Drawing Graphics and Text

Detailed Description

The Pt::Gfx drawing API provides the abstractions needed to render 2D content on different paint surfaces. A Painter can be used to draw lines, rectangles, ellipses, paths, text, images and bitmaps on paint surfaces such as Bitmap. Pen, Brush, Font, Transform and CompositionMode control how shapes, images and text are rendered.

Painting always targets a PaintSurface via a PaintContext, which represents an active painting scope. The Canvas is used by Painter to translate the high-level drawing commands into paint surface operations. Bitmap is the standard in-memory target and makes rendered content available as an image when pixels need to be inspected, copied or reused later.

Paths, transforms and scaling describe geometry independently from the underlying backend. Text drawing uses Font together with FontMetrics and TextMetrics so that layout and rendering can share the same font request and measurement model.

The drawing API focuses on rendering operations and paint state. Image, view and pixel classes in Pt::Gfx focus on image storage, format handling and direct pixel access.

Classes
class	Bitmap
	Off-screen drawing surface backed by an image. More...
class	ColorStop
	Color stop for a gradient brush. More...
class	ColorStops
	Ordered collection of gradient color stops. More...
class	Brush
	Fill description for shapes and text. More...
class	Canvas
	Backend canvas for drawing commands. More...
class	CompositionMode
	Blend mode used for drawing operations. More...
class	Font
	Font request used for text drawing and measurement. More...
class	FontMetrics
	Metrics that describe a font face at a given size. More...
class	Paint
	Paint state used by drawing operations. More...
class	PaintContext
	Active painting session for a surface. More...
class	Painter
	Concrete painter for Pt::Gfx paint targets. More...
class	PainterBase
	Base class for drawing commands and paint state. More...
class	PaintSurface
	Abstract target for drawing operations. More...
class	Path
	Vector path for drawing outlines and filled shapes. More...
class	PathElement
	Read-only view of a path element. More...
class	PathIterator
	Forward iterator over path elements. More...
class	Pen
	Attributes for the drawing of outlines. More...
class	Scaling
	Logical-to-physical unit conversion. More...
class	TextMetrics
	Metrics for a measured line of text. More...
class	Transform
	Affine transform for drawing coordinates. More...

Enumerations
enum	FillRule {   NonZero,   EvenOdd }
	Determines how overlapping subpaths of a filled shape are painted. More...

Enumeration Type Documentation

FillRule

enum FillRule

strong

When a Path contains overlapping subpaths, FillRule controls which enclosed regions are considered inside and therefore filled.

Enumerator
NonZero	Fills regions enclosed by a non-zero net winding count. For each point, a horizontal ray is cast and the signed number of path crossings is counted. If the result is non-zero the point is inside. This is the SVG and PostScript default.
EvenOdd	Fills regions enclosed by an odd number of path crossings. For each point, a horizontal ray is cast and the total number of path crossings is counted. If the result is odd the point is inside. Also known as the alternating rule.