This is a simple example of how to animate a drawable in Android.
This example is from the official android demo applications.
Here we have 5 java classes.
AnimateDrawable.java
AnimateDrawables.java
GraphicsActivity.java
PictureLayout.java
ProxyDrawable.java
AnimateDrawable.java
package com.coderzheaven.animatedrawable;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.Transformation;
public class AnimateDrawable extends ProxyDrawable {
private Animation mAnimation;
private Transformation mTransformation = new Transformation();
public AnimateDrawable(Drawable target) {
super(target);
}
public AnimateDrawable(Drawable target, Animation animation) {
super(target);
mAnimation = animation;
}
public Animation getAnimation() {
return mAnimation;
}
public void setAnimation(Animation anim) {
mAnimation = anim;
}
public boolean hasStarted() {
return mAnimation != null && mAnimation.hasStarted();
}
public boolean hasEnded() {
return mAnimation == null || mAnimation.hasEnded();
}
@Override
public void draw(Canvas canvas) {
Drawable dr = getProxy();
if (dr != null) {
int sc = canvas.save();
Animation anim = mAnimation;
if (anim != null) {
anim.getTransformation(
AnimationUtils.currentAnimationTimeMillis(),
mTransformation);
canvas.concat(mTransformation.getMatrix());
}
dr.draw(canvas);
canvas.restoreToCount(sc);
}
}
}
AnimateDrawables.java
package com.coderzheaven.animatedrawable;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.TranslateAnimation;
public class AnimateDrawables extends GraphicsActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new SampleView(this));
}
private static class SampleView extends View {
private AnimateDrawable mDrawable;
public SampleView(Context context) {
super(context);
setFocusable(true);
setFocusableInTouchMode(true);
Drawable dr = context.getResources().getDrawable(R.drawable.ic_launcher);
dr.setBounds(0, 0, dr.getIntrinsicWidth(), dr.getIntrinsicHeight());
Animation an = new TranslateAnimation(0, 100, 0, 200);
an.setDuration(2000);
an.setRepeatCount(-1);
an.initialize(10, 10, 10, 10);
mDrawable = new AnimateDrawable(dr, an);
an.startNow();
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.WHITE);
mDrawable.draw(canvas);
invalidate();
}
}
}
GraphicsActivity.java
package com.coderzheaven.animatedrawable;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
class GraphicsActivity extends Activity {
// set to true to test Picture
private static final boolean TEST_PICTURE = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public void setContentView(View view) {
if (TEST_PICTURE) {
ViewGroup vg = new PictureLayout(this);
vg.addView(view);
view = vg;
}
super.setContentView(view);
}
}
PictureLayout.java
package com.coderzheaven.animatedrawable;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Picture;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;
public class PictureLayout extends ViewGroup {
private final Picture mPicture = new Picture();
public PictureLayout(Context context) {
super(context);
}
public PictureLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
public void addView(View child) {
if (getChildCount() > 1) {
throw new IllegalStateException("PictureLayout can host only one direct child");
}
super.addView(child);
}
@Override
public void addView(View child, int index) {
if (getChildCount() > 1) {
throw new IllegalStateException("PictureLayout can host only one direct child");
}
super.addView(child, index);
}
@Override
public void addView(View child, LayoutParams params) {
if (getChildCount() > 1) {
throw new IllegalStateException("PictureLayout can host only one direct child");
}
super.addView(child, params);
}
@Override
public void addView(View child, int index, LayoutParams params) {
if (getChildCount() > 1) {
throw new IllegalStateException("PictureLayout can host only one direct child");
}
super.addView(child, index, params);
}
@Override
protected LayoutParams generateDefaultLayoutParams() {
return new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
final int count = getChildCount();
int maxHeight = 0;
int maxWidth = 0;
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (child.getVisibility() != GONE) {
measureChild(child, widthMeasureSpec, heightMeasureSpec);
}
}
maxWidth += getPaddingLeft() + getPaddingRight();
maxHeight += getPaddingTop() + getPaddingBottom();
Drawable drawable = getBackground();
if (drawable != null) {
maxHeight = Math.max(maxHeight, drawable.getMinimumHeight());
maxWidth = Math.max(maxWidth, drawable.getMinimumWidth());
}
setMeasuredDimension(resolveSize(maxWidth, widthMeasureSpec),
resolveSize(maxHeight, heightMeasureSpec));
}
private void drawPict(Canvas canvas, int x, int y, int w, int h,
float sx, float sy) {
canvas.save();
canvas.translate(x, y);
canvas.clipRect(0, 0, w, h);
canvas.scale(0.5f, 0.5f);
canvas.scale(sx, sy, w, h);
canvas.drawPicture(mPicture);
canvas.restore();
}
@Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(mPicture.beginRecording(getWidth(), getHeight()));
mPicture.endRecording();
int x = getWidth()/2;
int y = getHeight()/2;
drawPict(canvas, 0, 0, x, y, 1, 1);
drawPict(canvas, x, 0, x, y, -1, 1);
drawPict(canvas, 0, y, x, y, 1, -1);
drawPict(canvas, x, y, x, y, -1, -1);
}
@Override
public ViewParent invalidateChildInParent(int[] location, Rect dirty) {
location[0] = getLeft();
location[1] = getTop();
dirty.set(0, 0, getWidth(), getHeight());
return getParent();
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
final int count = super.getChildCount();
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (child.getVisibility() != GONE) {
final int childLeft = getPaddingLeft();
final int childTop = getPaddingTop();
child.layout(childLeft, childTop,
childLeft + child.getMeasuredWidth(),
childTop + child.getMeasuredHeight());
}
}
}
}
ProxyDrawable.java
package com.coderzheaven.animatedrawable;
import android.graphics.Canvas;
import android.graphics.ColorFilter;
import android.graphics.PixelFormat;
import android.graphics.drawable.Drawable;
public class ProxyDrawable extends Drawable {
private Drawable mProxy;
private boolean mMutated;
public ProxyDrawable(Drawable target) {
mProxy = target;
}
public Drawable getProxy() {
return mProxy;
}
public void setProxy(Drawable proxy) {
if (proxy != this) {
mProxy = proxy;
}
}
@Override
public void draw(Canvas canvas) {
if (mProxy != null) {
mProxy.draw(canvas);
}
}
@Override
public int getIntrinsicWidth() {
return mProxy != null ? mProxy.getIntrinsicWidth() : -1;
}
@Override
public int getIntrinsicHeight() {
return mProxy != null ? mProxy.getIntrinsicHeight() : -1;
}
@Override
public int getOpacity() {
return mProxy != null ? mProxy.getOpacity() : PixelFormat.TRANSPARENT;
}
@Override
public void setFilterBitmap(boolean filter) {
if (mProxy != null) {
mProxy.setFilterBitmap(filter);
}
}
@Override
public void setDither(boolean dither) {
if (mProxy != null) {
mProxy.setDither(dither);
}
}
@Override
public void setColorFilter(ColorFilter colorFilter) {
if (mProxy != null) {
mProxy.setColorFilter(colorFilter);
}
}
@Override
public void setAlpha(int alpha) {
if (mProxy != null) {
mProxy.setAlpha(alpha);
}
}
@Override
public Drawable mutate() {
if (mProxy != null && !mMutated && super.mutate() == this) {
mProxy.mutate();
mMutated = true;
}
return this;
}
}
Download the complete source code from here