Qt 5.11 | Qt Widgets | Font Sampler Example | mainwindow.cpp Example File

Qt 5.11.3 Reference Documentation

# mainwindow.cpp Example File

painting/fontsampler/mainwindow.cpp

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      #include <QtWidgets>
      #if defined(QT_PRINTSUPPORT_LIB)
      #include <QtPrintSupport/qtprintsupportglobal.h>
      #if QT_CONFIG(printdialog)
      #include <QPrinter>
      #include <QPrintDialog>
      #if QT_CONFIG(printpreviewdialog)
      #include <QPrintPreviewDialog>
      #endif
      #endif
      #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;
      }

      void MainWindow::on_printAction_triggered()
      {
      #if defined(QT_PRINTSUPPORT_LIB) && QT_CONFIG(printdialog)
          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);
      #endif
      }

      void MainWindow::printDocument(QPrinter *printer)
      {
      #if defined(QT_PRINTSUPPORT_LIB) && QT_CONFIG(printdialog)
          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();
      #endif
      }

      void MainWindow::on_printPreviewAction_triggered()
      {
      #if defined(QT_PRINTSUPPORT_LIB) && QT_CONFIG(printpreviewdialog)
          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();
      #endif
      }

      void MainWindow::printPage(int index, QPainter *painter, QPrinter *printer)
      {
      #if defined(QT_PRINTSUPPORT_LIB) && QT_CONFIG(printdialog)
          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
      }