Gain insights into computer graphics with Python's Pycairo library. Learn about pixel vs. vector graphics, create complex shapes, work with transforms, text, gradients, and more for VR and game development.

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Pycairo

In this course, you will use Python’s Pycairo library to draw complex shapes. So if you have an appetite for virtual reality, or game development, then this course will serve you well.

You will start with basic concepts like: What is the difference between pixel and vector graphics? After that, you will learn to make basic drawings and then you will move on to complex shapes. Throughout, you will cover important concepts like transform and state, working with text, gradients, and a whole lot more.

By the time you finish this course, you will have a powerful new library at your disposal, and you’ll be able to construct beautiful graphics that users will love.

Computer Graphics in Python and Pycairo

# What is masking?
**Masking** paints a pattern through a mask, which can be another pattern or surface, such as an image surface.

Masking allows us to use any pattern as a transparency mask on any other pattern.

As we discussed previously, a pattern can be a solid color, gradient, image, or surface with vector content.

There are three stages to this. 

First, we create the mask:

```
radial=cairo.RadialGradient(200, 200, 100, 200, 200, 200)
radial.add_color_stop_rgba(0, 0, 0, 0, 1)
radial.add_color_stop_rgba(1, 0, 0, 0, 0)
```
The pattern radial is a radial gradient. The center is `(200, 200)`, the inner circle has a radius of 100, and the outer circle has a radius of 200.

The stops use `add_color_stop_rgba` to create stops that have a transparency component. The first stop is black, with an alpha value of `1`, which makes it fully opaque. The outer circle is also black, with an alpha value of `0`, which makes it fully transparent.

The effect of this is to have a black central area, and an outer ring where the black fades out (it becomes more and more transparent). Beyond the outer circle, the gradient is fully transparent, so the white background shows through.

Next, we create the tiger image:

```
image = cairo.ImageSurface.create_from_png('tiger.png')
ctx.set_source_surface(image)
```
We create an ImageSurface from the PNG file, and set that surface as a current source with the use of the `set_source_surface` function. 

Now, we can create the output:

```
ctx.mask(radial)
```

We take the current source, the tiger `ImageSurface`, and apply it with the radial mask. This, effectively, applies the mask alpha channel to the image, which creates an image that is fully opaque in the center but fades out at the edges.

Learn about the concept of masking in Pycairo.

Introduction

Introduction to Vector Graphics

Basic Drawing Operations

Paths and Complex Shapes

Computer Color

Transforms and State

Working with Text

Gradients and Image Fills

Clipping, Masking and Compositing

Surfaces and Output Formats

Integration with Other Libraries

Conclusion

Masking

What is masking?