Feature: Block padding

[Igormandello]

Description

If we want to render a widget inside a block with a certain distance from its borders, we need to create another Layout element based on the outer Block, add a margin and render the Widget into it. Adding a padding property on the block element skips the creation of this second Layout.

This property works especially when rendering texts, as we can just create a block with padding and use it as the text wrapper:

let block = Block::default().borders(Borders::ALL).padding(4);
let paragraph = Paragraph::new("example paragraph").block(block);
f.render_widget(paragraph, area);

Rendering another widget should be easy too, using the .inner method:

let block = Block::default().borders(Borders::ALL).padding(4);
let inner_block = Block::default().borders(Borders::ALL);
let inner_area = block.inner(area);

f.render_widget(block, area);
f.render_widget(inner_block, inner_area);

Testing guidelines

The block.rs example contains two cases of use: one with an inner text and another with an inner block:

I've also changed the paragraph tests to include a padding of value 1 to the rendering tests.

Checklist

• I have read the contributing guidelines.
• I have added relevant tests.
• I have documented all new additions.

[alpha-tango-kilo]

This would be awesome! I hope this gets merged 🙌