CODEWITHSUNDEEP
android
Mika
Mika

Reputation: 5835

Animate a ListView unto the view

I am trying to achieve the effect of a piece of paper coming out of a slot with a list of items on it. I came up with one approach but as I am working on it I can't keep on thinking there must be a better way.

My approach: 

<LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="0dp"
    android:layout_weight="1"
    >
    <ListView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/orderDetailListView">

    </ListView>

</LinearLayout>

Animation code: 

final int newMargin = <some value>;
Animation a = new Animation() {

@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
    LayoutParams params = listView.getLayoutParams();
    params.leftMargin = (int)(newMargin * interpolatedTime);
    yourView.setLayoutParams(params);
    }
};

listView.startAnimation(a);

My question:

Is there a better way? I am not asking a suggestive question I merely want to know if there is a built in function of some sort that will make a view appear gradually from a set point.

Image from yplan app

Upvotes: 1

Views: 80

Answers (1)

rperryng
rperryng

Reputation: 3253

It seems like you are trying to achieve a simple translation animation. One way of approaching this situation is to use the Property Animation Api introduced in Api level 10 (and generously backported to api level 1 with Jake Wharton's nine old androids library).

A simple example could be the following

ObjectAnimator.ofFloat(theViewObject, "translationY", -theViewObject.getHeight(), 0)
        .setDuration(2000) // 2 seconds
        .start();

sometimes, calls like getHeight() or getRight() etc, return 0. This is because the view hasn't actually been drawn yet. To accomodate for this you can register a callback to know when the view has been drawn.

// Listen for when the view has been drawn so we can get its dimensions
final ViewTreeObserver viewTreeObserver = theViewObject.getViewTreeObserver();
if (viewTreeObserver.isAlive()) {
    viewTreeObserver.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
        @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
        @SuppressWarnings("deprecation")
        @Override
        public void onGlobalLayout() {

            ObjectAnimator.ofFloat(
                    theViewObject, "translationY", -theViewObject.getHeight(), 0)
                    .setDuration(2000) // 2 seconds
                    .start();

            // stop listening for updates to the view so that this is only called once
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                viewTreeObserver.removeOnGlobalLayoutListener(this);
            } else {
                viewTreeObserver.removeGlobalOnLayoutListener(this);
            }
        }
    });
}

Upvotes: 1

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