Graphics and Imaging

Images and 2D drawing. More...

Topics
	Images and Image Views
	Images, formats, views and pixels.
	Drawing Graphics and Text
	Rendering 2D shapes, text and images on paint surfaces.

Classes
class	Point
	Floating-point X and Y coordinates. More...
class	PointI
	Integer X and Y coordinates. More...
class	Rect
	Floating-point rectangle. More...
class	RectI
	Integer rectangle. More...
class	Size
	Floating-point width and height. More...
class	SizeI
	Integer width and height. More...

Detailed Description

This module is the portable graphics layer, so a caller stores pixels, inspects them, and draws shapes and text through the same types on every supported platform. It is two reader tasks that share geometry, not two separate libraries: images own or wrap pixel buffers, and painters render onto paint surfaces. A Bitmap is both a paint surface and an image source, so drawing results can be read back as pixels, and an Image can be drawn onto a surface.

Geometry is shared. Point, Size, and Rect are floating-point values used by drawing; PointI, SizeI, and RectI are integer pixel values used by images and by rounding. PointF, SizeF, and RectF are typedefs of the floating-point types. Drawing commands take logical coordinates. A Scaling on the paint surface converts those logical units to physical device pixels. Image width, height, and pixel positions are already physical pixels.

Ownership does not move when one type uses another. An image either owns its buffer or wraps a caller buffer that must outlive the image. A view refers to an image region and does not copy pixels. A Painter does not own the PaintSurface or PaintContext it paints on. The code that creates a surface, an image, or a wrapped buffer keeps it alive while painting or viewing is in progress.

Forms uses this module for widget painting. A Forms PaintSurface is another paint target, and a Forms Painter issues the same drawing commands. The Forms updating chapter documents when a widget paints; pens, brushes, paths, and text are documented here.

The rest of this chapter is the image model, then the drawing model.