QT += core gui
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
CONFIG += c++11
# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS
# You can also make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0
SOURCES += \
main.cpp \
mainwindow.cpp \
scribblearea.cpp
HEADERS += \
mainwindow.h \
scribblearea.h
FORMS += \
mainwindow.ui
TRANSLATIONS += \
EditPaint_en_IO.ts
# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QList>
#include <QMainWindow>
// ScribbleArea used to paint the image
class ScribbleArea;
class MainWindow : public QMainWindow
{
// Declares our class as a QObject which is the base class
// for all Qt objects
// QObjects handle events
Q_OBJECT
public:
MainWindow();
protected:
// Function used to close an event
void closeEvent(QCloseEvent *event) override;
// The events that can be triggered
private slots:
void open();
void save();
void penColor();
void penWidth();
void about();
private:
// Will tie user actions to functions
void createActions();
void createMenus();
// Will check if changes have occurred since last save
bool maybeSave();
// Opens the Save dialog and saves
bool saveFile(const QByteArray &fileFormat);
// What we'll draw on
ScribbleArea *scribbleArea;
// The menu widgets
QMenu *saveAsMenu;
QMenu *fileMenu;
QMenu *optionMenu;
QMenu *helpMenu;
// All the actions that can occur
QAction *openAct;
// Actions tied to specific file formats
QList<QAction *> saveAsActs;
QAction *exitAct;
QAction *penColorAct;
QAction *penWidthAct;
QAction *printAct;
QAction *clearScreenAct;
QAction *aboutAct;
QAction *aboutQtAct;
};
#endif
#ifndef SCRIBBLEAREA_H
#define SCRIBBLEAREA_H
#include <QColor>
#include <QImage>
#include <QPoint>
#include <QWidget>
class ScribbleArea : public QWidget
{
// Declares our class as a QObject which is the base class
// for all Qt objects
// QObjects handle events
Q_OBJECT
public:
ScribbleArea(QWidget *parent = 0);
// Handles all events
bool openImage(const QString &fileName);
bool saveImage(const QString &fileName, const char *fileFormat);
void setPenColor(const QColor &newColor);
void setPenWidth(int newWidth);
// Has the image been modified since last save
bool isModified() const { return modified; }
QColor penColor() const { return myPenColor; }
int penWidth() const { return myPenWidth; }
public slots:
// Events to handle
void clearImage();
void print();
protected:
void mousePressEvent(QMouseEvent *event) override;
void mouseMoveEvent(QMouseEvent *event) override;
void mouseReleaseEvent(QMouseEvent *event) override;
// Updates the scribble area where we are painting
void paintEvent(QPaintEvent *event) override;
// Makes sure the area we are drawing on remains
// as large as the widget
void resizeEvent(QResizeEvent *event) override;
private:
void drawLineTo(const QPoint &endPoint);
void resizeImage(QImage *image, const QSize &newSize);
// Will be marked true or false depending on if
// we have saved after a change
bool modified;
// Marked true or false depending on if the user
// is drawing
bool scribbling;
// Holds the current pen width & color
int myPenWidth;
QColor myPenColor;
// Stores the image being drawn
QImage image;
// Stores the location at the current mouse event
QPoint lastPoint;
};
#endif
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
// The main application
QApplication app(argc, argv);
// Create and open the main window
MainWindow window;
window.show();
// Display the main window
return app.exec();
}
#include <QtWidgets>
#include "mainwindow.h"
#include "scribblearea.h"
// MainWindow constructor
MainWindow::MainWindow()
{
// Create the ScribbleArea widget and make it
// the central widget
scribbleArea = new ScribbleArea;
setCentralWidget(scribbleArea);
// Create actions and menus
createActions();
createMenus();
// Set the title
setWindowTitle(tr("Paint Application"));
// Size the app
resize(500, 500);
}
// User tried to close the app
void MainWindow::closeEvent(QCloseEvent *event)
{
// If they try to close maybeSave() returns true
// if no changes have been made and the app closes
if (maybeSave()) {
event->accept();
} else {
// If there have been changes ignore the event
event->ignore();
}
}
// Check if the current image has been changed and then
// open a dialog to open a file
void MainWindow::open()
{
// Check if changes have been made since last save
// maybeSave() returns true if no changes have been made
if (maybeSave()) {
// Get the file to open from a dialog
// tr sets the window title to Open File
// QDir opens the current dirctory
QString fileName = QFileDialog::getOpenFileName(this,
tr("Open File"), QDir::currentPath());
// If we have a file name load the image and place
// it in the scribbleArea
if (!fileName.isEmpty())
scribbleArea->openImage(fileName);
}
}
// Called when the user clicks Save As in the menu
void MainWindow::save()
{
// A QAction represents the action of the user clicking
QAction *action = qobject_cast<QAction *>(sender());
// Stores the array of bytes of the users data
QByteArray fileFormat = action->data().toByteArray();
// Pass it to be saved
saveFile(fileFormat);
}
// Opens a dialog to change the pen color
void MainWindow::penColor()
{
// Store the chosen color from the dialog
QColor newColor = QColorDialog::getColor(scribbleArea->penColor());
// If a valid color set it
if (newColor.isValid())
scribbleArea->setPenColor(newColor);
}
// Opens a dialog that allows the user to change the pen width
void MainWindow::penWidth()
{
// Stores button value
bool ok;
// tr("Scribble") is the title
// the next tr is the text to display
// Get the current pen width
// Define the min, max, step and ok button
int newWidth = QInputDialog::getInt(this, tr("Scribble"),
tr("Select pen width:"),
scribbleArea->penWidth(),
1, 50, 1, &ok);
// Change the pen width
if (ok)
scribbleArea->setPenWidth(newWidth);
}
// Open an about dialog
void MainWindow::about()
{
// Window title and text to display
QMessageBox::about(this, tr("About Scribble"),
tr("<p>The <b>Scribble</b> example is awesome</p>"));
}
// Define menu actions that call functions
void MainWindow::createActions()
{
// Create the action tied to the menu
openAct = new QAction(tr("&Open..."), this);
// Define the associated shortcut key
openAct->setShortcuts(QKeySequence::Open);
// Tie the action to MainWindow::open()
connect(openAct, SIGNAL(triggered()), this, SLOT(open()));
// Get a list of the supported file formats
// QImageWriter is used to write images to files
foreach (QByteArray format, QImageWriter::supportedImageFormats()) {
QString text = tr("%1...").arg(QString(format).toUpper());
// Create an action for each file format
QAction *action = new QAction(text, this);
// Set an action for each file format
action->setData(format);
// When clicked call MainWindow::save()
connect(action, SIGNAL(triggered()), this, SLOT(save()));
// Attach each file format option menu item to Save As
saveAsActs.append(action);
}
// Create print action and tie to MainWindow::print()
printAct = new QAction(tr("&Print..."), this);
connect(printAct, SIGNAL(triggered()), scribbleArea, SLOT(print()));
// Create exit action and tie to MainWindow::close()
exitAct = new QAction(tr("E&xit"), this);
exitAct->setShortcuts(QKeySequence::Quit);
connect(exitAct, SIGNAL(triggered()), this, SLOT(close()));
// Create pen color action and tie to MainWindow::penColor()
penColorAct = new QAction(tr("&Pen Color..."), this);
connect(penColorAct, SIGNAL(triggered()), this, SLOT(penColor()));
// Create pen width action and tie to MainWindow::penWidth()
penWidthAct = new QAction(tr("Pen &Width..."), this);
connect(penWidthAct, SIGNAL(triggered()), this, SLOT(penWidth()));
// Create clear screen action and tie to MainWindow::clearImage()
clearScreenAct = new QAction(tr("&Clear Screen"), this);
clearScreenAct->setShortcut(tr("Ctrl+L"));
connect(clearScreenAct, SIGNAL(triggered()),
scribbleArea, SLOT(clearImage()));
// Create about action and tie to MainWindow::about()
aboutAct = new QAction(tr("&About"), this);
connect(aboutAct, SIGNAL(triggered()), this, SLOT(about()));
// Create about Qt action and tie to MainWindow::aboutQt()
aboutQtAct = new QAction(tr("About &Qt"), this);
connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt()));
}
// Create the menubar
void MainWindow::createMenus()
{
// Create Save As option and the list of file types
saveAsMenu = new QMenu(tr("&Save As"), this);
foreach (QAction *action, saveAsActs)
saveAsMenu->addAction(action);
// Attach all actions to File
fileMenu = new QMenu(tr("&File"), this);
fileMenu->addAction(openAct);
fileMenu->addMenu(saveAsMenu);
fileMenu->addAction(printAct);
fileMenu->addSeparator();
fileMenu->addAction(exitAct);
// Attach all actions to Options
optionMenu = new QMenu(tr("&Options"), this);
optionMenu->addAction(penColorAct);
optionMenu->addAction(penWidthAct);
optionMenu->addSeparator();
optionMenu->addAction(clearScreenAct);
// Attach all actions to Help
helpMenu = new QMenu(tr("&Help"), this);
helpMenu->addAction(aboutAct);
helpMenu->addAction(aboutQtAct);
// Add menu items to the menubar
menuBar()->addMenu(fileMenu);
menuBar()->addMenu(optionMenu);
menuBar()->addMenu(helpMenu);
}
bool MainWindow::maybeSave()
{
// Check for changes since last save
if (scribbleArea->isModified()) {
QMessageBox::StandardButton ret;
// Scribble is the title
// Add text and the buttons
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 save button clicked call for file to be saved
if (ret == QMessageBox::Save) {
return saveFile("png");
// If cancel do nothing
} else if (ret == QMessageBox::Cancel) {
return false;
}
}
return true;
}
bool MainWindow::saveFile(const QByteArray &fileFormat)
{
// Define path, name and default file type
QString initialPath = QDir::currentPath() + "/untitled." + fileFormat;
// Get selected file from dialog
// Add the proper file formats and extensions
QString fileName = QFileDialog::getSaveFileName(this, tr("Save As"),
initialPath,
tr("%1 Files (*.%2);;All Files (*)")
.arg(QString::fromLatin1(fileFormat.toUpper()))
.arg(QString::fromLatin1(fileFormat)));
// If no file do nothing
if (fileName.isEmpty()) {
return false;
} else {
// Call for the file to be saved
return scribbleArea->saveImage(fileName, fileFormat.constData());
}
}
#include <QtWidgets>
#if defined(QT_PRINTSUPPORT_LIB)
#include <QtPrintSupport/qtprintsupportglobal.h>
#if QT_CONFIG(printdialog)
#include <QPrinter>
#include <QPrintDialog>
#endif
#endif
#include "scribblearea.h"
ScribbleArea::ScribbleArea(QWidget *parent)
: QWidget(parent)
{
// Roots the widget to the top left even if resized
setAttribute(Qt::WA_StaticContents);
// Set defaults for the monitored variables
modified = false;
scribbling = false;
myPenWidth = 1;
myPenColor = Qt::blue;
}
// Used to load the image and place it in the widget
bool ScribbleArea::openImage(const QString &fileName)
{
// Holds the image
QImage loadedImage;
// If the image wasn't loaded leave this function
if (!loadedImage.load(fileName))
return false;
QSize newSize = loadedImage.size().expandedTo(size());
resizeImage(&loadedImage, newSize);
image = loadedImage;
modified = false;
update();
return true;
}
// Save the current image
bool ScribbleArea::saveImage(const QString &fileName, const char *fileFormat)
{
// Created to hold the image
QImage visibleImage = image;
resizeImage(&visibleImage, size());
if (visibleImage.save(fileName, fileFormat)) {
modified = false;
return true;
} else {
return false;
}
}
// Used to change the pen color
void ScribbleArea::setPenColor(const QColor &newColor)
{
myPenColor = newColor;
}
// Used to change the pen width
void ScribbleArea::setPenWidth(int newWidth)
{
myPenWidth = newWidth;
}
// Color the image area with white
void ScribbleArea::clearImage()
{
image.fill(qRgb(255, 255, 255));
modified = true;
update();
}
// If a mouse button is pressed check if it was the
// left button and if so store the current position
// Set that we are currently drawing
void ScribbleArea::mousePressEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton) {
lastPoint = event->pos();
scribbling = true;
}
}
// When the mouse moves if the left button is clicked
// we call the drawline function which draws a line
// from the last position to the current
void ScribbleArea::mouseMoveEvent(QMouseEvent *event)
{
if ((event->buttons() & Qt::LeftButton) && scribbling)
drawLineTo(event->pos());
}
// If the button is released we set variables to stop drawing
void ScribbleArea::mouseReleaseEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton && scribbling) {
drawLineTo(event->pos());
scribbling = false;
}
}
// QPainter provides functions to draw on the widget
// The QPaintEvent is sent to widgets that need to
// update themselves
void ScribbleArea::paintEvent(QPaintEvent *event)
{
QPainter painter(this);
// Returns the rectangle that needs to be updated
QRect dirtyRect = event->rect();
// Draws the rectangle where the image needs to
// be updated
painter.drawImage(dirtyRect, image, dirtyRect);
}
// Resize the image to slightly larger then the main window
// to cut down on the need to resize the 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)
{
// Used to draw on the widget
QPainter painter(&image);
// Set the current settings for the pen
painter.setPen(QPen(myPenColor, myPenWidth, Qt::SolidLine, Qt::RoundCap,
Qt::RoundJoin));
// Draw a line from the last registered point to the current
painter.drawLine(lastPoint, endPoint);
// Set that the image hasn't been saved
modified = true;
int rad = (myPenWidth / 2) + 2;
// Call to update the rectangular space where we drew
update(QRect(lastPoint, endPoint).normalized()
.adjusted(-rad, -rad, +rad, +rad));
// Update the last position where we left off drawing
lastPoint = endPoint;
}
// When the app is resized create a new image using
// the changes made to the image
void ScribbleArea::resizeImage(QImage *image, const QSize &newSize)
{
// Check if we need to redraw the image
if (image->size() == newSize)
return;
// Create a new image to display and fill it with white
QImage newImage(newSize, QImage::Format_RGB32);
newImage.fill(qRgb(255, 255, 255));
// Draw the image
QPainter painter(&newImage);
painter.drawImage(QPoint(0, 0), *image);
*image = newImage;
}
// Print the image
void ScribbleArea::print()
{
// Check for print dialog availability
}