Develop Reference

Android ArgbEvaluator calculate fraction

I've a little difficult in using ArgbEvaluator object.
I want to change the color of view from one color to another color in specific duration.So I write this code,it works well.
ValueAnimator animator = ValueAnimator.ofArgb(Color.RED,Color.BLUE);
animator.setDuration(5000);
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
#Override
public void onAnimationUpdate(ValueAnimator animation) {
int color = (int) animation.getAnimatedValue();
view.setBackgroundColor(color);
}
});
animator.start();
But I want to use ArgbEvaluator to animate like that.
public void setColor(fraction){
int color = evaluator.evaluate(fraction,startColor,endColor);
view.setBackgroundColor(color);
}
The above setColor method will be called agian and again for specific duration(eg-5000ms).
Here is my problem.
I don't know how to calculate fraction to change color within specific duration.
I want to know the calculation formula of fraction.Thanks.

Smooth color animation

I'm trying to create smooth color animation in my WaveView. Unfortunatelly animation is creating rainbow effect spamming through every color from start to end.
I'll need it to go from Red to Green with just (Red -> Orange - > Yellow - > Greenish -> Green) like on RGB tables.
Here's my ObjectAnimator:
ObjectAnimator waveColor = ObjectAnimator.ofInt(
mWaveView, "waveColor",Color.parseColor("#64ff0000"),Color.parseColor("#6400ff00"));
waveColor.setDuration(7000);
waveColor.setInterpolator(new LinearInterpolator());
animators.add(waveColor);
I have no idea how to make it to just go through that colors.

Check this Link:
Hope I have understood your question properly and it helps
ColorDrawable[] color = {new ColorDrawable(Color.RED), new ColorDrawable(Color.GREEN)};
TransitionDrawable trans = new TransitionDrawable(color);
//This will work also on old devices. The latest API says you have to use setBackground instead.
mWaveView.setBackgroundDrawable(trans);
trans.startTransition(7000);

best way use ValueAnimator and ColorUtils.blendARGB
ValueAnimator valueAnimator = ValueAnimator.ofFloat(0.0f, 1.0f);
valueAnimator.setDuration(325);
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
#Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
float fractionAnim = (float) valueAnimator.getAnimatedValue();
view.setColorBackground(ColorUtils.blendARGB(Color.parseColor("#FFFFFF")
, Color.parseColor("#000000")
, fractionAnim));
}
});
valueAnimator.start();

Android: how to use ValueAnimator

I want to do a translate animation using this following
public static void move(TextView view){
ValueAnimator va = ValueAnimator.ofFloat(0f, 3f);
int mDuration = 3000; //in millis
va.setDuration(mDuration);
va.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
public void onAnimationUpdate(ValueAnimator animation) {
}
});
va.setRepeatCount(5);
va.start();
}
But I don't know how to use onAnimationUpdate method.
Can anyone help please?

If you really, really, really want to use ValueAnimator for animating translation of the View you can do it this way (finishing your example, assuming you meant translationX.
Bare in mind that you're animating translation from 0px to 3px, so you probably won't see much difference.
fun move(view: TextView) {
val va = ValueAnimator.ofFloat(0f, 3f)
va.duration = 3000 //in millis
va.addUpdateListener { animation -> view.translationX = animation.animatedValue as Float }
va.repeatCount = 5
va.start()
}

ValueAnimator is a great tool for making animations. Usually we have three steps:
Step 1- Create your ValueAnimator class by
ValueAnimator animator = ValueAnimator.ofFloat(start value, end value);
Step 2- Adding one update listener and overriding at least onAnimationUpdate() function
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
#Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
float value = (float) animator.getAnimatedValue();
//this value should be used to update properties of views.
//just don't forget to run invalidate function of your views
// to redraw them.
}
});
Step 3-
animator.start();

How to animate ImageAlpha of ImageView

Since API16 ImageView.setImageAlpha(int) should be used instead of View.setAlpha(float) for better performance.
But how can I animate that value? I tried ValueAnimator without success.
ObjectAnimator.ofInt(imageView, "imageAlpha", 0).start();
I mean what Chet Haase is talking about here http://youtu.be/vQZFaec9NpA?t=33m

It should be fine. Maybe you forgot to specify the animation duration, or your alpha values are wrong (negative, too small, too close to notice)?
You can always animate using custom listener. It's longer, but easier to debug:
ValueAnimator animator = ValueAnimator.ofInt(0,255);
animator.setDuration(300);
animator.setInterpolator(new DecelerateInterpolator());
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
#Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
imageView.setImageAlpha(valueAnimator.getAnimatedValue());
}
});
animator.start();

ObjectAnimator on ProgressWheel by Todd-Davies

I am trying to make a ProgressWheel where the color change as the wheel fill up (the wheel start green at 0% and finish red at 100% with all the wheel become red over the time : not a rainbow).
So I am using an ObjectAnimator, the wheel take the entry color but I cannot manage to make it change color over time...
final ObjectAnimator animator = ObjectAnimator.ofInt(progressBar, "barColor", Color.GREEN, Color.RED);
animator.setDuration(remainingTime);
animator.setEvaluator(new ArgbEvaluator());
animator.setInterpolator(new DecelerateInterpolator(2));
animator.start();
Any idea?

I finally did this (it comes from another post on StackOverflow):
final ObjectAnimator colorAnimator = ObjectAnimator.ofObject(progressBar, "barColor", new ArgbEvaluator(), green, red);
colorAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
#Override
public void onAnimationUpdate(ValueAnimator animation) {
progressBar.refreshWheel();
}
});
colorAnimator.setInterpolator(new DecelerateInterpolator());
colorAnimator.setDuration(remainingTime);
colorAnimator.start();
and in ProgressWheel.java
public void refreshWheel() {
setupPaints();
}