This function level allows to use all power of the graphic and text operators in the work with PaintBox. The work with graphics, texts, styles and images is described here. It helps to create any practical page content filling.
A PDF viewer application maintains an internal data structure called the graphics state that holds current graphic control parameters. These parameters define the global framework within which the graphics operators execute. For example, the Fill operator implicitly uses the current color parameter, and the Stroke operator additionally uses the current line width parameter from the graphics state. The graphics state is initialized at the beginning of each page.
One of the key concepts of the PDF imaging model is a path which, in itself, an invisible contour without any markings on the page. Paths must be acted upon by path-painting operators to produce markings. A path may be stroked with a certain color and width, producing an actual curve on the page. A path may also be filled with a color. It may also be used to define a clipping path. Functions in this section are used to construct paths that are subsequently used to provide various effects.
Paths constructed by functions in the "Path construction" section are invisible, i.e., constructing a path does not produce any markings on the page. They must be stroked or filled.
These functions set is used to place in PaintBox in defined way. Except these functions we can set such properties as name, size and encoding of the font, character spacing, horizontal scaling, text rendering mode, word spacing. Also we may find out texts width.
There are functions not included in previous levels and which have own meanings with PaintBox work. These functions help to find out PaintBox size, to play metafile and to place image and to finish work normally.
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