QGraphicsView fit any size Image without scrollbar

Question

My work Environment: Qt 5.8 MSVC2015 64bit, QT GraphicsView, QGraphicsObject, Windows 7 64 bit.

I am loading image of any Size using QImage, try fit into QGraphicsView of fix size (Width 200 X Height 200). I don't want scrollbar in QGraphicsView.

In below example :

My QGraphicsView size will be always fix Width 200 X Height 200.
My Image size will may vary, but in below code my image Width 182 * Height 174.

So how I can any fit Image in a fix size QGraphicsView ?

 QImage *ImageData;
 QGraphicsView*  _ThumbNailView = new QGraphicsView(this);
_ThumbNailView->setFixedSize(200, 200);  //QGraphicsView will be alwyas constant.
 QGraphicsScene*    _scene =  new QGraphicsScene();
_scene->setSceneRect(0,0,200,200);
 ..........


 myQGraphicsItem* _thumbsquare = new myQGraphicsItem(imageWidth, imageHeight, ImageData);


 //Load image from buffer
    unsigned char *buffer;   ////some image Data get loaded here. 
    int imageWidth = 182;   //I am getting image Width 182, or any size.
    int imageHeight = 174; //I am getting image Height 174 or any size.
    size_t  size = imageWidth * imageHeight * 3;
    int  bytesPerLine = size / imageHeight;
    QImage* _image = new  QImage(reinterpret_cast<const uchar *>(buffer),182, 174, bytesPerLine, QImage::Format_RGB888);
    _thumbsquare->setMyImage(QImage);

...........    

 int width = _ThumbNailView->geometry().width();    // always const 200
 int height = _ThumbNailView->geometry().height(); // always const 200
_ThumbNailView->resize(width, height);
_scene->addItem(_thumbsquare);
_scene->setSceneRect(_scene->itemsBoundingRect());

// This don't work, make image very small
//_ThumbNailView->fitInView(QRectF(0, 0, 200, 200));

Above code result

Expected Full Fit Image without Scroll bar

Any suggestion or help is highly appreciated ?

Possible duplicate of Qt5 C++ QGraphicsView: Images don't fit view frame — Eligijus Pupeikis
@Eligijus: I tried above link which resolve my scroll bar issue. But If image width less than 200, it not fully occupy 200 width. QRectF bounds = _scene->sceneRect(); if (bounds.width() < 200) { bounds.setWidth(200); } if (bounds.height() < 200) { bounds.setHeight(200); } _ThumbNailView->fitInView(bounds, Qt::KeepAspectRatio); — Sandip

Sandip Sandip · Accepted Answer · 2017-07-10T08:47:13

@ Eligijus, Thanks for your help, it help me to find solution.

My code changes :

QRectF bounds = _scene->sceneRect();
QRectF rect  {0,0,200,200};
if (bounds.width() < 200)
{
    rect .setWidth(bounds.width());
    bounds.setWidth(200);
}
if (bounds.height() < 200)
{
    rect.setWidth(bounds.height());
    bounds.setHeight(200);
}
 _ThumbNailView->fitInView(bounds, Qt::KeepAspectRatio);
 QRectF changeRect  = _scene->sceneRect();
_ThumbNailView->updateGeometry();

But if image size less than 200, then you will face problem, else thing will go smoothly.

QGraphicsView fit any size Image without scrollbar

1 Answers