Develop Reference

onScrollChange() is not being called for every pixel scrolled on ScrollView

I want to add new child views after every 50 pixels of scrolling but the statement Log.d("scroll",scrollY+":"+oldScrollY); is missing some values i.e. scrollY = 149 and scrollY = 151 are there in Log but scrollY = 150 is missing. So the code doesn't run for scrollY = 150 and new child views is not added.
Although it works as it should for most of the values of scrollY but for few values of scrollY, the event is not being triggered.
How can i resolve this issue? Or is there any other way to achieve this.
public class MainActivity extends AppCompatActivity implements ScrollViewListener {
RelativeLayout parent;
TextView height;
ObservableScrollView scrollView;
int position=1;
View view1,view2;
#RequiresApi(api = Build.VERSION_CODES.M)
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
parent = (RelativeLayout) findViewById(R.id.parent);
scrollView = (ObservableScrollView) findViewById(R.id.scroll_view);
LayoutInflater inflater = LayoutInflater.from(this);
view1 = inflater.inflate(R.layout.education,null, false);
view1.setId(R.id.parent+position);
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
params.addRule(RelativeLayout.LEFT_OF,R.id.divider);
params.topMargin = 100;
params.rightMargin = 3;
parent.addView(view1, params);
position++;
final Animation leftAnimation = new TranslateAnimation(view1.getX()-50,view1.getX(),view1.getY()+100,view1.getY());
leftAnimation.setDuration(1000);
view1.setAnimation(leftAnimation);
scrollView.setOnScrollChangeListener(new View.OnScrollChangeListener() {
#Override
public void onScrollChange(View view, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
Log.d("scroll",scrollY+":"+oldScrollY);
if((scrollY-oldScrollY)>0 && scrollY%50 == 0)
{
Log.d("scroll","abcghfg");
if(position%2==0)
{
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
params.addRule(RelativeLayout.RIGHT_OF,R.id.divider);
// params.topMargin = (position-1)*(view1.getLayoutParams().height)+position*100;
params.topMargin = 30;
params.leftMargin = 3;
params.addRule(RelativeLayout.BELOW,parent.getChildAt(position-1).getId());
Log.d("scroll","abc");
view2 = LayoutInflater.from(MainActivity.this).inflate(R.layout.education,null,false);
view2.setId(R.id.parent+position);
Animation rightAimation = new TranslateAnimation(view2.getX()+50,view2.getX(),view2.getY()+100,view2.getY());
rightAimation.setDuration(1000);
view2.startAnimation(rightAimation);
parent.addView(view2, params);
}
else
{
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
params.addRule(RelativeLayout.LEFT_OF,R.id.divider);
//params.topMargin = (position-1)*(view1.getLayoutParams().height)+position*100;
params.topMargin = 30;
params.rightMargin = 3;
params.addRule(RelativeLayout.BELOW,parent.getChildAt(position-1).getId());
Log.d("scroll","def");
view2 = LayoutInflater.from(MainActivity.this).inflate(R.layout.education,null,false);
view2.setId(R.id.parent+position);
Animation animation = new TranslateAnimation(view2.getX()-50,view2.getX(),view2.getY()+100,view2.getY());
animation.setDuration(1000);
view2.startAnimation(animation);
parent.addView(view2, params);
}
position++;
}
}
});
}
}
Thanks in advance.

Android doesn't render every pixel in a scroll, because it would be bad for performance. If you scroll really slow, you will see that your callback will be called for every pixel, but if you scroll fast, it will be called just when the render triggers.
In your case, you need to check if it rendered 50 or more pixels since last time you rendered the last view.

Android GridLayout only shows last child

I am new to Android Development. I have been working with using a GridLayout to display Dynamically inserted ImageViews.
My issue is located in "onFocusWindowChanged" but I pasted my onCreate where I do my assignments of the images.
private List<Behavior> behaviors = null;
private static int NUM_OF_COLUMNS = 2;
private List<ImageView> images;
private GridLayout grid;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_behaviors);
XMLPullParserHandler parser = new XMLPullParserHandler();
try {
behaviors = parser.parse(getAssets().open("catagories.xml"));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
grid = (GridLayout) findViewById(R.id.behaviorGrid);
images = new ArrayList<ImageView>();
grid.setColumnCount(NUM_OF_COLUMNS);
grid.setRowCount(behaviors.size() / NUM_OF_COLUMNS);
for (Behavior behavior : behaviors)
images.add(this.getImageViewFromName(behavior.getName()));
}
#Override
public void onWindowFocusChanged(boolean hasFocus) {
super.onWindowFocusChanged(hasFocus);
View view = (View) findViewById(R.id.scrollView);
int width = (int) (view.getWidth() * .45);
Log.i("ViewWidth", Integer.toString(width));
GridLayout.LayoutParams lp = new GridLayout.LayoutParams();
lp.height = width;
lp.width = width;
int childCount = images.size();
ImageView image;
for (int i = 0; i < childCount-1; i++) {
image = images.get(i);
image.setLayoutParams(lp);
grid.addView(image);
}
}
In my (short) previous experience, using
grid.add(View);
worked fine, but now I am only seeing the last child display only. Looking through the debugger I can see that the gridview is being populated with more than just the last element, as well as the last imageview.
Thank you for your help

you should create a GridLayout.LayoutParams for each ImageView:
for (int i = 0; i < childCount-1; i++) {
GridLayout.LayoutParams lp = new GridLayout.LayoutParams();
lp.height = width;
lp.width = width;
......
}
GridLayout.LayoutParams contains location information, e.g [column:2, row:3]. In your code, all ImageViews are set the same GridLayout.LayoutParams, so they are located in the same cell(overlapping each other).
When use LinearLayout.LayoutParams instead, there is no location information in it. GridLayout will create a new GridLayout.LayoutParams for each child view, so all ImageViews use their own different GridLayout.LayoutParams and location.
Wish this help. You can read the GridLayout.java and ViewGroup.java for more details.

So I solved my issue, although I'm not sure how-
GridLayout.LayoutParams lp = new GridLayout.LayoutParams();
changed to...
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(x,y);
made it work just as I wanted it. But I'm not sure why- If anyone could explain, please do :)

how to set button in random position when the app start and after click

I've tried this code to change randomly the button position. But i'ts just dimensions, on the first click the button change position but on the other click not. Why?? some help? Thanks
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button btn = (Button) findViewById(R.id.run_button);
RelativeLayout.LayoutParams absParams = (RelativeLayout.LayoutParams) btn
.getLayoutParams();
DisplayMetrics displaymetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
int width = displaymetrics.widthPixels;
int height = displaymetrics.heightPixels;
Random r = new Random();
absParams.width = r.nextInt(width);
absParams.height = r.nextInt(height);
btn.setLayoutParams(absParams);
btn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
Random r = new Random();
btn.getX();
btn.getY();
btn.setX(r.nextFloat());
btn.setY(r.nextFloat());
}
});

I'm pretty sure the touch positions do not change when you call setX() and setY(). They stay at the original spot. You have to actually change the layout parameters so the layout is informed knows that your view is at that spot.
Like so:
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT); //The WRAP_CONTENT parameters can be replaced by an absolute width and height or the FILL_PARENT option)
params.leftMargin = 50; //Your X coordinate
params.topMargin = 60; //Your Y coordinate
childView.setLayoutParams(params);
Taken from: Android - Use of view.setX() and setY in api 8

Adding a view inside a custom view

I am trying to add a progressbar(circular spinner) inside a RelativeLayout. The relativeLayout is visible, however the progressbar doesn't show up. Following is the code I am using but it doesn't seem to work.
public class MyCustomView extends RelativeLayout
{
RelativeLayout rLayout;
ProgressBar mProgressbar;
public void init()
{
mProgressbar = new ProgressBar(mContext, null, android.R.attr.progressBarStyle);
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.addRule(RelativeLayout.CENTER_IN_PARENT);
mProgressbar.setLayoutParams(params);
rLayout = new RelativeLayout(mContext);
rLayout.setBackgroundColor(Color.CYAN);
rLayout.addView(mProgressbar);
addView(rLayout);
}
#Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
if(rLayout != null)
{
rLayout.layout(l, t, r, b);
}
}
}
What am I doing wrong?
EDIT:
I am trying to add a progressbar(circular spinner) inside a RelativeLayout. The relativeLayout is visible, however the progressbar doesn't show up. Following is the code I am using but it doesn't seem to work.
public class MyCustomView extends RelativeLayout
{
ProgressBar mProgressbar;
public void init()
{
mProgressbar = new ProgressBar(mContext, null, android.R.attr.progressBarStyle);
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.addRule(RelativeLayout.CENTER_IN_PARENT);
mProgressbar.setLayoutParams(params);
addView(mProgressbar);
}
}
Progressbar doesn't even show up now?
My Goals:
Showing ProgressBar in the center of the MyCustomView.

Android get programmatically created view's width

I have TextView created programmatically, like that:
TextView mTextView = new TextView(getApplicationContext());
final LayoutParams params = new TableLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
((MarginLayoutParams) params).setMargins(8, 8, 0, 0);
mTextView.setText(mText);
mTextView.setLayoutParams(params);
mTextView.setPadding(2, 2, 2, 2);
mTextView.setBackground(getResources().getDrawable(R.drawable.note_corps));
tagMap.addView(mTextView);
textViewsWidth = mTextView.getWidth();
But mTextView.getWidth() always returns 0
And if I try:
mTextView.getLayoutParams().width
It returns the LayoutParams corresponding value in the LayoutParams class (-1 or -2)
How can I get the view's width ?
EDIT I need to do this here:
#Override
public void onPostExecute(Hashtable<String, Integer> hash){
final ScrollView tagMapScroll = (ScrollView) findViewById(R.id.tagMapScroll);
final LinearLayout tagMap = (LinearLayout) findViewById(R.id.tagMap);
final ArrayList<Integer> arr = new ArrayList<Integer>(hash.values());
final Enumeration<String> e = hash.keys();
int index = 0;
int textViewsWidth = 0;
while(e.hasMoreElements()){
final TextView tV = new TextView(getApplicationContext());
tV.setTextColor(Color.parseColor("#666666"));
tV.setText(Html.fromHtml(randomColor() + e.nextElement()));
tV.setTextSize(arr.get(index));
final LayoutParams params = new TableLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
((MarginLayoutParams) params).setMargins(8, 8, 0, 0);
tV.setLayoutParams(params);
tV.setPadding(2, 2, 2, 2);
tV.setBackground(getResources().getDrawable(R.drawable.note_corps));
tagMap.addView(tV);
textViewsWidth += tV.getWidth();
index++;
}
tagMapScroll.setVisibility(ScrollView.VISIBLE);
}
EDIT SOLUTION I used this from #androiduser's answer:
mTextView.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
int width = mTextView.getMeasuredWidth();
int height = mTextView.getMeasuredHeight();
Problem solved !

I used this solution:
yourView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
// Ensure you call it only once
yourView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
// Here you can get the size :)
}
});

get this way:
tV.post(new Runnable() {
#Override
public void run() {
int width=tV.getMeasuredWidth();
}
});

those values are constant value for FILL_PARENT and WRAP_CONTENT. If you want to check the view size you can try this way:
tagMap.addView(mTextView);
tagMap.post(new Runnable() {
#Override
public void run() {
mTextView. getWidth();
}
});
you have to wait until android draws the TextView. This way you are posting a Runnable in the tagMap queue, that is executed, hopefully after the textview is draw (so it should be weight and height)

In this method you can get the width height of the view..
#Override
public void onWindowFocusChanged(boolean hasFocus) {
super.onWindowFocusChanged(hasFocus);
int width = mTextView.getWidth();
int height = mTextView.getHeight();
}
and define TextView mTextView as global

You have to use ViewTreeObserver class which is used to register listeners that can be notified of global changes in the view tree. Such global events include, but are not limited to, layout of the whole tree, beginning of the drawing pass, touch mode change.
In the Activity's onCreate mehotd put this:
ViewTreeObserver vto = mTextView.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
mTextView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
int viewWidth = mTextView.getMeasuredWidth();
}
});