大家不知道有沒有見過櫻花飄落和花瓣飄落的風景，沒見過沒關系，今天我們來說一下“在Android開發(fā)中怎么實現(xiàn)花瓣飄落效果？”這個效果的實現(xiàn)方法！
實現(xiàn)原理
- 首先需要生成繪制小花的坐標點，坐標點的橫坐標是根據(jù)控件的寬度隨機生成的，而縱坐標則設置為小花圖片高度的負值（這樣可以實現(xiàn)小花從屏幕外進入）。
- 將這些點存儲到集合當中。
- 遍歷集合根據(jù)點的位置繪制小花
- 繪制完后不斷增加各個點的縱坐標
實現(xiàn)步驟
1.定義變量將變量初始化
private SurfaceHolder mHolder;
private boolean mFlag = true;//繪制小花線程的開關標志
private ArrayList<PointF> mFlowers;//小花點的坐標集合
private Random mRandom;//負責隨機數(shù)生成
private Bitmap mBitmap;//小花的圖案
public FlowerView(Context context) {
super(context);
init();
}
public FlowerView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public FlowerView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init(){
mHolder = getHolder();
mHolder.addCallback(this);
//設置背景透明
this.setZOrderOnTop(true);
mHolder.setFormat(PixelFormat.TRANSLUCENT);
mFlowers = new ArrayList<>();
mRandom = new Random();
mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_hua);
}
2.實現(xiàn)添加花朵坐標點的方法
/**
* 添加花朵
*/
private void addFlower(){
PointF point = new PointF();
point.x=mRandom.nextInt(getWidth());//根據(jù)控件寬度隨機生成X軸坐標
point.y=-mBitmap.getHeight();//縱坐標設置為小花圖像的負值（產(chǎn)生從屏幕外進入的效果）
mFlowers.add(point);//將坐標點添加進集合
}
3.實現(xiàn)SurfaceHolder.Callback及Runnable接口
public class FlowerView extends SurfaceView implements SurfaceHolder.Callback,Runnable
4.在run方法中實現(xiàn)繪制邏輯
@Override
public void run() {
while (mFlag){
try {
Thread.sleep(80);//控制小花的下落速度
Canvas canvas = mHolder.lockCanvas();
PointF pointF = null;
//清屏操作（否則會殘留一些無用圖像）
if(canvas!=null){
canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
}else {
continue;
}
for(PointF point: mFlowers){
pointF = point;
canvas.drawBitmap(mBitmap,pointF.x,pointF.y,null);
int i = mRandom.nextInt(getHeight()/50)+getHeight()/50;//修改雨滴線的縱坐標，使其看起來在下雨
pointF.y=pointF.y+i;
}
mHolder.unlockCanvasAndPost(canvas);
addFlower();
//當繪制點的縱坐標大于控件高度時，將該點移除
if(mFlowers.size()>0&&pointF!=null&&pointF.y>=getHeight()){
mFlowers.remove(pointF);
}
}catch (Exception e){}
}
}
5.在SurfaceHolder.Callback的回調(diào)方法中開啟繪制線程
@Override
public void surfaceCreated(SurfaceHolder holder) {
mFlag = true;//surface創(chuàng)建時將線程開關打開
new Thread(this).start();//開啟線程繪制
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
mFlowers.clear();//當控件發(fā)生改變時清除之前的繪制點
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
mFlag = false;//當surface銷毀時關掉繪制線程
}
完整代碼展示
public class FlowerView extends SurfaceView implements SurfaceHolder.Callback,Runnable{
private SurfaceHolder mHolder;
private boolean mFlag = true;//繪制小花線程的開關標志
private ArrayList<PointF> mFlowers;//小花點的坐標集合
private Random mRandom;//負責隨機數(shù)生成
private Bitmap mBitmap;//小花的圖案
public FlowerView(Context context) {
super(context);
init();
}
public FlowerView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public FlowerView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init(){
mHolder = getHolder();
mHolder.addCallback(this);
//設置背景透明
this.setZOrderOnTop(true);
mHolder.setFormat(PixelFormat.TRANSLUCENT);
mFlowers = new ArrayList<>();
mRandom = new Random();
mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_hua);
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
mFlag = true;
new Thread(this).start();
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
mFlowers.clear();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
mFlag = false;
}
@Override
public void run() {
while (mFlag){
try {
Thread.sleep(80);
Canvas canvas = mHolder.lockCanvas();
PointF pointF = null;
//清屏操作
if(canvas!=null){
canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
}else {
continue;
}
for(PointF point: mFlowers){
pointF = point;
canvas.drawBitmap(mBitmap,pointF.x,pointF.y,null);
int i = mRandom.nextInt(getHeight()/50)+getHeight()/50;//修改雨滴線的縱坐標，使其看起來在下雨
pointF.y=pointF.y+i;
}
mHolder.unlockCanvasAndPost(canvas);
addFlower();
if(mFlowers.size()>0&&pointF!=null&&pointF.y>=getHeight()){
mFlowers.remove(pointF);
}
}catch (Exception e){}
}
}
/**
* 添加花朵
*/
private void addFlower(){
PointF point = new PointF();
point.x=mRandom.nextInt(getWidth());
point.y=-mBitmap.getHeight();
mFlowers.add(point);
}
}
那么本文中有關于：“在Android開發(fā)中怎么實現(xiàn)花瓣飄落效果？”這個問題的實現(xiàn)和思路我們就分享到這里了更多有關于Android的實現(xiàn)案例我們都可以在W3Cschool中進行學習和了解！
