I am trying to capture a screenshot of my application within the application. Its a Qt-based application. Is anyone aware of how to do this? Any suggestions are very welcome.
CV
You can tell any QWidget (including your QMainWindow) to render itself off-screen:
http://developer.qt.nokia.com/doc/qt-4.8/qwidget.html#render
Technically this is not a screenshot as it renders the widget explicitely for this purpose instead of capturing what is seen on-screen. For almost any purpose it doesn't matter.
If you have a GL widget, you can/must instead use grabFramebuffer() which has the advantage of capturing what is seen on the screen.
With this example you could get all your widget screen.
You could attach this method to any key press or signal, as you prefer, to get successive screenshot.
MyClass::screenshot()
{
QWidget *w = QApplication::activeWindow();
if(w) {
static int count = 0;
QPixmap p = QPixmap::grabWidget(w);
p.save(QString("/your/path/screenshot%1.png").arg(count));
count++;
}
}
QPixmap lets you do a window grab if you have the ID. My references are for PyQt but I'm sure you can make the adjustments:
How to get RGB values of QPixmap or QImage pixel - Qt, PyQt
http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/html/qpixmap.html#grabWindow
In modern QT 5+ it can be done like that:
void MainWindow::takeScreenshot(const QString screenshotFileName)
{
if(isActiveWindow())
{
auto grabbedScreenshot = QWidget::grab();
grabbedScreenshot.save(screenshotFileName);
}
}
Related
I have a QWidget as the child of another within my application. The task consists of putting the internal widget in full screen mode and being able to see it again in normal mode with the same button. This partly I have managed to do it in the following way:
if(!isFullScreen())
{
setWindowFlags(windowFlags() | Qt::Window);
showFullScreen();
}
else
{
setWindowFlags(windowFlags() & ~Qt::Window);
showNormal();
activateWindow();
}
The problem arises when you return to see the widget in normal mode. Things that happen:
The mouse cursor stays with pointing hand cursor.
The button to change mode remains in hover state (the background color is changed when the mouse is over)
Passing the mouse through other widget controls does not change its appearance
I have to click on the widget to fix the behavior. It's as if the widget did not receive events of any kind or something like that. I tried calling setFocus () and it did not work. I have also tried to send an event by hand in the following way but it has not worked either:
QMouseEvent my_event(QEvent::MouseButtonPress, QPointF (0, 0), Qt :: NoButton, 0, 0);
QApplication::sendEvent(this, & my_event);
Any ideas?
Thanks.
Cannot reproduce your issue on Xubuntu with Qt5.9.4.
However I did the same in my last job, and it worked correctly on all platforms. It was something like this, I think:
if(!isFullScreen())
{
setParent(0);
showFullScreen();
}
else
{
orignalParentLayout->addWidget(this); // better: insert at correct position
showNormal();
}
For this you have to add some knowledge about the parent's layout though. You could try to detect that info before going into full screen mode, but it is probably not worth the effort.
You could also try:
if(!isFullScreen())
{
logicalParent = parentWidget();
setParent(0);
showFullScreen();
}
else
{
setParent(logicalParent);
showNormal();
}
If you have no layout. You might also want to store the geometry before going to full screen.
i have some concatenate toolbar. For every toolbar i have call:
toolbar->setGeometry(x,y,width,height)
but i have no resize.
I try to call
toolbar->updateGeometry();
but nothing.
My goal is to expand every toolbar with my size definition
There is a good chance you are using this for repositioning your toolbars on init and saving at closing.
Here is a solid way to do that:
What you really need is to use the QMainWindow saveGeometry() and restoreGeometry() functions and save and load the byte array through the QSettings interface.
writeSettings
QSettings s;
s.beginGroup("MainWindow");
this->restoreGeometry(s.value("geometry").toByteArray());
this->restoreState(s.value("windowState").toByteArray());
s.endGroup();
readSettings
QSettings s;
s.beginGroup("MainWindow");
s.setValue("geometry", saveGeometry());
s.setValue("windowState", saveState());
s.endGroup();
Hope that helps.
You can try QWidget::resize( int w, int h ) to resize the toolbar.
toolbar-> resize( 200, 20 );
The toolbar's geometry is either managed by a layout or by the main window.
You'd need to show how is the toolbar used/displayed.
I implemented QLabel much like Qt's ImageViewer example, except I use QGridLayout for positioning my widgets. I also implemented similar lines for scaling my QLabel using QScrollBar, but QLabel just doesn't scale like it should inside the QScrollArea. I am not sure if it is related to some kind of GridLayout management issue or something else. I have been reading everywhere and trying different things for 3 days now. Below I list the relevant portion of my code.
In my Viewer class constructor:
{
imageLabel1 = new QLabel;
imageLabel1->setSizePolicy(QSizePolicy::Minimum, QSizePolicy::Minimum);
imageLabel1->setScaledContents(true);
scrollArea1 = new QScrollArea;
scrollArea1->setWidget(imageLabel1);
scrollArea1->setWidgetResizable(true);
....
QGridLayout *centralLayout = new QGridLayout;
centralLayout->addWidget(scrollArea1, 0, 0);
...}
and my scaleImage method:
void Viewer::scaleImage1(int factor)
{
Q_ASSERT(imageLabel1->pixmap());
scaleFactor *= (1 + factor);
//imageLabel1->resize(scaleFactor* imageLabel1->pixmap()->size());
imageLabel1->pixmap()->toImage().scaled(scaleFactor* imageLabel1->pixmap()->size(), Qt::KeepAspectRatio, Qt::FastTransformation);
imageLabel1->adjustSize();
adjustScrollBar(scrollArea1->horizontalScrollBar(), factor);
adjustScrollBar(scrollArea1->verticalScrollBar(), factor);
imageLabel1->update();
}
My scaleImage1 function is a public slot, and it receives signal from a scrollbar that goes between 0 and 2 so that, into the scaleFactor, the imageLabel1 is designed to be capable of being zoomed in up to 3 times its original size. But when I run the code, I don’t observe the imageLabel becoming enlarged inside the QScrollArea, which I saw in the imageViewer demo. The imageLabel1 simply retains the original size as it is loaded and does not respond to the valueChange() of scrollbar.
I'd appreciate your advice/tips very much.
I think is because you set QSizePolicy::Minimum to the imageLabel, try with MinimumExpanding or other that better fit your needs.
I'm using QPushButton in my mineSweeping game.
After changing from easy mode to hard mode, the number of QPushButton is supposed to change from 9x9 to 30x16.
So, I add QPushButton with the largest number(which is of hard mode) to GridLayout in constructor of MainWindow.
btnArr = new QPushButton[HARD_WIDTH * HARD_HEIGHT]; // member element
int index = 0;
for (int i = 0; i < HARD_HEIGHT; ++i) {
for (int j = 0; j < HARD_WIDTH; ++j) {
ui->mainGrid->addWidget(&btnArr[index], i, j, 1, 1,
Qt::AlignCenter);
++index;
}
}
Then if the user change mode(e.g.: easy mode to hard mode), resetBtn(HARD_WIDTH, HARD_HEIGHT); will be called.
void MainWindow::resetBtn(const int width, const int height)
{
int index = 0;
for (int i = 0; i < HARD_HEIGHT; ++i) {
for (int j = 0; j < HARD_WIDTH; ++j) {
if (j < width && i < height) {
btnArr[index].setVisible(true);
} else {
btnArr[index].setVisible(false);
}
++index;
}
}
}
The problem is that it seems the widget repaints each time setVisible is called. So in the hard mode case, it will be called 30x16 times, which caused strange effect like this:
So how can I set the widget not repaint during this loop?
Thanks in advance.
I think that you are trying to solve the wrong problem. You shouldn't be updating the widgets like this. If you necessarily want to, then hiding the parent widget of the layout before the change and showing it again afterwards should work.
A better approach is to use QStackedWidget and have all the boards prepared initially. Switching to a different board is then simply a matter of switching the active widget.
The total number of QPushButton is really big: 30x16 = 480!!! I don't use to make people change their programming logic, but in this case I think that using QPushButtons is not the better approach. The layout must have a really bad time trying to move the objects as they are added, and perhaps you are reaching some internal limit in refresh time for the layout to be repainted.
What I would have done is a custom widget with a custom paintEvent method. There you can divide its width and height in the number of columns and rows that you wish and paint the cells with pixmaps as the game is played.
For the mouse interaction, the best would have been to override the mousePressEvent with a custom logic that calculates the mouse position in the grid and calls the corresponding methods or emits signals indicating the position of the event. Not very hard to code. You can also use the event->buttons() method to know which mouse button was pressed and emit different signals if you wish.
I don't use to answer telling that it is better to change your whole program, but in this case I think you are going "the hard way". I know this is not the kind of answer you are looking for, but consider this possibility.
You could try calling setUpdatesEnabled(false) on the parent widget before doing those "massive" changes, and re-enable it once all is done.
Maybe I'm wrong but as far as I know Qt doesn't render the widget right after setVisible() is called. Rendering happens as a result of a 'render' event, except if you call render() manually.
From the official Qt doc (http://qt-project.org/doc/qt-4.8/qwidget.html#paintEvent):
Qt also tries to speed up painting by merging multiple paint events
into one. When update() is called several times or the window system
sends several paint events, Qt merges these events into one event with
a larger region (see QRegion::united()). The repaint() function does
not permit this optimization, so we suggest using update() whenever
possible.
My instincts tell me that it's not a painting problem rather a layouting (not enough space to present every button in 'hard mode').
Also I think you shouldn't use Qt::AlignCenter when you add your buttons to the layout, it will try to centerize every button in the layout. You should rather centerize the parent widget of the layout (if you don't have one create one and centerize it) and set size-policies correctly (QWidget setSizePolicy).
But as #Mat suggested if this really is a painting problem you can use setUpdatesEnabled(false/true) (if setUpdatesEnabled solves your problem please accept #Mat 's solution)
Try to enabling/disabling instead of visible/invisible:
void MainWindow::resetBtn(const int width, const int height)
{
int index = 0;
for (int i = 0; i < HARD_HEIGHT; i++)
for (int j = 0; j < HARD_WIDTH; j++)
btnArr[index++].setEnabled(j < width && i < height);
}
Seems to be possible with native controls (see here and here) so now I'm looking for some Qt code to do it.
I use this code for the second display in full screen successfully on both Windows & Linux
QRect screenres = QApplication::desktop()->screenGeometry(1/*screenNumber*/);
SecondDisplay secondDisplay = new SecondDisplay(); // Use your QWidget
secondDisplay->move(QPoint(screenres.x(), screenres.y()));
secondDisplay->resize(screenres.width(), screenres.height());
secondDisplay->showFullScreen();
One way of doing it in Qt5 is to use QWindow::setScreen to set the screen on which the window should be shown. QWidget has a windowHandle() that returns the pointer to the QWindow.
Here is how to show your widget on second screen in full-screen mode :
QWidget * widget = new QWidget();
widget->show();
widget->windowHandle()->setScreen(qApp->screens()[1]);
widget->showFullScreen();
My take on this:
auto const desktop(QApplication::desktop());
setGeometry(desktop->screenGeometry(1));
#ifndef Q_OS_WIN
setWindowState(Qt::WindowState(Qt::WindowFullScreen | windowState()));
#endif // Q_OS_WIN
showFullScreen first, then setGeometry.
Qt5 tested OK
This problem got solved while using window->showFullScreen() instead of window->show().