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POQt: Custom widget in QScrollArea
 

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  1. POQt: Custom widget in QScrollArea
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    <p>I am attempting to create a custom widget. My Widget renders itself unless it is inside a scroll area. The code below works. If I change the if(0) to an if(1) inside the MainWindow constructor, it will not render the "Hello World" string. I assume that I must (re)implement some additional methods, but so far I have not been able to find the correct ones with trial and error.</p> <pre><code>// hellowidget.h #ifndef HELLOWIDGET_H #define HELLOWIDGET_H #include &lt;QtGui&gt; class HelloWidget : public QWidget { Q_OBJECT public: HelloWidget(QWidget *parent = 0); void paintEvent(QPaintEvent *event); }; #endif // HELLOWIDGET_H // hellowidget.cpp #include "hellowidget.h" HelloWidget::HelloWidget(QWidget *parent) : QWidget(parent) { } void HelloWidget::paintEvent(QPaintEvent *event) { QPainter painter(this); painter.drawText(rect(), Qt::AlignCenter, "Hello World"); } // mainwindow.h #ifndef MAINWINDOW_H #define MAINWINDOW_H #include &lt;QtGui&gt; class MainWindow : public QMainWindow { Q_OBJECT public: MainWindow(QWidget *parent = 0); ~MainWindow(); private: }; #endif // MAINWINDOW_H // mainwindow.cpp #include "mainwindow.h" #include "hellowidget.h" MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) { HelloWidget *hello = new HelloWidget; QWidget *central = hello; if( 0 ) { QScrollArea *scroll = new QScrollArea ; scroll-&gt;setWidget(hello); central = scroll; } setCentralWidget( central ); } MainWindow::~MainWindow() { } // main.cpp #include &lt;QtGui/QApplication&gt; #include "mainwindow.h" int main(int argc, char *argv[]) { QApplication a(argc, argv); MainWindow w; w.show(); return a.exec(); } </code></pre>
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    1. COIs your paintEvent function being called? I would put a qDebug() statement in there, or break in a debugger. If it is not being called at all, I would think that it is probably a sizing issue, still. Try re-implementing resizeEvent() and see what sizes the widget is being set to. I would wager it is never being set larger than (0, 0), which would mean there was nothing to draw.
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      1. POQt: Custom widget in QScrollArea
      1. USCaleb Huitt - cjhuitt
 

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