Want to implement rectangle movements similar to in microsoft power point in my QGraphicsView

Qt Enthusiast

Hi All
I have a QgraphicsView and I have rectangles drawn inside the same

There is functionality in microsoft power point where When I press up key or down key , the right key or letf key the rectangular box moves

UP : vertically up on the Y axis
Down : vertically down on the Y axis
Right : right movement on right key press
Left : left movement on left key press

I want to implement the same functionality in my QGraphicsView any suggestions would help

jsulm

@Qt-Enthusiast You can use http://doc.qt.io/qt-5/qgraphicsview.html#mousePressEvent to select a rectangle.
Then use http://doc.qt.io/qt-5/qgraphicsview.html#keyPressEvent to move the selected rectangle.

Qt Enthusiast

First I select the rectangle and then the rectangle should move up when I use up arrow key

jsulm

@Qt-Enthusiast Why do you want to move mouse up? You want to move rectangle, not mouse cursor, right?
You use mousePressEvent to select a rectangle, not to move it. I mean, how do you decide which rectangle to move? I guess your user has to click on the rectangle to select it and then move?

jsulm

@Qt-Enthusiast What is "mouse up arrow key"?

Qt Enthusiast

@jsulm I hav e edited the text

jsulm

@Qt-Enthusiast Just use http://doc.qt.io/qt-5/qgraphicsview.html#keyPressEvent

Qt Enthusiast

could you guide a little bit more .on Keypress event what should I do so that rectangle moves up on pressing SHift+ arrow key

J.Hilk

@Qt-Enthusiast

you overwrite the function, in your QGraphicsView header

//xxx.h
protected:
void keyPressEvent(QKeyEvent *event);

than you handle the event in your cpp file

keyPressEvent(QKeyEvent *event){
    if( event->key == Qt::Key_Left){
     do stuff...
   }
}

Devopia53

@Qt-Enthusiast

If you want another way, do the following:

[...]
#include <QGraphicsRectItem>

class MyRectItem : public QGraphicsRectItem
{
public:
    explicit MyRectItem(QGraphicsItem *parent = 0);

    // QGraphicsItem interface
protected:
    virtual void keyPressEvent(QKeyEvent *event) override;
};

[...]

void MyRectItem::keyPressEvent(QKeyEvent *event)
{
    if (!flags().testFlag(QGraphicsItem::ItemIsMovable))
        return;

    if (!isSelected())
        return;

    switch (event->key()) {
        case Qt::Key_Left:  moveBy(-1, 0);  break;
        case Qt::Key_Right: moveBy(1, 0);   break;
        case Qt::Key_Up:    moveBy(0, -1);  break;
        case Qt::Key_Down:  moveBy(0, 1);   break;
    }
}

[...]
auto    item = new MyRectItem;
item->setRect(QRectF(-100, -100, 100, 100));
item->setFlags(QGraphicsItem::ItemIsMovable | QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable);
graphicsView->scene()->addItem(item);
[...]

Qt Enthusiast

In this I am not sure how to edit the locaation of existing rectangle. are you saying you are removing the previous rectangle

Qt Enthusiast

@Devopia53 In this I am not sure how to edit the locaation of existing rectangle. are you saying you are removing the previous rectangle

reply

J.Hilk

@Qt-Enthusiast
@Devopia53 pretty much wrote it out for you. Instead of the default QGraphicsItem you use the custom class MyRectItem he defined for you.

the last section between the 2 [...] even show you how to add a MyRectItem to your graphicsView.

Not much else can be done here

Qt Enthusiast

One more question If I have pressed Shift + Up key what should be value of event->key()

J.Hilk

@Qt-Enthusiast

Key Press event don't come simultaneously, so reimplement KeyReleaseEvent as well, to check if a shift key was pressed and relesed or is still pressed and adjust your KeyPress event accordingly

Qt Enthusiast

A small code will be helpful again

J.Hilk

@Qt-Enthusiast

//MyRectItem .h
private:
bool bShiftPressed = false;

protected:
    virtual void keyReleaseEvent(QKeyEvent *event) override;

//MyRectItem .cpp

void MyRectItem::keyPressEvent(QKeyEvent *event)
{
    if (!flags().testFlag(QGraphicsItem::ItemIsMovable))
        return;

    if (!isSelected())
        return;

if(!bShiftPressed)
    switch (event->key()) {
        case Qt::Key_Left:  moveBy(-1, 0);  break;
        case Qt::Key_Right: moveBy(1, 0);   break;
        case Qt::Key_Up:    moveBy(0, -1);  break;
        case Qt::Key_Down:  moveBy(0, 1);   break;
        case Qt::Key_Shift: bShiftPressed = true;
    }
else
    switch (event->key()) {
        case Qt::Key_Left:  moveBy(-10, 0);  break;
        case Qt::Key_Right: moveBy(10, 0);   break;
        case Qt::Key_Up:    moveBy(0, -10);  break;
        case Qt::Key_Down:  moveBy(0, 10);   break;
    }
}

void MyRectItem::keyReleaseEvent(QKeyEvent *event){
   if(event->key() == Qt::Key_Shift)
       bShiftPressed =false;
}

Qt Enthusiast

I this case up and down arrow key are associated with scrollbar movment . If there is scrollbar movement , then these macros does =move but scrollbar is still moveBy works

Any suggestions on how to avoid this issue

jsulm

@Qt-Enthusiast said in Want to implement rectangle movements similar to in microsoft power point in my QGraphicsView:

I this case up and down arrow key are associated with scrollbar movment . If there is scrollbar movement , then these macros does =move but scrollbar is still moveBy works

Could you please rephrase this? I really cannot understand what you mean.

Qt Enthusiast

In my case the UP key moves the scrollbar up ,

but with Shift+Up key with the code you suggested the Shift+key moves the scroll bar up not the object

in this action on Up takes precedence on action on other key . COuld you let me know what should be done