1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
|
/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia. For licensing terms and
** conditions see http://qt.digia.com/licensing. For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights. These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QtGui>
class MyScrollArea : public QAbstractScrollArea
{
public:
MyScrollArea(QWidget *w);
void setWidget(QWidget *w);
protected:
void scrollContentsBy(int dx, int dy);
void resizeEvent(QResizeEvent *event);
private:
void updateWidgetPosition();
void updateArea();
QWidget *widget;
};
MyScrollArea::MyScrollArea(QWidget *widget)
: QAbstractScrollArea()
{
setWidget(widget);
}
void MyScrollArea::setWidget(QWidget *w)
{
widget = w;
widget->setParent(viewport());
if (!widget->testAttribute(Qt::WA_Resized))
widget->resize(widget->sizeHint());
verticalScrollBar()->setValue(0);
verticalScrollBar()->setValue(0);
updateArea();
}
void MyScrollArea::updateWidgetPosition()
{
//! [0]
int hvalue = horizontalScrollBar()->value();
int vvalue = verticalScrollBar()->value();
QPoint topLeft = viewport()->rect().topLeft();
widget->move(topLeft.x() - hvalue, topLeft.y() - vvalue);
//! [0]
}
void MyScrollArea::scrollContentsBy(int /*dx*/, int /*dy*/)
{
updateWidgetPosition();
}
void MyScrollArea::updateArea()
{
//! [1]
QSize areaSize = viewport()->size();
QSize widgetSize = widget->size();
verticalScrollBar()->setPageStep(widgetSize.height());
horizontalScrollBar()->setPageStep(widgetSize.width());
verticalScrollBar()->setRange(0, widgetSize.height() - areaSize.height());
horizontalScrollBar()->setRange(0, widgetSize.width() - areaSize.width());
updateWidgetPosition();
//! [1]
}
void MyScrollArea::resizeEvent(QResizeEvent *event)
{
updateArea();
}
int main(int argv, char **args)
{
QApplication app(argv, args);
QPixmap pixmap("mypixmap.png");
QLabel label;
label.setPixmap(pixmap);
MyScrollArea area(&label);
area.resize(300, 300);
area.show();
area.setWidget(&label);
return app.exec();
}
|
