PyCairo - 设置上下文颜色

在本文中，我们将看到如何在 pycairo Python中设置上下文颜色。 Pycairo 是一个Python模块，为 Cairo 图形库提供绑定。这个库用于在Python中创建 SVG 即矢量文件。打开 SVG 文件进行查看（只读）的最简单快捷的方法是使用现代 Web 浏览器，如 Chrome、Firefox、Edge 或 Internet Explorer——几乎所有这些浏览器都应该为 SVG 格式提供某种渲染支持。可以使用 RGBA 模型设置颜色，RGBA 代表红绿蓝 alpha。虽然它有时被描述为色彩空间，但它实际上是补充有第四个 Alpha 通道的三通道 RGB 颜色模型。

In order to this we will use set_source_rgba method with the Context object

Syntax: context.set_source_rgba(0, 0, 0, 1)

Argument: It takes color format in RGBA model

Return: It returns None  

示例 1：

Python

# importing pycairo
import cairo
  
# creating a SVG surface
# here geek007 is file name & 700, 700 is dimension
with cairo.SVGSurface("geek007.svg", 700, 700) as surface:
  
    # creating a cairo context object for SVG surface
    # useing Context method
    context = cairo.Context(surface)
  
    # setting color of the context
    context.set_source_rgba(0, 0, 0, 1)
  
    # setting of line width
    context.set_line_width(4)
  
    # move the context to x,y position
    context.move_to(40, 30)
  
    # creating a rectangle(square)
    context.rectangle(100, 100, 100, 100)
  
    # stroke out the color and width property
    context.stroke()
  
  
# printing message when file is saved
print("File Saved")

Setting color of the context

 context.set_source_rgba (0, 0, 0, 1)

输出 ：

示例 2：

蟒蛇3

# importing pycairo
import cairo
  
# creating a SVG surface 
# here geek007 is file name & 700, 700 is dimension
with cairo.SVGSurface("geek007.svg", 700, 700) as surface:
      
    # creating a cairo context object for SVG surface
    #useing Context method
    context = cairo.Context(surface)
      
    # setting color of the context
    context.set_source_rgba(4, 0, 4, 0.5)
      
    # setting of line width
    context.set_line_width(40)
  
  
    # move the context to x,y position
    context.move_to(40, 30) 
      
     #creating a rectangle(square)
    context.rectangle(100, 100, 100, 100)
      
    # stroke out the color and width property
    context.stroke()
  
    
      
# printing message when file is saved
print("File Saved")

Setting color of the context

   context.set_source_rgba (4, 0, 4, 0.5)

输出 ：

示例 3：

蟒蛇3

# importing pycairo
import cairo
  
# creating a SVG surface
# here geek007 is file name & 700, 700 is dimension
with cairo.SVGSurface("geek007.svg", 700, 700) as surface:
  
    # creating a cairo context object for SVG surface
    # useing Context method
    context = cairo.Context(surface)
  
    # setting color of the context
    context.set_source_rgba(180, 150, 0, 0.5)
  
    # setting of line width
    context.set_line_width(40)
  
    # move the context to x,y position
    context.move_to(40, 30)
  
    # creating a rectangle(square)
    context.rectangle(100, 100, 100, 100)
  
    # stroke out the color and width property
    context.stroke()
  
  
# printing message when file is saved
print("File Saved")

Setting color of the context

context.set_source_rgba (180, 150, 0, 0.5)

输出 ：