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50
51#include <QtWidgets>
52
53class MyScrollArea : public QAbstractScrollArea
54{
55public:
56 MyScrollArea(QWidget *w);
57 void setWidget(QWidget *w);
58
59protected:
60 void scrollContentsBy(int dx, int dy) override;
61 void resizeEvent(QResizeEvent *event) override;
62
63private:
64 void updateWidgetPosition();
65 void updateArea();
66
67 QWidget *widget;
68};
69
70MyScrollArea::MyScrollArea(QWidget *widget)
71 : QAbstractScrollArea()
72{
73 setWidget(widget);
74}
75
76void MyScrollArea::setWidget(QWidget *w)
77{
78 widget = w;
79 widget->setParent(viewport());
80 if (!widget->testAttribute(attribute: Qt::WA_Resized))
81 widget->resize(widget->sizeHint());
82
83 verticalScrollBar()->setValue(0);
84 verticalScrollBar()->setValue(0);
85
86 updateArea();
87}
88
89void MyScrollArea::updateWidgetPosition()
90{
91//! [0]
92 int hvalue = horizontalScrollBar()->value();
93 int vvalue = verticalScrollBar()->value();
94 QPoint topLeft = viewport()->rect().topLeft();
95
96 widget->move(ax: topLeft.x() - hvalue, ay: topLeft.y() - vvalue);
97//! [0]
98}
99
100void MyScrollArea::scrollContentsBy(int dx, int dy)
101{
102 Q_UNUSED(dx);
103 Q_UNUSED(dy);
104 updateWidgetPosition();
105}
106
107void MyScrollArea::updateArea()
108{
109//! [1]
110 QSize areaSize = viewport()->size();
111 QSize widgetSize = widget->size();
112
113 verticalScrollBar()->setPageStep(areaSize.height());
114 horizontalScrollBar()->setPageStep(areaSize.width());
115 verticalScrollBar()->setRange(min: 0, max: widgetSize.height() - areaSize.height());
116 horizontalScrollBar()->setRange(min: 0, max: widgetSize.width() - areaSize.width());
117 updateWidgetPosition();
118//! [1]
119}
120
121void MyScrollArea::resizeEvent(QResizeEvent *event)
122{
123 Q_UNUSED(event);
124 updateArea();
125}
126

source code of qtbase/src/widgets/doc/snippets/myscrollarea/myscrollarea.cpp