MOBSYS Prefinals

user interaction

the ___ in mobile apps typically involves tapping, typing using gestures, or talking

• think about how users will use your app

• minimize steps

• use UI elements that are easy to access, understand, use

• follow android’s best practices

• meet user’s expectations

these are the five things to keep in mind when designing an interactive app

button

is usually a rectangle or rounded rectangle with a descriptive caption or icon in its center, can have text, icon, or both

normal, disabled, pressed

these are the three states of a button

raised button

this appears lifted from the screen—the shading around it indicates that it is possible to tap or click it

flat button

also known as a borderless button, is a text-only button that looks flat and doesn’t have a shadow

they include ImageView and floating action buttons (FAB)

what are the two things that clickable images include?

ImageView

is used to display image resources and can be turned into a button

by adding the android:onClick attribute in the XML layout

in what way can we turn an ImageView into a button

in app > src > main > res > drawable folder of the project

the image for the ImageView must already be stored where?

floating action button (FAB)

a circular button that appears to float above the layout

touch gesture

this occurs when a user places one or more fingers on the touchscreen, and the app interprets that patten of touches as a particular gesture, such as a tap, touch and hold, double tap, fling, or scroll

input controls

these are interactive elements in the app’s UI that accept data input

(EditText)

a text field ___ is used for entering and modifying text

check box

is used for selecting one or more options

radio button

this restricts the user to select only one option from a set

spinner

is a dropdown menu for selecting only one option

toggle button

this lets the user change a setting between 2 states

switch

a type of toggle button called ___ (for android 4.0+) provides a slider for selection

SeekBar

a ___ is dragged to the left or right to indicate a current progress level

event

this occurs when the user interacts with an input control or item in the user interface

event listener

this is an interface in the view class that contains a single callback method

when the view to which the listener has been registered is triggered by user interaction with the item in the UI

in event listeners, when will the callback methods be called?

• onClick()

• onLongClick()

• onKey()

• onTouch()

these are the four common callback methods

onClick()

method when the user either touches or focuses upon the item

onLongClick()

method when the user either touches or focuses upon the item for a second

onKey()

method when the user is focused on the item and presses or releases a hardware key on the device

onTouch()

when the user performs an action qualified as a touch event (a press, a release, or any movement gesture on the screen)

yes, these two are often used

do most input controls use onClick() and onTouch()?

drawable

is a graphic that can be drawn to the screen and uses the class of the same name for adding rich images in an app with minimal impact on its performance

• WebP

• PNG

• JPG/JPEG

• GIF

• BMP

these are the 5 image formats that android supports

WebP

a modern image format developed by google that provides superior lossless and lossy compression for images on the web

portable network graphics

what does PNG mean?

joint photographic experts group

what does JPG/JPEG mean?

graphics interchange format

what does GIF mean?

bitmap

what does BMP mean?

WebP, PNG, and JPG

these are the three recommended image formats

app/src/main/res/drawable

the image file should be saved in the ___ folder of the project (path)

style

is a collection of attributes that define the look and format of a view

platform styles

the styles that android provides are called ___

add a <style> element inside a <resources> element in any xml file located in the values folder inside the project’s res folder

how can we create a style?

• name

• parent (optional)

• any number of <item> elements as child elements of <style> and each item includes one style attribute

a <style> element includes these three:

inheritance

allows a style to inherit the properties of an existing style

use the parent attribute to specify the resource ID of the style you want to inherit

how can we inherit a platform style?

use the name of the style you want to inherit as the first part of the new style’s name and separate the parts with a period

how can we inherit a custom style?

theme

is a collection of attributes that define the look and format of an activity or an entire app. any style an be used for this