegerBase(base);
 }

 static void formatPrintableCharacters(QTextStream &str, const QByteArray &data)
 {
     for (int i = 0, size = data.size(); i < size; ++i) {
         const char c = data.at(i);
         switch (c) {
         case '\0':
             str << "\\0";
             break;
         case '\t':
             str << "\\t";
             break;
         case '\r':
             str << "\\r";
             break;
         case '\n':
             str << "\\n";
             break;
         default:
             if (c >= 32 && uchar(c) < 127)
                 str << ' ' << c;
             else
                 str << "..";
             break;
         }
     }
 }

 static QString formatHexDump(const QByteArray &data)
 {
     enum { lineWidth = 16 };
     QString result;
     QTextStream str(&result);
     str.setIntegerBase(16);
     str.setPadChar(QLatin1Char('0'));
     const int fieldWidth = str.fieldWidth();
     const QTextStream::FieldAlignment alignment = str.fieldAlignment();
     for (int a = 0, size = data.size(); a < size; a += lineWidth) {
         str.setFieldAlignment(QTextStream::AlignRight);
         str.setFieldWidth(8);
         str << a;
         str.setFieldWidth(fieldWidth);
         str.setFieldAlignment(alignment);

         const int end = qMin(a + lineWidth, size);
         const QByteArray line = data.mid(a, end - a);

         formatHex(str, line);
         indent(str, 3 * (lineWidth - line.size()));

         str << ' ';
         formatPrintableCharacters(str, line);
         indent(str, 2 * (lineWidth - line.size()));
         str << '\n';
     }
     return result;
 }

 PreviewForm::PreviewForm(QWidget *parent)
     : QDialog(parent)
 {
     setWindowFlags(windowFlags() & ~Qt::WindowContextHelpButtonHint);
     encodingComboBox = new QComboBox;

     QLabel *encodingLabel = new QLabel(tr("&Encoding:"));
     encodingLabel->setBuddy(encodingComboBox);

     textEdit = new QPlainTextEdit;
     textEdit->setLineWrapMode(QPlainTextEdit::NoWrap);
     textEdit->setReadOnly(true);
     hexDumpEdit = new QPlainTextEdit;
     hexDumpEdit->setLineWrapMode(QPlainTextEdit::NoWrap);
     hexDumpEdit->setReadOnly(true);
     hexDumpEdit->setFont(QFontDatabase::systemFont(QFontDatabase::FixedFont));

     QDialogButtonBox *buttonBox =
         new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel);
     okButton = buttonBox->button(QDialogButtonBox::Ok);

     connect(encodingComboBox, QOverload<int>::of(&QComboBox::activated),
             this, &PreviewForm::updateTextEdit);
     connect(buttonBox, &QDialogButtonBox::accepted, this, &QDialog::accept);
     connect(buttonBox, &QDialogButtonBox::rejected, this, &QDialog::reject);

     QGridLayout *mainLayout = new QGridLayout(this);
     mainLayout->addWidget(encodingLabel, 0, 0);
     mainLayout->addWidget(encodingComboBox, 0, 1);
     tabWidget = new QTabWidget;
     tabWidget->addTab(textEdit, tr("Preview"));
     tabWidget->addTab(hexDumpEdit, tr("Hex Dump"));
     mainLayout->addWidget(tabWidget, 1, 0, 1, 2);
     statusLabel = new QLabel;
     mainLayout->addWidget(statusLabel, 2, 0, 1, 2);
     mainLayout->addWidget(buttonBox, 3, 0, 1, 2);

     const QRect screenGeometry = QApplication::desktop()->screenGeometry(this);
     resize(screenGeometry.width() * 2 / 5, screenGeometry.height() / 2);
 }

 void PreviewForm::setCodecList(const QList<QTextCodec *> &list)
 {
     encodingComboBox->clear();
     foreach (const QTextCodec *codec, list) {
         encodingComboBox->addItem(QLatin1String(codec->name()),
                                   QVariant(codec->mibEnum()));
     }
 }

 void PreviewForm::reset()
 {
     decodedStr.clear();
     textEdit->clear();
     hexDumpEdit->clear();
     statusLabel->clear();
     statusLabel->setStyleSheet(QString());
     okButton->setEnabled(false);
     tabWidget->setCurrentIndex(0);
 }

 void PreviewForm::setEncodedData(const QByteArray &data)
 {
     reset();
     encodedData = data;
     hexDumpEdit->setPlainText(formatHexDump(data));
     updateTextEdit();
 }

 void PreviewForm::updateTextEdit()
 {
     int mib = encodingComboBox->itemData(
                       encodingComboBox->currentIndex()).toInt();
     const QTextCodec *codec = QTextCodec::codecForMib(mib);
     const QString name = QLatin1String(codec->name());

     QTextCodec::ConverterState state;
     decodedStr = codec->toUnicode(encodedData.constData(), encodedData.size(), &state);

     bool success = true;
     if (state.remainingChars) {
         success = false;
         const QString message =
             tr("%1: conversion error at character %2")
             .arg(name).arg(encodedData.size() - state.remainingChars + 1);
         statusLabel->setText(message);
         statusLabel->setStyleSheet(QStringLiteral("background-color: \"red\";"));
     } else if (state.invalidChars) {
         statusLabel->setText(tr("%1: %n invalid characters", 0, state.invalidChars).arg(name));
         statusLabel->setStyleSheet(QStringLiteral("background-color: \"yellow\";"));
     } else {
         statusLabel->setText(tr("%1: %n bytes converted", 0, encodedData.size()).arg(name));
         statusLabel->setStyleSheet(QString());
     }
     if (success)
         textEdit->setPlainText(decodedStr);
     else
         textEdit->clear();
     okButton->setEnabled(success);
 }