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This example shows how to use Qt's scrollview. This is a widget optimized for very large contents.
Implementation:
/****************************************************************************
** $Id: qt/scrollview.cpp 3.0.4 edited Oct 15 2001 $
**
** Copyright (C) 1992-2000 Trolltech AS. All rights reserved.
**
** This file is part of an example program for Qt. This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/
#include <qscrollview.h>
#include <qapplication.h>
#include <qmenubar.h>
#include <qpopupmenu.h>
#include <qpushbutton.h>
#include <qpainter.h>
#include <qpixmap.h>
#include <qmessagebox.h>
#include <qlayout.h>
#include <qlabel.h>
#include <qmultilineedit.h>
#include <qsizegrip.h>
#include <stdlib.h>
static const int style_id = 0x1000;
static const int lw_id = 0x2000;
static const int mlw_id = 0x4000;
static const int mw_id = 0x8000;
static const int max_lw = 16;
static const int max_mlw = 5;
static const int max_mw = 10;
class BigShrinker : public QFrame {
Q_OBJECT
public:
BigShrinker(QWidget* parent) :
QFrame(parent)
{
setFrameStyle(QFrame::Box|QFrame::Sunken);
int h=35;
int b=0;
for (int y=0; y<2000-h; y+=h+10) {
if (y == 0) {
QButton* q=new QPushButton("Quit", this);
connect(q, SIGNAL(clicked()), qApp, SLOT(quit()));
} else {
QString str;
if ( b > 0 ) {
str.sprintf("Button %d", b++);
} else {
str = "I'm shrinking!";
++b;
}
(new QPushButton(str, this))->move(y/2,y);
}
}
resize(1000,2000);
startTimer(250);
}
void timerEvent(QTimerEvent*)
{
int w=width();
int h=height();
if ( w > 50 ) w -= 1;
if ( h > 50 ) h -= 2;
resize(w,h);
}
void mouseReleaseEvent(QMouseEvent* e)
{
emit clicked(e->x(), e->y());
}
signals:
void clicked(int,int);
};
class BigMatrix : public QScrollView {
QMultiLineEdit *dragging;
public:
BigMatrix(QWidget* parent) :
QScrollView(parent,"matrix", WStaticContents),
bg("bg.ppm")
{
bg.load("bg.ppm");
resizeContents(400000,300000);
dragging = 0;
}
void viewportMousePressEvent(QMouseEvent* e)
{
int x, y;
viewportToContents( e->x(), e->y(), x, y );
dragging = new QMultiLineEdit(viewport(),"Another");
dragging->setText("Thanks!");
dragging->resize(100,100);
addChild(dragging, x, y);
showChild(dragging);
}
void viewportMouseReleaseEvent(QMouseEvent*)
{
dragging = 0;
}
void viewportMouseMoveEvent(QMouseEvent* e)
{
if ( dragging ) {
int mx, my;
viewportToContents( e->x(), e->y(), mx, my );
int cx = childX(dragging);
int cy = childY(dragging);
int w = mx - cx + 1;
int h = my - cy + 1;
QString msg;
msg.sprintf("at (%d,%d) %d by %d",cx,cy,w,h);
dragging->setText(msg);
dragging->resize(w,h);
}
}
protected:
void drawContents(QPainter* p, int cx, int cy, int cw, int ch)
{
// The Background
if ( !bg.isNull() ) {
int rowheight=bg.height();
int toprow=cy/rowheight;
int bottomrow=(cy+ch+rowheight-1)/rowheight;
int colwidth=bg.width();
int leftcol=cx/colwidth;
int rightcol=(cx+cw+colwidth-1)/colwidth;
for (int r=toprow; r<=bottomrow; r++) {
int py=r*rowheight;
for (int c=leftcol; c<=rightcol; c++) {
int px=c*colwidth;
p->drawPixmap(px, py, bg);
}
}
} else {
p->fillRect(cx, cy, cw, ch, QColor(240,222,208));
}
// The Numbers
{
QFontMetrics fm=p->fontMetrics();
int rowheight=fm.lineSpacing();
int toprow=cy/rowheight;
int bottomrow=(cy+ch+rowheight-1)/rowheight;
int colwidth=fm.width("00000,000000 ")+3;
int leftcol=cx/colwidth;
int rightcol=(cx+cw+colwidth-1)/colwidth;
QString str;
for (int r=toprow; r<=bottomrow; r++) {
int py=r*rowheight;
for (int c=leftcol; c<=rightcol; c++) {
int px=c*colwidth;
str.sprintf("%d,%d",c,r);
p->drawText(px+3, py+fm.ascent(), str);
}
}
// The Big Hint
if (leftcol<10 && toprow<5) {
p->setFont(QFont("Charter",30));
p->setPen(red);
QString text;
text.sprintf("HINT: Look at %d,%d",215000/colwidth,115000/rowheight);
p->drawText(100,50,text);
}
}
// The Big X
{
if (cx+cw>200000 && cy+ch>100000 && cx<230000 && cy<130000) {
// Note that some X server cannot even handle co-ordinates
// beyond about 4000, so you might not see this.
p->drawLine(200000,100000,229999,129999);
p->drawLine(229999,100000,200000,129999);
// X marks the spot!
p->setFont(QFont("Charter",100));
p->setPen(blue);
p->drawText(215000-500,115000-100,1000,200,AlignCenter,"YOU WIN!!!!!");
}
}
}
private:
QPixmap bg;
};
class ScrollViewExample : public QWidget {
Q_OBJECT
public:
ScrollViewExample(int technique, QWidget* parent=0, const char* name=0) :
QWidget(parent,name)
{
QMenuBar* menubar = new QMenuBar(this);
Q_CHECK_PTR( menubar );
QPopupMenu* file = new QPopupMenu( menubar );
Q_CHECK_PTR( file );
menubar->insertItem( "&File", file );
file->insertItem( "Quit", qApp, SLOT(quit()) );
vp_options = new QPopupMenu( menubar );
Q_CHECK_PTR( vp_options );
vp_options->setCheckable( TRUE );
menubar->insertItem( "&ScrollView", vp_options );
connect( vp_options, SIGNAL(activated(int)),
this, SLOT(doVPMenuItem(int)) );
vauto_id = vp_options->insertItem( "Vertical Auto" );
vaoff_id = vp_options->insertItem( "Vertical AlwaysOff" );
vaon_id = vp_options->insertItem( "Vertical AlwaysOn" );
vp_options->insertSeparator();
hauto_id = vp_options->insertItem( "Horizontal Auto" );
haoff_id = vp_options->insertItem( "Horizontal AlwaysOff" );
haon_id = vp_options->insertItem( "Horizontal AlwaysOn" );
vp_options->insertSeparator();
corn_id = vp_options->insertItem( "cornerWidget" );
if (technique == 1) {
vp = new QScrollView(this);
BigShrinker *bs = new BigShrinker(0);//(vp->viewport());
vp->addChild(bs);
bs->setAcceptDrops(TRUE);
QObject::connect(bs, SIGNAL(clicked(int,int)),
vp, SLOT(center(int,int)));
} else {
vp = new BigMatrix(this);
if ( technique == 3 )
vp->enableClipper(TRUE);
srand(1);
for (int i=0; i<30; i++) {
QMultiLineEdit *l = new QMultiLineEdit(vp->viewport(),"First");
l->setText("Drag out more of these.");
l->resize(100,100);
vp->addChild(l, rand()%800, rand()%10000);
}
vp->viewport()->setBackgroundMode(NoBackground);
}
f_options = new QPopupMenu( menubar );
Q_CHECK_PTR( f_options );
f_options->setCheckable( TRUE );
menubar->insertItem( "F&rame", f_options );
connect( f_options, SIGNAL(activated(int)),
this, SLOT(doFMenuItem(int)) );
f_options->insertItem( "No Frame", style_id );
f_options->insertItem( "Box", style_id|QFrame::Box );
f_options->insertItem( "Panel", style_id|QFrame::Panel );
f_options->insertItem( "WinPanel", style_id|QFrame::WinPanel );
f_options->insertSeparator();
f_options->insertItem( "Plain", style_id|QFrame::Plain );
f_options->insertItem( "Raised", style_id|QFrame::Raised );
f_laststyle = f_options->indexOf(
f_options->insertItem( "Sunken", style_id|QFrame::Sunken ));
f_options->insertSeparator();
lw_options = new QPopupMenu( menubar );
Q_CHECK_PTR( lw_options );
lw_options->setCheckable( TRUE );
for (int lw = 1; lw <= max_lw; lw++) {
QString str;
str.sprintf("%d Pixels", lw);
lw_options->insertItem( str, lw_id | lw );
}
f_options->insertItem( "Line Width", lw_options );
connect( lw_options, SIGNAL(activated(int)),
this, SLOT(doFMenuItem(int)) );
mlw_options = new QPopupMenu( menubar );
Q_CHECK_PTR( mlw_options );
mlw_options->setCheckable( TRUE );
for (int mlw = 0; mlw <= max_mlw; mlw++) {
QString str;
str.sprintf("%d Pixels", mlw);
mlw_options->insertItem( str, mlw_id | mlw );
}
f_options->insertItem( "Midline Width", mlw_options );
connect( mlw_options, SIGNAL(activated(int)),
this, SLOT(doFMenuItem(int)) );
mw_options = new QPopupMenu( menubar );
Q_CHECK_PTR( mw_options );
mw_options->setCheckable( TRUE );
for (int mw = 0; mw <= max_mw; mw++) {
QString str;
str.sprintf("%d Pixels", mw);
mw_options->insertItem( str, mw_id | mw );
}
f_options->insertItem( "Margin Width", mw_options );
connect( mw_options, SIGNAL(activated(int)),
this, SLOT(doFMenuItem(int)) );
setVPMenuItems();
setFMenuItems();
QVBoxLayout* vbox = new QVBoxLayout(this);
vbox->setMenuBar(menubar);
menubar->setSeparator(QMenuBar::InWindowsStyle);
vbox->addWidget(vp);
vbox->activate();
corner = new QSizeGrip(this);
corner->hide();
}
private slots:
void doVPMenuItem(int id)
{
if (id == vauto_id ) {
vp->setVScrollBarMode(QScrollView::Auto);
} else if (id == vaoff_id) {
vp->setVScrollBarMode(QScrollView::AlwaysOff);
} else if (id == vaon_id) {
vp->setVScrollBarMode(QScrollView::AlwaysOn);
} else if (id == hauto_id) {
vp->setHScrollBarMode(QScrollView::Auto);
} else if (id == haoff_id) {
vp->setHScrollBarMode(QScrollView::AlwaysOff);
} else if (id == haon_id) {
vp->setHScrollBarMode(QScrollView::AlwaysOn);
} else if (id == corn_id) {
bool corn = !vp->cornerWidget();
vp->setCornerWidget(corn ? corner : 0);
} else {
return; // Not for us to process.
}
setVPMenuItems();
}
void setVPMenuItems()
{
QScrollView::ScrollBarMode vm = vp->vScrollBarMode();
vp_options->setItemChecked( vauto_id, vm == QScrollView::Auto );
vp_options->setItemChecked( vaoff_id, vm == QScrollView::AlwaysOff );
vp_options->setItemChecked( vaon_id, vm == QScrollView::AlwaysOn );
QScrollView::ScrollBarMode hm = vp->hScrollBarMode();
vp_options->setItemChecked( hauto_id, hm == QScrollView::Auto );
vp_options->setItemChecked( haoff_id, hm == QScrollView::AlwaysOff );
vp_options->setItemChecked( haon_id, hm == QScrollView::AlwaysOn );
vp_options->setItemChecked( corn_id, !!vp->cornerWidget() );
}
void doFMenuItem(int id)
{
if (id & style_id) {
int sty;
if (id == style_id) {
sty = 0;
} else if (id & QFrame::MShape) {
sty = vp->frameStyle()&QFrame::MShadow;
sty = (sty ? sty : QFrame::Plain) | (id&QFrame::MShape);
} else {
sty = vp->frameStyle()&QFrame::MShape;
sty = (sty ? sty : QFrame::Box) | (id&QFrame::MShadow);
}
vp->setFrameStyle(sty);
} else if (id & lw_id) {
vp->setLineWidth(id&~lw_id);
} else if (id & mlw_id) {
vp->setMidLineWidth(id&~mlw_id);
} else {
vp->setMargin(id&~mw_id);
}
vp->update();
setFMenuItems();
}
void setFMenuItems()
{
int sty = vp->frameStyle();
f_options->setItemChecked( style_id, !sty );
for (int i=1; i <= f_laststyle; i++) {
int id = f_options->idAt(i);
if (id & QFrame::MShape)
f_options->setItemChecked( id,
((id&QFrame::MShape) == (sty&QFrame::MShape)) );
else
f_options->setItemChecked( id,
((id&QFrame::MShadow) == (sty&QFrame::MShadow)) );
}
for (int lw=1; lw<=max_lw; lw++)
lw_options->setItemChecked( lw_id|lw, vp->lineWidth() == lw );
for (int mlw=0; mlw<=max_mlw; mlw++)
mlw_options->setItemChecked( mlw_id|mlw, vp->midLineWidth() == mlw );
for (int mw=0; mw<=max_mw; mw++)
mw_options->setItemChecked( mw_id|mw, vp->margin() == mw );
}
private:
QScrollView* vp;
QPopupMenu* vp_options;
QPopupMenu* f_options;
QPopupMenu* lw_options;
QPopupMenu* mlw_options;
QPopupMenu* mw_options;
QSizeGrip* corner;
int vauto_id, vaoff_id, vaon_id,
hauto_id, haoff_id, haon_id,
corn_id;
int f_laststyle;
};
int main( int argc, char **argv )
{
QApplication a( argc, argv );
ScrollViewExample ve1(1,0,"ve1");
ScrollViewExample ve2(2,0,"ve2");
ScrollViewExample ve3(3,0,"ve3");
ve1.setCaption("Qt Example - Scrollviews");
ve1.show();
ve2.setCaption("Qt Example - Scrollviews");
ve2.show();
ve3.setCaption("Qt Example - Scrollviews");
ve3.show();
QObject::connect(qApp, SIGNAL(lastWindowClosed()), qApp, SLOT(quit()));
return a.exec();
}
#include "scrollview.moc"
See also Examples.
| Copyright © 2002 Trolltech | Trademarks | Qt version 3.0.4
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