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Flag Quiz App
1
CS7030: Mobile App Development
assets Folder
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drawable folder
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Image contents at the root level
assets folder
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AssetManager open an InputStream to read image file name; next
create a Drawable object from the stream; finally display the object
on an ImageView using setImageDrawable method
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Images can be organized in subfolders
Accessed via AssetManager
InputStream stream = assets.open(region + "/“ +
nextImageName +".png");
Drawable flag =
Drawable.createFromStream(stream,nextImageName);
flagImageView.setImageDrawable(flag);
CS7030: Mobile App Development
String Resource
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strings.xml
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Create string array
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<string-array name="regionsList">
<item>Africa</item>
<item>Asia</item>
<item>Europe</item>
<item>North_America</item>
<item>Oceania</item>
<item>South_America</item>
</string-array>
getResources().getStringArray(R.array.
regionsList);
CS7030: Mobile App Development
Animation Category
Tweened Animations
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Scale animations (resize)
Rotate animations
Alpha animations (transparency)
Translate animations (move)
Frame-by-Frame Animations
An animation set may contain any
combination of tweened animations
CS7030: Mobile App Development
Animation xml file
<set
mlns:android="http://schemas.android.com/apk/res/android"
android:interpolator="@android:anim/decelerate_interpolator">
<translate
android:fromXDelta="0" android:toXDelta="-5%p"
android:duration="100"/>
<translate
android:fromXDelta="-5%p" android:toXDelta="5%p"
android:duration="100" android:startOffset="100"/>
<translate
android:fromXDelta="5%p" android:toXDelta="-5%p"
android:duration="100" android:startOffset="200"/>
</set>
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CS7030: Mobile App Development
Attributes of Animations
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fromXDelta: the view’s offset when the animation starts
toXDelta: the view’s offset when the animation ends
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These attributes can have
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Absolute values (in pixels)
A percentage of the animated View’s size
A percentage of the animated View’s parent’s size
-5%p indicates the View move to the left by 5% of the parent’s width
5% indicates the View move to the right by 5% of the View’s width
duration: how long the animation lasts in milliseconds
startOffset: the number of milliseconds into the future at
which an animation should begin
CS7030: Mobile App Development
Load Tweened Animations
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Create a folder called anim under res folder
Create new xml files in the anim folder. Add a set tag in the xml files:
<set xmlns:android="http://schemas.android.com/apk/res/android"
android:interpolator="@android:anim/decelerate_interpolator">
</set>
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Add rotate, alpha, scale, or translate tag in the set tag.
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Use AnimationUtils.loadAnimation to load the xml file, and
then create an object of Animation
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startAnimation
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shakeAnimation = AnimationUtils.loadAnimation(this,
R.anim.incorrect_shake);
flagImageView.startAnimation(shakeAnimation);
CS7030: Mobile App Development
Handler
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postDelayed receives Runnable as arguments to
execute and a delay in milliseconds
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Each Handler instance is associated with a single
thread and that thread's message queue.
There are two main uses for a Handler:
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to schedule messages and runnables to be
executed as some point in the future
to enqueue an action to be performed on a different
thread than your own.
CS7030: Mobile App Development