problem with drag/pan and save older finger position

in Android Processing • 11 months ago

I'm trying to add pan to my app, I think for pan I should subtract older finger position from new position and then translate , is it what I want ?

boolean surfaceTouchEvent(MotionEvent event) {
pointNum=event.getPointerCount();
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
//User is pressing on finger
float x0=event.getX(0);
float y0=event.getY(0);
mode = false; //DRAG
break;
case MotionEvent.ACTION_POINTER_DOWN:
x1=event.getX(0);x2=event.getX(1);
y1=event.getY(0);y2=event.getY(1);
float z4 = dist(x1,y1,x2,y2);
mode = true; // pinch
break;
case MotionEvent.ACTION_POINTER_UP:
// User is released one of the fingers.
break;
case MotionEvent.ACTION_MOVE:
if (mode = false){
x1=event.getX(0)-x0;
y1=event.getY(0)-y0;
}
if (mode = true){
x1=event.getX(0);x2=event.getX(1);
y1=event.getY(0);y2=event.getY(1);
float z3 = dist(x1,y1,x2,y2);
if ( z3 > z4 ){
zoom += 0.1;
}
else if ( z3 < z4){
zoom -= 0.1;
}
}
break;
}
return super.surfaceTouchEvent(event);
}

I saved older positions in case MotionEvent.ACTION_POINTER_DOWN for zoom and case MotionEvent.ACTION_DOWN for pan

this is the errors :

-compile:
[javac] Compiling 2 source files to C:\DOCUME~1\T0P4568\LOCALS~1\Temp\android893850823480544580.pde\bin\classes
[javac] C:\DOCUME~1\T0P4568\LOCALS~1\Temp\android893850823480544580.pde\src\changethispackage\beforesubmitting\tothemarket\sketch_may28a\sketch_may28a.java:118: variable x0 might not have been initialized
[javac] x1=event.getX(0)-x0;
[javac] ^
[javac] C:\DOCUME~1\T0P4568\LOCALS~1\Temp\android893850823480544580.pde\src\changethispackage\beforesubmitting\tothemarket\sketch_may28a\sketch_may28a.java:119: variable y0 might not have been initialized
[javac] y1=event.getY(0)-y0;
[javac] ^
[javac] C:\DOCUME~1\T0P4568\LOCALS~1\Temp\android893850823480544580.pde\src\changethispackage\beforesubmitting\tothemarket\sketch_may28a\sketch_may28a.java:125: variable z4 might not have been initialized
[javac] if ( z3 > z4 ){
[javac] ^
[javac] 3 errors

please help!

Replies(2)

calsign

Re: problem with drag/pan and save older finger position

11 months ago

Not sure about the way you're going about doing it, but your error is caused because you haven't properly initialized any of your variables... You're declaring them in one case statement and trying to use them in another.
Try declaring and initializing them all outside of the switch statement...

On a side note, go to Edit > Auto Format to make your code easier to read...

mataarsak

Re: problem with drag/pan and save older finger position

11 months ago

how can I initiate the outside the switch ? for example I should save the old position in MotionEvent.ACTION_POINTER_DOWN because it's the place where recognize the second finger touch the screen and case MotionEvent.ACTION_MOVE is where we get the movement . In android I think it's how we that but I'm not sure how can I do this in processing. I want to compare the old distance between two fingers and the new one to perfom zoomming .

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