How to make smooth frame animation in android?

问题:

I made a frame animation. But the transitition between images is bad looking. How can I apply a crossfade effect to it ?

When using TransitionDrawable i get the proper result but it stops after one execution.

Any one has an idea how to resolve it?

public void startAnimation() {
    if (logoAnimation != null) {
        if (logoAnimation.isRunning()) {
            logoAnimation.stop();
        }
        logoAnimation.start();
    }
}

private int setLogoAnimation(int animationID, int targetID) {
    imageView = (ImageView) window.findViewById(targetID);
    imageView.setImageResource(animationID);
    logoAnimation = (AnimationDrawable) imageView.getDrawable();

    if (imageView != null && logoAnimation != null) {
        return 1;
    } else {
        return 0;
    }
}

Than I simply run it by object.startAnimation(); I works, but the animation is ugly and I need it to be smooth.

回答1:

If you want to crossfade between two pictures, why not use an AlphaAnimation which will alter the transparency of two views and will create the effect that you require.

Create two animations:

res/anim/fadeout.xml

<?xml version="1.0" encoding="utf-8"?>
<alpha xmlns:android="http://schemas.android.com/apk/res/android"
    android:interpolator="@android:anim/accelerate_interpolator"
    android:fromAlpha="1.0" android:toAlpha="0.0"
    android:duration="@android:integer/config_mediumAnimTime" />

res/anim/fadein.xml

<?xml version="1.0" encoding="utf-8"?>
<alpha xmlns:android="http://schemas.android.com/apk/res/android"
    android:interpolator="@android:anim/accelerate_interpolator"
    android:fromAlpha="0.0" android:toAlpha="1.0"
    android:duration="@android:integer/config_mediumAnimTime" />

and then override the default transition between activities:

startActivity( new Intent( this, SecondActivity.class ) );
overridePendingTransition( R.anim.fadeout, R.anim.fadein );

or you can apply animations to specific widgets:

Animation animation = AnimationUtils.loadAnimation( this, R.anim.fadeout );
image1.startAnimation( animation );

I am currently in the middle of a series on animation on my blog which may give you some further information.

回答2:

By using frame animation increasing frame number can help you to get a good result. In my case the result was satisfactory on my HTC Evo.

While using tween animation you can use linear interpolator. For rotation for example

<?xml version="1.0" encoding="UTF-8"?>  
<rotate  
    xmlns:android="http://schemas.android.com/apk/res/android"  
    android:fromDegrees="0"  
    android:toDegrees="359"  
    android:pivotX="50%"  
    android:pivotY="50%"  
    android:repeatCount="infinite"  
    android:duration="1000"  
    android:interpolator="@anim/linear_interpolator" />  

And you interpolator file content here

<?xml version="1.0" encoding="utf-8"?>
<linearInterpolator xmlns:android="http://schemas.android.com/apk/res/android" />

This is for rotation, you can see full list here.

http://developer.android.com/guide/topics/resources/animation-resource.html

or you can read a blog post that I write how to make a loading animation.

http://yekmer.posterous.com/how-to-make-a-loading-animator-in-android