Sources_For_Linux/Qwt/doc/man/man3/QwtGraphic.3

.TH "QwtGraphic" 3 "Mon Dec 28 2020" "Version 6.1.6" "Qwt User's Guide" \" -*- nroff -*-
.ad l
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.SH NAME
QwtGraphic \- A paint device for scalable graphics\&.  

.SH SYNOPSIS
.br
.PP
.PP
\fC#include <qwt_graphic\&.h>\fP
.PP
Inherits \fBQwtNullPaintDevice\fP\&.
.SS "Public Types"

.in +1c
.ti -1c
.RI "enum \fBRenderHint\fP { \fBRenderPensUnscaled\fP = 0x1 }"
.br
.ti -1c
.RI "typedef QFlags< \fBRenderHint\fP > \fBRenderHints\fP"
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.RI "Render hints\&. "
.in -1c
.SS "Public Member Functions"

.in +1c
.ti -1c
.RI "\fBQwtGraphic\fP ()"
.br
.RI "Constructor\&. "
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.RI "\fBQwtGraphic\fP (const \fBQwtGraphic\fP &)"
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.RI "Copy constructor\&. "
.ti -1c
.RI "virtual \fB~QwtGraphic\fP ()"
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.RI "Destructor\&. "
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.RI "\fBQwtGraphic\fP & \fBoperator=\fP (const \fBQwtGraphic\fP &)"
.br
.RI "Assignment operator\&. "
.ti -1c
.RI "void \fBreset\fP ()"
.br
.RI "Clear all stored commands\&. "
.ti -1c
.RI "bool \fBisNull\fP () const"
.br
.ti -1c
.RI "bool \fBisEmpty\fP () const"
.br
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.RI "void \fBrender\fP (QPainter *) const"
.br
.RI "Replay all recorded painter commands\&. "
.ti -1c
.RI "void \fBrender\fP (QPainter *, const QSizeF &, Qt::AspectRatioMode=Qt::IgnoreAspectRatio) const"
.br
.RI "Replay all recorded painter commands\&. "
.ti -1c
.RI "void \fBrender\fP (QPainter *, const QRectF &, Qt::AspectRatioMode=Qt::IgnoreAspectRatio) const"
.br
.RI "Replay all recorded painter commands\&. "
.ti -1c
.RI "void \fBrender\fP (QPainter *, const QPointF &, Qt::Alignment=Qt::AlignTop|Qt::AlignLeft) const"
.br
.RI "Replay all recorded painter commands\&. "
.ti -1c
.RI "QPixmap \fBtoPixmap\fP () const"
.br
.RI "Convert the graphic to a QPixmap\&. "
.ti -1c
.RI "QPixmap \fBtoPixmap\fP (const QSize &, Qt::AspectRatioMode=Qt::IgnoreAspectRatio) const"
.br
.RI "Convert the graphic to a QPixmap\&. "
.ti -1c
.RI "QImage \fBtoImage\fP () const"
.br
.RI "Convert the graphic to a QImage\&. "
.ti -1c
.RI "QImage \fBtoImage\fP (const QSize &, Qt::AspectRatioMode=Qt::IgnoreAspectRatio) const"
.br
.RI "Convert the graphic to a QImage\&. "
.ti -1c
.RI "QRectF \fBscaledBoundingRect\fP (double sx, double sy) const"
.br
.RI "Calculate the target rectangle for scaling the graphic\&. "
.ti -1c
.RI "QRectF \fBboundingRect\fP () const"
.br
.ti -1c
.RI "QRectF \fBcontrolPointRect\fP () const"
.br
.ti -1c
.RI "const QVector< \fBQwtPainterCommand\fP > & \fBcommands\fP () const"
.br
.ti -1c
.RI "void \fBsetCommands\fP (QVector< \fBQwtPainterCommand\fP > &)"
.br
.RI "Append paint commands\&. "
.ti -1c
.RI "void \fBsetDefaultSize\fP (const QSizeF &)"
.br
.RI "Set a default size\&. "
.ti -1c
.RI "QSizeF \fBdefaultSize\fP () const"
.br
.RI "Default size\&. "
.ti -1c
.RI "void \fBsetRenderHint\fP (\fBRenderHint\fP, bool on=true)"
.br
.ti -1c
.RI "bool \fBtestRenderHint\fP (\fBRenderHint\fP) const"
.br
.in -1c
.SS "Protected Member Functions"

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.RI "virtual QSize \fBsizeMetrics\fP () const"
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.RI "virtual void \fBdrawPath\fP (const QPainterPath &)"
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.RI "virtual void \fBdrawPixmap\fP (const QRectF &, const QPixmap &, const QRectF &)"
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.RI "Store a pixmap command in the command list\&. "
.ti -1c
.RI "virtual void \fBdrawImage\fP (const QRectF &, const QImage &, const QRectF &, Qt::ImageConversionFlags)"
.br
.RI "Store a image command in the command list\&. "
.ti -1c
.RI "virtual void \fBupdateState\fP (const QPaintEngineState &state)"
.br
.RI "Store a state command in the command list\&. "
.in -1c
.SH "Detailed Description"
.PP 
A paint device for scalable graphics\&. 

\fBQwtGraphic\fP is the representation of a graphic that is tailored for scalability\&. Like QPicture it will be initialized by QPainter operations and can be replayed later to any target paint device\&.
.PP
While the usual image representations QImage and QPixmap are not scalable Qt offers two paint devices, that might be candidates for representing a vector graphic:
.PP
.IP "\(bu" 2
QPicture
.br
 Unfortunately QPicture had been forgotten, when Qt4 introduced floating point based render engines\&. Its API is still on integers, what make it unusable for proper scaling\&.
.IP "\(bu" 2
QSvgRenderer/QSvgGenerator
.br
 Unfortunately QSvgRenderer hides to much information about its nodes in internal APIs, that are necessary for proper layout calculations\&. Also it is derived from QObject and can't be copied like QImage/QPixmap\&.
.PP
.PP
\fBQwtGraphic\fP maps all scalable drawing primitives to a QPainterPath and stores them together with the painter state changes ( pen, brush, transformation \&.\&.\&. ) in a list of QwtPaintCommands\&. For being a complete QPaintDevice it also stores pixmaps or images, what is somehow against the idea of the class, because these objects can't be scaled without a loss in quality\&.
.PP
The main issue about scaling a \fBQwtGraphic\fP object are the pens used for drawing the outlines of the painter paths\&. While non cosmetic pens ( QPen::isCosmetic() ) are scaled with the same ratio as the path, cosmetic pens have a fixed width\&. A graphic might have paths with different pens - cosmetic and non-cosmetic\&.
.PP
\fBQwtGraphic\fP caches 2 different rectangles:
.PP
.IP "\(bu" 2
control point rectangle
.br
 The control point rectangle is the bounding rectangle of all control point rectangles of the painter paths, or the target rectangle of the pixmaps/images\&.
.IP "\(bu" 2
bounding rectangle
.br
 The bounding rectangle extends the control point rectangle by what is needed for rendering the outline with an unscaled pen\&.
.PP
.PP
Because the offset for drawing the outline depends on the shape of the painter path ( the peak of a triangle is different than the flat side ) scaling with a fixed aspect ratio always needs to be calculated from the control point rectangle\&.
.PP
\fBSee also\fP
.RS 4
\fBQwtPainterCommand\fP 
.RE
.PP

.SH "Member Typedef Documentation"
.PP 
.SS "typedef QFlags<\fBRenderHint\fP> \fBQwtGraphic::RenderHints\fP"

.PP
Render hints\&. The default setting is to disable all hints 
.SH "Member Enumeration Documentation"
.PP 
.SS "enum \fBQwtGraphic::RenderHint\fP"
Hint how to render a graphic 
.PP
\fBSee also\fP
.RS 4
\fBsetRenderHint()\fP, \fBtestRenderHint()\fP 
.RE
.PP

.PP
\fBEnumerator\fP
.in +1c
.TP
\fB\fIRenderPensUnscaled \fP\fP
When rendering a \fBQwtGraphic\fP a specific scaling between the \fBcontrolPointRect()\fP and the coordinates of the target rectangle is set up internally in \fBrender()\fP\&.
.PP
When RenderPensUnscaled is set this specific scaling is applied for the control points only, but not for the pens\&. All other painter transformations ( set up by application code ) are supposed to work like usual\&.
.PP
\fBSee also\fP
.RS 4
\fBrender()\fP; 
.RE
.PP

.SH "Constructor & Destructor Documentation"
.PP 
.SS "QwtGraphic::QwtGraphic ()"

.PP
Constructor\&. Initializes a null graphic 
.PP
\fBSee also\fP
.RS 4
\fBisNull()\fP 
.RE
.PP

.SS "QwtGraphic::QwtGraphic (const \fBQwtGraphic\fP & other)"

.PP
Copy constructor\&. 
.PP
\fBParameters\fP
.RS 4
\fIother\fP Source 
.RE
.PP
\fBSee also\fP
.RS 4
\fBoperator=()\fP 
.RE
.PP

.SH "Member Function Documentation"
.PP 
.SS "QRectF QwtGraphic::boundingRect () const"
The bounding rectangle is the \fBcontrolPointRect()\fP extended by the areas needed for rendering the outlines with unscaled pens\&.
.PP
\fBReturns\fP
.RS 4
Bounding rectangle of the graphic 
.RE
.PP
\fBSee also\fP
.RS 4
\fBcontrolPointRect()\fP, \fBscaledBoundingRect()\fP 
.RE
.PP

.SS "const QVector< \fBQwtPainterCommand\fP > & QwtGraphic::commands () const"

.PP
\fBReturns\fP
.RS 4
List of recorded paint commands 
.RE
.PP
\fBSee also\fP
.RS 4
\fBsetCommands()\fP 
.RE
.PP

.SS "QRectF QwtGraphic::controlPointRect () const"
The control point rectangle is the bounding rectangle of all control points of the paths and the target rectangles of the images/pixmaps\&.
.PP
\fBReturns\fP
.RS 4
Control point rectangle 
.RE
.PP
\fBSee also\fP
.RS 4
\fBboundingRect()\fP, \fBscaledBoundingRect()\fP 
.RE
.PP

.SS "QSizeF QwtGraphic::defaultSize () const"

.PP
Default size\&. When a non empty size has been assigned by \fBsetDefaultSize()\fP this size will be returned\&. Otherwise the default size is the size of the bounding rectangle\&.
.PP
The default size is used in all methods rendering the graphic, where no size is explicitly specified\&.
.PP
\fBReturns\fP
.RS 4
Default size 
.RE
.PP
\fBSee also\fP
.RS 4
\fBsetDefaultSize()\fP, \fBboundingRect()\fP 
.RE
.PP

.SS "void QwtGraphic::drawImage (const QRectF & rect, const QImage & image, const QRectF & subRect, Qt::ImageConversionFlags flags)\fC [protected]\fP, \fC [virtual]\fP"

.PP
Store a image command in the command list\&. 
.PP
\fBParameters\fP
.RS 4
\fIrect\fP traget rectangle 
.br
\fIimage\fP Image to be painted 
.br
\fIsubRect\fP Reactangle of the pixmap to be painted 
.br
\fIflags\fP Image conversion flags
.RE
.PP
\fBSee also\fP
.RS 4
QPaintEngine::drawImage() 
.RE
.PP

.PP
Reimplemented from \fBQwtNullPaintDevice\fP\&.
.SS "void QwtGraphic::drawPath (const QPainterPath & path)\fC [protected]\fP, \fC [virtual]\fP"
Store a path command in the command list
.PP
\fBParameters\fP
.RS 4
\fIpath\fP Painter path 
.RE
.PP
\fBSee also\fP
.RS 4
QPaintEngine::drawPath() 
.RE
.PP

.PP
Reimplemented from \fBQwtNullPaintDevice\fP\&.
.SS "void QwtGraphic::drawPixmap (const QRectF & rect, const QPixmap & pixmap, const QRectF & subRect)\fC [protected]\fP, \fC [virtual]\fP"

.PP
Store a pixmap command in the command list\&. 
.PP
\fBParameters\fP
.RS 4
\fIrect\fP target rectangle 
.br
\fIpixmap\fP Pixmap to be painted 
.br
\fIsubRect\fP Reactangle of the pixmap to be painted
.RE
.PP
\fBSee also\fP
.RS 4
QPaintEngine::drawPixmap() 
.RE
.PP

.PP
Reimplemented from \fBQwtNullPaintDevice\fP\&.
.SS "bool QwtGraphic::isEmpty () const"

.PP
\fBReturns\fP
.RS 4
True, when the bounding rectangle is empty 
.RE
.PP
\fBSee also\fP
.RS 4
\fBboundingRect()\fP, \fBisNull()\fP 
.RE
.PP

.SS "bool QwtGraphic::isNull () const"

.PP
\fBReturns\fP
.RS 4
True, when no painter commands have been stored 
.RE
.PP
\fBSee also\fP
.RS 4
\fBisEmpty()\fP, \fBcommands()\fP 
.RE
.PP

.SS "\fBQwtGraphic\fP & QwtGraphic::operator= (const \fBQwtGraphic\fP & other)"

.PP
Assignment operator\&. 
.PP
\fBParameters\fP
.RS 4
\fIother\fP Source 
.RE
.PP
\fBReturns\fP
.RS 4
A reference of this object 
.RE
.PP

.SS "void QwtGraphic::render (QPainter * painter) const"

.PP
Replay all recorded painter commands\&. 
.PP
\fBParameters\fP
.RS 4
\fIpainter\fP Qt painter 
.RE
.PP

.SS "void QwtGraphic::render (QPainter * painter, const QPointF & pos, Qt::Alignment alignment = \fCQt::AlignTop | Qt::AlignLeft\fP) const"

.PP
Replay all recorded painter commands\&. The graphic is scaled to the \fBdefaultSize()\fP and aligned to a position\&.
.PP
\fBParameters\fP
.RS 4
\fIpainter\fP Qt painter 
.br
\fIpos\fP Reference point, where to render 
.br
\fIalignment\fP Flags how to align the target rectangle to pos\&. 
.RE
.PP

.SS "void QwtGraphic::render (QPainter * painter, const QRectF & rect, Qt::AspectRatioMode aspectRatioMode = \fCQt::IgnoreAspectRatio\fP) const"

.PP
Replay all recorded painter commands\&. The graphic is scaled to fit into the given rectangle
.PP
\fBParameters\fP
.RS 4
\fIpainter\fP Qt painter 
.br
\fIrect\fP Rectangle for the scaled graphic 
.br
\fIaspectRatioMode\fP Mode how to scale - See Qt::AspectRatioMode 
.RE
.PP

.SS "void QwtGraphic::render (QPainter * painter, const QSizeF & size, Qt::AspectRatioMode aspectRatioMode = \fCQt::IgnoreAspectRatio\fP) const"

.PP
Replay all recorded painter commands\&. The graphic is scaled to fit into the rectangle of the given size starting at ( 0, 0 )\&.
.PP
\fBParameters\fP
.RS 4
\fIpainter\fP Qt painter 
.br
\fIsize\fP Size for the scaled graphic 
.br
\fIaspectRatioMode\fP Mode how to scale - See Qt::AspectRatioMode 
.RE
.PP

.SS "void QwtGraphic::reset ()"

.PP
Clear all stored commands\&. 
.PP
\fBSee also\fP
.RS 4
\fBisNull()\fP 
.RE
.PP

.SS "QRectF QwtGraphic::scaledBoundingRect (double sx, double sy) const"

.PP
Calculate the target rectangle for scaling the graphic\&. 
.PP
\fBParameters\fP
.RS 4
\fIsx\fP Horizontal scaling factor 
.br
\fIsy\fP Vertical scaling factor
.RE
.PP
\fBNote\fP
.RS 4
In case of paths that are painted with a cosmetic pen ( see QPen::isCosmetic() ) the target rectangle is different to multiplying the bounding rectangle\&.
.RE
.PP
\fBReturns\fP
.RS 4
Scaled bounding rectangle 
.RE
.PP
\fBSee also\fP
.RS 4
\fBboundingRect()\fP, \fBcontrolPointRect()\fP 
.RE
.PP

.SS "void QwtGraphic::setCommands (QVector< \fBQwtPainterCommand\fP > & commands)"

.PP
Append paint commands\&. 
.PP
\fBParameters\fP
.RS 4
\fIcommands\fP Paint commands 
.RE
.PP
\fBSee also\fP
.RS 4
\fBcommands()\fP 
.RE
.PP

.SS "void QwtGraphic::setDefaultSize (const QSizeF & size)"

.PP
Set a default size\&. The default size is used in all methods rendering the graphic, where no size is explicitly specified\&. Assigning an empty size means, that the default size will be calculated from the bounding rectangle\&.
.PP
The default setting is an empty size\&.
.PP
\fBParameters\fP
.RS 4
\fIsize\fP Default size
.RE
.PP
\fBSee also\fP
.RS 4
\fBdefaultSize()\fP, \fBboundingRect()\fP 
.RE
.PP

.SS "void QwtGraphic::setRenderHint (\fBRenderHint\fP hint, bool on = \fCtrue\fP)"
Toggle an render hint
.PP
\fBParameters\fP
.RS 4
\fIhint\fP Render hint 
.br
\fIon\fP true/false
.RE
.PP
\fBSee also\fP
.RS 4
\fBtestRenderHint()\fP, \fBRenderHint\fP 
.RE
.PP

.SS "QSize QwtGraphic::sizeMetrics () const\fC [protected]\fP, \fC [virtual]\fP"

.PP
\fBReturns\fP
.RS 4
Ceiled \fBdefaultSize()\fP 
.RE
.PP

.PP
Implements \fBQwtNullPaintDevice\fP\&.
.SS "bool QwtGraphic::testRenderHint (\fBRenderHint\fP hint) const"
Test a render hint
.PP
\fBParameters\fP
.RS 4
\fIhint\fP Render hint 
.RE
.PP
\fBReturns\fP
.RS 4
true/false 
.RE
.PP
\fBSee also\fP
.RS 4
\fBsetRenderHint()\fP, \fBRenderHint\fP 
.RE
.PP

.SS "QImage QwtGraphic::toImage () const"

.PP
Convert the graphic to a QImage\&. All pixels of the image get initialized by 0 ( transparent ) before the graphic is scaled and rendered on it\&.
.PP
The format of the image is QImage::Format_ARGB32_Premultiplied\&.
.PP
The size of the image is the default size ( ceiled to integers ) of the graphic\&.
.PP
\fBReturns\fP
.RS 4
The graphic as image in default size 
.RE
.PP
\fBSee also\fP
.RS 4
\fBdefaultSize()\fP, \fBtoPixmap()\fP, \fBrender()\fP 
.RE
.PP

.SS "QImage QwtGraphic::toImage (const QSize & size, Qt::AspectRatioMode aspectRatioMode = \fCQt::IgnoreAspectRatio\fP) const"

.PP
Convert the graphic to a QImage\&. All pixels of the image get initialized by 0 ( transparent ) before the graphic is scaled and rendered on it\&.
.PP
The format of the image is QImage::Format_ARGB32_Premultiplied\&.
.PP
\fBParameters\fP
.RS 4
\fIsize\fP Size of the image 
.br
\fIaspectRatioMode\fP Aspect ratio how to scale the graphic
.RE
.PP
\fBReturns\fP
.RS 4
The graphic as image 
.RE
.PP
\fBSee also\fP
.RS 4
\fBtoPixmap()\fP, \fBrender()\fP 
.RE
.PP

.SS "QPixmap QwtGraphic::toPixmap () const"

.PP
Convert the graphic to a QPixmap\&. All pixels of the pixmap get initialized by Qt::transparent before the graphic is scaled and rendered on it\&.
.PP
The size of the pixmap is the default size ( ceiled to integers ) of the graphic\&.
.PP
\fBReturns\fP
.RS 4
The graphic as pixmap in default size 
.RE
.PP
\fBSee also\fP
.RS 4
\fBdefaultSize()\fP, \fBtoImage()\fP, \fBrender()\fP 
.RE
.PP

.SS "QPixmap QwtGraphic::toPixmap (const QSize & size, Qt::AspectRatioMode aspectRatioMode = \fCQt::IgnoreAspectRatio\fP) const"

.PP
Convert the graphic to a QPixmap\&. All pixels of the pixmap get initialized by Qt::transparent before the graphic is scaled and rendered on it\&.
.PP
\fBParameters\fP
.RS 4
\fIsize\fP Size of the image 
.br
\fIaspectRatioMode\fP Aspect ratio how to scale the graphic
.RE
.PP
\fBReturns\fP
.RS 4
The graphic as pixmap 
.RE
.PP
\fBSee also\fP
.RS 4
\fBtoImage()\fP, \fBrender()\fP 
.RE
.PP

.SS "void QwtGraphic::updateState (const QPaintEngineState & state)\fC [protected]\fP, \fC [virtual]\fP"

.PP
Store a state command in the command list\&. 
.PP
\fBParameters\fP
.RS 4
\fIstate\fP State to be stored 
.RE
.PP
\fBSee also\fP
.RS 4
QPaintEngine::updateState() 
.RE
.PP

.PP
Reimplemented from \fBQwtNullPaintDevice\fP\&.

.SH "Author"
.PP 
Generated automatically by Doxygen for Qwt User's Guide from the source code\&.