From a simplistic overview I have a custom View that contains some bitmaps the user can drag around and resize.
The way I do this is fairly standard as in I override onTouchEvent in my CustomView and check if the user is touching within an image, etc.
My problem comes when I want to place this CustomView in a ScrollView. This works, but the ScrollView and the CustomView seem to compete for MotionEvents, i.e. when I try to drag an image it either moves sluggishly or the view scrolls.
I'm thinking I may have to extend a ScrollView so I can override onInterceptTouchEvent and let it know if the user is within the bounds of an image not to try and scroll. But then because the ScrollView is higher up in the hierarchy how would I get access to the CustomView's current state?
Is there a better way?
Normally Android uses a long press to begin a drag in cases like these since it helps disambiguate when the user intends to drag an item vs. scroll the item's container. But if you have an unambiguous signal when the user begins dragging an item, try getParent().requestDisallowInterceptTouchEvent(true) from the custom view when you know the user is beginning a drag. (Docs for this method here.) This will prevent the ScrollView from intercepting touch events until the end of the current gesture.
None of the solutions found worked "out of the box" for me, probably because my custom view extends View, not ViewGroup, and thus I can't implement onInterceptTouchEvent.
Also calling getParent().requestDisallowInterceptTouchEvent(true) was throwing NPE, or doing nothing at all.
Finally this is how I solved the problem:
Inside your custom onTouchEvent call requestDisallow... when your view will take care of the event. For example:
#Override
public boolean onTouchEvent(MotionEvent event) {
Point pt = new Point( (int)event.getX(), (int)event.getY() );
if (event.getAction() == MotionEvent.ACTION_DOWN) {
if (/*this is an interesting event my View will handle*/) {
// here is the fix! now without NPE
if (getParent() != null) {
getParent().requestDisallowInterceptTouchEvent(true);
}
clicked_on_image = true;
}
} else if (event.getAction() == MotionEvent.ACTION_MOVE) {
if (clicked_on_image) {
//do stuff, drag the image or whatever
}
} else if (event.getAction() == MotionEvent.ACTION_UP) {
clicked_on_image = false;
}
return true;
}
Now my custom view works fine, handling some events and letting scrollView catch the ones we don't care about. Found the solution here: http://android-devblog.blogspot.com.es/2011/01/scrolling-inside-scrollview.html
Hope it helps.
There is an Android event called MotionEvent.ACTION_CANCEL (value = 3). All I do is override my custom control's onTouchEvent method and capture this value. If I detect this condition then I respond accordingly.
Here is some code:
#Override
public boolean onTouchEvent(MotionEvent event) {
if(isTouchable) {
int maskedAction = event.getActionMasked();
if (maskedAction == MotionEvent.ACTION_DOWN) {
this.setTextColor(resources.getColor(R.color.octane_orange));
initialClick = event.getX();
} else if (maskedAction == MotionEvent.ACTION_UP) {
this.setTextColor(defaultTextColor);
endingClick = event.getX();
checkIfSwipeOrClick(initialClick, endingClick, range);
} else if(maskedAction == MotionEvent.ACTION_CANCEL)
this.setTextColor(defaultTextColor);
}
return true;
}
Related
Is it possible to know in a ListView if a item is pressed / touched (but not clicked) and know which?
I tried with "OnTouchListener" but without success (I can intercept UP and Down events on the ListView but not on the elements).
I tried also "OnItemLongClickListener" but I have to wait when I want information immediately.
Do you have an idea ?
Thank you in advance.
Edit (solution) :
I put the following code in my adapter in the item view.
view.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
image.setImageResource(R.drawable.image2);
}
else if (event.getAction() == MotionEvent.ACTION_UP) {
image.setImageResource(R.drawable.image1);
}
return true;
}
});
And now, when I touch an item, the picture becomes "image2" and when I do not touch the screen, it returns to "image1".
But there is a problem, if I press an item (the image2 appears well) and I move my finger in the list view and I do not touch the screen, it stays on for the image2, "MotionEvent.ACTION_UP" could not execute.
Do you have any idea how to do that as soon as I do not touch the screen, it must return on image1?
Thank you for your help.
You can set SetOnTouchListener to item view when your adapter create it.
you just try yo implement the Listener then you can override the function or please add your rough work part
I'm using an on touch listener to display and hide some volume controls, on ACTION_DOWN the controls are displayed and on ACTION_UP they are hidden. I want to be able to touch the controls without lifting my finger, I tried using the ACTION_MOVE motion and was unable to get it to work as the event is never triggered. I thought about drag event but I am unsure if it would be appropriate for this.
public boolean onTouch(View v, MotionEvent e)
{
if(v == audioControls)
{
if(e.getAction() == MotionEvent.ACTION_DOWN)
showVolumeControls();
else if(e.getAction() == MotionEvent.ACTION_UP)
hideVolumeControls();
}
else if(e.getAction() == MotionEvent.ACTION_MOVE)
{
if(v == mute)
//Do stuff with this volume control
}
return true;
}
#Demand answer, read my comment - here is the code:
public boolean onTouch(View v, MotionEvent e)
{
if(v == mute && e.getAction() == MotionEvent.ACTION_MOVE)
{
Toast.makeText(getApplicationContext(), "Muted.", Toast.LENGTH_SHORT).show();
hideVolumeControls();
return true;
}
else
return false;
}
So, you need to uderstand how android touch events work. If you touch down on View1, set onTouchListener for that view and return true for that event - other view will never get motion events from same chain.
For you it's mean that if you touch down on "audioControls" then no other views can catch motion events until you release your finger.
You can return false in your onTouch method. In this case parentView for audioControls will also catch all motionEvents. But views, which is not parent for audioControls in the view hierarchy will not catch motionEvent.
You need to catch all motion events in the container for your views and dispatch them for your self. This is the only way to catch motionEvents from one chain in defferent views.
UPDATE:
I will try to explain a little bit more.
Imagine you have layout like this:
<LinearLayout id="#+id/container">
<View id="#+id/view1"/>
<View id="#+id/view2"/>
</LinearLayout>
And you want to touch down on view1 and move your finger to view2. Android touch event flow can't do this. Only one view can catch whole event chain.
So you need to add onTouchListener to your container and do something like this.
public boolean onTouch(MotionEvent event) {
float x = event.getX();
float y = event.getY();
for (int i = 0; i<container.getChildCount(); i++) {
View child = container.getChildAt(i);
if (x>child.getLeft() && x < child.getRight() && y < child.getBottom() && y > child.getTop()) {
/*do whatever you want with this view. Child will be view1 or view2, depends on coords;*/
break;
}
}
}
Please note, I wrote this code right there and could make some mistake. I've tried to show the idea.
I'm not sure if this is a device issue or an issue with my code but I created a simple draggable sortable list using a relative layout and image views. I have very specific reasons for doing it this way and that is not my question.
The problem I'm having is occasionally it will totally freeze my app. The item will get stuck in the dragging state. If I lift my finger the shadow (dragging) object is still on the screen and if I touch the screen it will move to that spot. This will go on for about a minute and then I will get an error saying the app is non responsive with the option to kill it or wait. The only useful bit in the logcat is as follows:
12-09 14:23:13.157: W/WindowManager(16415): Drag is in progress but there is no drag window handle.
Then when the app times out I get this as an error
12-09 14:59:09.782: E/ActivityManager(16415): ANR in com.appname.appname (com.appname.appname/.MainActivity)
12-09 14:59:09.782: E/ActivityManager(16415): Reason: keyDispatchingTimedOut
I googled this error message and the only info was someone with no drag listener and another person saying it was the device touch sensor not keeping up.
Ideally, I'd love to fix this error and prevent it from happening in the first place. It does seem to happen mostly if I drag quickly, but I can't very well ask my users not to drag quickly... right?
Alternatively, is there a way that I could detect that dragging has frozen the app and interrupt the drag. Like set a timer on the touch listener and if there are no drag_location messages within like a second or two interrupt the drag? The timer stuff I know how to do, but I don't know how I would force the drag to stop while it's frozen. Any ideas?
Here's the code:
setup
//happens once when the app loads
RelativeLayout trackList = (RelativeLayout) findViewById(R.id.nsTrackList1);
trackList.setOnDragListener(new MyTrackDragListener(this));
//happens in a loop for each "track" (image view)
trackButton = new ImageView(this);
trackButton.setImageDrawable(nsPackages[trackId].banner[bannerSizeSelector]);
trackButton.setOnTouchListener(new MyTrackTouchListener());
On touch
public class MyTrackTouchListener implements OnTouchListener {
boolean isDragging=false;
float prevX, prevY;
public boolean onTouch(View view, MotionEvent motionEvent) {
if(motionEvent.getPointerCount() < 2 && !isDragging) return false;
if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
isDragging=false;
prevX=0;
prevY=0;
return true;
} else if (motionEvent.getAction() == MotionEvent.ACTION_MOVE) {
if(isDragging) return true;
boolean wasFirst = (prevX == 0 || prevY == 0);
float theTotalDiff = Math.abs(prevX - motionEvent.getX()) + Math.abs(prevY - motionEvent.getY());
prevX=motionEvent.getX();
prevY=motionEvent.getY();
if(wasFirst) return true;
if(theTotalDiff <3) return true;
ClipData data = ClipData.newPlainText("", "");
DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
view.startDrag(data, shadowBuilder, view, 0);
int thisViewId = view.getId();
//hide view
view.setVisibility(View.GONE);
isDragging=true;
return true;
} else if (motionEvent.getAction() == MotionEvent.ACTION_UP || motionEvent.getAction() == MotionEvent.ACTION_CANCEL) {
isDragging=false;
return true;
}else {
Integer thisAction = motionEvent.getAction();
Log.d("looper","Motion action: "+thisAction.toString());
return false;
}
}
}
On Drag
class MyTrackDragListener implements OnDragListener {
public static boolean isDragging=false;
private MainActivity parent;
public MyTrackDragListener(MainActivity myAct){
parent=myAct;
}
#Override
public boolean onDrag(View v, DragEvent event) {
int action = event.getAction();
switch (event.getAction()) {
case DragEvent.ACTION_DRAG_STARTED:
isDragging=true;
// do nothing
return true;
case DragEvent.ACTION_DROP:
View view = (View) event.getLocalState();
parent.doDropSort(view,(int) event.getY());
return true;
case DragEvent.ACTION_DRAG_ENDED:
if(isDragging && event.getResult()==false){
View view2 = (View) event.getLocalState();
parent.doDropSort(view2,(int) event.getY(),true);
return true;
}
isDragging=false;
break;
case DragEvent.ACTION_DRAG_LOCATION:
parent.doDragHover((int) event.getY());
return true;
default:
Log.d("looper","drag other... "+String.valueOf(event.getAction()));
}
return false;
}
}
A few things I already tried
Removing the drag listener entirely
Always return true from onDrag
Always return false from onDrag
Basically every combination of return true/false in drag and touch
Removing the 2 finger and Action_Move part and triggering drag on Action_down instead
Same results. Drag and drop works perfectly about 70% of the time and then suddenly does the freezing behavior described above. Sometimes it's on the very first drag sometimes it's after several. I've noticed on consistent pattern except possibly drag speed. It seems to USUALLY happen when I'm dragging quickly, but drag direction or where I drag to doesn't seem to matter.
YAY! I Figured it out. Here's the answer incase it helps someone in the future.
I finally narrowed it down to only the top list item (don't know how I missed that) and then started commenting out lines until it didn't break which narrowed it down to this line:
view.setVisibility(View.GONE);
The way my list was set up each item used the Layout Property BELOW in a relative layout (except the top item). Once I removed the top item from the view the 2nd to top item was below an item which was visibility GONE so it didn't know what to do. The solution was to set the parameter of the next item in the view. Luckily I manually set the view IDs of my track buttons (there are other views that scroll too.. labels and such) so they are sequential. So my fix was simply finding the item with id+1 and making it become the top item by setting BELOW to zero like this...
// the top item in my list is ALWAYS view id 1
if(thisViewId == 1){
ImageView nextTrackButton = (ImageView) trackList.findViewById(thisViewId+1);
LayoutParams ntLP = (LayoutParams) nextTrackButton.getLayoutParams();
ntLP.addRule(RelativeLayout.BELOW,0);
nextTrackButton.setLayoutParams(ntLP);
}
//hide view
view.setVisibility(View.GONE);
I have a custom view which I call "Node" that is a child of a custom ViewGroup called "NodeGrid". The "NodeGrid" class more specifically extends RelativeLayout.
I have the following code snippet in my custom view class ("Node"):
private boolean isBeingDragged = false;
#Override
public boolean onTouchEvent(MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN)
{
isBeingDragged = true;
}
else if (event.getAction() == MotionEvent.ACTION_UP)
{
isBeingDragged = false;
}
else if (event.getAction() == MotionEvent.ACTION_MOVE)
{
if (isBeingDragged)
{
float xPosition = event.getX();
float yPosition = event.getY();
//change the x and y position here
}
}
return false;
}
The problem:
After having set breakpoints in this code, it seems like onTouchEvent is getting called only for the MotionEvent.ACTION_DOWN case, but not for either of the other two cases ("action up" or "action move"). Does anyone know of anything off hand that could be causing this to happen?
Also (could be related):
Does it matter how the view is added to the ViewGroup? I noticed that in addition to "addView" there are other methods for adding children to a ViewGroup such as "addFocusables" and "addTouchables". Right now I am simply adding the child view to the ViewGroup using "addView".
From the SDK Documentation:
onTouch() - This returns a boolean to indicate whether your listener consumes this event. The important thing is that this event can have multiple actions that follow each other. So, if you return false when the down action event is received, you indicate that you have not consumed the event and are also not interested in subsequent actions from this event. Thus, you will not be called for any other actions within the event, such as a finger gesture, or the eventual up action event.
You need to return true when the ACTION_DOWN event is triggered to indicate that you are interested in the subsequent calls relating to that same event.
HTH
Problem description:
I have a TextView on a RelativeLayout and I want to color it red when the user touches it, and go on another page when he clicks on it.
So I tried to set an OnClickListener to do the click, and an OnTouchListener to implement the touch function (MotionEvent.ACTION_DOWN) but this combination doesn't work, because OnTouchListener makes OnClickListener non-functional (don't know why).
On forums people say that we can implement the OnClick by the OnTouch MotionEvent.ACTION_UP, but this one can be triggered out of my TextView layout (the TextView gonna be clicked if you press it and drag your finger out of him to release) and this is not the desired behavior because I want:
click = press + release on the TextView.
Can someone give me a solution for this please?
you may call View.performClick() when action_up. Hope it helps.
your_txtView.setOnClickListener(new TextView.OnClickListener(){
public void onClick(View v) {
// TODO Auto-generated method stub
}
});
your_txtView.setOnTouchListener(new TextView.OnTouchListener(){
#Override
public boolean onTouch(View v, MotionEvent event) {
if (MotionEvent.ACTION_DOWN == event.getAction()) {
} else if (MotionEvent.ACTION_UP == event.getAction()) {
v.performClick();
}
return true;
}
});
Adel, is the problem with the first click, or you don't get any click at all?
There is this issue if you have multiple clickable layout you don't get any click events for the first. That's because it makes it first selected and then you get the click event, try the below code.
private class CustomTouchListener implements OnTouchListener {
#Override
public boolean onTouch(View v, MotionEvent event) {
TextView tv = (TextView) v.findViewById(R.id.single_line_text);
if (event.getAction() == MotionEvent.ACTION_DOWN) {
tv.setTextColor(COLOR_WHEN_PRESSED);
} else if (event.getAction() == MotionEvent.ACTION_UP) {
tv.setTextColor(COLOR_WHEN_RELEASED);
// Action of click goes here
} else if (event.getAction() == MotionEvent.ACTION_CANCEL) {
tv.setTextColor(COLOR_WHEN_RELEASED);
// To handle release outside the layout region
}
return false;
}
}
This is working in my current implementation if you set the touch listener for your layout.
You also need to set below on your layout
android:focusable="true"
android:focusableInTouchMode="true"
android:clickable="true"
Hope it helps!!!
EDIT: Additionally, there should be a flag in both DOWN and UP. Set it in DOWN and check if its set in UP. This will avoid a bug where user might tap anywhere in the screen and then hover on your textview and release it.
Had the same problem. Solved it by returning false from ACTION_MOVE. I've been fighting with it for few hours, trying various things, but seems like i've kept overlooking this little issue... And now it makes sense. When you return true from onTouch, futher processing is stopped, so that OnClickListener is not aware of any movements and triggers onClick even after pointer have moved outside of view.