Qt animation problem - flickering geometry animation

I have a problem creating a simple animation with Qt animation. I have a small image located at the bottom right corner of the screen, i am trying to create animation that will enlarge the picture by streching it from the the top left corner of the image and streching it to the center of the screen. I managed to do that, but, it's very notiable that qanimation makes it flicker (the right border of the picture, and it doesn't turns out good) I also did that with no animation, but wi开发者_如何学JAVAth a timer, and changing window geometry , but i had the same problem, seems that it's not refreshing fast enough, creating flickering in the right border of the picture.

here are the 2 examples:

1 - using property animation (geometery)

animation = new QPropertyAnimation(this, "geometry");
animation->setDuration(555);
animation->setEasingCurve(QEasingCurve::Linear);
animation->setStartValue(QRect(availableScreenSize.width()  -minWidth
    -WINDOW_PADDING,availableScreenSize.height() - minHeight
    -WINDOW_PADDING,minWidth,minHeight));
animation->setEndValue(QRect(availableScreenSize.width() - maxWidth
    -WINDOW_PADDING,availableScreenSize.height() - maxHeight
    -WINDOW_PADDING,maxWidth,maxHeight));

2 - using a timer

#include "widget.h"
#include "ui_widget.h"
#include <QDesktopWidget>
#include <QDebug>

Widget::Widget(QWidget *parent) :
QWidget(parent),
ui(new Ui::Widget)
{
    ui->setupUi(this);
    this->setStyleSheet("background:transparent;");
    this->setWindowFlags(Qt::FramelessWindowHint | Qt::WindowStaysOnTopHint
        | Qt::Tool);

    availableScreenSize = qApp->desktop()->availableGeometry();

    //Growing from right to left
    this->setGeometry(availableScreenSize.width() - 165,
        availableScreenSize.height()-95,160,90);
    //Growing from left to right
    //this->setGeometry(200,200,160,90);

    timeLine = new QTimeLine();
    timeLine->setDuration(2222);
    timeLine->setFrameRange(1, 800);
    connect(timeLine, SIGNAL(frameChanged(int)), this, SLOT(update()));

    counter = 0;

    timeLine->start();
}

Widget::~Widget()
{
    delete ui;
}

void Widget: aintEvent(QPaintEvent * /* event */)
{
    counter++;
    qDebug() << counter;

    qApp->processEvents();
    //Growing from right to left
    this->setGeometry(availableScreenSize.width()  -165 
        - this->width()-1,availableScreenSize.height() - 95
        - this->height()-1,this->width()+1,this->height()+1);

    //Growing from left to right
    //this->setGeometry(200,200,this->width()+1,this->height()+1);

    if(timeLine->currentFrame() == 800)
    {
        qApp->exit(1);
    }
}

Now the weired thing here is that if the animation is from left 2 right - it looks smooth... once the direction is changed from right 2 left the entire right border is "jumpy" .

I'll appriciate any help that you can give me. Thanks!

---

I'm experiencing the same problem currently with animating scaling of my QGraphicsPixmapItem. Unlike your case, I'm using setScale(scaleValue) instead of setGeometry because that method is not available for QGraphicsPixmapItem. I was able to remove the flicker using the following code (Note: I'm using PySide binding for QT but you should be able to find the corresponding C++ methods easily):

In my initializer for my QGraphicsPixmapItem class, I called:

self.setTransformationMode(Qt.SmoothTransformation)
self.setCacheMode(PySide.QtGui.QGraphicsItem.DeviceCoordinateCache)

In my QGraphicsView:

self.setCacheMode(QGraphicsView.CacheBackground)
self.setRenderHints(PySide.QtGui.QPainter.Antialiasing | PySide.QtGui.QPainter.SmoothPixmapTransform)

Even though the flicker is gone, the animation is still a bit jerky.

If anyone has a better solution, would really appreciate it if you could post it. Thanks.

---

For your parent widget and on the widget on where animation is happening you can set this flag :

parentWidget.setAttribute(Qt::WA_NoSystemBackground); animatingWidget.setAttribute(Qt::WA_NoSystemBackground);