With this example we are going to demonstrate how to create and display a Sprite animation in an Android Application.
A Sprite animation is a moving image animation that you will have seen in a gif image. For example imagine a human walking.
To create this kind of animation in Android is simple. In short, to create and use a Sprite Animation you should:
- create an image with all the movement frames. For simplicity make sure that all the frames have the same size
- determine the size of the frame.
- create a bitmap that will contain all the frames
- give a frame period in milliseconds which will represented the amount of time that each frame will be displayed
- create an
updatefunction that will update the frame that is displayed according to the actual application time
as shown in the code snippets below:
package net.obviam.walking.model;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
public class ElaineAnimated {
private static final String TAG = ElaineAnimated.class.getSimpleName();
private Bitmap bitmap; // the animation sequence
private Rect sourceRect; // the rectangle to be drawn from the animation bitmap
private int frameNr; // number of frames in animation
private int currentFrame; // the current frame
private long frameTicker; // the time of the last frame update
private int framePeriod; // milliseconds between each frame (1000/fps)
private int spriteWidth; // the width of the sprite to calculate the cut out rectangle
private int spriteHeight; // the height of the sprite
private int x; // the X coordinate of the object (top left of the image)
private int y; // the Y coordinate of the object (top left of the image)
public ElaineAnimated(Bitmap bitmap, int x, int y, int width, int height, int fps, int frameCount) {
this.bitmap = bitmap;
this.x = x;
this.y = y;
currentFrame = 0;
frameNr = frameCount;
spriteWidth = bitmap.getWidth() / frameCount;
spriteHeight = bitmap.getHeight();
sourceRect = new Rect(0, 0, spriteWidth, spriteHeight);
framePeriod = 1000 / fps;
frameTicker = 0l;
}
public Bitmap getBitmap() {
return bitmap;
}
public void setBitmap(Bitmap bitmap) {
this.bitmap = bitmap;
}
public Rect getSourceRect() {
return sourceRect;
}
public void setSourceRect(Rect sourceRect) {
this.sourceRect = sourceRect;
}
public int getFrameNr() {
return frameNr;
}
public void setFrameNr(int frameNr) {
this.frameNr = frameNr;
}
public int getCurrentFrame() {
return currentFrame;
}
public void setCurrentFrame(int currentFrame) {
this.currentFrame = currentFrame;
}
public int getFramePeriod() {
return framePeriod;
}
public void setFramePeriod(int framePeriod) {
this.framePeriod = framePeriod;
}
public int getSpriteWidth() {
return spriteWidth;
}
public void setSpriteWidth(int spriteWidth) {
this.spriteWidth = spriteWidth;
}
public int getSpriteHeight() {
return spriteHeight;
}
public void setSpriteHeight(int spriteHeight) {
this.spriteHeight = spriteHeight;
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
// the update method for Elaine
public void update(long gameTime) {
if (gameTime > frameTicker + framePeriod) {
frameTicker = gameTime;
// increment the frame
currentFrame++;
if (currentFrame >= frameNr) {
currentFrame = 0;
}
}
// define the rectangle to cut out sprite
this.sourceRect.left = currentFrame * spriteWidth;
this.sourceRect.right = this.sourceRect.left + spriteWidth;
}
// the draw method which draws the corresponding frame
public void draw(Canvas canvas) {
// where to draw the sprite
Rect destRect = new Rect(getX(), getY(), getX() + spriteWidth, getY() + spriteHeight);
canvas.drawBitmap(bitmap, sourceRect, destRect, null);
canvas.drawBitmap(bitmap, 20, 150, null);
Paint paint = new Paint();
paint.setARGB(50, 0, 255, 0);
canvas.drawRect(20 + (currentFrame * destRect.width()), 150, 20 + (currentFrame * destRect.width()) + destRect.width(), 150 + destRect.height(), paint);
}
}
This was an example of how to create Sprite Animations in Android.
Related Article:
Reference: Sprite Animation with Android from our JCG partner Tamas Jano at the “Against The Grain” blog.
