Update

CustomView/Advance/[6]Path_Bezier.md

@@ -387,6 +387,176 @@ public class Bezier2 extends View {
 
 #### 代码：
 
+``` java
+public class Bezier3 extends View {
+    private static final float C = 0.551915024494f;     // 一个常量，用来计算绘制圆形贝塞尔曲线控制点的位置
+
+    private Paint mPaint;
+    private int mCenterX, mCenterY;
+
+    private PointF mCenter = new PointF(0,0);
+    private float mCircleRadius = 200;                  // 圆的半径
+    private float mDifference = mCircleRadius*C;        // 圆形的控制点与数据点的差值
+
+    private float[] mData = new float[8];               // 顺时针记录绘制圆形的四个数据点
+    private float[] mCtrl = new float[16];              // 顺时针记录绘制圆形的八个控制点
+
+    private float mDuration = 1000;                     // 变化总时长
+    private float mCurrent = 0;                         // 当前已进行时长
+    private float mCount = 100;                         // 将时长总共划分多少份
+    private float mPiece = mDuration/mCount;            // 每一份的时长
+
+
+    public Bezier3(Context context) {
+        this(context, null);
+
+    }
+
+    public Bezier3(Context context, AttributeSet attrs) {
+        super(context, attrs);
+
+        mPaint = new Paint();
+        mPaint.setColor(Color.BLACK);
+        mPaint.setStrokeWidth(8);
+        mPaint.setStyle(Paint.Style.STROKE);
+        mPaint.setTextSize(60);
+
+
+        // 初始化数据点
+
+        mData[0] = 0;
+        mData[1] = mCircleRadius;
+
+        mData[2] = mCircleRadius;
+        mData[3] = 0;
+
+        mData[4] = 0;
+        mData[5] = -mCircleRadius;
+
+        mData[6] = -mCircleRadius;
+        mData[7] = 0;
+
+        // 初始化控制点
+
+        mCtrl[0]  = mData[0]+mDifference;
+        mCtrl[1]  = mData[1];
+
+        mCtrl[2]  = mData[2];
+        mCtrl[3]  = mData[3]+mDifference;
+
+        mCtrl[4]  = mData[2];
+        mCtrl[5]  = mData[3]-mDifference;
+
+        mCtrl[6]  = mData[4]+mDifference;
+        mCtrl[7]  = mData[5];
+
+        mCtrl[8]  = mData[4]-mDifference;
+        mCtrl[9]  = mData[5];
+
+        mCtrl[10] = mData[6];
+        mCtrl[11] = mData[7]-mDifference;
+
+        mCtrl[12] = mData[6];
+        mCtrl[13] = mData[7]+mDifference;
+
+        mCtrl[14] = mData[0]-mDifference;
+        mCtrl[15] = mData[1];
+    }
+
+
+    @Override
+    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
+        super.onSizeChanged(w, h, oldw, oldh);
+        mCenterX = w / 2;
+        mCenterY = h / 2;
+    }
+
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        super.onDraw(canvas);
+         drawCoordinateSystem(canvas);       // 绘制坐标系
+
+        canvas.translate(mCenterX, mCenterY); // 将坐标系移动到画布中央
+        canvas.scale(1,-1);                 // 翻转Y轴
+
+        drawAuxiliaryLine(canvas);
+
+
+        // 绘制贝塞尔曲线
+        mPaint.setColor(Color.RED);
+        mPaint.setStrokeWidth(8);
+
+        Path path = new Path();
+        path.moveTo(mData[0],mData[1]);
+
+        path.cubicTo(mCtrl[0],  mCtrl[1],  mCtrl[2],  mCtrl[3],     mData[2], mData[3]);
+        path.cubicTo(mCtrl[4],  mCtrl[5],  mCtrl[6],  mCtrl[7],     mData[4], mData[5]);
+        path.cubicTo(mCtrl[8],  mCtrl[9],  mCtrl[10], mCtrl[11],    mData[6], mData[7]);
+        path.cubicTo(mCtrl[12], mCtrl[13], mCtrl[14], mCtrl[15],    mData[0], mData[1]);
+
+        canvas.drawPath(path, mPaint);
+
+        mCurrent += mPiece;
+        if (mCurrent < mDuration){
+
+            mData[1] -= 120/mCount;
+            mCtrl[7] += 80/mCount;
+            mCtrl[9] += 80/mCount;
+
+            mCtrl[4] -= 20/mCount;
+            mCtrl[10] += 20/mCount;
+
+        //    postInvalidateDelayed((long) mPiece);
+        }
+    }
+
+    // 绘制辅助线
+    private void drawAuxiliaryLine(Canvas canvas) {
+        // 绘制数据点和控制点
+        mPaint.setColor(Color.GRAY);
+        mPaint.setStrokeWidth(20);
+
+        for (int i=0; i<8; i+=2){
+            canvas.drawPoint(mData[i],mData[i+1], mPaint);
+        }
+
+        for (int i=0; i<16; i+=2){
+            canvas.drawPoint(mCtrl[i], mCtrl[i+1], mPaint);
+        }
+
+
+        // 绘制辅助线
+        mPaint.setStrokeWidth(4);
+
+        for (int i=2, j=2; i<8; i+=2, j+=4){
+            canvas.drawLine(mData[i],mData[i+1],mCtrl[j],mCtrl[j+1],mPaint);
+            canvas.drawLine(mData[i],mData[i+1],mCtrl[j+2],mCtrl[j+3],mPaint);
+        }
+        canvas.drawLine(mData[0],mData[1],mCtrl[0],mCtrl[1],mPaint);
+        canvas.drawLine(mData[0],mData[1],mCtrl[14],mCtrl[15],mPaint);
+    }
+
+    // 绘制坐标系
+    private void drawCoordinateSystem(Canvas canvas) {
+        canvas.save();                      // 绘制做坐标系
+
+        canvas.translate(mCenterX, mCenterY); // 将坐标系移动到画布中央
+        canvas.scale(1,-1);                 // 翻转Y轴
+
+        Paint fuzhuPaint = new Paint();
+        fuzhuPaint.setColor(Color.RED);
+        fuzhuPaint.setStrokeWidth(5);
+        fuzhuPaint.setStyle(Paint.Style.STROKE);
+
+        canvas.drawLine(0, -2000, 0, 2000, fuzhuPaint);
+        canvas.drawLine(-2000, 0, 2000, 0, fuzhuPaint);
+
+        canvas.restore();
+    }
+}
+
+```
 
 ## 三.总结