Android开发之PathMeasure的基本用法

前言：PathMeasure是Path的测量类，ok！我们来看下有那些用法。

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关于PathMeasure(path,false);中的第二个参数，true都会自动测量path包括闭合部分的长度 ，false则反之！

我们来看下具体案例。

代码：

import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Path;import android.graphics.PathMeasure;import android.util.Log;import android.view.View;import static android.R.attr.x;import static android.R.attr.y;import static android.content.ContentValues.TAG;/** * Created by Fly on 2017/6/14. */public class CustomView extends View {    private Paint paint;    private int mViewHeight;    private int mViewWidth;    public CustomView(Context context) {        super(context);        paint = new Paint();        paint.setColor(Color.RED);        paint.setStyle(Paint.Style.STROKE);        paint.setStrokeWidth(10);    }    @Override    protected void onSizeChanged(int w, int h, int oldw, int oldh) {        super.onSizeChanged(w, h, oldw, oldh);        mViewHeight = h;        mViewWidth = w;    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        canvas.translate(mViewWidth / 2, mViewHeight / 2);        Path path = new Path();        path.lineTo(0, 200);        path.lineTo(200, 200);        path.lineTo(200, 0);        PathMeasure measure1 = new PathMeasure(path, false);        PathMeasure measure2 = new PathMeasure(path, true);        Log.i("---length1---", measure1.getLength() + "");        Log.i("---length2---", measure2.getLength() + "");        //forceClosed:不管path绘制的是否关闭，forceClosed=true都会自动测量path包括闭合部分的长度        canvas.drawPath(path, paint);    }}

运行效果图：

打印信息：

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nextContour属性：

        Path path = new Path();        //多条路径的效果需要关闭硬件加速        path.addRect(-200, -200, 200, 200, Path.Direction.CW);        path.addRect(-100, -100, 100, 100, Path.Direction.CW);        PathMeasure measure = new PathMeasure(path, false);        float length1 = measure.getLength();        boolean nextContour = measure.nextContour();//获取下一个路径，有可能没有多个路径了，返回false        float length2 = measure.getLength();        Log.i("---nextContour---", nextContour + "");        Log.i("---length1---", length1 + "");        Log.i("---length2---", length2 + "");        canvas.drawPath(path, paint);

运行效果图：

日志打印：

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截取片段：

        Path path = new Path();        path.addRect(-200, -200, 200, 200, Path.Direction.CW);        PathMeasure measure = new PathMeasure(path, false);        float length = measure.getLength();        Log.i("---length---", length + "");        canvas.drawPath(path, paint);        Path path1 = new Path();//        path1.lineTo(-300, -300);//        path1.lineTo(-200, 0);//        path1.lineTo(-200, 0);//        path1.lineTo(0, 0);        //startWithMoveTo:false，代表该起始点是否位上一个的结束点(是否保持连续性)。//        measure.getSegment(200, 600, path1, false);        measure.getSegment(200, 600, path1, true);        paint.setColor(Color.GREEN);        canvas.drawPath(path1, paint);

效果图：

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getPosTan：

        Path path = new Path();        path.addCircle(0, 0, 300, Path.Direction.CW);        PathMeasure measure = new PathMeasure(path, false);        float[] pos = new float[2];        float[] tan = new float[2];//tan=y/x        measure.getPosTan(measure.getLength() / 4, pos, tan);        Log.i("---------->", "position:x-" + pos[0] + ", y-" + pos[1]);        Log.i("---------->", "tan:x-" + tan[0] + ", y-" + tan[1]);        canvas.drawPath(path, paint);

看下效果：

打印日志：

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