sketcheditor.h

#ifndef SKETCHEDITOR_H
#define SKETCHEDITOR_H

#include <QObject>
#include <QString>
#include <QStack>
#include <QImage>
#include <QGraphicsSceneMouseEvent>
#include <QStyleOptionGraphicsItem>
#include <QDeclarativeItem>

class SketchEditor : public QDeclarativeItem
{
    Q_OBJECT

    Q_PROPERTY(int  mode       READ mode       WRITE setMode)
    Q_PROPERTY(int  helperSize READ helperSize WRITE setHelperSize)
    Q_PROPERTY(int  radius     READ radius     WRITE setRadius)
    Q_PROPERTY(bool changed    READ changed)

    Q_ENUMS(Mode)
    Q_ENUMS(MouseState)

public:
    explicit SketchEditor(QDeclarativeItem *parent = 0);
    virtual ~SketchEditor();

    int  mode() const;
    void setMode(const int &mode);

    int  helperSize() const;
    void setHelperSize(const int &size);

    int  radius() const;
    void setRadius(const int &radius);

    bool changed() const;

    Q_INVOKABLE void openImage(const QString &image_url);
    Q_INVOKABLE void saveImage(const QString &image_url);

    Q_INVOKABLE void undo();

    virtual void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget*);

    enum Mode {
        ModeScroll,
        ModeOriginal,
        ModeEffected
    };

    enum MouseState {
        MousePressed,
        MouseMoved,
        MouseReleased
    };

public slots:
    void effectedImageReady(const QImage &effected_image);

signals:
    void imageOpened();
    void imageOpenFailed();

    void imageSaved();
    void imageSaveFailed();

    void undoAvailabilityChanged(bool available);

    void mouseEvent(int event_type, int x, int y);

    void helperImageReady(const QImage &helper_image);

protected:
    virtual void mousePressEvent(QGraphicsSceneMouseEvent *event);
    virtual void mouseMoveEvent(QGraphicsSceneMouseEvent *event);
    virtual void mouseReleaseEvent(QGraphicsSceneMouseEvent *event);

private:
    void SaveUndoImage();
    void ChangeImageAt(bool save_undo, int center_x, int center_y);

    static const int UNDO_DEPTH  = 4,
                     BRUSH_SIZE  = 16;

    static const qreal IMAGE_MPIX_LIMIT = 1.0;

    bool           IsChanged;
    int            CurrentMode, HelperSize, GaussianRadius;
    QImage         LoadedImage, OriginalImage, EffectedImage, CurrentImage;
    QStack<QImage> UndoStack;
};

class SketchPreviewGenerator : public QDeclarativeItem
{
    Q_OBJECT

    Q_PROPERTY(int radius READ radius WRITE setRadius)

public:
    explicit SketchPreviewGenerator(QDeclarativeItem *parent = 0);
    virtual ~SketchPreviewGenerator();

    int  radius() const;
    void setRadius(const int &radius);

    Q_INVOKABLE void openImage(const QString &image_url);

    virtual void paint(QPainter *painter, const QStyleOptionGraphicsItem*, QWidget*);

public slots:
    void sketchImageReady(const QImage &sketch_image);

signals:
    void imageOpened();
    void imageOpenFailed();

    void generationStarted();
    void generationFinished();

private:
    void StartSketchGenerator();

    static const qreal IMAGE_MPIX_LIMIT = 0.2;

    bool   SketchGeneratorRunning, RestartSketchGenerator;
    int    GaussianRadius;
    QImage LoadedImage, SketchImage;
};

class SketchImageGenerator : public QObject
{
    Q_OBJECT

public:
    explicit SketchImageGenerator(QObject *parent = 0);
    virtual ~SketchImageGenerator();

    void setGaussianRadius(const int &radius);
    void setInput(const QImage &input_image);

public slots:
    void start();

signals:
    void imageReady(const QImage &output_image);
    void finished();

private:
    int    GaussianRadius;
    QImage InputImage;
};

#endif // SKETCHEDITOR_H