Ketvirtoji Android mobilių programėlių kūrimo paskaitą

1. Android
mobilių programėlių kūrimo įvadas

2. Drawable Resources
A drawable resource is a general concept for a graphic that can be drawn to the screen and
which you can retrieve with APIs such as getDrawable(int) or apply to another XML resource with
attributes such as android:drawable and android:icon.
Bitmap File - A bitmap graphic file (.png, .jpg, or .gif). State List - An XML file that references different
Creates a BitmapDrawable. bitmap graphics for different states (for example, to
use a different image when a button is pressed).
Nine-Patch File - A PNG file with stretchable regions to Creates a StateListDrawable.
allow image resizing based on content (.9.png).
Creates a NinePatchDrawable. Shape Drawable - An XML file that defines a
geometric shape, including colors and gradients.
Animation Resource - An animation defined in XML Creates a ShapeDrawable.
that modifies properties of the target object, such as
background color or alpha value, over a set amount of Transition Drawable - An XML file that defines a
time. drawable that can cross-fade between two drawable
resources. Creates a TransitionDrawable.

3. Bitmap
A bitmap image. Android supports bitmap files in a three
formats:
- .png (preferred)
- .jpg (acceptable)
- .gif (discouraged).
Note: Bitmap files may be automatically optimized with
lossless image compression by the aapt tool during the build
process. For example, a true-color PNG that does not require
more than 256 colors may be converted to an 8-bit PNG with
a color palette.

4. XML Bitmap
An XML bitmap is a resource defined in XML
that points to a bitmap file. The effect is an
alias for a raw bitmap file. The XML can
specify additional properties for the bitmap
such as dithering and tiling.
Note: You can use a <bitmap> element as a
child of an <item> element. For example,
when creating a state list or layer list, you can
exclude the android:drawable attribute from an
<item> element and nest a <bitmap> inside it
that defines the drawable item.

5. Nine-Patch File
A NinePatchDrawable graphic is a stretchable
bitmap image, which Android will automatically
resize to accommodate the contents of the
View in which you have placed it as the
background. An example use of a NinePatch
is the backgrounds used by standard Android
buttons — buttons must stretch to
accommodate strings of various lengths. A
NinePatch drawable is a standard PNG image
that includes an extra 1-pixel-wide border. It
must be saved with the extension .9.png, and
saved into the res/drawable/ directory of your
project.

6. XML Nine-Patch
An XML Nine-Patch is a resource defined in
XML that points to a Nine-Patch file. The XML
can specify dithering for the image.

7. Layer List
A LayerDrawable is a drawable object that
manages an array of other drawables. Each
drawable in the list is drawn in the order of the
list—the last drawable in the list is drawn on
top.
Each drawable is represented by an <item>
element inside a single <layer-list> element.

8. State List
A StateListDrawable is a drawable object
defined in XML that uses a several different
images to represent the same graphic,
depending on the state of the object. For
example, a Button widget can exist in one of
several different states (pressed, focused, or
niether) and, using a state list drawable, you
can provide a different background image for
each state.

9. State List
Note: Remember that Android applies the first
item in the state list that matches the current
state of the object. So, if the first item in the
list contains none of the state attributes
above, then it is applied every time, which is
why your default value should always be last
(as demonstrated in the following example).

10. Transition Drawable
A TransitionDrawable is a drawable object that
can cross-fade between the two drawable
resources.
Each drawable is represented by an <item>
element inside a single <transition> element.
No more than two items are supported. To
transition forward, call startTransition(). To
transition backward, call reverseTransition().

11. Clip Drawable
A drawable defined in XML that clips another
drawable based on this Drawable's current
level. You can control how much the child
drawable gets clipped in width and height
based on the level, as well as a gravity to
control where it is placed in its overall
container. Most often used to implement
things like progress bars.

12. Shape Drawable
This is a generic shape defined in XML.
Common use - a Drawable with a color gradient for buttons, backgrounds, etc.

13. Shape Drawable

14. Support Library
The support library for v4 provides access to several classes introduced with Android 3.0 and
beyond, plus some updated version of existing classes, and even some APIs that currently don't
exist in the Android platform. Some of the most useful and notable classes that have
counterparts in the v4 support library are:
- Fragment
- FragmentManager
- FragmentTransaction
- ListFragment
- DialogFragment
- LoaderManager
- Loader
- AsyncTaskLoader
- CursorLoader

15. Fragments

16. Fragments
To manage your fragments and
loaders, you must use the
methods
FragmentActivity.getSupportFrag
mentManager() and
FragmentActivity.getSupportLoad
erManager() (instead of the
getFragmentManager() and
getLoaderManager() methods).

17. Fragments
Implementation of PagerAdapter that uses a
Fragment to manage each page. This class
also handles saving and restoring of
fragment's state.
This version of the pager is more useful when
there are a large number of pages, working
more like a list view. When pages are not
visible to the user, their entire fragment may
be destroyed, only keeping the saved state of
that fragment. This allows the pager to hold
on to much less memory associated with each
visited page as compared to
FragmentPagerAdapter at the cost of
potentially more overhead when switching
between pages.

18. Fragments

19. Adapters
Adapters are used to provide the data to the ListView
object. The adapter also defines how each row is the
ListView is displayed.
The adapter is assigned to the ListView via the
setAdapter method on the ListView object.
An adapter extend the BaseAdapter class. Android
provides some standard adapters; the most important
are ArrayAdapter and CursorAdapter.
ArrayAdapter can handle data based on Arrays or
java.util.List.
SimpleCursorAdapter can handle database related
data. This description focuses on the non database
case.

20. Adapters

21. Async Task

22. RecognitionListener
Used for receiving notifications
from the SpeechRecognizer when
the recognition related events
occur. All the callbacks are
executed on the Application main
thread.

23. RecognitionListener

24. Q&A
v.valkaitis@appcamp.lt