previewform.cpp Example File

  /****************************************************************************
  **
  ** Copyright (C) 2016 The Qt Company Ltd.
  ** Contact: https://www.qt.io/licensing/
  **
  ** This file is part of the examples of the Qt Toolkit.
  **
  ** $QT_BEGIN_LICENSE:BSD$
  ** Commercial License Usage
  ** Licensees holding valid commercial Qt licenses may use this file in
  ** accordance with the commercial license agreement provided with the
  ** Software or, alternatively, in accordance with the terms contained in
  ** a written agreement between you and The Qt Company. For licensing terms
  ** and conditions see https://www.qt.io/terms-conditions. For further
  ** information use the contact form at https://www.qt.io/contact-us.
  **
  ** BSD License Usage
  ** Alternatively, you may use this file under the terms of the BSD license
  ** as follows:
  **
  ** "Redistribution and use in source and binary forms, with or without
  ** modification, are permitted provided that the following conditions are
  ** met:
  **   * Redistributions of source code must retain the above copyright
  **     notice, this list of conditions and the following disclaimer.
  **   * Redistributions in binary form must reproduce the above copyright
  **     notice, this list of conditions and the following disclaimer in
  **     the documentation and/or other materials provided with the
  **     distribution.
  **   * Neither the name of The Qt Company Ltd nor the names of its
  **     contributors may be used to endorse or promote products derived
  **     from this software without specific prior written permission.
  **
  **
  ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
  **
  ** $QT_END_LICENSE$
  **
  ****************************************************************************/

  #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);

      typedef void(QComboBox::*ComboBoxIntSignal)(int);
      connect(encodingComboBox, static_cast<ComboBoxIntSignal>(&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);
  }