Scribble area
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#ifndef SCRIBBLEAREA_H
#define SCRIBBLEAREA_H
#include <QColor>
#include <QImage>
#include <QPoint>
#include <QWidget>
class ScribbleArea : public QWidget
{
Q_OBJECT
public:
ScribbleArea(QWidget *parent = 0);
bool openImage(const QString &fileName);
bool saveImage(const QString &fileName, const char *fileFormat);
void setPenColor(const QColor &newColor);
void setPenWidth(int newWidth);
bool isModified() const { return modified; }
QColor penColor() const { return myPenColor; }
int penWidth() const { return myPenWidth; }
public slots:
void clearImage();
void print();
protected:
void mousePressEvent(QMouseEvent *event);
void mouseMoveEvent(QMouseEvent *event);
void mouseReleaseEvent(QMouseEvent *event);
void paintEvent(QPaintEvent *event);
void resizeEvent(QResizeEvent *event);
private:
void drawLineTo(const QPoint &endPoint);
void resizeImage(QImage *image, const QSize &newSize);
bool modified;
bool scribbling;
int myPenWidth;
QColor myPenColor;
QImage image;
QPoint lastPoint;
};
#endif
#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);
painter.drawImage(QPoint(0, 0), image);
}
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
}
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QList>
#include <QMainWindow>
class ScribbleArea;
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow();
protected:
void closeEvent(QCloseEvent *event);
private slots:
void open();
void save();
void penColor();
void penWidth();
void about();
private:
void createActions();
void createMenus();
bool maybeSave();
bool saveFile(const QByteArray &fileFormat);
ScribbleArea *scribbleArea;
QMenu *saveAsMenu;
QMenu *fileMenu;
QMenu *optionMenu;
QMenu *helpMenu;
QAction *openAct;
QList<QAction *> saveAsActs;
QAction *exitAct;
QAction *penColorAct;
QAction *penWidthAct;
QAction *printAct;
QAction *clearScreenAct;
QAction *aboutAct;
QAction *aboutQtAct;
};
#endif
#include <QtGui>
#include "mainwindow.h"
#include "scribblearea.h"
MainWindow::MainWindow()
{
scribbleArea = new ScribbleArea;
setCentralWidget(scribbleArea);
createActions();
createMenus();
setWindowTitle(tr("Scribble"));
resize(500, 500);
}
void MainWindow::closeEvent(QCloseEvent *event)
{
if (maybeSave()) {
event->accept();
} else {
event->ignore();
}
}
void MainWindow::open()
{
if (maybeSave()) {
QString fileName = QFileDialog::getOpenFileName(this,
tr("Open File"), QDir::currentPath());
if (!fileName.isEmpty())
scribbleArea->openImage(fileName);
}
}
void MainWindow::save()
{
QAction *action = qobject_cast<QAction *>(sender());
QByteArray fileFormat = action->data().toByteArray();
saveFile(fileFormat);
}
void MainWindow::penColor()
{
QColor newColor = QColorDialog::getColor(scribbleArea->penColor());
if (newColor.isValid())
scribbleArea->setPenColor(newColor);
}
void MainWindow::penWidth()
{
bool ok;
int newWidth = QInputDialog::getInteger(this, tr("Scribble"),
tr("Select pen width:"),
scribbleArea->penWidth(),
1, 50, 1, &ok);
if (ok)
scribbleArea->setPenWidth(newWidth);
}
void MainWindow::about()
{
QMessageBox::about(this, tr("About Scribble"),
tr("<p>The <b>Scribble</b> example shows how to use QMainWindow as the "
"base widget for an application, and how to reimplement some of "
"QWidget's event handlers to receive the events generated for "
"the application's widgets:</p><p> We reimplement the mouse event "
"handlers to facilitate drawing, the paint event handler to "
"update the application and the resize event handler to optimize "
"the application's appearance. In addition we reimplement the "
"close event handler to intercept the close events before "
"terminating the application.</p><p> The example also demonstrates "
"how to use QPainter to draw an image in real time, as well as "
"to repaint widgets.</p>"));
}
void MainWindow::createActions()
{
openAct = new QAction(tr("&Open..."), this);
openAct->setShortcut(tr("Ctrl+O"));
connect(openAct, SIGNAL(triggered()), this, SLOT(open()));
foreach (QByteArray format, QImageWriter::supportedImageFormats()) {
QString text = tr("%1...").arg(QString(format).toUpper());
QAction *action = new QAction(text, this);
action->setData(format);
connect(action, SIGNAL(triggered()), this, SLOT(save()));
saveAsActs.append(action);
}
printAct = new QAction(tr("&Print..."), this);
connect(printAct, SIGNAL(triggered()), scribbleArea, SLOT(print()));
exitAct = new QAction(tr("E&xit"), this);
exitAct->setShortcut(tr("Ctrl+Q"));
connect(exitAct, SIGNAL(triggered()), this, SLOT(close()));
penColorAct = new QAction(tr("&Pen Color..."), this);
connect(penColorAct, SIGNAL(triggered()), this, SLOT(penColor()));
penWidthAct = new QAction(tr("Pen &Width..."), this);
connect(penWidthAct, SIGNAL(triggered()), this, SLOT(penWidth()));
clearScreenAct = new QAction(tr("&Clear Screen"), this);
clearScreenAct->setShortcut(tr("Ctrl+L"));
connect(clearScreenAct, SIGNAL(triggered()),
scribbleArea, SLOT(clearImage()));
aboutAct = new QAction(tr("&About"), this);
connect(aboutAct, SIGNAL(triggered()), this, SLOT(about()));
aboutQtAct = new QAction(tr("About &Qt"), this);
connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt()));
}
void MainWindow::createMenus()
{
saveAsMenu = new QMenu(tr("&Save As"), this);
foreach (QAction *action, saveAsActs)
saveAsMenu->addAction(action);
fileMenu = new QMenu(tr("&File"), this);
fileMenu->addAction(openAct);
fileMenu->addMenu(saveAsMenu);
fileMenu->addAction(printAct);
fileMenu->addSeparator();
fileMenu->addAction(exitAct);
optionMenu = new QMenu(tr("&Options"), this);
optionMenu->addAction(penColorAct);
optionMenu->addAction(penWidthAct);
optionMenu->addSeparator();
optionMenu->addAction(clearScreenAct);
helpMenu = new QMenu(tr("&Help"), this);
helpMenu->addAction(aboutAct);
helpMenu->addAction(aboutQtAct);
menuBar()->addMenu(fileMenu);
menuBar()->addMenu(optionMenu);
menuBar()->addMenu(helpMenu);
}
bool MainWindow::maybeSave()
{
if (scribbleArea->isModified()) {
QMessageBox::StandardButton ret;
ret = QMessageBox::warning(this, tr("Scribble"),
tr("The image has been modified.\n"
"Do you want to save your changes?"),
QMessageBox::Save | QMessageBox::Discard
| QMessageBox::Cancel);
if (ret == QMessageBox::Save) {
return saveFile("png");
} else if (ret == QMessageBox::Cancel) {
return false;
}
}
return true;
}
bool MainWindow::saveFile(const QByteArray &fileFormat)
{
QString initialPath = QDir::currentPath() + "/untitled." + fileFormat;
QString fileName = QFileDialog::getSaveFileName(this, tr("Save As"),
initialPath,
tr("%1 Files (*.%2);;All Files (*)")
.arg(QString(fileFormat.toUpper()))
.arg(QString(fileFormat)));
if (fileName.isEmpty()) {
return false;
} else {
return scribbleArea->saveImage(fileName, fileFormat);
}
}
#include <QApplication>
#include "mainwindow.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MainWindow window;
window.show();
return app.exec();
}
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