Develop Reference

android ImageView one finger rotation

I looked on many posts but couldnt find the answer.
I would like to rotate an root image with another small image that is located on the lower side of the root image.
while rotation its working but the first time I press it, it jumps to 45 degrees because of the math.tan(), I think I have a calculation problem.
rotateImage.setOnTouchListener(new OnTouchListener() {
#Override
public boolean onTouch(View view, MotionEvent event) {
final int action = MotionEventCompat.getActionMasked(event);
switch (action) {
case MotionEvent.ACTION_UP:
break;
case MotionEvent.ACTION_DOWN:
rotateX = event.getRawX() - rotateImage.getWidth() / 2;
rotateY = event.getRawY() - rotateImage.getHeight() / 2;
break;
case MotionEvent.ACTION_MOVE:
float angle = (float) Math.toDegrees(Math.atan2(event.getRawY() - rotateY, event.getRawX() - rotateX));
if (angle < 0){
angle += 360;
}
mBinding.getRoot().setRotation(angle);
}
return true;
}
});
please advice.

I think this library can help you.
https://github.com/kencheung4/android-StickerView

how to detect finger swipe in android

i am trying to do finger swipe but it is not detected .i am trying to draw a path which describes the area through which finger swipe but only when i swipe with force then only swipe get detected and else not detected
public boolean onTouchEvent(MotionEvent event) {
if (System.currentTimeMillis() - lastClick > 500) {
lastClick = System.currentTimeMillis();
synchronized (getHolder()) {
int eventaction = event.getAction();
if(event.getPressure()>0.00001||event.getSize()>0.00001)
{
float a,b,c;
switch(eventaction)
{
case MotionEvent.ACTION_DOWN:
xdown = event.getX();
ydown =event.getY();
pres=true;
break;
case MotionEvent.ACTION_MOVE:
if(pres)
{
xmove = event.getX();
ymove =event.getY();
a = (float) Math.sqrt(Math.pow(xdown - xmove,2) +Math.pow( ydown - ymove,2));
b=(float) (xdown-(((xdown - xmove) / a) * 150));
c=(float) (ydown-((( ydown - ymove)/a)*150));
move.moveTo(xdown, ydown);
move.lineTo(b, c);
pres=false;
lmove=true;
}
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_POINTER_UP:
move.reset();
xmove = 0;
ymove =0;
xdown=0;
ydown=0;
lmove=false;
pres=false;
break;
default:
return true;
}
}
}}
return true;
}

Android has a class for that. Check http://developer.android.com/reference/android/view/GestureDetector.html
I believe it is one of in touch events

See the code here: Simple swipe gesture to activity tutorial?
Using a SimpleOnGestureListener is easiest, and if you override the onFling method, it's easy/

Transfer longpress from one android view to another, without releasing finger

We have a longpress detection on a button. When detected, the view should be dismissed (back to the game view) and the object chosen with the button shall be at the coordinates of the longpress. That's the easy part, the hard part is to then change the coordinates with the finger, without releasing it.
Okay so i'm trying to reformulate this: We have two views displayed on top of eachother. What we want is a longclick detected in the top view, to then dismiss the top view, and without releasing the finger, get touchevents in the bottom view.
This is our class gameView: (this code contains a lot of code unneccesay for the problem)
#Override
public boolean onTouchEvent(MotionEvent event) {
gestureDetector.onTouchEvent(event);
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
mode = DRAG;
//We assign the current X and Y coordinate of the finger to startX and startY minus the previously translated
//amount for each coordinates This works even when we are translating the first time because the initial
//values for these two variables is zero.
startX = event.getX() - previousTranslateX;
startY = event.getY() - previousTranslateY;
break;
case MotionEvent.ACTION_MOVE:
translateX = event.getX() - startX;
translateY = event.getY() - startY;
gestureHandler.setTranslation(translateX, translateY);
//We cannot use startX and startY directly because we have adjusted their values using the previous translation values.
//This is why we need to add those values to startX and startY so that we can get the actual coordinates of the finger.
double distance = Math.sqrt(Math.pow(event.getX() - (startX + previousTranslateX), 2) +
Math.pow(event.getY() - (startY + previousTranslateY), 2)
);
if(distance > 0) {
dragged = true;
}
break;
case MotionEvent.ACTION_POINTER_DOWN:
mode = ZOOM;
scaleToX = event.getX();
scaleToY = event.getY();
break;
case MotionEvent.ACTION_UP:
mode = NONE;
dragged = false;
//All fingers went up, so let's save the value of translateX and translateY into previousTranslateX and
//previousTranslate
previousTranslateX = translateX;
previousTranslateY = translateY;
int x = (int)((-translateX/scaleFactorX)+(event.getX()/this.scaleFactorX));
int y = (int)((-translateY/scaleFactorY)+(event.getY()/this.scaleFactorY));
map.click(getContext(), x, y);
for(CastleTile castleTile : map.getCastleTiles()) {
if(castleTile.getRect().contains((int)((-translateX/scaleFactorX)+(event.getX()/this.scaleFactorX)), (int)((-translateY/scaleFactorY)+(event.getY()/this.scaleFactorY)))){
Log.d("Castle to your service", "Boes");
castleSettings.show();
}
}
break;
case MotionEvent.ACTION_POINTER_UP:
mode = DRAG;
//This is not strictly necessary; we save the value of translateX and translateY into previousTranslateX
//and previousTranslateY when the second finger goes up
previousTranslateX = translateX;
previousTranslateY = translateY;
break;
}
detector.onTouchEvent(event);
//We redraw the canvas only in the following cases:
//
// o The mode is ZOOM
// OR
// o The mode is DRAG and the scale factor is not equal to 1 (meaning we have zoomed) and dragged is
// set to true (meaning the finger has actually moved)
if ((mode == DRAG && scaleFactorX != 1f && scaleFactorY != 1f && dragged) || mode == ZOOM) {
invalidate();
}
return true;
}
#Override
public boolean onLongClick(View v) {
castleSettings.dismiss();
return true;
}
And this is the gestureHandler:
public void onLongPress(MotionEvent event) {
map.longClick(context, (int)((-translateX/scaleFactorX)+(event.getX()/this.scaleFactorX)), (int)((-translateY/scaleFactorY)+(event.getY()/this.scaleFactorY)));
}
Sorry for eventual lack of information or bad explaination :)

Detect scale and translate gestures without ScaleGestureDetector

I try to implement multi-touch-gesture detection for API level 7. That means I do not have a ScaleGestureDetector. At the moment I have something like this but it does not work well and I have more open questions on it than a full understanding:
public boolean onTouchEvent(MotionEvent ev)
{
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) // why mask it with ACTION_MASK?
{
case MotionEvent.ACTION_DOWN:
{
mLastTouchX=ev.getX();
mLastTouchY=ev.getY();
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_POINTER_DOWN:
{
mLastTouchX2=ev.getX();
mLastTouchY2=ev.getY();
if (ev.getPointerCount()>1)
mActivePointerId2 = ev.getPointerId(1);
break;
}
case MotionEvent.ACTION_MOVE:
{
int pointerIndex;
float x=0.0f,y=0.0f;
try
{
if ((mActivePointerId!=INVALID_POINTER_ID) || (mActivePointerId2!=INVALID_POINTER_ID))
{
// get one of the active pointers - unfortunately here I'm not sure which one is the active one so I only can guess
pointerIndex= ev.findPointerIndex(mActivePointerId);
x= ev.getX(pointerIndex);
y= ev.getY(pointerIndex);
}
if ((mActivePointerId!=INVALID_POINTER_ID) && (mActivePointerId2!=INVALID_POINTER_ID))
{
float d1,d2;
pointerIndex = ev.findPointerIndex(mActivePointerId2);
if (pointerIndex<0) return false;
float x2 = ev.getX(pointerIndex);
float y2 = ev.getY(pointerIndex);
d1=android.util.FloatMath.sqrt((x-x2)*(x-x2)+(y-y2)*(y-y2));
d2=android.util.FloatMath.sqrt((mLastTouchX-mLastTouchX2)*(mLastTouchX-mLastTouchX2)+
(mLastTouchY-mLastTouchY2)*(mLastTouchY-mLastTouchY2));
if ((d1>0) && (d2>0)) // seems to be a scale gesture with two pointers
{
float w,h,s;
transOffsetX=0.0f;
transOffsetY=0.0f;
s=d1/d2;
mScaleFactor*=s;
matrix.postScale(s,s);
w=(scrWidth-(scrWidth*s))/2.0f;
h=(scrHeight-(scrHeight*s))/2.0f;
matrix.postTranslate(w,h);
imgOffsetX+=w;
imgOffsetY+=h;
}
mLastTouchX2 = x2;
mLastTouchY2 = y2;
}
else if (mScaleFactor==1.0) // seems to be a translate gesture with only one pointer
{
mScaleFactor=1.0f;
transOffsetX+=(x-mLastTouchX);
transOffsetY+=(y-mLastTouchY);
matrix.setTranslate(transOffsetX,transOffsetY);
}
if ((mActivePointerId!=INVALID_POINTER_ID) || (mActivePointerId2!=INVALID_POINTER_ID))
{
mLastTouchX = x;
mLastTouchY = y;
}
}
catch (ArrayIndexOutOfBoundsException aioobe)
{
// this is really strange, this exception can be caused by
// pointerIndex= ev.findPointerIndex(mActivePointerId);
// x= ev.getX(pointerIndex);
// above which seems to be a Android bug?
}
break;
}
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
{
breakMapThread=true;
mActivePointerId = INVALID_POINTER_ID;
mActivePointerId2 = INVALID_POINTER_ID;
// gestrue seems to be finished so trigger update of the view here
...
break;
}
}
return true;
}
The whole thing is working really lousy. Scale gestures cause high, additional translations, a single tap into the view causes a translation too and translations are not very accurate. Beside of that I found some motion event constants ACTION_POINTER_1/2/3_DOWN/UP which never seem to be used. So I'm absolutely unsure if my whole assignment form _DOWN/_UP to the pointers one and two are correct.
Any ideas, hints, tips to get this thing working?

One idea is to find the source of ScaleGestureDetector and include it into your project.
But there are problems: sometimes the system detects click and longclick (especially when a finger goes out of window boundaries).

Touch move gesture logic...how to determine direction of movement in 2d?

How can i determine the direction of gesture ? The use case is shown in the image link. what is the right logic for detecting in which direction the person is trying to move the ball in the circular path ? I have called the direction method in move gesture...Can someone help me fine tune this ... ?
http://www.shrenikvikam.com/wp-content/uploads/2011/04/214e422a43E11S3.png-150x134.png
private String getDirection(float firstTouchX, float finalTouchX){
if((firstTouchX - finalTouchX)>0)
return "Left";
else
return "Right";
}
#Override
public boolean onTouchEvent(MotionEvent event) {
int action = event.getAction();
switch (action) {
// MotionEvent class constant signifying a finger-down event
case MotionEvent.ACTION_DOWN: {
Log.d("ACTION DOWN","Value ->");
final float x = event.getX();
final float y = event.getY();
initialTouchX = x;
initialTouchY = y;
break;
}
// MotionEvent class constant signifying a finger-drag event
case MotionEvent.ACTION_MOVE: {
final float x = event.getX();
final float y = event.getY();
final String direction = getDirection(initialTouchX,x);
Log.d("ACTION MOVE","diff in initial and cur value of x ->" + direction + (initialTouchX - x) + initialTouchX + "y->" + initialTouchY);
break;
}
// MotionEvent class constant signifying a finger-up event
case MotionEvent.ACTION_UP: {
Log.d("ACTION UP","Value ->");
break;
}
}
return true;
}

It seems like the slope of the line formed by the two touch points should be equal to the tangent of the circle at that point. This link has most of the math to pursue such a solution
I have used the difference between angles to the center point of the circle with good success. That may be the way to go as well.

If you are trying to determine which way to move the ball around the ciricle, it doesn't make sense for getDirection to return "Left" and "Right", it should be working with "Clockwise" and "Counterclockwise". Consider, for example, when the ball is at the 20 marker in your image: At this point every point on the circle is "Right" of where you are now...
In order to determine if the ball is moving clockwise or counterclockwise you need to consider both the x and y co-ordinates of the touch points, the x co-ordinate alone is not sufficient. You also need to know where the centre of the circle is. I would suggest in order to determine the direction of movement, you calculate the angle between the touch points and the centre of the circle.

prevTouchX = event.getHistoricalX(event.getHistorySize()-1);
currentTouchX = event.getX();
if(currentTouchX<prevTouchX){
Log.d("LEFT",event.getX()+" and "+event.getY());
}
if(currentTouchX>prevTouchX){
Log.d("RIGHT",event.getX()+" and "+event.getY());
}
Similarly for UP/DOWN

I use this code for rotating a view. It works very well. Have a look at this;
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
firstX = event.getX();
firstY = event.getY();
break;
case MotionEvent.ACTION_MOVE:
int dx =(int) (event.getX() - firstX);
int dy =(int) (event.getY() - firstY);
Log.d("Distance Rotate Touch",Integer.toString((int) (firstX-dx)));
if (signView.getRotation()<180){
if (firstX - dx > 15 && firstY - dy > 15 ){
View.setRotation(signView.getRotation()-5);
}else if(firstX - dx < -15 && firstY - dy < 15 ){
View.setRotation(signView.getRotation()+5);
}
}else {
if (firstX - dx > 10 && firstY - dy < -10 ){
View.setRotation(signView.getRotation()+5);
}else if(firstX-dx < -10 && firstY - dy < -15 ){
View.setRotation(signView.getRotation()-5);
}
}
break;
default: return true;
}