在C ++中移动数组的函数

Question

I am trying to make a function that will move the parts of an array (which is made of widgets) around a circle. It builds and runs but the icons do not appear. Can someone tell me why?

Here is the function in the .cpp file

    void setIconWidgetLocation(iconWidget *w, float arcSize)
{
    int outerRadius = 100;
    int innerRadius = 60;
    int radius = (outerRadius + innerRadius)/2;
    arcSize = 2.0 * M_PI/ 5;

    iconWidget *icon[5];

    QSizeF size = w->size();
    QPointF center(size.width(),size.height());
    center /= 2.0;

    //Loop for finding the circles and moving them
    for(int i = 0; i<5; i++)
    {
        icon[i] = new iconWidget;

        //Finding the Icon center on the circle
        double x = center.x() + radius * sin(arcSize * i);
        double y = center.y() + radius * cos(arcSize * i);

        x -= 10/2;
        y -= 10/2;

        //moves icons into place
        icon[i]->move(x,y);

    }
}

and here is the header file

#ifndef ZMENUWIDGET_H
#define ZMENUWIDGET_H
#include "iconwidget.h"

#include <QWidget>

class zMenuWidget : public QWidget
{
    Q_OBJECT

    iconWidget *icon[5];

public:
    explicit zMenuWidget(QWidget *parent = 0);

    void paintEvent(QPaintEvent *event);

    void resizeEvent(QResizeEvent *event);

signals:

public slots:

};

#endif // ZMENUWIDGET_H

here is the call of the setIconWidgetLocation.

#include "zmenuwidget.h"
#include <QPaintEvent>
#include <QResizeEvent>
#include <QPainter>
#include <QColor>
#include <QPainterPath>
#include <cmath>

setIconWidgetLocation(iconWidget *w, float arcSize);

zMenuWidget::zMenuWidget(QWidget *parent) :
    QWidget(parent)
{

}

Answer 1

You don't actually call the function. What you have shown is a function declaration (aka prototype ). All it does is tell the compiler that your function exists and states how it is called.

Before I go there, you have a few things to iron out first. Namely, the parameters don't make sense. Your function creates and lays out icons for your menu. So passing in an iconWidget is confusing. Also, you pass arcSize but then calculate it inside the function. I expect that this function should actually be a member of zMenuWidget . Finally, it doesn't just set the locations, it also creates the icons, so the naming is misleading.

Let's address all these things in one hit:

void zMenuWidget::createAndLayoutIcons()
{
    int outerRadius = 100;
    int innerRadius = 60;
    int radius = (outerRadius + innerRadius)/2;
    double arcSize = 2.0 * M_PI/ 5;

    QSizeF size = w->size();
    QPointF center(size.width(),size.height());
    center /= 2.0;

    //Loop for finding the circles and moving them
    for(int i = 0; i<5; i++)
    {
        icon[i] = new iconWidget(this);

        //Finding the Icon center on the circle
        double x = center.x() + radius * sin(arcSize * i);
        double y = center.y() + radius * cos(arcSize * i);

        x -= 10/2;
        y -= 10/2;

        //moves icons into place
        icon[i]->move(x,y);
    }
}

Notice that I have removed the locally-defined icon array from this function, because it's defined in your zMenuWidget class. That's the other hint that you needed to make your function a member of the class.

I also modified the icon creation part to pass the menu widget's pointer to your new icon widget (as its parent). I assume your iconWidget accepts a parent pointer:

        icon[i] = new iconWidget(this);

Now in the constructor for zMenuWidget , you create your icons:

zMenuWidget::zMenuWidget( QWidget *parent)
    : QWidget(parent)
{
    createAndLayoutIcons(this);
}

That should get you moving in the right direction.