Android开发之PathMeasure的基本用法-白红宇

Android开发之PathMeasure的基本用法

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发布时间：2019-03-24

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PathMeasure测量类

PathMeasure是Android图形库中用于测量路径长度的强大工具，支持闭合和非闭合路径的测量。它能够帮助开发者快速获取路径数据，节省手动计算的时间。这一功能在绘图、游戏开发等场景中都有广泛应用。

forceClosed参数的作用

PathMeasure(path, false);默认情况下，measure.isClosed()返回的值与path的闭合状态有关。如果想要强制闭合路径，无论Path本身是否闭合，可以通过forceClosed属性来处理。例如，forceClosed=true时，measure.getLength()将包括路径的闭合部分的测量结果。这一功能特别有用，当路径并非闭合时，仍能完整测量所有边线。

我们来看看实际案例

代码示例：

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;

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() + "");      canvas.drawPath(path, paint);  }

}

运行效果图：

接下来看看PathMeasure的其他方法

nextContour属性

代码示例：

Path path = new Path();

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();

float length2 = measure.getLength();