Signals with enum

[sonichy]

enum {
    LINE_DRAW,
    RECT_DRAW,
    ELLIPSE_DRAW,
    TEXT_DRAW,
    IMAGE_DRAW
} draw_type;

signals:
    newItem(enum draw_type);

[6thC]

MOC needs to be aware of them, see:
Q_ENUM(draw_type)
Q_ENUM_NS(draw_type) - if inside namespace

[Chris Kawa]

To add to what @6thC said this is not the correct syntax. You're defining a variable of an anonymous enum type.
Should be:

enum DrawType {
    LINE_DRAW,
    RECT_DRAW,
    ELLIPSE_DRAW,
    TEXT_DRAW,
    IMAGE_DRAW
};

signals:
    void newItem(DrawType drawType) const;