added null pointer check and assert

[wxWidgets.git] / docs / latex / wx / graphicscontext.tex

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%% Name:        graphicsfont.tex
%% Purpose:     wxGraphicsFont class documentation
%% Author:      Stefan Csomor
%% Modified by:
%% Created:     08.06.2004
%% RCS-ID:      $Id$
%% Copyright:   (c) Stefan Csomor
%% License:     wxWindows license
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\section{\class{wxGraphicsContext}}\label{wxgraphicscontext}

A wxGraphicsContext instance is the object that is drawn upon. It is created by a renderer using the CreateContext calls.., this can be either directly using a renderer 
instance, or indirectly using the static convenience CreateXXX functions of wxGraphicsContext that always delegate the task to the default renderer.

\wxheading{Derived from}

\helpref{wxGraphicsObject}{wxgraphicsobject}\\
\helpref{wxObject}{wxobject}

\wxheading{Include files}

<wx/graphics.h>

\wxheading{Library}

\helpref{wxCore}{librarieslist}

\latexignore{\rtfignore{\wxheading{Members}}}

\membersection{wxGraphicsContext::Create}\label{wxgraphicscontextcreate}

\func{wxGraphicsContext*}{Create}{\param{const wxWindowDC\& }{dc}}

Creates a wxGraphicsContext from a wxWindowDC (eg a wxPaintDC).

\func{wxGraphicsContext*}{Create}{\param{wxWindow* }{window}}

Creates a wxGraphicsContext from a wxWindow.

\wxheading{See also}

\helpref{wxGraphicsRenderer:: CreateContext}{wxgraphicsrenderercreatecontext}

\membersection{wxGraphicsContext::CreateFromNative}\label{wxgraphicscontextcreatefromnative}

Creates a wxGraphicsContext from a native context. This native context must be eg a CGContextRef for Core Graphics, a Graphics pointer for GDIPlus or a 
cairo\_t pointer for cairo.

\func{wxGraphicsContext*}{CreateFromNative}{\param{void * }{context}}

Creates a wxGraphicsContext from a native window. 

\wxheading{See also}

\helpref{wxGraphicsRenderer:: CreateContextFromNativeContext}{wxgraphicsrenderercreatecontextfromnativecontext}

\membersection{wxGraphicsContext::CreateFromNativeWindow}\label{wxgraphicscontextcreatefromnativewindow}

\func{wxGraphicsContext*}{CreateFromNativeWindow}{\param{void * }{window}}

\wxheading{See also}

\helpref{wxGraphicsRenderer:: CreateContextFromNativeWindow}{wxgraphicsrenderercreatecontextfromnativewindow}

\membersection{wxGraphicsContext::CreatePen}\label{wxgraphicscontextcreatepen}

\constfunc{wxGraphicsPen}{CreatePen}{\param{const wxPen\& }{pen}}

Creates a native pen from a wxPen.

\membersection{wxGraphicsContext::CreateBrush}\label{wxgraphicscontextcreatebrush}

\constfunc{wxGraphicsBrush}{CreateBrush}{\param{const wxBrush\& }{brush}}

Creates a native brush from a wxBrush.

\membersection{wxGraphicsContext::CreateRadialGradientBrush}\label{wxgraphicscontextcreateradialgradientbrush}

\constfunc{wxGraphicsBrush}{CreateRadialGradientBrush}{\param{wxDouble }{xo}, \param{wxDouble }{yo}, \param{wxDouble }{xc}, \param{wxDouble }{yc}, 
\param{wxDouble }{radius}, \param{const wxColour\& }{oColor}, \param{const wxColour\& }{cColor}}

Creates a native brush, having a radial gradient originating at (xo,yc) with color oColour and ends on a circle around (xc,yc) with radius r and color cColour

\membersection{wxGraphicsContext::CreateLinearGradientBrush}\label{wxgraphicscontextcreatelineargradientbrush}

\constfunc{wxGraphicsBrush}{CreateLinearGradientBrush}{\param{wxDouble }{x1}, \param{wxDouble }{y1}, \param{wxDouble }{x2}, \param{wxDouble }{y2}, 
\param{const }{wxColour\&c1}, \param{const }{wxColour\&c2}}

Creates a native brush, having a linear gradient, starting at (x1,y1) with color c1 to (x2,y2) with color c2

\membersection{wxGraphicsContext::CreateFont}\label{wxgraphicscontextcreatefont}

\constfunc{wxGraphicsFont}{CreateFont}{\param{const wxFont\& }{font}, \param{const wxColour\& }{col = *wxBLACK}}

Creates a native graphics font from a wxFont and a text colour.

\membersection{wxGraphicsContext::CreateMatrix}\label{wxgraphicscontextcreatematrix}

\constfunc{wxGraphicsMatrix}{CreateMatrix}{\param{wxDouble }{a = 1.0}, \param{wxDouble }{b = 0.0}, \param{wxDouble }{c = 0.0}, \param{wxDouble }{d = 1.0}, 
\param{wxDouble }{tx = 0.0}, \param{wxDouble }{ty = 0.0}}

Creates a native affine transformation matrix from the passed in values. The defaults result in an identity matrix.

\membersection{wxGraphicsContext::CreatePath}\label{wxgraphicscontextcreatepath}

\constfunc{wxGraphicsPath}{CreatePath}{\void}

Creates a native graphics path which is initially empty.

\membersection{wxGraphicsContext::Clip}\label{wxgraphicscontextclip}

\func{void}{Clip}{\param{const wxRegion\& }{region}}

Clips drawings to the region, combined to current clipping region

\func{void}{Clip}{\param{wxDouble }{x}, \param{wxDouble }{y}, \param{wxDouble }{w}, \param{wxDouble }{h}}

Clips drawings to the rectangle.

\membersection{wxGraphicsContext::ResetClip}\label{wxgraphicscontextresetclip}

\func{void}{ResetClip}{\void}

Resets the clipping to original shape.

\membersection{wxGraphicsContext::DrawBitmap}\label{wxgraphicscontextdrawbitmap}

\func{void}{DrawBitmap}{\param{const wxBitmap\& }{bmp}, \param{wxDouble }{x}, \param{wxDouble }{y}, \param{wxDouble }{w}, \param{wxDouble }{h}}

Draws the bitmap. In case of a mono bitmap, this is treated as a mask and the current brushed is used for filling.

\membersection{wxGraphicsContext::DrawEllipse}\label{wxgraphicscontextdrawellipse}

\func{void}{DrawEllipse}{\param{wxDouble }{x}, \param{wxDouble }{y}, \param{wxDouble }{w}, \param{wxDouble }{h}}

Draws an ellipse.

\membersection{wxGraphicsContext::DrawIcon}\label{wxgraphicscontextdrawicon}

\func{void}{DrawIcon}{\param{const wxIcon\& }{icon}, \param{wxDouble }{x}, \param{wxDouble }{y}, \param{wxDouble }{w}, \param{wxDouble }{h}}

Draws the icon.


\membersection{wxGraphicsContext::DrawLines}\label{wxgraphicscontextdrawlines}

\func{void}{DrawLines}{\param{size\_t }{n}, \param{const wxPoint2DDouble* }{points}, \param{int }{fillStyle = wxODDEVEN\_RULE}}

Draws a polygon.


\membersection{wxGraphicsContext::DrawPath}\label{wxgraphicscontextdrawpath}

\func{void}{DrawPath}{\param{const wxGraphicsPath\& }{path}, \param{int }{fillStyle = wxODDEVEN\_RULE}}

Draws the path by first filling and then stroking.


\membersection{wxGraphicsContext::DrawRectangle}\label{wxgraphicscontextdrawrectangle}

\func{void}{DrawRectangle}{\param{wxDouble }{x}, \param{wxDouble }{y}, \param{wxDouble }{w}, \param{wxDouble }{h}}

Draws a rectangle.


\membersection{wxGraphicsContext::DrawRoundedRectangle}\label{wxgraphicscontextdrawroundedrectangle}

\func{void}{DrawRoundedRectangle}{\param{wxDouble }{x}, \param{wxDouble }{y}, \param{wxDouble }{w}, \param{wxDouble }{h}, \param{wxDouble }{radius}}

Draws a rounded rectangle.

\membersection{wxGraphicsContext::DrawText}\label{wxgraphicscontextdrawtext}

\func{void}{DrawText}{\param{const wxString\& }{str}, \param{wxDouble }{x}, \param{wxDouble }{y}, \param{wxDouble }{angle}}

\func{void}{DrawText}{\param{const wxString\& }{str}, \param{wxDouble }{x}, \param{wxDouble }{y}}

Draws a text at the defined position, at the given angle.

\membersection{wxGraphicsContext::FillPath}\label{wxgraphicscontextfillpath}

\func{void}{FillPath}{\param{const wxGraphicsPath\& }{path}, \param{int }{fillStyle = wxODDEVEN\_RULE}}

Fills the path with the current brush.

\membersection{wxGraphicsContext::StrokePath}\label{wxgraphicscontextstrokepath}

\func{void}{StrokePath}{\param{const wxGraphicsPath\& }{path}}

Strokes along a path with the current pen.


\membersection{wxGraphicsContext::GetNativeContext}\label{wxgraphicscontextgetnativecontext}

\func{void *}{GetNativeContext}{\void}

Returns the native context (CGContextRef for Core Graphics, Graphics pointer for GDIPlus and cairo\_t pointer for cairo).

\membersection{wxGraphicsContext::GetPartialTextExtents}\label{wxgraphicscontextgetpartialtextextents}

\constfunc{void}{GetPartialTextExtents}{\param{const wxString\& }{text}, \param{wxArrayDouble\& }{widths}}

Fills the {\it widths} array with the widths from the beginning of 
{\it text} to the corresponding character of {\it text}.  

\membersection{wxGraphicsContext::GetTextExtent}\label{wxgraphicscontextgettextextent}

\constfunc{void}{GetTextExtent}{\param{const wxString\& }{text}, \param{wxDouble* }{width}, \param{wxDouble* }{height}, \param{wxDouble* }{descent}, 
\param{wxDouble* }{externalLeading}}

Gets the dimensions of the string using the currently selected font.
\rtfsp{\it string} is the text string to measure, {\it w} and {\it h} are
the total width and height respectively, {\it descent} is the
dimension from the baseline of the font to the bottom of the
descender, and {\it externalLeading} is any extra vertical space added
to the font by the font designer (usually is zero).

\membersection{wxGraphicsContext::Rotate}\label{wxgraphicscontextrotate}

\func{void}{Rotate}{\param{wxDouble }{angle}}

Rotates the current transformation matrix (radians),

\membersection{wxGraphicsContext::Scale}\label{wxgraphicscontextscale}

\func{void}{Scale}{\param{wxDouble }{xScale}, \param{wxDouble }{yScale}}

Scales the current transformation matrix.

\membersection{wxGraphicsContext::Translate}\label{wxgraphicscontexttranslate}

\func{void}{Translate}{\param{wxDouble }{dx}, \param{wxDouble }{dy}}

Translates the current transformation matrix.

\membersection{wxGraphicsContext::GetTransform}\label{wxgraphicscontextgettransform}

\constfunc{wxGraphicsMatrix}{GetTransform}{\void}

Gets the current transformation matrix of this context.

\membersection{wxGraphicsContext::SetTransform}\label{wxgraphicscontextsettransform}

\func{void}{SetTransform}{\param{const wxGraphicsMatrix\& }{matrix}}

Sets the current transformation matrix of this context

\membersection{wxGraphicsContext::ConcatTransform}\label{wxgraphicscontextconcattransform}

\func{void}{ConcatTransform}{\param{const wxGraphicsMatrix\& }{matrix}}

Concatenates the passed in transform with the current transform of this context

\membersection{wxGraphicsContext::SetBrush}\label{wxgraphicscontextsetbrush}

\func{void}{SetBrush}{\param{const wxBrush\& }{brush}}

\func{void}{SetBrush}{\param{const wxGraphicsBrush\& }{brush}}

Sets the brush for filling paths.

\membersection{wxGraphicsContext::SetFont}\label{wxgraphicscontextsetfont}

\func{void}{SetFont}{\param{const wxFont\& }{font}, \param{const wxColour\& }{colour}}


\func{void}{SetFont}{\param{const wxGraphicsFont\& }{font}}

Sets the font for drawing text.


\membersection{wxGraphicsContext::SetPen}\label{wxgraphicscontextsetpen}

\func{void}{SetPen}{\param{const wxGraphicsPen\& }{pen}}

\func{void}{SetPen}{\param{const wxPen\& }{pen}}

Sets the pen used for stroking.

\membersection{wxGraphicsContext::StrokeLine}\label{wxgraphicscontextstrokeline}

\func{void}{StrokeLine}{\param{wxDouble }{x1}, \param{wxDouble }{y1}, \param{wxDouble }{x2}, \param{wxDouble }{y2}}

Strokes a single line.

\membersection{wxGraphicsContext::StrokeLines}\label{wxgraphicscontextstrokelines}

\func{void}{StrokeLines}{\param{size\_t }{n}, \param{const wxPoint2DDouble* }{beginPoints}, \param{const wxPoint2DDouble* }{endPoints}}

\func{void}{StrokeLines}{\param{size\_t }{n}, \param{const wxPoint2DDouble* }{points}}

Stroke disconnected lines from begin to end points, fastest method available for this purpose.