mainwindow.cpp Example File

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  #include <QtWidgets>
  #ifndef QT_NO_PRINTER
  #include <QPrinter>
  #include <QPrintDialog>
  #include <QPrintPreviewDialog>
  #endif

  #include "mainwindow.h"

  MainWindow::MainWindow(QWidget *parent)
     : QMainWindow(parent)
  {
      setupUi(this);

      sampleSizes << 32 << 24 << 16 << 14 << 12 << 8 << 4 << 2 << 1;
      markedCount = 0;
      setupFontTree();

      connect(quitAction, SIGNAL(triggered()), qApp, SLOT(quit()));
      connect(fontTree, SIGNAL(currentItemChanged(QTreeWidgetItem*,QTreeWidgetItem*)),
              this, SLOT(showFont(QTreeWidgetItem*)));
      connect(fontTree, SIGNAL(itemChanged(QTreeWidgetItem*,int)),
              this, SLOT(updateStyles(QTreeWidgetItem*,int)));

      fontTree->setItemSelected(fontTree->topLevelItem(0), true);
      showFont(fontTree->topLevelItem(0));
  }

  void MainWindow::setupFontTree()
  {
      QFontDatabase database;
      fontTree->setColumnCount(1);
      fontTree->setHeaderLabels(QStringList() << tr("Font"));

      foreach (QString family, database.families()) {
          const QStringList styles = database.styles(family);
          if (styles.isEmpty())
              continue;

          QTreeWidgetItem *familyItem = new QTreeWidgetItem(fontTree);
          familyItem->setText(0, family);
          familyItem->setCheckState(0, Qt::Unchecked);
          familyItem->setFlags(familyItem->flags() | Qt::ItemIsAutoTristate);

          foreach (QString style, styles) {
              QTreeWidgetItem *styleItem = new QTreeWidgetItem(familyItem);
              styleItem->setText(0, style);
              styleItem->setCheckState(0, Qt::Unchecked);
              styleItem->setData(0, Qt::UserRole, QVariant(database.weight(family, style)));
              styleItem->setData(0, Qt::UserRole + 1, QVariant(database.italic(family, style)));
          }
      }
  }

  void MainWindow::on_clearAction_triggered()
  {
      QTreeWidgetItem *currentItem = fontTree->currentItem();
      foreach (QTreeWidgetItem *item, fontTree->selectedItems())
          fontTree->setItemSelected(item, false);
      fontTree->setItemSelected(currentItem, true);
  }

  void MainWindow::on_markAction_triggered()
  {
      markUnmarkFonts(Qt::Checked);
  }

  void MainWindow::on_unmarkAction_triggered()
  {
      markUnmarkFonts(Qt::Unchecked);
  }

  void MainWindow::markUnmarkFonts(Qt::CheckState state)
  {
      QList<QTreeWidgetItem *> items = fontTree->selectedItems();
      foreach (QTreeWidgetItem *item, items) {
          if (item->checkState(0) != state)
              item->setCheckState(0, state);
      }
  }

  void MainWindow::showFont(QTreeWidgetItem *item)
  {
      if (!item)
          return;

      QString family;
      QString style;
      int weight;
      bool italic;

      if (item->parent()) {
          family = item->parent()->text(0);
          style = item->text(0);
          weight = item->data(0, Qt::UserRole).toInt();
          italic = item->data(0, Qt::UserRole + 1).toBool();
      } else {
          family = item->text(0);
          style = item->child(0)->text(0);
          weight = item->child(0)->data(0, Qt::UserRole).toInt();
          italic = item->child(0)->data(0, Qt::UserRole + 1).toBool();
      }

      QString oldText = textEdit->toPlainText().trimmed();
      bool modified = textEdit->document()->isModified();
      textEdit->clear();
      QFont font(family, 32, weight, italic);
      font.setStyleName(style);
      textEdit->document()->setDefaultFont(font);

      QTextCursor cursor = textEdit->textCursor();
      QTextBlockFormat blockFormat;
      blockFormat.setAlignment(Qt::AlignCenter);
      cursor.insertBlock(blockFormat);

      if (modified)
          cursor.insertText(QString(oldText));
      else
          cursor.insertText(QString("%1 %2").arg(family).arg(style));

      textEdit->document()->setModified(modified);
  }

  void MainWindow::updateStyles(QTreeWidgetItem *item, int column)
  {
      if (!item || column != 0)
          return;

      Qt::CheckState state = item->checkState(0);
      QTreeWidgetItem *parent = item->parent();

      if (parent) {
          // Only count style items.
          if (state == Qt::Checked)
              ++markedCount;
          else
              --markedCount;
      }

      printAction->setEnabled(markedCount > 0);
      printPreviewAction->setEnabled(markedCount > 0);
  }

  QMap<QString, StyleItems> MainWindow::currentPageMap()
  {
      QMap<QString, StyleItems> pageMap;

      for (int row = 0; row < fontTree->topLevelItemCount(); ++row) {
          QTreeWidgetItem *familyItem = fontTree->topLevelItem(row);
          QString family;

          if (familyItem->checkState(0) == Qt::Checked) {
              family = familyItem->text(0);
              pageMap[family] = StyleItems();
          }

          for (int childRow = 0; childRow < familyItem->childCount(); ++childRow) {
              QTreeWidgetItem *styleItem = familyItem->child(childRow);
              if (styleItem->checkState(0) == Qt::Checked)
                  pageMap[family].append(styleItem);
          }
      }

      return pageMap;
  }

  #if !defined(QT_NO_PRINTER) && !defined(QT_NO_PRINTDIALOG)
  void MainWindow::on_printAction_triggered()
  {
      pageMap = currentPageMap();

      if (pageMap.count() == 0)
          return;

      QPrinter printer(QPrinter::HighResolution);
      QPrintDialog dialog(&printer, this);
      if (dialog.exec() != QDialog::Accepted)
          return;

      int from = printer.fromPage();
      int to = printer.toPage();
      if (from <= 0 && to <= 0)
          printer.setFromTo(1, pageMap.keys().count());

      printDocument(&printer);
  }

  void MainWindow::printDocument(QPrinter *printer)
  {
      printer->setFromTo(1, pageMap.count());

      QProgressDialog progress(tr("Preparing font samples..."), tr("&Cancel"),
                               0, pageMap.count(), this);
      progress.setWindowModality(Qt::ApplicationModal);
      progress.setWindowTitle(tr("Font Sampler"));
      progress.setMinimum(printer->fromPage() - 1);
      progress.setMaximum(printer->toPage());

      QPainter painter;
      painter.begin(printer);
      bool firstPage = true;

      for (int page = printer->fromPage(); page <= printer->toPage(); ++page) {

          if (!firstPage)
              printer->newPage();

          qApp->processEvents();
          if (progress.wasCanceled())
              break;

          printPage(page - 1, &painter, printer);
          progress.setValue(page);
          firstPage = false;
      }

      painter.end();
  }

  void MainWindow::on_printPreviewAction_triggered()
  {
      pageMap = currentPageMap();

      if (pageMap.count() == 0)
          return;

      QPrinter printer(QPrinter::HighResolution);
      QPrintPreviewDialog preview(&printer, this);
      connect(&preview, SIGNAL(paintRequested(QPrinter*)),
              this, SLOT(printDocument(QPrinter*)));
      preview.exec();
  }

  void MainWindow::printPage(int index, QPainter *painter, QPrinter *printer)
  {
      QString family = pageMap.keys()[index];
      StyleItems items = pageMap[family];

      // Find the dimensions of the text on each page.
      qreal width = 0.0;
      qreal height = 0.0;
      foreach (QTreeWidgetItem *item, items) {
          QString style = item->text(0);
          int weight = item->data(0, Qt::UserRole).toInt();
          bool italic = item->data(0, Qt::UserRole + 1).toBool();

          // Calculate the maximum width and total height of the text.
          foreach (int size, sampleSizes) {
              QFont font(family, size, weight, italic);
              font.setStyleName(style);
              font = QFont(font, painter->device());
              QFontMetricsF fontMetrics(font);
              QRectF rect = fontMetrics.boundingRect(
              QString("%1 %2").arg(family).arg(style));
              width = qMax(rect.width(), width);
              height += rect.height();
          }
      }

      qreal xScale = printer->pageRect().width() / width;
      qreal yScale = printer->pageRect().height() / height;
      qreal scale = qMin(xScale, yScale);

      qreal remainingHeight = printer->pageRect().height()/scale - height;
      qreal spaceHeight = (remainingHeight / 4.0) / (items.count() + 1);
      qreal interLineHeight = (remainingHeight / 4.0) / (sampleSizes.count() * items.count());

      painter->save();
      painter->translate(printer->pageRect().width() / 2.0, printer->pageRect().height() / 2.0);
      painter->scale(scale, scale);
      painter->setBrush(QBrush(Qt::black));

      qreal x = -width / 2.0;
      qreal y = -height / 2.0 - remainingHeight / 4.0 + spaceHeight;

      foreach (QTreeWidgetItem *item, items) {
          QString style = item->text(0);
          int weight = item->data(0, Qt::UserRole).toInt();
          bool italic = item->data(0, Qt::UserRole + 1).toBool();

          // Draw each line of text.
          foreach (int size, sampleSizes) {
              QFont font(family, size, weight, italic);
              font.setStyleName(style);
              font = QFont(font, painter->device());
              QFontMetricsF fontMetrics(font);
              QRectF rect = fontMetrics.boundingRect(QString("%1 %2").arg(
                            font.family()).arg(style));
              y += rect.height();
              painter->setFont(font);
              painter->drawText(QPointF(x, y), QString("%1 %2").arg(family).arg(style));
              y += interLineHeight;
          }
          y += spaceHeight;
      }

      painter->restore();
  }
  #endif // QT_NO_PRINTER