previewform.cpp Example File | Qt Widgets 5.12.10

- Qt 5.12
- Qt Widgets
- Text Codecs Example
- previewform.cpp Example File
- Qt 5.12.10 Reference Documentation

# previewform.cpp Example File

tools/codecs/previewform.cpp

     /****************************************************************************
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     ** Contact: https://www.qt.io/licensing/
     **
     ** This file is part of the examples of the Qt Toolkit.
     **
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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);
     }