cairo

• zetcode:

  • https://zetcode.com/gfx/pycairo/introduction/

作用：存储所有图形参数（状态参数和如何绘制）

  The drawing context holds all of the graphics state parameters that describe how drawing is
  to be done. This includes information such as line width, color, the surface to draw to, and
  many other things. It allows the actual drawing functions to take fewer arguments to
  simplify the interface.

由点组成的线或图形。

  A path is a collection of points used to create primitive shapes such as lines, arcs,
  and curves.

• lines
• arcs
• curves

类型

• closed path
• open path

创建步骤

• create empty path
• define a path

• make visible

  • by stroking (线宽？)

    • 方法：strok()

  • or filling them (填充)

    • 方法： fill()

类似画笔：A source is the paint we use in drawing. We can compare the source to a pen or ink that we use to draw the outlines and fill the shapes.

四种基本 source 类型

• colors
• gradients
• patterns
• images

输出端，类似纸张，eg: PDF surface, Win32 surface, Xlib surface

source 绘制到 surface 前的处理，opaque(不透明)部分被复制上去， transparent(透明)部分不被复制

绘制内容（source when drawing onto a sourface）

  In PyCairo, a pattern is something that you can read from and that is used as the
  source or mask of a drawing operation.