Develop Reference

javaFX translate animation doesn't trigger in both directions?

Right now I'm trying to code a simple abacus with JavaFX. There are balls on horizontal rails arranged in a gridpane, and I'm using a translateTransition to move them to the right on click. The following is the code I have right now, which works fine on any of the balls in the grid except it only animates the movement to the right. On the second click, the ball jumps back to the left to its original position without the animation and I can't figure out why it's not animating. Any help or ideas would be greatly appreciated!
private void onClick(final Circle circle) {
circle.setOnMouseClicked(new EventHandler<MouseEvent>() {
public void handle(MouseEvent mouseEvent) {
//set movement direction, check if circle has been moved
int targetX = 200;
if (circle.getTranslateX() > 1) {
targetX = 0;
}
//animation trigger and details
TranslateTransition push = new TranslateTransition(Duration.millis(500));
push.setNode(circle);
push.setFromX(circle.getCenterX());
push.setToX(targetX);
push.play();
}
});
}

Bridge building algorithm in Java?

I am making a bridge building game for Android. As you know there are two coordinates for drawing a line.
Firstly, When we push "put" button and select a dot then it's the first coordinate of the line, secondly the coordinates where we keep touching on screen is always displayed as the second coordinate, lastly, where we release our finger is decided as the second coordinate of the line. And there will be more than one lines.
I'd be glad if anyone explain these to me.

You will have to override the onTouchEvent function of the respective activity:
#Override
public boolean onTouchEvent(MotionEvent event) {
int action = event.getActionMasked();
float x = event.getX();
float y = event.getY();
if (action == MotionEvent.ACTION_DOWN) {
// save the coordinates somewhere
} else if (action == MotionEvent.ACTION_UP) {
// save the coordinates as well
} else if (action == MotionEvent.ACTION_MOVE) {
// display the coordinates
}
}
Then you simply have to use the stored coordinates to draw a line between the coordinates, e.g. within a canvas that is located on your activity.
You will find a sophisticated example here: http://www.vogella.com/tutorials/AndroidTouch/article.html

libGDX touch in effect after touch

I use the following code to match the user touch to a ball object's position, so when the user touches the ball it bounce back up. Code:
int x1 = Gdx.input.getX();
int y1 = Gdx.input.getY();
Vector3 input = new Vector3(x1, y1, 0);
cam.unproject(input);
if(ball.getBoundingCircle().contains(input.x, input.y)) {
ballBounce();
}
But I have a problem with the touch. If the user touches a certain position on screen for a moment and a ball (after a while more appear) about to reach the position the user touched, the ball will recognize itself as been touched and the ballBounce(); method will start and continue with other balls that reach to the same position until the user touch another position on the screen but then that position will be fixed till the new one... Do someone know how I can bypass that problem so if the user stop touching the screen then where he\she touched won't affect the ball objects?

It seems that you are not using any input processor.
Make your class implement InputProcessor and make your touchDown method look like this.
#Override
touchDown(InputEvent event, float x, float y, int pointer, int button) {
Vector3 input = new Vector3(x, y, 0);
cam.unproject(input);
if (ball.getBoundingCircle().contains(input.x, input.y)) {
ballBounce();
}
}
ClickListener (LibGDX API)

How do I program a Scrollable SurfaceView in Android Java?

I am trying to draw an image that is larger than the screen, and let the user scroll around it. The image is some graphs that are calculated by my code from some data. (This is in Android using Java).
What I want is a View (actually a SurfaceView) that can be scrolled by the user. I have tried putting a SurfaceView inside a ScrollView but the whole image drawn by the SurfaceView is very large and so (a) there are performance issues as my app is drawing the whole SurfaceView when it should only need to do the part that is in the viewport and (b) my app crashes with "dimensions too large... out of memory" errors.
It would be best for me if the View could implement scrolling (vertical only) and then pass the y-value to my code so it could draw the visible part of my image in the viewport.
Alternatively I could capture the 'mouse' events and calculate the y-value myself.
Does anyone have any code so that I can do this?
Update: I should clarify, the image is drawn by my program code using Canvas.drawLine() and the like. I can calculate which parts of the image fit within my viewport, provided I have the state of the scroll as a y-value, and I can calculate the absolute y-coordinate of each point by subtracting scroll y-value. What I need is something that works to find when the user scrolls the image and what the resulting y-value is. A scrollbar would also be nice.
Update: I am using SurfaceView so that I can update the image from another Thread and so improve user interface performance.

if you really have just a draw content... you don't need a scrollable client then...
have a model (x,y,lines, etc)
have a pan & zoom
draw a scaled/zoomed instance of the model
just draw the content (sorry - no scroller in this solution)
#Override
public boolean onTouchEvent(MotionEvent event) {
boolean isProcessed = scaleGestureDetector.onTouchEvent(event);
if (isProcessed) {
// Handle touch events here...
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
start.set(event.getX(), event.getY());
tap( event.getX(), event.getY() );
mode = DRAG_OR_TAP;
break;
case MotionEvent.ACTION_POINTER_DOWN:
break;
case MotionEvent.ACTION_UP:
break;
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
break;
case MotionEvent.ACTION_MOVE:
if (mode == DRAG_OR_TAP) {
doPan(event.getX() - start.x, event.getY() - start.y);
start.set(event.getX(), event.getY());
}
break;
}
}
myView.scale(currentPan, currentScaleFactor);
invalidate();
return true;
}
private void doPan(float panX, float panY) {
currentPan.x = currentPan.x + panX;
currentPan.y = currentPan.y + panY;
}
private void tap(float x, float y) {
...
}
and last not least use the scaleListener
private class ScaleListener extends
ScaleGestureDetector.SimpleOnScaleGestureListener {
#Override
public boolean onScale(ScaleGestureDetector detector) {
float value = detector.getScaleFactor();
currentScaleFactor = currentScaleFactor * value;
// don't let the object get too small or too large.
boolean doesntMatch = false;
if (currentScaleFactor < 1f || currentScaleFactor > 20f){
currentScaleFactor = Math.max(1f, Math.min(currentScaleFactor, 20f));
doesntMatch = true;
}
if(!doesntMatch){
//scale the viewport as well
currentPan.x = currentPan.x*value;
currentPan.y = currentPan.y*value;
}
return true;
}
}

you can simply use a WebView to display an image
provides pan
provides zoom
no library required
has a scrollbar
Android: Easiest way to make a WebView display a Bitmap?
i'm not sure if i really hit your question...

Understanding Multitouch on Android?

I found this article: http://android-developers.blogspot.ca/2010/06/making-sense-of-multitouch.html which helped my understanding but I'm still not sure how to do what I'm trying to do.
In my game, I have a virtual analog stick and some buttons. Only 2 fingers will ever register at once. This is what I want. One for the analog stick and one for a button.
The main thing I'm unsure of is, say I put a finger down on the analog stick and move it around, then put a finger on the button, then release the button, the analog stick should keep moving to my first finger.
And vice versa, if the button touches first and then the analog stick, if I let go of the analog stick the button should still be pushed down.
Do touch pointers work in this fashion on Android, as in, once I put my finger down, regardless of any other fingers I put up or down, it will remember my first finger in order and give it a down, move move move up events?
Thanks
Ideally I wish I had a function like this:
void onTouch(int fingerID, int action, int x, int y)
{
}
Where each finger that is put down will receive down, move and up event when that finger goes up.
The game is a racing game so they need to be able to steer and push gas at the same time.
My problem is similar to this
identified multi touch pointer in action_move
Edit:
I have this code:
private void onTouch(int finger, int action, float x, float y)
{
if(action == MotionEvent.ACTION_DOWN || action == MotionEvent.ACTION_POINTER_DOWN)
{
createInput(finger, x, y);
}
else if(action == MotionEvent.ACTION_MOVE)
{
inputMove(finger, x, y);
}
else if(action == MotionEvent.ACTION_UP || action == MotionEvent.ACTION_POINTER_UP)
{
destroyInput(finger, x, y);
}
}
public void onTouch(MotionEvent ev)
{
final int pointerCount = ev.getPointerCount();
for (int p = 0; p < pointerCount; p++) {
onTouch(ev.getPointerId(p), ev.getAction(), ev.getX(p), ev.getY(p));
}
}
But it only works for the first one.

So from the examples given right in the MotionEvent class:
public boolean onTouch(MotionEvent ev) {
final int pointerCount = ev.getPointerCount();
for (int p = 0; p < pointerCount; p++) {
onTouch(ev.getPointerId(p), ev.getAction(), ev.getX(p), ev.getY(p));
}
return true;
}

You could take a look at the way the pinch is handled in AChartEngine for zoom. See this code, starting at line 80. It may look complex at the beginning, but it may help you on handling more use cases.