Develop Reference

Android move view to a touched position

I'm trying to develop an android application similar to "on color measurement" or "color grab" which are already on google play.
I have problem with getting the exact position of a view (which acts like focus square) and move it to the position where the user touches the screen. I have done a lot of searches but all of them ended in onTouchEvent() which I used it but it does not work properly or maybe I have done something wrong.
Actually the view moves but it won't be placed exactly where the user touch, it will go below the touched area in y axis with a distance.
here is my code where the mFocusRectangle is the custom view which I want to move to the touched position:
#Override
public boolean onTouchEvent(MotionEvent event) {
int action = event.getAction();
if (event.getPointerCount() > 1) {
// handle multi-touch events
} else {
// handle single touch events
if(action==MotionEvent.ACTION_DOWN){
}
if (action == MotionEvent.ACTION_UP) {
int pointerId = event.getPointerId(0);
int pointerIndex = event.findPointerIndex(pointerId);
// Get the pointer's current position
float x = event.getX(pointerIndex);
float y = event.getY(pointerIndex);
mFocusRectangle.showStart();
mFocusRectangle.setX(x);
mFocusRectangle.setY(y);
}
}
return true;
}
I have also tried MotionEvent.ACTION_DOWN but the result is the same.
Thanks in advance.

try this
float x = event.getX(pointerIndex) - (mFocusRectangle.getWidth() / 2);
float y = event.getY(pointerIndex) - (mFocusRectangle.getHeight() / 2);
credits:
Manitoba - Android move view on touch event

MotionEvent.ACTION_DOWN in Android is too sensitive. This event is received even if the screen is simply touched for a moment

I have a layout(A table layout). Whenever the user performs a "down" gesture, a specific function needs to be called. However,the ontouchlistener captures the event immediately instead of waiting until the user performs a proper "pull down" gesture.
My code is :
homePageTableLayout.setOnTouchListener(new View.OnTouchListener() {
public boolean onTouch(View view, MotionEvent event) {
if ((event.getAction() == MotionEvent.ACTION_DOWN)) {
startSyncData();
}
return true;
}
});
Currently, what's happening is that the startSyncData() function gets called immediately.
The end result should be somewhat similar to the commonly used "pulltorefresh" library for android but in this usecase, I don't have to update the view. I just have to post some data to the server.
I can't use the "pulltorefresh" library because it does not support "pulling" a tablelayout. I tried putting the tablelayout inside a scrollview but that only spoiled the UI.

You can try doing it in ACTION_MOVE or ACTION_UP - if you need it to be done exclusively on swipe down gesture, this should help, introduce four global floats: x, y, x1, y1, then in ACTION_DOWN:
x = event.getX();
y = event.getY();
ACTION_MOVE or ACTION_UP:
x1 = event.getX();
y1 = event.getY();
and then in ACTION_UP:
if (y1 > y) { //pointer moved down (y = 0 is at the top of the screen)
startSyncData();
}

Its not that easy. It works properly since you are catching MotionEvent.ACTION_DOWN. It doesn't mean a gesture like swipe down it means that user touched the screen (finger down, the touch or gesture just started). Now you need to catch MotionEvent.ACTION_UP (finger up, gesture or touch ends here) and decide if there was a gesture you need. http://developer.android.com/training/gestures/detector.html
http://developer.android.com/training/gestures/index.html

MotionEvent.ACTION_MOVE repeatedly gets called. So if you want startSyncData() to run after moving a certain distance, calculate how much you want the user to move before running the method.
The key is that ACTION_DOWN is not a downwards movement on the screen, but it means the user pressed down onto the screen.
homePageTableLayout.setOnTouchListener(new View.OnTouchListener() {
public boolean onTouch(View view, MotionEvent event) {
if ((event.getAction() == MotionEvent.ACTION_DOWN)) {
startFlg = 1;
} else if ((event.getAction() == MotionEvent.ACTION_MOVE)) {
if (startFlg==1){
// Calculate distance moved by using event.getRawX() and event.getRawX() and THEN run your method
startSyncData();
}
}
return true;
}
});

Cancel button press if user moves finger off button

Here is my very standard button onTouchListener:
b.setOnTouchListener(new OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
if ((event.getAction() & MotionEvent.ACTION_MASK) == MotionEvent.ACTION_DOWN) {
b.setPressed(true);
}
if ((event.getAction() & MotionEvent.ACTION_MASK) == MotionEvent.ACTION_UP) {
b.setPressed(false);
// Do the button action stuff here
}
return true;
}
});
When the user presses down on the button I set the button to "pressed". When the user lifts the finger I set the button to "not pressed" and then do the stuff the button is supposed to do.
This is all great except for the case where the user presses the button and then, while continuing to keep the finger down, moves the finger outside of the button area. When the finger is lifted the ACTION_UP stuff runs anyway. I would like for this behavior to act as a "cancel" of the button press. So, as soon as the pressed finger moves outside the button area I'd like to b.setPressed(false); and then NOT do the button action stuff when the finger is raised.
I've tried using MotionEvent.ACTION_CANCEL and MotionEvent.ACTION_OUTSIDE (as suggested by How to detect when finger slides off the ImageButton?) but I must be missing something because they're not working.
From Detect when a user moves off of a button in Android it would appear that this can be done with event.getX() and event.getY(). If getX() is negative you're off the left and if getY() is negative you're off the top, but to figure out if you're off the right or bottom I'll have to figure out the size of the button and then... there has to be a simpler way. Is there?

You had the right answer. Use getWidth() and getHeight() to get the width and height and check if x or y is greater.
ACTION_CANCEL doesn't work because CANCEL is generated when a parent view takes control of the touch events, like a ListView does when scrolling.
ACTION_OUTSIDE only happens in some unusual cases where you request it. It isn't going to be generated for just a normal MOVE or UP.

Since no one posted any code, here is one. A Boolean is used to indicate when the respective actions should be performed.
The MotionEvent.ACTION_MOVE event is handled to check if the finger is moved out of the bounds. If yes, b.setPressed(false); is called and the boolean is used to indicate that MotionEvent.ACTION_UP shouldn't be fired the next time, ie to cancel the button click.
And in MotionEvent.ACTION_UP, call b.setPressed(false); only if our boolean doesn't indicate a skip (as mentioned above). And if it does, invert the boolean so that button action stuff would execute the next time.
private Boolean notNow = false;
private Rect rect; // Variable rect to hold the bounds of the view
b.setOnTouchListener(new OnTouchListener(){
#Override
public boolean onTouch(View v, MotionEvent event){
if ((event.getAction() & MotionEvent.ACTION_MASK) == MotionEvent.ACTION_DOWN){
b.setPressed(true);
rect = new Rect(v.Left, v.Top, v.Right, v.Bottom);
}
if ((event.getAction() & MotionEvent.ACTION_MASK) == MotionEvent.ACTION_UP){
if (!notNow){
b.setPressed(false);
}
else //button press canceled
notNow = false;
}
if((event.getAction() & MotionEvent.ACTION_MASK) == MotionEvent.ACTION_MOVE){
if(!notNow)
if (!rect.contains(v.getLeft() + (int) event.getX(), v.getTop() + (int) event.getY())){
// finger moved out of bounds
b.setPressed(false);
notNow = true; //cancel button press the next time
}
}
return true;
});

How do you make an onTouchListener keep going as long as the view is being pressed?

I am using a small square RelativeLayout as a game pad for movement in a neighboring GLSurfaceView.
I set it up so that in the onTouch method of the RelativeLayout's onTouchListenner I call a method built into the GLSurfaceView that updates the translation and rotation coordinates for my drawing.
I have everything working fine, except for the fact that touch events are only triggered if the user moves his or her finger on the RelativeLayout.
I would like it to feel a little bit like a joystick: if you leave your finger pressed on the top of the RelativeLayout, then you will keep going "up" ( or more programatically: the event.getX() and event.getY() that were sent last should get looped, or re-sent, in the GLSurfaceView until the user either moves his finger inside the RelativeLayout, or stops touching the RelativeLayout altogether.)
What should I use to detect whether or not the RelativeLayout is currently being touched (even if there is no motion in the said touch)?
Thanks!

So this is what I came up pretty much simultaneously with csmcklvey
if(event.getAction()==MotionEvent.ACTION_UP)
gM.isTouchedL = false;
else
gM.isTouchedL = true;
return true;
Where .isTouchedL is the "control boolean" I use in the GLSurfaceView
Green lit csmc's answer anyways! :)

I have used rotation animation in one of my apps, which is using the onTouchEven of view. Major function has been performed in event "ACTION_MOVE". It will help you, to get through.
public boolean onTouch(View v, MotionEvent event)
{
final float xc = volumeButton.getWidth() / 2;
final float yc = volumeButton.getHeight() / 2;
final float x = event.getX();
final float y = event.getY();
switch (event.getAction())
{
case MotionEvent.ACTION_DOWN:
{
// volumeButton.clearAnimation();
// mCurrAngle = Math.toDegrees(Math.atan2(x - xc, yc - y));
break;
}
case MotionEvent.ACTION_MOVE:
{
mPrevAngle = mCurrAngle;
mCurrAngle = Math.toDegrees(Math.atan2(x - xc, yc - y));
animate(mPrevAngle, mCurrAngle, 100);
break;
}
case MotionEvent.ACTION_UP :
{
mPrevAngle = mCurrAngle = 0;
break;
}
}
return true;
}

You might be able to use the event.getAction() method of the MotionEvent parameter of your onTouch() method. You can check to see if it is MotionEvent.ACTION_DOWN or MotionEvent.ACTION_UP.
if (event.getAction() == MotionEvent.ACTION_DOWN) {
//start something
}
else if (event.getAction() == MotionEvent.ACTION_UP) {
//stop something
}
My thought is that you might be able to start or stop a thread in this manner but either way this might at least give you some more information about when the user actually presses and lifts his/her finger.

rotate image depending on user touch on screen

i am developing game.i am displaying gun object center bottom of the screen.when user tap on screen i need to rotate gun that direction.i done rotating image.but when user tap on screen i need to rotate image that direction.can you please help me
Thanks in advance
Aswan

is your image a bitmap? could you convert it to one? Would an onClick listener not work and when the user clicks do something like.. http://www.anddev.org/resize_and_rotate_image_-_example-t621.html
Seeing some code as to what you've attempting would be nice also. The following will help you with checking if the bitmap has been clicked in case you're stuck on that also http://developer.android.com/reference/android/view/View.html .
I've never attemped this myself but I think that would work. Try redrawing the bitmap when you have resized it.

Just use onTouchListener for your View and use this code for that
#Override
public boolean onTouch(View v, MotionEvent event) {
float currentX = event.getX();
float currentY = event.getY();
Log.i(TAG, "action type is"+event.getAction());
switch (event.getAction()) {
case MotionEvent.ACTION_MOVE: {
Log.i(TAG, "Entering in onTouch");
double rotationAngleRadians = Math.atan2(currentX - dialer.centerX, dialer.centerY - currentY);
dialer.rotationAngle = (int) Math.toDegrees(rotationAngleRadians);
Log.i(TAG, "rotaion angle"+dialer.rotationAngle);
dialer.invalidate();
return true;
}
}
return true;
}