This is a sample activity which shows how RotateAnimation works along with draw text in a path such as a circle.
Underlying Algorithm:
Basic description of algorithm in step by step form:
1.) Create a Project AnimationSample.
2.) To display text in circular path, use this code snippet inside onDraw() method:
Path circle = new Path();
int centerX = canvas.getWidth() / 2;
int centerY = canvas.getHeight() / 2;
int r = Math.min(centerX, centerY);
circle.addCircle(centerX, centerY, r, Direction.CW);
Paint paint = new Paint();
paint.setColor(Color.GREEN);
paint.setTextSize(30);
paint.setAntiAlias(true);
canvas.drawTextOnPath(AnimatedTxt, circle, 0, 30, paint);
3.) To Animate the text in Rotation create a method like createAnim() :
private void createAnim(Canvas canvas) {
rotateAnim = new RotateAnimation(0, 360, canvas.getWidth() / 2, canvas.getHeight() / 2);
rotateAnim.setRepeatMode(Animation.REVERSE);
rotateAnim.setRepeatCount(Animation.INFINITE);
rotateAnim.setDuration(10000L);
rotateAnim.setInterpolator(new AccelerateDecelerateInterpolator());
startAnimation(rotateAnim);
}
4.) Run the application.
Steps to Create:
1.) Open Eclipse. Use the New Project Wizard and select Android Project Give the respective project name i.e. AnimationSample. Enter following information:
Project name: AnimationSample
Build Target: Android 2.3
Application name: AnimationSample
Package name: com.anim.AnimationSample
Create Activity: AnimationSample
On Clicking Finish AnimationSample code structure is generated with the necessary Android Packages being imported along with AnimationSample.java. AnimationSample class will look like following:
package com.anim.AnimationSample;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Path.Direction;
import android.os.Bundle;
import android.view.View;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.view.animation.Animation;
import android.view.animation.RotateAnimation;
public class AnimationSample extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new GraphicsView(this));
}
private static class GraphicsView extends View {
private static final String AnimatedTxt =
"This Sample Program Shows, Aniamtion Using Path. This is very simple and easy to understand.";
private Animation rotateAnim;
public GraphicsView(Context context) {
super(context);
}
private void createAnim(Canvas canvas) {
rotateAnim = new RotateAnimation(0, 360, canvas.getWidth() / 2, canvas.getHeight() / 2);
rotateAnim.setRepeatMode(Animation.REVERSE);
rotateAnim.setRepeatCount(Animation.INFINITE);
rotateAnim.setDuration(10000L);
rotateAnim.setInterpolator(new AccelerateDecelerateInterpolator());
startAnimation(rotateAnim);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// creates the animation the first time
if (rotateAnim == null) {
createAnim(canvas);
}
Path circle = new Path();
int centerX = canvas.getWidth() / 2;
int centerY = canvas.getHeight() / 2;
int r = Math.min(centerX, centerY);
circle.addCircle(centerX, centerY, r, Direction.CW);
Paint paint = new Paint();
paint.setColor(Color.GREEN);
paint.setTextSize(30);
paint.setAntiAlias(true);
canvas.drawTextOnPath(AnimatedTxt, circle, 0, 30, paint);
}
}
}
Output –The final output:
