qcanvas.3qt

Trolltech公司发布的基于C++图形开发环境

'\" t
.TH QCanvas 3qt "24 January 2005" "Trolltech AS" \" -*- nroff -*-
.\" Copyright 1992-2001 Trolltech AS.  All rights reserved.  See the
.\" license file included in the distribution for a complete license
.\" statement.
.\"
.ad l
.nh
.SH NAME
QCanvas \- 2D graphic area upon which
.br
.PP
\fC#include <qcanvas.h>\fR
.PP
Inherits QObject.
.PP
.SS "Public Members"
.in +1c
.ti -1c
.BI "\fBQCanvas\fR ( QObject * " "parent" " = 0, const char * " "name" " = 0 ) "
.br
.ti -1c
.BI "\fBQCanvas\fR ( int " "w" ", int h ) "
.br
.ti -1c
.BI "\fBQCanvas\fR ( QPixmap " "p" ", int " "h" ", int " "v" ", int " "tilewidth" ", int tileheight ) "
.br
.ti -1c
.BI "virtual \fB~QCanvas\fR () "
.br
.ti -1c
.BI "virtual void \fBsetTiles\fR ( QPixmap " "tiles" ", int " "h" ", int " "v" ", int " "tilewidth" ", int tileheight ) "
.br
.ti -1c
.BI "virtual void \fBsetBackgroundPixmap\fR ( const QPixmap & p ) "
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.ti -1c
.BI "QPixmap \fBbackgroundPixmap\fR () const"
.br
.ti -1c
.BI "virtual void \fBsetBackgroundColor\fR ( const QColor & c ) "
.br
.ti -1c
.BI "QColor \fBbackgroundColor\fR () const"
.br
.ti -1c
.BI "virtual void \fBsetTile\fR ( int " "x" ", int " "y" ", int tilenum ) "
.br
.ti -1c
.BI "int \fBtile\fR ( int " "x" ", int y ) const"
.br
.ti -1c
.BI "int \fBtilesHorizontally\fR () const"
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.ti -1c
.BI "int \fBtilesVertically\fR () const"
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.ti -1c
.BI "int \fBtileWidth\fR () const"
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.ti -1c
.BI "int \fBtileHeight\fR () const"
.br
.ti -1c
.BI "virtual void \fBresize\fR ( int " "width" ", int height ) "
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.ti -1c
.BI "int \fBwidth\fR () const"
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.ti -1c
.BI "int \fBheight\fR () const"
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.ti -1c
.BI "QSize \fBsize\fR () const"
.br
.ti -1c
.BI "bool \fBonCanvas\fR ( int " "x" ", int y ) const"
.br
.ti -1c
.BI "bool \fBonCanvas\fR ( const QPoint & p ) const"
.br
.ti -1c
.BI "bool \fBvalidChunk\fR ( int " "x" ", int y ) const"
.br
.ti -1c
.BI "bool \fBvalidChunk\fR ( const QPoint & p ) const"
.br
.ti -1c
.BI "int \fBchunkSize\fR () const"
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.ti -1c
.BI "virtual void \fBretune\fR ( int " "chunksize" ", int " "maxclusters" "=100 ) "
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.ti -1c
.BI "bool \fBsameChunk\fR ( int " "x1" ", int " "y1" ", int " "x2" ", int y2 ) const (internal)"
.br
.ti -1c
.BI "virtual void \fBsetChangedChunk\fR ( int " "i" ", int j ) (internal)"
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.ti -1c
.BI "virtual void \fBsetChangedChunkContaining\fR ( int " "x" ", int y ) (internal)"
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.ti -1c
.BI "virtual void \fBsetAllChanged\fR () "
.br
.ti -1c
.BI "virtual void \fBsetChanged\fR ( const QRect & inarea ) "
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.ti -1c
.BI "void \fBaddItemToChunk\fR ( QCanvasItem *, int " "i" ", int j ) (internal)"
.br
.ti -1c
.BI "void \fBremoveItemFromChunk\fR ( QCanvasItem *, int " "i" ", int j ) (internal)"
.br
.ti -1c
.BI "void \fBaddItemToChunkContaining\fR ( QCanvasItem *, int " "x" ", int y ) (internal)"
.br
.ti -1c
.BI "void \fBremoveItemFromChunkContaining\fR ( QCanvasItem *, int " "x" ", int y ) (internal)"
.br
.ti -1c
.BI "QCanvasItemList \fBallItems\fR () "
.br
.ti -1c
.BI "QCanvasItemList \fBcollisions\fR ( const QPoint & ) const"
.br
.ti -1c
.BI "QCanvasItemList \fBcollisions\fR ( const QRect & ) const"
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.ti -1c
.BI "QCanvasItemList \fBcollisions\fR ( const QPointArray & " "pa" ", const QCanvasItem * " "item" ", bool exact ) const"
.br
.ti -1c
.BI "virtual void \fBaddView\fR ( QCanvasView * ) (internal)"
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.ti -1c
.BI "virtual void \fBremoveView\fR ( QCanvasView * ) (internal)"
.br
.ti -1c
.BI "void \fBdrawArea\fR ( const QRect &, QPainter * " "p" "=0, bool " "double_buffer" "=TRUE ) (internal)"
.br
.ti -1c
.BI "virtual void \fBaddItem\fR ( QCanvasItem * ) (internal)"
.br
.ti -1c
.BI "virtual void \fBaddAnimation\fR ( QCanvasItem * ) (internal)"
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.ti -1c
.BI "virtual void \fBremoveItem\fR ( QCanvasItem * ) (internal)"
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.ti -1c
.BI "virtual void \fBremoveAnimation\fR ( QCanvasItem * ) (internal)"
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.ti -1c
.BI "virtual void \fBsetAdvancePeriod\fR ( int ms ) "
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.ti -1c
.BI "virtual void \fBsetUpdatePeriod\fR ( int ms ) "
.br
.ti -1c
.BI "virtual void \fBsetDoubleBuffering\fR ( bool y ) "
.br
.in -1c
.SS "Public Slots"
.in +1c
.ti -1c
.BI "virtual void \fBadvance\fR () "
.br
.ti -1c
.BI "virtual void \fBupdate\fR () "
.br
.in -1c
.SS "Signals"
.in +1c
.ti -1c
.BI "void \fBresized\fR () "
.br
.in -1c
.SS "Protected Members"
.in +1c
.ti -1c
.BI "virtual void \fBdrawBackground\fR ( QPainter &, const QRect & area ) "
.br
.ti -1c
.BI "virtual void \fBdrawForeground\fR ( QPainter &, const QRect & area ) "
.br
.in -1c
.SH DESCRIPTION
The QCanvas class is a 2D graphic area upon which QCanvasItem objects exist.
.PP
A QCanvas contains any number of QCanvasItem subclassed objects and has any number of QCanvasView widgets observing some part of the canvas.
.PP
A canvas containing many items is different to a widgets containing many subwidgets in the following ways:
.TP
Items are drawn much faster than widgets, especially when non-rectangular.
.TP
Items use less memory than widgets.
.TP
You can do efficient item-to-item hit tests ("collision detection") with items in a canvas.
.TP
Finding items in an area is efficient.
.TP
You can have multiple views of a canvas.
.PP
Widgets of course offer richer functionality, such as hierarchies, events, layout, etc.
.SH "Drawing"