Qt Beginner QPainter

[seniorc]

Hello,

My file :

drawgraph.h,drawgraph.cpp
graphicscreen.h,graphicscreen.cpp,graphicscreen.ui

I have map in my drawgraph class.

QMap<QString,Coordinate*> corMap;

QMap<QString,Coordinate*> corMap;

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and my Coordinate struct

struct Coordinate{
    double cor_X;
    double cor_Y;
};

struct Coordinate{
    double cor_X;
    double cor_Y;
};

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I want paint line this coordinate and i'm working QPainter class but i have a problem.

void GraphicScreen::paintEvent(QPaintEvent *);

void GraphicScreen::paintEvent(QPaintEvent *);

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in my graphicscreen header file but i dont understand how can i do this,drawing my QMap information.I've tried

void GraphicScreen::draw(QMap ....);

void GraphicScreen::draw(QMap ....);

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but it not working.