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Qt-interest Archive, September 2007
how to keep the image ratio during dragging?

Message 1 in thread

ImageViewer developers,

I have a QScrollArea which holds a pixmap image.
After setWidgetResizable(true) the image fits the whole area.
My question is how to how to keep the image ratio during resize dragging?

There are three types of dragging: horizontal, vertical, and diagonal.
Is there a method to distinguish them, because I need to recalculate the 
width, for example, if drag vertically.

Thanks in advance,
Lingfa


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Message 2 in thread

Lingfa Yang wrote:

> ImageViewer developers,
>
> I have a QScrollArea which holds a pixmap image.
> After setWidgetResizable(true) the image fits the whole area.
> My question is how to how to keep the image ratio during resize dragging?
>
> There are three types of dragging: horizontal, vertical, and diagonal.
> Is there a method to distinguish them, because I need to recalculate 
> the width, for example, if drag vertically.
>
> Thanks in advance,
> Lingfa
>
>
More details:
1) subclassing:
class ImageViewer1 : public QScrollArea

2) setWidget:
ImageViewer1::ImageViewer1()
{
    imageLabel = new QLabel;
    this->setWidget(imageLabel);
}

3) setPixmap:
    this->imageLabel->setPixmap(pixmap);

4)   setWidgetResizable:
    this->setWidgetResizable(true);//   fitToWindow

5) Catch event:
void ImageViewer1::resizeEvent ( QResizeEvent * event ) // [virtual 
protected]
{

    QSize oldSize = event->oldSize();
    QSize size = event->size();


    //  change size ...

    imageLabel->resize(size);  // does not work ???
    //QAbstractScrollArea::resizeEvent(event);
}


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