Subtitles – tracking the video progression

Let's add subtitles to our application. We will do this in four simple steps:

1. Create a Subtitle widget (subtitle.kv) derived from the Label class that will display the subtitles

2. Place a Subtitle instance (video.kv) on top of the video widget

3. Create a Subtitles class (subtitles.py) that will read and parse a subtitle file

4. Track the Video progression (video.py) to display the corresponding subtitle

The Step 1 involves the creation of a new widget in the subtitle.kv file:

88. # File name: subtitle.kv
89. <Subtitle@Label>:
90.     halign: 'center'
91.     font_size: '20px'
92.     size: self.texture_size[0] + 20, self.texture_size[1] + 20
93.     y: 50
94.     bcolor: .1, .1, .1, 0
95.     canvas.before:
96.         Color:
97.             rgba: self.bcolor
98.         Rectangle:
99.             pos: self.pos
100.             size: self.size

There are two interesting elements in this code. The first one is the definition of the size property (line 92...