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IpePainter Class Reference
[Ipe Base]

Interface for drawing. More...

List of all members.

Public Methods


Detailed Description

Interface for drawing.

IpePainter-derived classes are used for drawing to the screen and for generating PDF output.

The IpePainter maintains a stack of graphics states, which includes stroke and fill color, line width, dash style, miter limit, line cap and line join, and the current transformation matrix. The IpePainter class takes care of maintaining this stack, and setting of the attributes in the current graphics state.

Setting an attribute with a symbolic value is resolved immediately using the IpeStyleSheet attached to the IpePainter, so calling the Stroke() or Fill() methods of IpePainter will return the current absolute color.

Attributes must not be changed after a path has been started. (Although this does not seem to be stated explicitely in the PDF Reference, Acrobat Reader 4 complains if the dash style is set after a path has been defined.)

Derived classes need to implement the functions for drawing paths, images, and texts.

A null color is drawn as if it was void. Ipe objects exploit this: only group objects ever need to explicitly contain a 'void' color.

A null dash style is drawn as solid.

A null line width is drawn as whatever is the standard of the drawing medium.


Constructor & Destructor Documentation

IpePainter::IpePainter const IpeStyleSheet   style
 

Constructor takes a (cascaded) style sheet, which is not owned.

The initial graphics state contains null attributes and default line cap and line join.

IpePainter::~IpePainter   [virtual]
 

Virtual destructor.


Member Function Documentation

void IpePainter::Transform const IpeMatrix   m [virtual]
 

Concatenate a matrix to current transformation matrix.

void IpePainter::Untransform bool    direct [virtual]
 

Reset transformation to original one, but with different origin/direction.

This changes the current transformation matrix to the one set before the first Push operation, but maintaining the current origin. If direct is true, then the x-direction is also kept.

void IpePainter::Translate const IpeVector   v [virtual]
 

Concatenate a translation to current transformation matrix.

void IpePainter::BeginPath const IpeVector   v [virtual]
 

Start a new open path.

void IpePainter::BeginClosedPath const IpeVector   v [virtual]
 

Start a new closed path.

void IpePainter::LineTo const IpeVector   v [virtual]
 

Add line segment to path.

void IpePainter::CurveTo const IpeVector   v1,
const IpeVector   v2,
const IpeVector   v3
[virtual]
 

Add a Bezier segment to path.

void IpePainter::CurveTo const IpeBezier   bezier [inline]
 

Overloaded function.

Assumes current position is bezier.iV[0]

void IpePainter::Rect const IpeRect   re [virtual]
 

Add a rectangle to the path.

Has a default implementation in terms of LineTo, but derived classes can reimplement for efficiency.

void IpePainter::EndPath   [virtual]
 

End open path.

void IpePainter::EndClosedPath   [virtual]
 

End closed path.

void IpePainter::Push   [virtual]
 

Save current graphics state.

void IpePainter::Pop   [virtual]
 

Restore previous graphics state.

void IpePainter::DrawPath   [virtual]
 

Fill and/or stroke a path (depending on color).

As in PDF, an "path" can consist of several components that are defined by sequences of BeginClosedPath() and EndClosedPath().

void IpePainter::DrawBitmap IpeBitmap    bitmap [virtual]
 

Render a bitmap.

Assumes the transformation matrix has been set up to map the unit square to the image area on the paper.

void IpePainter::DrawText const IpeText   text [virtual]
 

Render a text object.

Stroke color is already set, and the origin is the lower-left corner of the text box.

void IpePainter::DrawEllipse  
 

Draw the unit circle.

PDF does not have an "arc" or "circle" primitive, so to draw an arc, circle, or ellipse, Ipe has to translate it into a sequence of Bezier curves.

The approximation is based on the following: The unit circle arc from (1,0) to (cos a, sin a) be approximated by a Bezier spline with control points (1, 0), (1, beta) and their mirror images along the line with slope a/2, where beta = 4.0 * (1.0 - cos(a/2)) / (3 * sin(a/2))

Ipe draws circles by drawing four Bezier curves for the quadrants, and arcs by patching together quarter circle approximations with a piece computed from the formula above.

This does not modify the transformation matrix. The path is generated as a sequence BeginClosedPath .. CurveTo .. EndClosedPath, but is not actually drawn (DrawPath is not called).

void IpePainter::DrawArc double    alpha
 

Draw an arc of the unit circle of length alpha.

alpha is normalized to [0, 2 pi], and applied starting from the point (1,0).

The function works by generating a sequence of Bezier splines (see DrawEllipse for details of the transformation). It only generates calls to CurveTo. It is assumed that the caller has already executed a MoveTo to the beginning of the arc at (1,0).

This function may modify the transformation matrix.

void IpePainter::SetStroke IpeAttribute    color
 

Set stroke color, resolving symbolic color.

void IpePainter::SetFill IpeAttribute    color
 

Set fill color, resolving symbolic color.

void IpePainter::SetLineWidth IpeAttribute    wid
 

Set line width, resolving symbolic value.

void IpePainter::SetDashStyle IpeAttribute    dash
 

Set dash style, resolving symbolic value.

void IpePainter::SetLineCap IpeAttribute    cap
 

Set line cap.

void IpePainter::SetLineJoin IpeAttribute    join
 

Set line join.

void IpePainter::SetWindRule IpeAttribute    rule
 

Set wind rule (wind or even-odd).

void IpePainter::SetTextSize IpeAttribute    size
 

Set font size of text objects.

Paradoxically, this isn't actually used to render text, but for saving Ipegroup objects! Text goes through the Pdflatex interface, and the visitor that scans for text objects and writes them to the Latex source file finds the text size information itself.

void IpePainter::SetMarkSize IpeAttribute    size
 

Set size of mark objects.

void IpePainter::SetMarkShape int    shape
 

Set shape of mark objects.

const IpeStyleSheet* IpePainter::StyleSheet   const [inline]
 

Return style sheet.

IpeAttribute IpePainter::Stroke   const [inline]
 

Return current stroke color (always absolute).

IpeAttribute IpePainter::Fill   const [inline]
 

Return current fill color (always absolute).

const IpeMatrix& IpePainter::Matrix   const [inline]
 

Return current transformation matrix.

IpeAttribute IpePainter::LineWidth   const [inline]
 

Return current line width (always absolute).

IpeAttribute IpePainter::DashStyle   const [inline]
 

Return current dash style (always absolute).

IpeAttribute IpePainter::LineCap   const [inline]
 

Return current line cap.

IpeAttribute IpePainter::LineJoin   const [inline]
 

Return current line join.

IpeAttribute IpePainter::WindRule   const [inline]
 

Return current wind rule.

IpeAttribute IpePainter::TextSize   const [inline]
 

Return current text font size.

IpeAttribute IpePainter::MarkSize   const [inline]
 

Return current mark size.

int IpePainter::MarkShape   const [inline]
 

Return current mark shape.

const IpeRepository* IpePainter::Repository   const [inline]
 

Return repository.


The documentation for this class was generated from the following files: