DiscretePathEffect example

android.graphics.DiscretePathEffect chop the path into lines of segmentLength, randomly deviating from the original path by deviation.


Main layout, /res/layout/activity_main.xml.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context="com.example.androidview.MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="android-coding.blogspot.com" />
    
    <TextView 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="segmentLength"/>
    <SeekBar 
        android:id="@+id/segmentLength"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="100"
        android:progress="30"/>
    
    <TextView 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="deviation"/>
    <SeekBar 
        android:id="@+id/deviation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="100"
        android:progress="30"/>
    
    <TextView 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="strokeWidth"/>
    <SeekBar 
        android:id="@+id/strokeWidth"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="100"
        android:progress="20"/>
    
    <com.example.androidview.MyView
        android:id="@+id/myview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

MainActivity.java

package com.example.androidview;

import android.app.Activity;
import android.graphics.PathDashPathEffect;
import android.graphics.PathDashPathEffect.Style;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.Spinner;

public class MainActivity extends Activity {
 
 private MyView myView;
 private SeekBar seekBarSegmentLength, seekBarDeviation;
 private SeekBar seekBarStrokeWidth;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  
  myView = (MyView)findViewById(R.id.myview);
  
  seekBarSegmentLength = (SeekBar)findViewById(R.id.segmentLength);
  seekBarSegmentLength.setOnSeekBarChangeListener(seekBarSegmentLengthChangeListener);
  seekBarDeviation = (SeekBar)findViewById(R.id.deviation);
  seekBarDeviation.setOnSeekBarChangeListener(seekBarDeviationChangeListener);
  
  seekBarStrokeWidth = (SeekBar)findViewById(R.id.strokeWidth);
  seekBarStrokeWidth.setOnSeekBarChangeListener(seekBarStrokeWidthChangeListener);
 }
 
 OnSeekBarChangeListener seekBarSegmentLengthChangeListener =
  new OnSeekBarChangeListener(){

   @Override
   public void onProgressChanged(SeekBar seekBar, int progress,
     boolean fromUser) {
    myView.setSegmentLength(progress);
   }

   @Override
   public void onStartTrackingTouch(SeekBar seekBar) {}

   @Override
   public void onStopTrackingTouch(SeekBar seekBar) {}
  
 };
 
 
 
 OnSeekBarChangeListener seekBarDeviationChangeListener =
  new OnSeekBarChangeListener(){

   @Override
   public void onProgressChanged(SeekBar seekBar, int progress,
     boolean fromUser) {
    myView.setDeviation(progress);
   }

   @Override
   public void onStartTrackingTouch(SeekBar seekBar) {}
    @Override
   public void onStopTrackingTouch(SeekBar seekBar) {}
   
 };
 
 OnSeekBarChangeListener seekBarStrokeWidthChangeListener =
  new OnSeekBarChangeListener(){

   @Override
   public void onProgressChanged(SeekBar seekBar, int progress,
     boolean fromUser) {
    myView.setStrokeWidth(progress);
   }

   @Override
   public void onStartTrackingTouch(SeekBar seekBar) {}
    @Override
   public void onStopTrackingTouch(SeekBar seekBar) {}
   
 };
 
}

MyView.java

package com.example.androidview;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.DiscretePathEffect;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Path.Direction;
import android.util.AttributeSet;
import android.view.View;

public class MyView extends View {

 Paint paintBorder, paintCircle;
 Path pathBorder, pathCircle;
 
 Path pathShape;
 float segmentLength;
 float deviation;

 public MyView(Context context) {
  super(context);
  init();
 }

 public MyView(Context context, AttributeSet attrs) {
  super(context, attrs);
  init();
 }

 public MyView(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  init();
 }

 private void init() {
  paintBorder = new Paint();
  paintBorder.setColor(Color.BLUE);
  paintBorder.setStrokeWidth(20);
  paintBorder.setStyle(Paint.Style.STROKE);
  
  paintCircle = new Paint();
  paintCircle.setColor(Color.RED);
  paintCircle.setStrokeWidth(20);
  paintCircle.setStyle(Paint.Style.STROKE);

  pathBorder = new Path();
  pathCircle = new Path();
  
  pathShape = new Path();
  pathShape.moveTo(0, 0);
  pathShape.lineTo(10, 20);
  pathShape.lineTo(20, 0);
  pathShape.close();
  
  segmentLength = 30.0f;
  deviation = 30.0f;
 }

 @SuppressLint("DrawAllocation")
 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  canvas.drawColor(Color.GRAY);

  pathBorder.reset();
  pathBorder.moveTo(50,  50);
  pathBorder.lineTo(50, getHeight()-50);
  pathBorder.lineTo(getWidth()-50, getHeight()-50);
  pathBorder.lineTo(getWidth()-50, 50);
  pathBorder.close();
  
  float radius;
  pathCircle.reset();
  if(getWidth()>getHeight()){
   radius = getHeight()/4;
  }else{
   radius = getWidth()/4;
  }
  pathCircle.addCircle(getWidth()/2, getHeight()/2, radius, Direction.CCW);

  DiscretePathEffect discretePathEffect =
    new DiscretePathEffect(segmentLength, deviation);
  paintBorder.setPathEffect(discretePathEffect);
  paintCircle.setPathEffect(discretePathEffect);
  
  canvas.drawPath(pathBorder, paintBorder);
  canvas.drawPath(pathCircle, paintCircle);

 }
 
 public void setDeviation(int dev){
  deviation = (float)dev;
  invalidate();
 }
 
 public void setSegmentLength(int seglen){
  
  //force segmentLength not 0
  if (seglen==0){
   seglen = 1;
  }
   
  segmentLength = (float)seglen;
  invalidate();
 }
 
 public void setStrokeWidth(int strwidth){
  paintBorder.setStrokeWidth(strwidth);
  paintCircle.setStrokeWidth(strwidth);
  invalidate();
 }

}

- More examples of drawing path on custom View.