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(guān)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(shè)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(guān)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(shè)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(shè)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(guān)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(guān)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(guān)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(shè)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(guān)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(guān)于Android的實現(xiàn)案例我們都可以在W3Cschool中進行學習和了解!