android实现简单圆弧效果

最近项目完成就开始搞一些有用没用的东西，以前面试的时候有人问我那种圆弧效果怎么做，还问我翻牌效果，我只看过，没有做过，现在有空了，而且想到可能会用到就做个简单的
圆弧很简单，自定义个View,创建个Paint，设置 arcPaint.setStyle(Paint.Style.STROKE)再设置圆弧的宽，再在onDraw内调用canvas.drawArc()就好了
现在只做一个带刻度的圆弧和一个开口地方是圆角的圆弧。其他各种效果以后再摸索

ArcView.java

public class ArcView extends View {
  private Paint textPaint;
  private Paint arcPaint;
  private Shader backGradient;
  private Xfermode xfermode;
  private RectF oval = new RectF();
  public ArcView(Context context) {
    super(context);
    init();
  }
 
  public ArcView(Context context, @Nullable AttributeSet attrs) {
    super(context, attrs);
    init();
  }
  private int type = 0;
 
  public void setType(int type) {
    this.type = type;
    if(type == 1){
      start = 10;
    }
  }
  private void init(){
    arcPaint = new Paint();
    arcPaint.setAntiAlias(true);
    if(type == 0){
      xfermode = new PorterDuffXfermode(PorterDuff.Mode.CLEAR);
    }
 
    textPaint = new Paint();
    textPaint.setAntiAlias(true);
    textPaint.setColor(Color.WHITE);
    textPaint.setTextSize(50);
    textPaint.setStyle(Paint.Style.FILL);
    textPaint.setTextAlign(Paint.Align.CENTER);
 
  }
 
  private int strokeWidth = 40;
 
  public void setStrokeWidth(int strokeWidth) {
    this.strokeWidth = strokeWidth;
  }
 
  private int max = 100;
 
  public void setMax(int max) {
    this.max = max;
  }
 
  private int progress;
 
  public void setProgress(int progress) {
    this.progress = progress;
    postInvalidate();
  }
 
  private int start = 0;
 
  public void setStart(int start) {
    if(type == 1){
      if(start < 10){
 start = 10;
      }
    }else{
      if(start < 0){
 start = 0;
      }
    }
 
    this.start = start;
  }
 
  @Override
  protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    if(getWidth() != 0){
      int width = getWidth();
      int height = getHeight();
      int cx = width/2;
      int cy = height/2;
      if(backGradient == null){
 oval.set( strokeWidth/2, strokeWidth/2,
     width - strokeWidth/2, height - strokeWidth/2);
 int colorStart = getResources().getColor(R.color.colorPrimary);
 int color2 = Color.GREEN;
 int colorEnd = Color.RED;
 
 backGradient = new SweepGradient(cx,cy,new int[]{color2 ,colorStart, colorEnd},new float[]{0.1f,0.4f,0.9f});
 
 postInvalidate();
      }else{
 int sc = 0;
 if(type == 0){
   sc = canvas.saveLayer(0, 0, canvas.getWidth(), canvas.getHeight(), null, Canvas.ALL_SAVE_FLAG);
 }else{
   canvas.save();
 }
 
 canvas.rotate(90,cx,cy);
 arcPaint.setColor(Color.GRAY);
 arcPaint.setStyle(Paint.Style.STROKE);
 arcPaint.setStrokeWidth(strokeWidth);
 if(type == 1){
   arcPaint.setStrokeCap(Paint.Cap.ROUND);
 }
 
 int s =start;
 int e = start*2;
 //底色
 canvas.drawArc(oval,s,360 - e,false,arcPaint);
 arcPaint.setShader(backGradient);
 //渐变
 int sweep = (int) (progress*1.0f/max*(360 - e));
 canvas.drawArc(oval,s,sweep,false,arcPaint);
 
 arcPaint.setShader(null);
 
 
 if(type == 0){
   //刻度
   arcPaint.setXfermode(xfermode);
   arcPaint.setStyle(Paint.Style.STROKE);
   arcPaint.setStrokeWidth(5);
 
   for (int i = 0; i < 36;i++){
     canvas.drawLine(0,cy,getWidth(),cy,arcPaint);
     canvas.rotate(5,cx,cy);
   }
   arcPaint.setXfermode(null);
   canvas.restoreToCount(sc);
 }else{
   canvas.restore();
 }
 
 Paint.FontMetrics fontMetrics = textPaint.getFontMetrics();
 float top = fontMetrics.top;
 float bottom = fontMetrics.bottom;
 int baseLineY = (int) (cy - top/2 - bottom/2);
 canvas.drawText(progress+"%",cx,baseLineY,textPaint);
 
 //十字线，用来参考的，可删除
 canvas.drawLine(cx,0,cx,height,textPaint);
 canvas.drawLine(0,cy,width,cy,textPaint);
 
      }
 
    }
 
  }
}

activity_main.xml

MainActivity.java

public class MainActivity extends AppCompatActivity {
 
  private SeekBar seekBar;
  private ArcView arcView0;
  private ArcView arcView1;
 
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    arcView0 = findViewById(R.id.arc_view_0);
    arcView1 = findViewById(R.id.arc_view_1);
    arcView0.setType(0);
    arcView1.setType(1);
    arcView0.setStart(10);
    arcView1.setStart(0);
 
    seekBar = findViewById(R.id.seek_bar);
    seekBar.setonSeekBarChangeListener(new SeekBar.onSeekBarChangeListener() {
      @Override
      public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
 arcView0.setProgress(progress);
 arcView1.setProgress(progress);
      }
 
      @Override
      public void onStartTrackingTouch(SeekBar seekBar) {
 
      }
 
      @Override
      public void onStopTrackingTouch(SeekBar seekBar) {
 
      }
    });
  }
}

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