上一篇《Android 自定义View(四) 叶子飘动+旋转效果》实现了单片叶子的滑动及旋转，下面实现多片叶子的滑动旋转功能

实现思路比较简单，就是添加一个叶子Leaf类，储存每片叶子的信息，

然后随机产生叶子的坐标及旋转角度，最后实时获取每片叶子信息，添加到画布中

1、Leaf.java 叶子类

private class Leaf { // 叶子的坐标 float x, y; // 旋转角度 int rotateAngle; // 起始时间(ms) long startTime; }

2、初始化每片叶子的信息，然后保存到list中

//使叶子初始时间有间隔 int addTime; private Leaf getLeaf() { Random random = new Random(); Leaf leaf = new Leaf(); //随机初始化叶子初始角度 leaf.rotateAngle = random.nextInt(360); //随机初始化叶子启动时间 addTime += random.nextInt((int) (cycleTime)); leaf.startTime = System.currentTimeMillis() + cycleTime + addTime; return leaf; } private List<Leaf> getLeafs(int leafSize) { List<Leaf> list = new LinkedList<Leaf>(); for (int i=0; i<leafSize; i++) { list.add(getLeaf()); } return list; }

3、接下去就是改写getLocation()及getRotate()方法，使其返回每片叶子的坐标及旋转角度

//获取每片叶子在XY轴上的滑动值 private void getLocation(Leaf leaf) { float betweenTime = leaf.startTime - System.currentTimeMillis(); //周期结束再加一个cycleTime if(betweenTime < 0) { leaf.startTime = System.currentTimeMillis() + cycleTime + new Random().nextInt((int) (cycleTime)); betweenTime = cycleTime; } //通过时间差计算出叶子的坐标 float fraction = (float) betweenTime / cycleTime; float x = (int)(width * fraction); leaf.x = x; float w = (float) ((float) 2 * Math.PI / width); int y = (int) (18 * Math.sin(w * x)) + (height-mLeafHeight)/2; leaf.y = y; } //获取每片叶子的旋转角度 private void getRotate(Leaf leaf) { float scale = ((leaf.startTime - System.currentTimeMillis())%cycleTime)/ (float)cycleTime; int rotate = (int)(scale * 360); leaf.rotateAngle = rotate; }

4、在onDraw()方法中，画出每片叶子

@Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //画叶子 int size = leafList.size(); for (int i=0; i<size; i++) { Leaf leaf = leafList.get(i); //获取叶子坐标 getLocation(leaf); //获取叶子旋转角度 getRotate(leaf); canvas.save(); Matrix matrix = new Matrix(); //设置滑动 matrix.postTranslate(leaf.x, leaf.y); //设置旋转 matrix.postRotate(leaf.rotateAngle, leaf.x + mLeafWidth / 2, leaf.y + mLeafHeight / 2); //添加叶子到画布 canvas.drawBitmap(mLeafBitmap, matrix, new Paint()); canvas.restore(); } //调用onDraw()重复滑动 postInvalidate(); }

完整代码：

public class LeafView extends View { private String TAG = "--------LeafView"; private Resources mResources; //背景图、叶子 private Bitmap mLeafBitmap, bgBitmap; //整个控件的宽度和高度 private int width, height; private Paint bgPaint; private RectF bgRect; private Rect bgDestRect; //存放叶子lsit private List<Leaf> leafList; //叶子的宽和高 private int mLeafWidth, mLeafHeight; //叶子滑动一周的时间5秒 private final static long cycleTime = 5000; //叶子数量 private final static int leafNumber = 5; public LeafView(Context context, AttributeSet attrs) { super(context, attrs); mResources = getResources(); mLeafBitmap = ((BitmapDrawable) mResources.getDrawable(R.drawable.leaf, null)).getBitmap(); mLeafWidth = mLeafBitmap.getWidth(); mLeafHeight = mLeafBitmap.getHeight() bgBitmap = ((BitmapDrawable) mResources.getDrawable(R.drawable.leaf_kuang, null)).getBitmap(); bgPaint = new Paint(); bgPaint.setColor(mResources.getColor(R.color.bg_color)); //获取所有叶子的信息，放入list leafList = getLeafs(leafNumber); } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); width = w; height = h; bgDestRect = new Rect(0, 0 , width, height); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); bgRect = new RectF(0, 0 , width, height); //画背景颜色到画布 canvas.drawRect(bgRect, bgPaint); //画背景图片到画布 canvas.drawBitmap(bgBitmap, null, bgDestRect, null); //画叶子 int size = leafList.size(); for (int i=0; i<size; i++) { Leaf leaf = leafList.get(i); //获取叶子坐标 getLocation(leaf); //获取叶子旋转角度 getRotate(leaf); canvas.save(); Matrix matrix = new Matrix(); //设置滑动 matrix.postTranslate(leaf.x, leaf.y); //设置旋转 matrix.postRotate(leaf.rotateAngle, leaf.x + mLeafWidth / 2, leaf.y + mLeafHeight / 2); //添加叶子到画布 canvas.drawBitmap(mLeafBitmap, matrix, new Paint()); canvas.restore(); } //调用onDraw()重复滑动 postInvalidate(); } //获取每片叶子在XY轴上的滑动值 private void getLocation(Leaf leaf) { float betweenTime = leaf.startTime - System.currentTimeMillis(); //周期结束再加一个cycleTime if(betweenTime < 0) { leaf.startTime = System.currentTimeMillis() + cycleTime + new Random().nextInt((int) (cycleTime)); betweenTime = cycleTime; } //通过时间差计算出叶子的坐标 float fraction = (float) betweenTime / cycleTime; float x = (int)(width * fraction); leaf.x = x; float w = (float) ((float) 2 * Math.PI / width); int y = (int) (18 * Math.sin(w * x)) + (height-mLeafHeight)/2; leaf.y = y; } //获取每片叶子的旋转角度 private void getRotate(Leaf leaf) { float scale = ((leaf.startTime - System.currentTimeMillis())%cycleTime)/ (float)cycleTime; int rotate = (int)(scale * 360); leaf.rotateAngle = rotate; } private class Leaf { // 叶子的坐标 float x, y; // 旋转角度 int rotateAngle; // 起始时间(ms) long startTime; } private List<Leaf> getLeafs(int leafSize) { List<Leaf> list = new LinkedList<Leaf>(); for (int i=0; i<leafSize; i++) { list.add(getLeaf()); } return list; } //使叶子初始时间有间隔 int addTime; private Leaf getLeaf() { Random random = new Random(); Leaf leaf = new Leaf(); leaf.rotateAngle = random.nextInt(360); addTime += random.nextInt((int) (cycleTime)); leaf.startTime = System.currentTimeMillis() + cycleTime + addTime; return leaf; }}

这里还有很多瑕疵，比如叶子的滑动范围覆盖了边框等等

需要图片等信息的可以从下面的Github地址下载，不过原文比较复杂

参考 https://github.com/Ajian-studio/GALeafLoading

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。