How to distinguish between move and click in onTouchEvent()?

In my application, I need to handle both move and click events.

A click is a sequence of one ACTION_DOWN action, several ACTION_MOVE actions and one ACTION_UP action. In theory, if you get an ACTION_DOWN event and then an ACTION_UP event - it means that the user has just clicked your View.

But in practice, this sequence doesn't work on some devices. On my Samsung Galaxy Gio I get such sequences when just clicking my View: ACTION_DOWN, several times ACTION_MOVE, then ACTION_UP. I.e. I get some unexpectable OnTouchEvent firings with ACTION_MOVE action code. I never (or almost never) get sequence ACTION_DOWN -> ACTION_UP.

I also cannot use OnClickListener because it does not gives the position of the click. So how can I detect click event and differ it from move?

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It's very difficult for an ACTION_DOWN to occur without an ACTION_MOVE occurring. The slightest twitch of your finger on the screen in a different spot than where the first touch occurred will trigger the MOVE event. Also, I believe a change in finger pressure will also trigger the MOVE event. I would use an if statement in the Action_Move method to try to determine the distance away the move occurred from the original DOWN motion. if the move occurred outside some set radius, your MOVE action would occur. It's probably not the best, resource efficient way to do what your trying but it should work.

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Below code will solve your problem



@Override
public boolean onTouchEvent(MotionEvent event) {
switch(event.getAction()) {
case(MotionEvent.ACTION_DOWN):
x1 = event.getX();
y1 = event.getY();
break;
case(MotionEvent.ACTION_UP): {
x2 = event.getX();
y2 = event.getY();
dx = x2-x1;
dy = y2-y1;


if(Math.abs(dx) > Math.abs(dy))
{
if(dx>0) move(1); //right
else if (dx == 0) move(5); //click
else move(2); //left
}
else
{
if(dy>0) move(3); // down
else if (dy == 0) move(5); //click
else move(4); //up
}
}
}
return true;
}
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最佳答案

Here's another solution that is very simple and doesn't require you to worry about the finger being moved. If you are basing a click as simply the distance moved then how can you differentiate a click and a long click.

You could put more smarts into this and include the distance moved, but i'm yet to come across an instance when the distance a user can move in 200 milliseconds should constitute a move as opposed to a click.

setOnTouchListener(new OnTouchListener() {
private static final int MAX_CLICK_DURATION = 200;
private long startClickTime;


@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN: {
startClickTime = Calendar.getInstance().getTimeInMillis();
break;
}
case MotionEvent.ACTION_UP: {
long clickDuration = Calendar.getInstance().getTimeInMillis() - startClickTime;
if(clickDuration < MAX_CLICK_DURATION) {
//click event has occurred
}
}
}
return true;
}
});
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To get most optimized recognition of click event We have to consider 2 things:

  1. Time difference between ACTION_DOWN and ACTION_UP.
  2. Difference between x's,y's when user touch and when release the finger.

Actually i combine the logic given by Stimsoni and Neethirajan

So here is my solution:

        view.setOnTouchListener(new OnTouchListener() {


private final int MAX_CLICK_DURATION = 400;
private final int MAX_CLICK_DISTANCE = 5;
private long startClickTime;
private float x1;
private float y1;
private float x2;
private float y2;
private float dx;
private float dy;


@Override
public boolean onTouch(View view, MotionEvent event) {
// TODO Auto-generated method stub


switch (event.getAction())
{
case MotionEvent.ACTION_DOWN:
{
startClickTime = Calendar.getInstance().getTimeInMillis();
x1 = event.getX();
y1 = event.getY();
break;
}
case MotionEvent.ACTION_UP:
{
long clickDuration = Calendar.getInstance().getTimeInMillis() - startClickTime;
x2 = event.getX();
y2 = event.getY();
dx = x2-x1;
dy = y2-y1;


if(clickDuration < MAX_CLICK_DURATION && dx < MAX_CLICK_DISTANCE && dy < MAX_CLICK_DISTANCE)
Log.v("","On Item Clicked:: ");


}
}


return  false;
}
});
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I got the best results by taking into account:

  1. Primarily, the distance moved between ACTION_DOWN and ACTION_UP events. I wanted to specify the max allowed distance in density-indepenent pixels rather than pixels, to better support different screens. For example, 15 DP.
  2. Secondarily, the duration between the events. One second seemed good maximum. (Some people "click" quite "thorougly", i.e. slowly; I still want to recognise that.)

Example:

/**
* Max allowed duration for a "click", in milliseconds.
*/
private static final int MAX_CLICK_DURATION = 1000;


/**
* Max allowed distance to move during a "click", in DP.
*/
private static final int MAX_CLICK_DISTANCE = 15;


private long pressStartTime;
private float pressedX;
private float pressedY;


@Override
public boolean onTouchEvent(MotionEvent e) {
switch (e.getAction()) {
case MotionEvent.ACTION_DOWN: {
pressStartTime = System.currentTimeMillis();
pressedX = e.getX();
pressedY = e.getY();
break;
}
case MotionEvent.ACTION_UP: {
long pressDuration = System.currentTimeMillis() - pressStartTime;
if (pressDuration < MAX_CLICK_DURATION && distance(pressedX, pressedY, e.getX(), e.getY()) < MAX_CLICK_DISTANCE) {
// Click event has occurred
}
}
}
}


private static float distance(float x1, float y1, float x2, float y2) {
float dx = x1 - x2;
float dy = y1 - y2;
float distanceInPx = (float) Math.sqrt(dx * dx + dy * dy);
return pxToDp(distanceInPx);
}


private static float pxToDp(float px) {
return px / getResources().getDisplayMetrics().density;
}

The idea here is the same as in Gem's solution, with these differences:

  • This calculates the actual Euclidean distance between the two points.
  • This uses dp instead of px.

Update (2015): also check out Gabriel's fine-tuned version of this.

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Taking Jonik's lead I built a slightly more fine tuned version, that doesn't register as a click if you move your finger and then return to the spot before letting go:

So here is my solution:

/**
* Max allowed duration for a "click", in milliseconds.
*/
private static final int MAX_CLICK_DURATION = 1000;


/**
* Max allowed distance to move during a "click", in DP.
*/
private static final int MAX_CLICK_DISTANCE = 15;


private long pressStartTime;
private float pressedX;
private float pressedY;
private boolean stayedWithinClickDistance;


@Override
public boolean onTouchEvent(MotionEvent e) {
switch (e.getAction()) {
case MotionEvent.ACTION_DOWN: {
pressStartTime = System.currentTimeMillis();
pressedX = e.getX();
pressedY = e.getY();
stayedWithinClickDistance = true;
break;
}
case MotionEvent.ACTION_MOVE: {
if (stayedWithinClickDistance && distance(pressedX, pressedY, e.getX(), e.getY()) > MAX_CLICK_DISTANCE) {
stayedWithinClickDistance = false;
}
break;
}
case MotionEvent.ACTION_UP: {
long pressDuration = System.currentTimeMillis() - pressStartTime;
if (pressDuration < MAX_CLICK_DURATION && stayedWithinClickDistance) {
// Click event has occurred
}
}
}
}


private static float distance(float x1, float y1, float x2, float y2) {
float dx = x1 - x2;
float dy = y1 - y2;
float distanceInPx = (float) Math.sqrt(dx * dx + dy * dy);
return pxToDp(distanceInPx);
}


private static float pxToDp(float px) {
return px / getResources().getDisplayMetrics().density;
}
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If you want to react on click only, use:

if (event.getAction() == MotionEvent.ACTION_UP) {


}
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Use the detector, It works, and it will not raise in case of dragging

Field:

private GestureDetector mTapDetector;

Initialize:

mTapDetector = new GestureDetector(context,new GestureTap());

Inner class:

class GestureTap extends GestureDetector.SimpleOnGestureListener {
@Override
public boolean onDoubleTap(MotionEvent e) {


return true;
}


@Override
public boolean onSingleTapConfirmed(MotionEvent e) {
// TODO: handle tap here
return true;
}
}

onTouch:

@Override
public boolean onTouch(View v, MotionEvent event) {
mTapDetector.onTouchEvent(event);
return true;
}

Enjoy :)

小开

Adding to the above answers ,if you want to implement both onClick and Drag actions then my code below can you guys. Taking some of the help from @Stimsoni :

     // assumed all the variables are declared globally;


public boolean onTouch(View view, MotionEvent event) {


int MAX_CLICK_DURATION = 400;
int MAX_CLICK_DISTANCE = 5;




switch (event.getAction())
{
case MotionEvent.ACTION_DOWN: {
long clickDuration1 = Calendar.getInstance().getTimeInMillis() - startClickTime;




startClickTime = Calendar.getInstance().getTimeInMillis();
x1 = event.getX();
y1 = event.getY();




break;


}
case MotionEvent.ACTION_UP:
{
long clickDuration = Calendar.getInstance().getTimeInMillis() - startClickTime;
x2 = event.getX();
y2 = event.getY();
dx = x2-x1;
dy = y2-y1;


if(clickDuration < MAX_CLICK_DURATION && dx < MAX_CLICK_DISTANCE && dy < MAX_CLICK_DISTANCE) {
Toast.makeText(getApplicationContext(), "item clicked", Toast.LENGTH_SHORT).show();
Log.d("clicked", "On Item Clicked:: ");


//    imageClickAction((ImageView) view,rl);
}


}
case MotionEvent.ACTION_MOVE:


long clickDuration = Calendar.getInstance().getTimeInMillis() - startClickTime;
x2 = event.getX();
y2 = event.getY();
dx = x2-x1;
dy = y2-y1;


if(clickDuration < MAX_CLICK_DURATION && dx < MAX_CLICK_DISTANCE && dy < MAX_CLICK_DISTANCE) {
//Toast.makeText(getApplicationContext(), "item clicked", Toast.LENGTH_SHORT).show();
//  Log.d("clicked", "On Item Clicked:: ");


//    imageClickAction((ImageView) view,rl);
}
else {
ClipData clipData = ClipData.newPlainText("", "");
View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);


//Toast.makeText(getApplicationContext(), "item dragged", Toast.LENGTH_SHORT).show();
view.startDrag(clipData, shadowBuilder, view, 0);
}
break;
}


return  false;
}
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Using Gil SH answer, I improved it by implementing onSingleTapUp() rather than onSingleTapConfirmed(). It is much faster and won't click the view if dragged/moved.

GestureTap:

public class GestureTap extends GestureDetector.SimpleOnGestureListener {
@Override
public boolean onSingleTapUp(MotionEvent e) {
button.performClick();
return true;
}
}

Use it like:

final GestureDetector gestureDetector = new GestureDetector(getApplicationContext(), new GestureTap());
button.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
gestureDetector.onTouchEvent(event);
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
return true;
case MotionEvent.ACTION_UP:
return true;
case MotionEvent.ACTION_MOVE:
return true;
}
return false;
}
});
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Rather than distance / time diff based approaches, You can make use of GestureDetector in combination with setOnTouchListener to achieve this. GestureDetector would detect the click while you can use OnTouchListener for other touch based events, e.g detecting drag.

Here is a sample code for reference:

Class MyCustomView() {


fun addClickAndTouchListener() {
val gestureDetector = GestureDetector(
context,
object : GestureDetector.SimpleOnGestureListener() {
override fun onSingleTapConfirmed(e: MotionEvent?): Boolean {
// Add your onclick logic here
return true
}
}
)


setOnTouchListener { view, event ->
when {
gestureDetector.onTouchEvent(event) -> {
// Your onclick logic would be triggered through SimpleOnGestureListener
return@setOnTouchListener true
}
event.action == MotionEvent.ACTION_DOWN -> {
// Handle touch event
return@setOnTouchListener true
}
event.action == MotionEvent.ACTION_MOVE -> {
// Handle drag
return@setOnTouchListener true
}
event.action == MotionEvent.ACTION_UP -> {
// Handle Drag over
return@setOnTouchListener true
}
else -> return@setOnTouchListener false
}
}


}
}

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