People have become used to interacting with a device by tapping and swiping on a touchscreen. In this recipe, we'll take a look at how you can detect when a user is touching the screen, and let your sketch respond to that interaction. We'll make a simple drawing application to see how it's done.
We'll start by writing the setup() function and declare a boolean variable. If the value of this variable is true, we'll draw some things on the screen.
boolean touching = false;
void setup()
{
size( displayWidth, displayHeight );
smooth();
background( 0 );
}To respond to a user touching the screen, we'll override the surfaceTouchevent() method. If we detect a touch we'll set the touching variable to true:
public boolean surfaceTouchEvent( MotionEvent event )
{
if ( event.getAction() == 2 ) {
touching = true;
} else {
touching = false;
}
return super.surfaceTouchEvent( event );
}