Develop Reference

RecyclerView get height of first visible item

How can i calculate the height of the first visible item in my recyclerview ?
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
switch (newState) {
case RecyclerView.SCROLL_STATE_IDLE:
Log.d("scroll_stop","The RecyclerView is not scrolling : ");
View firstItemView = mGLM.findViewByPosition(mGLM.findFirstVisibleItemPosition());
View mVizibleView= mPlm.findViewByPosition(mGLM.findFirstVisibleItemPosition());
}
});
But this give me the full height of the view

Taking the Size of any RecyclerView Item is pointless, If you getHeight() or getWidth() of any item it's just gonna give a Null Error and your app is gonna crash.
What you can do, Is to Use your ViewHolder from recyclerView Adapter and First set a Specific Height to any Item you want and Then use that Height somewhere Else.
Look at the Code Below, Maybe helps:
class myViewHolder extends RecyclerView.ViewHolder {
RemaltiveLayout itemLayout;
public myViewHolder(View itemView) {
super(itemView);
itemLayout = (RemaltiveLayout) itemView.findViewById(R.id.myItemLayout);
itemLayout.getLayoutParams().height = res.getDimensionPixelSize(R.dimen.height_value);
}
You should be able to use item at a specific location position as well
This is not gonna work with Width though, cause items are always being stretched to fill columns of layoutManager

Steps to get first item height:
Get the layout manager from the recyclerview reference in onScrolled()
Get the first the visible item position using layoutManager.findFirstVisibleItemPosition()
If fist visible item position is 0 then get the 0th child height layoutManager.getChildAt(0)
Sample code:
RecyclerView.OnScrollListener scrollListener = new RecyclerView.OnScrollListener() {
#Override
public void onScrolled(#NonNull RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
LinearLayoutManager layoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
if (layoutManager != null) {
int child0Height = 0;
int currentFirstVisibleItem = layoutManager.findFirstVisibleItemPosition();
if (currentFirstVisibleItem == 0) {
final View childAt0 = layoutManager.getChildAt(0);
if (childAt0 != null) {
child0Height = childAt0.getHeight();
}
}
}
}
};

How to restrict ItemtouchHelper to swipe only left to right

Hi I am using recycler view and apply ITEMTOUCHHELPER its working.
I apply Logic (direction == ItemTouchHelper.LEFT) then delete item.
All of these things work correctly.
But when I swipe right side and then swipe left side. It give dX value >0.which means swiping done on right side.
If I delete an item no issue If I leave it as it is and swipe again then this strange behavior start.
When I swipe multiple times from left side then it gives dX<0 means then it starts again working.
Here is my Implementation
private void initSwipe(){
ItemTouchHelper.SimpleCallback simpleItemTouchCallback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
#Override
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
return false;
}
#Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
int position = viewHolder.getAdapterPosition();
if (direction == ItemTouchHelper.LEFT){
Cursor cursor = ((BookRecyclerAdapter)recyclerView.getAdapter()).getCursor();
cursor.moveToPosition(position);
int pageNo = cursor.getInt(cursor.getColumnIndex(BookMarkContract.AddsEntry.COLUMN_NAME_PAGE_NO));
dbHelper.deletePageNo(pageNo);
bookRecyclerAdapter.swapCursor(dbHelper.getAllBookMarks());
bookRecyclerAdapter.notifyItemRemoved(position);
bookRecyclerAdapter.notifyDataSetChanged();
}
else
return;
}
#Override
public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {
Bitmap icon;
Log.d("dX",""+dX);
if(actionState == ItemTouchHelper.ACTION_STATE_SWIPE){
if(dX>0)
{
dX=0;
}
View itemView = viewHolder.itemView;
float height = (float) itemView.getBottom() - (float) itemView.getTop();
float width = height / 3;
if(dX>0)
return;
else {
p.setColor(Color.parseColor("#D32F2F"));
RectF background = new RectF((float) itemView.getRight() + dX, (float) itemView.getTop(), (float) itemView.getRight(), (float) itemView.getBottom());
c.drawRect(background, p);
icon = BitmapFactory.decodeResource(getResources(), R.drawable.ic_rub);
RectF icon_dest = new RectF((float) itemView.getRight() - 2 * width, (float) itemView.getTop() + width, (float) itemView.getRight() - width, (float) itemView.getBottom() - width);
c.drawBitmap(icon, null, icon_dest, p);
}
}
super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
}
};
ItemTouchHelper itemTouchHelper = new ItemTouchHelper(simpleItemTouchCallback);
itemTouchHelper.attachToRecyclerView(recyclerView);
}
Here is my log cat Snippet of when i Swipping left but it gives me dX >0
PROBLEM IN ONE LINE
SWIPPING LEFT SIDE GIVES dX >0
QUESTION
Why I am getting this strange behavior ? it feels like an app is hanging
But it is not hanging it is swiping right side even When I swipe LEFT.

If you only want to allow leftswipe, this is your solution:
#Override
public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
//int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
int swipeFlags = ItemTouchHelper.START;
return makeMovementFlags(dragFlags, swipeFlags);
}

Here is what I think it is a more cleaner and simpler solution.
When you extend ItemTouchHelper.SimpleCallback in order to get the custom behavior, you should pass the directions for your items to be swiped or dragged, you don't need to override getMovementFlags since this method uses the drag and swipe directions we are about to pass. For example:
public class RecyclerItemTouchHelper extends ItemTouchHelper.SimpleCallback {
public RecyclerItemTouchHelper(int dragDirs, int swipeDirs) {
super(dragDirs, swipeDirs);
}
// ...
}
Now, in your activity or fragment, when you setup your recycler view you can specify the swiping and dragging behavior like this:
// 0 means no dragging at all and the 2nd parameters means only swipe left is allowed
RecyclerItemTouchHelper helper = new RecyclerItemTouchHelper(0, ItemTouchHelper.LEFT);
new ItemTouchHelper(helper).attachToRecyclerView(yourRecyclerView);
Now you can configure your dragging and swiping however you want. I hope it helps!
For more information you can take a look at the official documentation, there's pretty much the exact example you need:
https://developer.android.com/reference/android/support/v7/widget/helper/ItemTouchHelper.SimpleCallback

How to access the LayoutManager from the RecyclerView's ItemDecoration class?

I haven't been able to find any post about it...
We have the good old RecyclerView.ItemDecoration code (taken from Suleiman's Mansonry Github project):
public class SpacesItemDecoration extends RecyclerView.ItemDecoration {
private final int mSpace;
public SpacesItemDecoration(int space) {
this.mSpace = space;
}
#Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
outRect.left = mSpace;
outRect.right = mSpace;
outRect.bottom = mSpace;
// Add top margin only for the first item to avoid double space between items
if (parent.getChildAdapterPosition(view) == 0)
outRect.top = mSpace;
}
}
I want to have a condition that sets mSpace (offset/margin) depending on the current LayoutManager in the RecyclerView.
For example:
if(/* LayoutManager is LinearLayoutManager*/){
//Set larger margin
}else{
//Set lower margin
}

So... as I was re-reading the question to check if anything was missing, and I realized that you actually get a RecyclerView reference (parent) as an argument of getItemOffsets().
So you can just call parent.getLayoutManager() from inside the function.
Example:
#Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
if (parent.getLayoutManager() instanceof LinearLayoutManager){
margin = 2;
}else if (parent.getLayoutManager() instanceof StaggeredGridLayoutManager){
margin = 1;
}else{
margin = 0;
}
//Do magic
}

Measure height of multi-line TextView before rendering

What i've tried to far:
Calling measure()
tv.measure(0, 0);
int height = tv.getMeasuredHeight();
Calling measure() with specified sizes/modes
int widthMeasureSpec = View.MeasureSpec.makeMeasureSpec(99999, View.MeasureSpec.AT_MOST);
int heightMeasureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
tv.measure(widthMeasureSpec, heightMeasureSpec);
int height = tv.getMeasuredHeight();
Calling getTextBounds()
Rect bounds = new Rect();
tv.getPaint().getTextBounds(tv.getText().toString(), 0, tv.getText().length(), bounds);
int height = bounds.height();
Calling measure() and then calling getTextBounds()
Calling getLineCount() * getLineHeight()
None seem to work. They all return incorrect values (container view gets incorrect height - it's either too small or too large)
Ideas on how to calculate this simple thing??

You need to specify the available width so the height can be properly calculated.
Note: In cases where you just need to get the height of a view that is already drawn, use ViewTreeObserver. See this question for a thing to consider in that case.
This is why I do, in a piece of code where I want to scale a view from hidden to its full necessary height:
int availableWidth = getParentWidth(viewToScale);
int widthSpec = View.MeasureSpec.makeMeasureSpec(availableWidth, View.MeasureSpec.AT_MOST);
int heightSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
viewToScale.measure(widthSpec, heightSpec);
int measuredHeight = viewToScale.getMeasuredHeight();
// Offtopic: Now I animate the height from 1 to measuredHeight (0 doesn't work)
You may pass the availableWidth yourself, but I calculate it from the parent:
private int getParentWidth(View viewToScale)
{
final ViewParent parent = viewToScale.getParent();
if (parent instanceof View) {
final int parentWidth = ((View) parent).getWidth();
if (parentWidth > 0) {
return parentWidth;
}
}
throw new IllegalStateException("View to scale must have parent with measured width");
}

Where are you calling those methods?
The best way to do what you are trying to do is to use ViewTreeObserver and add onPreDrawListener.
Take a look at this i think it will help

What you can do here is get ViewTreeObserver associated with this TextView and add OnGlobalLayoutListener to it:
final ViewTreeObserver vto = textView.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
// textView dimensions are calculated at this stage, but textView
// isn't rendered yet. Do what you need to do and remove OnGlobalLayoutListener
// after
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
textView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
} else {
textView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
}
}
}

I had a similar problem recently, trying to measure the height of a ViewGroup containing several multiline TextView.
What worked for me was to measure() the TextView, then add (lineCount-1)*lineHeight to its measuredHeight.
Here is the code to measure only one TextView :
private int getMeasuredHeight(TextView textView) {
textView.measure(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
int height = textView.getMeasuredHeight();
height += (textView.getLineCount()-1) * textView.getLineHeight();
return height;
}
And in the case of a ViewGroup with many TextViews, here is my code :
private int getMeasuredHeight(ViewGroup viewGroup) {
viewGroup.measure(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
int height = viewGroup.getMeasuredHeight();
for(TextView textView : findAllTextView(viewGroup)) {
height += (textView.getLineCount()-1) * textView.getLineHeight();
}
return height;
}
private List<TextView> findAllTextView(ViewGroup v) {
List<TextView> result = new ArrayList<>();
for (int i = 0; i < v.getChildCount(); i++) {
Object child = v.getChildAt(i);
if (child instanceof TextView)
result.add((TextView) child);
else if (child instanceof ViewGroup)
for(TextView tv: findAllTextView((ViewGroup) child))
result.add(tv);
}
return result;
}

Android RecyclerView smooth scroll to view that's animating their height

I have a RecyclerView with Expandable Child Views, when the child ViewGroup is clicked it inflates an amount of views animating the ViewGroup height from 0 to the measured viewgroup height, like the following gif:
The problem is: I'm calling smoothScrollToPosition on recyclerView, it smooth scroll to the view position, but it considers the current view height, which is still not expanded, in the above gif i'm touching on the under view of the recyclerview, which dont scroll to position because the view is already visible, but when i touch again (calling the smoothscrolltoposition again) it scroll the view to the correct position, because the view is already expanded.
Is there any approach to scroll the view to the top of screen or just scroll to make content visible?
For references:
This is the method called to inflate the views:
collapsible_content.removeAllViews();
for(int i = 0; i < 5; i++) {
View link_view = getLayoutInflater().inflate(R.layout.list_item_timeline_step_link, collapsible_content, false);
TextView text = (TextView) link_view.findViewById(R.id.step_link_text);
text.setText("Test");
collapsible_content.addView(link_view);
}
And this is my method to expand:
public void toggle() {
collapsible_content.measure(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
Animation a;
if (mExpanded) {
a = new ExpandAnimation(collapsible_content.getLayoutParams().height, 0);
} else {
a = new ExpandAnimation(collapsible_content.getLayoutParams().height, getMeasuredHeight());
}
a.setDuration(mAnimationDuration);
collapsible_content.startAnimation(a);
mExpanded = !mExpanded;
}
And the animation:
private class ExpandAnimation extends Animation {
private final int mStartHeight;
private final int mDeltaHeight;
public ExpandAnimation(int startHeight, int endHeight) {
mStartHeight = startHeight;
mDeltaHeight = endHeight - startHeight;
}
#Override
protected void applyTransformation(float interpolatedTime,
Transformation t) {
final int newHeight = (int) (mStartHeight + mDeltaHeight *
interpolatedTime);
collapsible_content getLayoutParams().height = newHeight;
if (newHeight <= 0) {
collapsible_content setVisibility(View.GONE);
} else {
collapsible_content setVisibility(View.VISIBLE);
}
collapsible_content requestLayout();
}
#Override
public boolean willChangeBounds() {
return true;
}
}

My solution was to constant check for view bottom within applyTransformation method, and compare it with RecyclerView height, if the bottom get higher than the RV height, i scroll by the diff values:
final int bottom = collapsible_content.getBottom();
final int listViewHeight = mRecyclerView.getHeight();
if (bottom > listViewHeight) {
final int top = collapsible_content.getTop();
if (top > 0) {
mRecyclerView.smoothScrollBy(0, Math.min(bottom - listViewHeight + mRecyclerView.getPaddingBottom(), top));
}
}
The trick was to use Math.min to get the view top, so it don't scroll up making the top not visible.
Solution based on ListViewAnimations

Add an animationlistener and start the scrolling of the recyclerview after the expanding animation is finished.