Scroll to certain position on application Android example code
ScrollTo(), getTop(), getBottom(), getLeft(), getRight(), ScrollView, LinearLayout Android Java xml example.
How get position of a View.
MainClass.java
main.xml
How get position of a View.
MainClass.java
/*
public void scrollTo (int x, int y)
Since: API Level 1
Set the scrolled position of your view. This will cause a call to onScrollChanged(int, int, int, int) and the view will be invalidated.
This version also clamps the scrolling to the bounds of our child.
Parameters
x the x position to scroll to
y the y position to scroll to
*/
// sroll to top of hscrollViewMain
ScrollView hscrollViewMain = (ScrollView)findViewById(R.id.scrollViewMain);
hscrollViewMain.scrollTo(0, 0); // scroll to application top
// get position of a View
EditText hEdit = (EditText)findViewById(R.id.username_edit);
int nY_Pos = hEdit.getTop(); // getBottom(); X_pos getLeft(); getRight();
// scroll to top of hEdit
hscrollViewMain.scrollTo(0,nY_Pos);
main.xml
<LinearLayout
xmlns:android="//schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<ScrollView
android:id="@*id/scrollViewMain"
android:layout_width="fill_parent"
android:layout_height="0dip"
android:layout_weight="1">
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:orientation="vertical"
android:paddingTop="5dip"
android:paddingBottom="13dip"
android:paddingLeft="20dip"
android:paddingRight="20dip">
<TextView
android:id="@+id/message"
android:textAppearance="?android:attr/textAppearanceSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="5dip" />
<TextView
android:textAppearance="?android:attr/textAppearanceSmall"
android:textStyle="bold"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/login_activity_username_label" />
<EditText
android:id="@+id/username_edit"
android:singleLine="true"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:minWidth="250dip"
android:scrollHorizontally="true"
android:capitalize="none"
android:autoText="false"
android:inputType="textEmailAddress" />
</LinearLayout>
</ScrollView>
</LinearLayout>
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choreographer skipped frames
Create filter with TAG regex to disable Choreographer messages, see code and picture below:
Create filter with TAG regex to disable Choreographer messages, see code and picture below:
^((?!Choreographer).)*$
Bitmap size calculation:
bmpHeight * bmpWidth
For example:
Resolution of image 1024x860 = 880 640 pixels
If every pixel get 4 byte of memory:
880 640x4= 3 522 560 (3.5MB)
Get bitmap size without allocation of memory:
Get Memory size:
Make your bitmap not bigger as maxMemory size
final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
bmpHeight * bmpWidth
For example:
Resolution of image 1024x860 = 880 640 pixels
If every pixel get 4 byte of memory:
880 640x4= 3 522 560 (3.5MB)
Get bitmap size without allocation of memory:
BitmapFactory.Options options = new BitmapFactory.Options();
// If set to true, the decoder will return null (no bitmap), but the out... fields will still
// be set, allowing the caller to query the bitmap without having to allocate the memory for its pixels.
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(getResources(), R.drawable.my_image, options);
int imageHeight = options.outHeight; // 1024
int imageWidth = options.outWidth; // 860
String imageType = options.outMimeType; // .jpg .png .gif
Get Memory size:
Make your bitmap not bigger as maxMemory size
final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
float density = getResources().getDisplayMetrics().density;
Debug.MemoryInfo memoryInfo = new Debug.MemoryInfo();
Debug.getMemoryInfo(memoryInfo);
final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
final int freeMemory = (int) (Runtime.getRuntime().freeMemory() / 1024);
String memMessage = String.format(
"Free=%d kB,
MaxMem=%d kB,
Memory: Pss=%.2f MB, Private=%.2f MB, Shared=%.2f MB",
freeMemory,
maxMemory,
memoryInfo.getTotalPss() / 1024.0,
memoryInfo.getTotalPrivateDirty() / 1024.0,
memoryInfo.getTotalSharedDirty() / 1024.0);
((TextView)findViewById(R.id.textViewInfo)).setText(memMessage );
Problem in Android application:
Solution: check code for set and get selection
E/AndroidRuntime(416): FATAL EXCEPTION: main
E/AndroidRuntime(416): java.lang.IndexOutOfBoundsException
E/AndroidRuntime(416): at java.util.Arrays$ArrayList.get(Arrays.java:75)
E/AndroidRuntime(416): at android.widget.ArrayAdapter.getItem(ArrayAdapter.java:298)
E/AndroidRuntime(416): at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:351)
E/AndroidRuntime(416): at android.widget.ArrayAdapter.getView(ArrayAdapter.java:323)
E/AndroidRuntime(416): at android.widget.Spinner.makeAndAddView(Spinner.java:192)
E/AndroidRuntime(416): at android.widget.Spinner.layout(Spinner.java:151)
E/AndroidRuntime(416): at android.widget.Spinner.onLayout(Spinner.java:115)
Solution: check code for set and get selection
// Spinner _spin1 contain only 49 items
// you can set max 48 ( range 0 - 48)
// 50 is IndexOutOfBoundsException
_spin1.setSelection(50);
Spinner, ArrayAdapter, setOnItemSelectedListener, onItemSelected, setDropDownViewResource
MainClass.java
strings.xml
MainClass.java
public class Vypocet extends Activity {
Spinner hSpinnerMetry;
// .......
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
hSpinnerMetry = (Spinner) findViewById(R.id.idSpinnerMetry);
ArrayAdapter<CharSequence> adapterMetry = ArrayAdapter.createFromResource(
this, R.array.metry_array, android.R.layout.simple_spinner_item);
adapterMetry.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
hSpinnerMetry.setAdapter(adapterMetry);
hSpinnerMetry.setOnItemSelectedListener(
new OnItemSelectedListener() {
public void onItemSelected(
AdapterView<?> parent, View view, int position, long id) {
int nPos = position;
}
public void onNothingSelected(AdapterView<?> parent) {
}
});
}
}
strings.xml
<string-array name="metry_array">
<item>m</item>
<item>dm</item>
<item>cm</item>
<item>mm</item>
</string-array>
Editace: 2011-09-20 15:29:14
Počet článků v kategorii: 396
Url:scroll-to-certain-position-on-application-android-example-code