Qt 5.11 | Qt Widgets | Text Codecs Example | previewform.cpp Example File

Qt 5.11.3 Reference Documentation

# previewform.cpp Example File

tools/codecs/previewform.cpp

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      ** 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);
      }