Develop Reference

ScrollView scrolls down when view size changes

I currently have a ScrollView with a LinearLayout. I'm changing some content dynamically, e.g. setting a long text passage dynamically, and adding dynamic layouts (buttons etc.). This causes the linear layout's height to change, which causes the ScrollView to scroll down. How can I keep the current scroll position while the layout is being dynamically updated?
<ScrollView
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical
android:gravity="center_horizontal"
>
<!-- Dynamic Content Here -->
</LinearLayout>
</ScrollView>

One option i would suggest is to save the scroll position in a bundle and restore it.
#Override
protected void onSaveInstanceState(Bundle outState) {
outState.putInt("xPos", scrollView.getScrollX());
outState.putInt("yPos", scrollView.getScrollY());
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
...
int scrollX = savedInstanceState.getInt("xPos"); // Default value 0
int scrollY = savedInstanceState.getInt("yPos");
scrollView.scrollTo(scrollX, scrollY);
}

I think with this steps you can do it :
Create a custom scroll view that extends from scrollview
Define a boolean property for enabling and disabling scroll
Check the boolean variable on the onScollChanged method and return false if is true
Set the boolean variable true before adding dynamic views to it's container
Set it to false when adding done
I hope these help you

Reload a View on Orientation Change

In my Activity I have a View that "depends" from screen orientation. If it's in landscape mode, i use a layout under layout-large-hand, but if it's in portrait mode, I use the layouts under the layouts folder.
The Activity shows also a Map with some markers and informations.
In my AndroidManifest i have
android:configChanges="orientation|screenSize"
But the activity shows only the layout on portrait mode.
How can I fix this?
EDIT 3/12:
I have a layout like this:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<fragment
android:id="#+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent"
class="com.google.android.gms.maps.MapFragment" />
<include
android:id="#+id/my_view"
layout="#layout/my_view"
android:visibility="gone" />
</RelativeLayout>
and i want that my_view changes the layout, but map remains with all markers, zoom level, position, ecc ecc...
my_view is visible when i click on a Button created dinamically in the activity.
EDIT 2:
Like SweetWisher ツ says, i was trying to setup a custom behaviour for the views. But when i rotate the device, the map disappear. This is part of my code in the activity:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initUI();
}
private void initUI() {
setContentView(R.layout.my_layout);
if (mp == null) {
mp = MapFragment.newInstance();
}
getFragmentManager().beginTransaction().replace(R.id.placeholder, mp).commit();
initUIStuff()
}
private void initUIStuff(){
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
initUI();
}
#Override
protected void onStart() {
super.onStart();
initGMap();
}
#Override
protected void onResume() {
super.onResume();
initGMap();
}
private void initGMap() {
if (mp != null {
//Initialize Map
}
}

If you use android:configChanges="orientation" in your Manifest you're preventing Android from doing default reset of view hierarchy on screen orientation change. You have to manually change your views in onConfigurationChanged method and by that I mean inflate your desired layout and replace your old layout with it. If you want to take advantage of Android automatic view hierarchy reset don't use android:configChanges="orientation".
Edit:
Use following code to add map fragment through XML:
<fragment
android:id="#+id/map"
android:name="com.google.android.gms.maps.MapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent" />
You also don't need now 'onConfigurationChange' method so delete it.

How to preven the gridview scroll by default once dataset changed

I have an activity which contains a ScrollView, and also I have a GridView inside the ScrollView, the layout:
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/root">
<RelativeLayout
android:padding="10dp"
android:layout_width="match_parent"
android:layout_height="match_parent">
.........
<com.test.android.view.ScrollableGridView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:numColumns="auto_fit"
android:columnWidth="100dp"
android:verticalSpacing="2dp"
android:focusable="false"
android:clickable="false">
</com.test.android.view.ScrollableGridView>
</RelativeLayout>
</ScrollView>
public class ScrollableGridView extends GridView {
#Override
public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int expandSpec = MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2, MeasureSpec.AT_MOST);
super.onMeasure(widthMeasureSpec, expandSpec);
ViewGroup.LayoutParams params = getLayoutParams();
params.height = getMeasuredHeight();
}
}
Why I use the custome gridview is to make sure the gridview can expand to its max height(check this).
Now once the activity loaded, I will load data from the server, then call the:
gridAdapter.notifyDatasetChanged();
Then the activity will scroll to the grid view which means user can not see the content above the gridview.
I have tried that:
mScrollView.scrollTo(0,mScrollView.getBottom());
But it does not work.
Any idea to fix it?

Issue:
GridView is being scrolled automatically.
Reason:
When the screen is loaded, it finds the first focusable View from its ViewHierarchy and sets the focus to that View.
Solution:
You can set focus to some other View so that Android does not focus the GridView at first,so it won't scroll automatically.
Example:
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/root">
<RelativeLayout
android:padding="10dp"
android:id="#+id/rlContainer" //you may set id and requestfocus from java code as well
android:focusable="true" //add this
android:focusableInTouchMode="true" //add this
android:layout_width="match_parent"
android:layout_height="match_parent">
......... //you can also add focusable,focusableInTouchMode to any other view before the GridView
<com.test.android.view.ScrollableGridView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:numColumns="auto_fit"
android:columnWidth="100dp"
android:verticalSpacing="2dp"
android:focusable="false"
android:clickable="false">
</com.test.android.view.ScrollableGridView>
</RelativeLayout>
From java code,
inside onCreate() method of your Activity
RelativeLayout rlContainer = (RelativeLayout) findViewById(R.id.rlContainer);
rlContainer.requestFocus();

A better option will be to scroll to the GridView's top. Also, you should post the scrollTo(int, int) call:
mScrollView.post(new Runnable() {
#Override
public void run() {
mScrollView.scrollTo(0, mGridView.getTop());
}
});
Edit:
So, from what I can gather:
on first load, GridView is at the top & visible
then, you load some data from the server
some layout container above the GridView is updated with data - this increases the layout's size and the GridView is pushed down
Lets say that the layout container above the GridView is mLayoutContainer. After adding data to this container, add a OnPreDrawListener to it:
mLayoutContainer.getViewTreeObserver().addOnPreDrawListener(
new ViewTreeObserver.OnPreDrawListener() {
#Override
public boolean onPreDraw() {
// remove the OnPreDrawListener
mLayoutContainer.getViewTreeObserver().removeOnPreDrawListener(this);
// update scrollY for the ScrollView
// since mLayoutContainer is about to be drawn, its height
// is available.
mScrollView.setScrollY(mScrollView.getScrollY()
+ mLayoutContainer.getHeight());
// we're allowing the current draw pass
return true;
}
});
This is basically a state-restore operation. We are asserting that prior state was perfect - state changed resulting in the GridView being pushed down - counter state change by scrolling ScrollView by an equal amount.

Android toggle button display wrong value after orientation change

Here is my problem.
I've got a simple activity which set a layout, and add rows in a table-layout(itself in a scroll view).
Those table-rows have a custom layout with a text-field and a toggle button.
Each toggle button has a value taken from a database, and when I first create the activity, the values are OK. But when I turn the device and then change the orientation, all the toggles-button take "false" value. I printed the values that I set in the Logcat, and the values are the good ones (those in the database).
I thought something like the layout I want is hidden behind another layout, but I made some tests and the text-fields change with new values, so I really don't understand why the toggle buttons don't work.
Here is the code :
TableRow layout :
<?xml version="1.0" encoding="utf-8"?>
<TableRow xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
>
<RelativeLayout
android:id="#+id/relativelayout_row_parametres"
android:layout_width="fill_parent"
android:layout_height="50dp"
android:layout_weight="1.0">
<TextView
android:id="#+id/textview_row_parametres"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textColor="#android:color/black"
android:textStyle="bold"
android:textSize="20sp"
android:layout_marginLeft="2dp"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
/>
<ToggleButton
android:id="#+id/togglebutton_row_parametres"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:layout_marginRight="2dp"
android:textOn="#string/togglebutton_on"
android:textOff="#string/togglebutton_off" />
</RelativeLayout>
</TableRow>
Activity Layout :
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical">
<ImageView style="#style/header" />
<LinearLayout
android:layout_width="fill_parent" android:layout_height="0dp"
android:layout_weight="0.8"
android:background="#drawable/gradient_bg"
android:padding="10dip"
android:orientation="vertical">
<ScrollView
android:layout_width="fill_parent" android:layout_height="0dp"
android:layout_weight="0.85"
android:fillViewport="true"
android:padding="10dip"
android:layout_gravity="center">
<TableLayout
android:id="#+id/tablelayout_parametres"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#drawable/cornered_bg"
android:paddingTop="5dip"
android:paddingBottom="5dip">
</TableLayout>
</ScrollView>
<Button
android:id="#+id/button_parametres_accept"
android:gravity="center"
android:text="#string/accept_changes"
android:layout_width="wrap_content"
android:layout_height="0dp"
android:layout_weight="0.15"
android:layout_gravity="center_horizontal" />
</LinearLayout>
</LinearLayout>
And the activity code:
public class Parameters extends Activity {
#Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
}
#Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final Map<String, Boolean> changes = new HashMap<String, Boolean>();
final Context ctx = getApplicationContext();
LanguageManager.updateConfig(this);
setContentView(R.layout.parametres);
CountryDB[] countries = Database.instance(getApplicationContext()).getCountries();
TableLayout tabLayout = (TableLayout) findViewById(R.id.tablelayout_parametres);
for(int i =0; i<countries.length; i++){
TableRow newRow = (TableRow) getLayoutInflater().inflate(R.layout.row_parametres, null);
TextView textView = (TextView) newRow.findViewById(R.id.textview_row_parametres);
ToggleButton toggleButton = (ToggleButton) newRow.findViewById(R.id.togglebutton_row_parametres);
toggleButton.setChecked(countries[i].isToSynchronize());
toggleButton.setTag(countries[i]);
Log.e("setChecked",""+toggleButton.getId()+"/"+countries[i].isToSynchronize());
textView.setText(countries[i].getLabel());
toggleButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
CountryDB countryTemp = (CountryDB) v.getTag();
changes.put(countryTemp.getLabel(), ((ToggleButton)v).isChecked());
}
});
tabLayout.addView(newRow);
TableRow rowDivider = (TableRow) getLayoutInflater().inflate(R.layout.row_divider, null);
tabLayout.addView(rowDivider);
}
Button buttonValidation = (Button) findViewById(R.id.button_parameters_accept);
buttonValidation.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Iterator<String> iterator = changes.keySet().iterator();
while(iterator.hasNext()){
String stringTemp = iterator.next();
Database.instance(ctx).updateCountry(stringTemp, changes.get(stringTemp));
}
Intent intent = new Intent(ctx, Splash.class);
String result = "restart";
String from = "parameters";
Intent returnIntent = new Intent();
returnIntent.putExtra("result", result);
returnIntent.putExtra("from", from);
setResult(RESULT_OK, returnIntent);
startActivity(intent);
}
});
}
}
In the Log.e, I print the values, and they are good, the display on togglebuttons is wrong, they are just all "false".
Thanks for your help.

Between onCreate() and onResume() , Android tries to restore the old state of the toggle Buttons. Since they don't have unique ID's , Android wont succeed and everything is false again. Try to move your setChecked() calls into onResume() ( maybe onStart() works too).
Here is a pretty good answer to the same Question:
ToggleButton change state on orientation changed

you have to save data before Orientation.
Android have method onSaveImstamceState(Bundle outState) and onRestoreInstanceState(BundleInstaceState)
override these method in Activity.

There's a simpler solution: you only need to add configChanges property to your activity declaration, like stated here. This way you can prevent Activity restart when orientation changes. So in your manifest you should have something like
<activity android:name=".Parameters"
android:configChanges="orientation|keyboardHidden">
or if your buildTarget>=13
<activity android:name=".Parameters"
android:configChanges="orientation|keyboardHidden|screenSize">
Edit: Like reported on comments below, this is not an optimal solution. The main drawback is reported in a note of the document linked above:
Note: Handling the configuration change yourself can make it much more difficult to use alternative resources, because the system does not automatically apply them for you. This technique should be considered a last resort when you must avoid restarts due to a configuration change and is not recommended for most applications.

View over Canvas Visibility issue

I have this layout:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<com.components.game.GameView
android:id="#+id/game_id"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
<RelativeLayout
android:id="#+id/ChatLayout"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:visibility="invisible"
android:focusable="true"
android:focusableInTouchMode="true" >
<Button
android:id="#+id/ChatCancelButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="X" />
<Button
android:id="#+id/ChatOkButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:text="OK" />
<EditText
android:id="#+id/ChatEditText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toLeftOf="#+id/ChatOkButton"
android:layout_toRightOf="#+id/ChatCancelButton"
android:maxLength="50"
android:singleLine="true" />
</RelativeLayout>
</RelativeLayout>
It's a RelativeLayout over a canvas. At start time it's invisible but when a user clicks a button the layout should become visible.
The problem is that it's not becoming visible. The layout is there but it's just not drawing it. If I press the position where the layout should appear it receives the event and opens the keyboard but it's not drawing the whole layout.
What is the problem?
If I set the RelativeLayout to visible at the beginning it works fine. it shows the layout and if I toggle between invisible and visible it works fine.
I made a workaround that almost always works.
I start the layout visible and than do that in the oncreate:
chatLayout.postDelayed(new Runnable() {
#Override
public void run() {
chatLayout.setVisibility(View.INVISIBLE);
}
}, 50);
But I don't like it and want to understand what's the problem.
The code:
It starts from a canvas button which send a message to a handler:
public void showInputLayout() {
Message.obtain(gameHandler, SHOW_INPUT_LAYOUT).sendToTarget();
}
In the handler:
case SHOW_INPUT_LAYOUT:
gameActivity.setChatVisibility(true);
break;
setChatVisibility:
public void setChatVisibility(boolean isVisible) {
int visible = isVisible ? View.VISIBLE : View.INVISIBLE;
chatLayout.setVisibility(visible);
if(isVisible){
chatEditText.setFocusable(true);
chatEditText.requestFocus();
}
}

Add a click listener to RelativeLayout and switch the visibility between GONE and VISIBLE. Try something like this:
int visibility = View.VISIBLE;
RelativeLayout layout = (RelativeLayout)findViewById(R.id.ChatLayout);
layout.setVisibility(visibility);
layout.setOnClickListener(new View.OnClickListener{
public void onClick(View v)
{
if(visibility == View.VISIBLE)
visibility = View.GONE;
else
visibility = View.VISIBLE;
v.setVisibility(visibility);
}
})

I ran into a similar issue recently, and for my case the problem was actually in the onDraw() method of the view underneath (should be com.components.game.GameView in your case). See if you can add calls to Canvas' getSaveCount(), save() and restoreToCount() in your drawing code, similar to this:
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int saveCount = canvas.getSaveCount();
canvas.save();
// custom drawing code here ...
// use Region.Op.INTERSECT for adding clipping regions
canvas.restoreToCount(saveCount);
}
I believe what happened was that sometimes the framework set the clipping regions for the elements on top of our Canvas-drawing widget before our onDraw() method is called so we need to make sure that those regions are preserved.
Hope this helps.