一、原理说明
主要是通过计算轨迹的坐标点加入到集合中，然后对集合进行相应截取，传入canvas中。
二、具体代码实现
/**
* 原理是先通过尺寸把各个轨迹的坐标计算出来，然后再截取相应坐标，进行重绘。
*
* @author lz
* @Time 2019-3-27
*/
public class RotateTrackView extends View {
/**
* 起始点横坐标
*/
private float startXPoint;
/**
* 起始点纵坐标
*/
private float startYPoint;
/**
* 宽度
*/
private float width;
/**
* 高度
*/
private float heigth;
/**
* 圆角半径
*/
private float radius;
/**
* 图形点集合
*/
float[] mPoints;
/**
* 画笔
*/
private Paint mPaint;
/**
* 标志位
*/
private final int LeftUp = 0;
private final int LeftDown = 1;
private final int RightDown = 2;
private final int RightUp = 3;
/**
* 停止动画标志位
*/
private boolean isPause = false;
/**
* 动画开始位置起点
*/
private int indexBegin = 0;
/**
* 动画结束位置，也就是整个动画的长度
*/
private int indexEnd = 200;
private int LENGTH = 200;
private int TIME = 1;
/**
* 截取的轨迹点集合
*/
private float[] snackPoints;
public RotateTrackView(Context context) {
super(context);
}
public RotateTrackView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public RotateTrackView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
public RotateTrackView(Context context, float startXPoint, float startYPoint, float width, float heigth, float radius) {
this(context);
this.startXPoint = startXPoint;
this.startYPoint = startYPoint;
this.heigth = heigth;
this.width = width;
this.radius = radius;
// 初始化画笔
mPaint = new Paint();
mPaint.setColor(Color.RED);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeWidth(8);
// 轨迹计算
ArrayList<Float> mPointLists = new ArrayList<>();
addXPoints(width, radius, startXPoint, startYPoint, mPointLists);
addCircleArgle(RightUp, radius, mPointLists);
addYPoints(heigth, radius, mPointLists.get(mPointLists.size() - 1), mPointLists.get(mPointLists.size() - 2), mPointLists);
addCircleArgle(RightDown, radius, mPointLists);
reduceXPoints(width, radius, mPointLists.get(mPointLists.size() - 2), mPointLists.get(mPointLists.size() - 1), mPointLists);
addCircleArgle(LeftDown, radius, mPointLists);
reduceYPoints(heigth, radius, mPointLists.get(mPointLists.size() - 1), mPointLists.get(mPointLists.size() - 2), mPointLists);
addCircleArgle(LeftUp, radius, mPointLists);
// 将list集合转换成canvas接受的float数组
mPoints = new float[mPointLists.size()];
for (int i = 0; i < mPointLists.size(); i++) {
mPoints[i] = mPointLists.get(i);
}
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (snackPoints.length == LENGTH) {
canvas.drawPoints(snackPoints, mPaint);
}
}
/**
* x轴向右计算
*
* @param length
* @param radius
* @param addNumber
* @param constantNumber
* @param list
*/
private void addXPoints(float length, float radius, float addNumber, float constantNumber, List<Float> list) {
for (int i = 1; i < (length - 2 * radius); i++) {
float pointX = addNumber + i;
float pointY = constantNumber;
list.add(pointX);
list.add(pointY);
}
}
private void reduceXPoints(float length, float radius, float addNumber, float constantNumber, List<Float> list) {
for (int i = 1; i < (length - 2 * radius); i++) {
float pointX = addNumber - i;
float pointY = constantNumber;
list.add(pointX);
list.add(pointY);
}
}
private void addYPoints(float length, float radius, float addNumber, float constantNumber, List<Float> list) {
for (int i = 1; i < (length - 2 * radius); i++) {
float pointX = addNumber + i;
float pointY = constantNumber;
list.add(pointY);
list.add(pointX);
}
}
private void reduceYPoints(float length, float radius, float addNumber, float constantNumber, List<Float> list) {
for (int i = 1; i < (length - 2 * radius); i++) {
float pointX = addNumber - i;
float pointY = constantNumber;
list.add(pointY);
list.add(pointX);
}
}
/**
* 由于上下左右四个圆的轨迹坐标计算方式是不一样的，需要单独处理
*
* @param position
* @param radius
* @param list
*/
private void addCircleArgle(int position, float radius, List<Float> list) {
int argle = 0;
float x = list.get(list.size() - 2);
float y = list.get(list.size() - 1);
for (int i = 0; i < 90; i += 10) {
argle = i + 10;
switch (position) {
case RightUp:
float x1 = (float) (x + Math.sin((Math.PI / 180) * argle) * radius);
float y1 = (float) (y + (radius - Math.cos((Math.PI / 180) * argle) * radius));
list.add(x1);
list.add(y1);
break;
case RightDown:
float x2 = (float) (x - (radius - Math.cos((Math.PI / 180) * argle) * radius));
float y2 = (float) (y + (Math.sin((Math.PI / 180) * argle) * radius));
list.add(x2);
list.add(y2);
break;
case LeftDown:
float x3 = (float) (x - (Math.sin((Math.PI / 180) * argle) * radius));
float y3 = (float) (y - (radius - Math.cos((Math.PI / 180) * argle) * radius));
list.add(x3);
list.add(y3);
break;
case LeftUp:
float x4 = (float) (x + (radius - Math.cos((Math.PI / 180) * argle) * radius));
float y4 = (float) (y - (Math.sin((Math.PI / 180) * argle) * radius));
list.add((float) (x + (radius - Math.cos((Math.PI / 180) * argle) * radius)));
list.add((float) (y - (Math.sin((Math.PI / 180) * argle) * radius)));
break;
default:
break;
}
}
}
/**
* 开始动画
*/
public void startAnim() {
Thread thread = new Thread() {
@Override
public void run() {
super.run();
while (!isPause) {
RotateTrackView.this.post(new Runnable() {
@Override
public void run() {
invalidate();
}
});
indexBegin += 2;
indexEnd += 2;
if (indexEnd < mPoints.length) {
snackPoints = (Arrays.copyOfRange(mPoints, indexBegin, indexEnd));
} else if (indexBegin == mPoints.length) {
indexBegin = 0;
indexEnd = LENGTH;
} else {
float[] floats2 = Arrays.copyOfRange(mPoints, indexBegin, mPoints.length);
float[] floats3 = Arrays.copyOf(floats2, LENGTH);
int length = floats2.length;
for (int i = 0; i < (LENGTH - floats2.length); i++) {
floats3[length] = mPoints[i];
length++;
}
snackPoints = floats3;
}
try {
Thread.sleep(TIME);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
};
thread.start();
}
/**
* 停止动画
*/
public void stopAnim() {
isPause = true;
}
/**
* 设置轨迹粗细
*/
public void setLinesWidth(int width) {
mPaint.setStrokeWidth(width);
}
}
三、使用方法
public class MainActivity extends AppCompatActivity {
private RotateTrackView rotateTrackView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// 创建RotateTrackView， 设置起始坐标、宽、高、圆角半径
rotateTrackView = new RotateTrackView(this, 500, 600, 250, 180, 30);
setContentView(rotateTrackView);
// 设置画笔粗细
rotateTrackView.setLinesWidth(20);
// 开始动画
rotateTrackView.startAnim();
}
}
四、效果展示
RotateTrackView.gif
