Qt Reference Documentation

# scribblearea.cpp Example File

widgets/scribble/scribblearea.cpp

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     ** This file is part of the examples of the Qt Toolkit.
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     #include <QtGui>

     #include "scribblearea.h"

     ScribbleArea::ScribbleArea(QWidget *parent)
         : QWidget(parent)
     {
         setAttribute(Qt::WA_StaticContents);
         modified = false;
         scribbling = false;
         myPenWidth = 1;
         myPenColor = Qt::blue;
     }

     bool ScribbleArea::openImage(const QString &fileName)
     {
         QImage loadedImage;
         if (!loadedImage.load(fileName))
             return false;

         QSize newSize = loadedImage.size().expandedTo(size());
         resizeImage(&loadedImage, newSize);
         image = loadedImage;
         modified = false;
         update();
         return true;
     }

     bool ScribbleArea::saveImage(const QString &fileName, const char *fileFormat)
     {
         QImage visibleImage = image;
         resizeImage(&visibleImage, size());

         if (visibleImage.save(fileName, fileFormat)) {
             modified = false;
             return true;
         } else {
             return false;
         }
     }

     void ScribbleArea::setPenColor(const QColor &newColor)
     {
         myPenColor = newColor;
     }

     void ScribbleArea::setPenWidth(int newWidth)
     {
         myPenWidth = newWidth;
     }

     void ScribbleArea::clearImage()
     {
         image.fill(qRgb(255, 255, 255));
         modified = true;
         update();
     }

     void ScribbleArea::mousePressEvent(QMouseEvent *event)
     {
         if (event->button() == Qt::LeftButton) {
             lastPoint = event->pos();
             scribbling = true;
         }
     }

     void ScribbleArea::mouseMoveEvent(QMouseEvent *event)
     {
         if ((event->buttons() & Qt::LeftButton) && scribbling)
             drawLineTo(event->pos());
     }

     void ScribbleArea::mouseReleaseEvent(QMouseEvent *event)
     {
         if (event->button() == Qt::LeftButton && scribbling) {
             drawLineTo(event->pos());
             scribbling = false;
         }
     }

     void ScribbleArea::paintEvent(QPaintEvent *event)
     {
         QPainter painter(this);
         QRect dirtyRect = event->rect();
         painter.drawImage(dirtyRect, image, dirtyRect);
     }

     void ScribbleArea::resizeEvent(QResizeEvent *event)
     {
         if (width() > image.width() || height() > image.height()) {
             int newWidth = qMax(width() + 128, image.width());
             int newHeight = qMax(height() + 128, image.height());
             resizeImage(&image, QSize(newWidth, newHeight));
             update();
         }
         QWidget::resizeEvent(event);
     }

     void ScribbleArea::drawLineTo(const QPoint &endPoint)
     {
         QPainter painter(&image);
         painter.setPen(QPen(myPenColor, myPenWidth, Qt::SolidLine, Qt::RoundCap,
                             Qt::RoundJoin));
         painter.drawLine(lastPoint, endPoint);
         modified = true;

         int rad = (myPenWidth / 2) + 2;
         update(QRect(lastPoint, endPoint).normalized()
                                          .adjusted(-rad, -rad, +rad, +rad));
         lastPoint = endPoint;
     }

     void ScribbleArea::resizeImage(QImage *image, const QSize &newSize)
     {
         if (image->size() == newSize)
             return;

         QImage newImage(newSize, QImage::Format_RGB32);
         newImage.fill(qRgb(255, 255, 255));
         QPainter painter(&newImage);
         painter.drawImage(QPoint(0, 0), *image);
         *image = newImage;
     }

     void ScribbleArea::print()
     {
     #ifndef QT_NO_PRINTER
         QPrinter printer(QPrinter::HighResolution);

         QPrintDialog *printDialog = new QPrintDialog(&printer, this);
         if (printDialog->exec() == QDialog::Accepted) {
             QPainter painter(&printer);
             QRect rect = painter.viewport();
             QSize size = image.size();
             size.scale(rect.size(), Qt::KeepAspectRatio);
             painter.setViewport(rect.x(), rect.y(), size.width(), size.height());
             painter.setWindow(image.rect());
             painter.drawImage(0, 0, image);
         }
     #endif // QT_NO_PRINTER
     }