Mobile interfaces and navigation
The mobile screen: densities and units (dp, sp), 48 dp touch targets, adaptive layouts; the four navigation patterns (stack, bottom tabs, drawer, modal window) and the back stack.
- 29 cards
- 6 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- Concepts
- Questions
- Sort and link
- The numbers
- Scenarios
- Understand
A few cards from the deck
Density-independent pixel (dp): what is it?
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An Android length unit that keeps the same physical size on every screen: 1 dp equals 1 pixel on a 160 dots-per-inch screen.
The real pixel count is obtained by multiplying by the density: a 48 dp button takes 48 pixels at density 1 and 144 pixels at density 3, but measures the same in the hand.
The user opens Home, then List, then Detail, then Cart (from the detail), then presses Back twice. Which screen is shown?
- List
- Home
- Detail
- Cart
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List
The stack is Home, List, Detail, Cart. A first Back pops Cart and shows Detail, a second pops Detail and shows List. Back does not jump to home.
Margins, buttons and icons are measured in …, but text size is expressed in ….
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Margins, buttons and icons are measured in dp, but text size is expressed in sp.
sp also follows the font size set by the user; dp does not take it into account.
Scale-independent pixel (sp): what is it?
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A unit reserved for text size: it follows the density like dp, and also the font size setting chosen by the user.
Writing text in dp would stop it from growing for a visually impaired person who enlarged their font in settings. Everything else in the interface is measured in dp.