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[操作系统]android自定义渐变圆环进度条


先看下效果:

 

分析:比较常见于扫描结果、进度条等场景

利用canvas.drawArc(RectF oval, float startAngle, float sweepAngle, boolean useCenter, Paint paint)绘制圆弧

Paint的一些属性定义粗细、颜色、样式等

LinearGradient实现颜色的线型渐变

同样的道理,可以画出长条进度条,扇图饼图等,感兴趣可以试下..

package com.liujing.progressviewdemo;/*** * 自定义圆弧进度条 * * @author liujing */public class ProgressView extends View {  //分段颜色   private static final int[] SECTION_COLORS = { Color.GREEN, Color.YELLOW,      Color.RED };  private static final String[] ALARM_LEVEL = { "安全", "低危", "中危", "高危" };  private float maxCount;  private float currentCount;  private int score;  private String crrentLevel;  private Paint mPaint;  private Paint mTextPaint;  private int mWidth, mHeight;  public ProgressView(Context context, AttributeSet attrs, int defStyleAttr) {    super(context, attrs, defStyleAttr);    init(context);  }  public ProgressView(Context context, AttributeSet attrs) {    this(context, attrs, 0);  }  public ProgressView(Context context) {    this(context, null);  }  private void init(Context context) {    mPaint = new Paint();    mTextPaint = new Paint();  }  @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    initPaint();    RectF rectBlackBg = new RectF(20, 20, mWidth - 20, mHeight - 20);    canvas.drawArc(rectBlackBg, 0, 360, false, mPaint);    mPaint.setColor(Color.BLACK);    canvas.drawText(score + "分", mWidth / 2, mHeight / 2, mTextPaint);    mTextPaint.setTextSize(40);    if (crrentLevel != null) {      canvas.drawText(crrentLevel, mWidth / 2, mHeight / 2 + 50,          mTextPaint);    }    float section = currentCount / maxCount;    if (section <= 1.0f / 3.0f) {      if (section != 0.0f) {        mPaint.setColor(SECTION_COLORS[0]);      } else {        mPaint.setColor(Color.TRANSPARENT);      }    } else {      int count = (section <= 1.0f / 3.0f * 2) ? 2 : 3;      int[] colors = new int[count];      System.arraycopy(SECTION_COLORS, 0, colors, 0, count);      float[] positions = new float[count];      if (count == 2) {        positions[0] = 0.0f;        positions[1] = 1.0f - positions[0];      } else {        positions[0] = 0.0f;        positions[1] = (maxCount / 3) / currentCount;        positions[2] = 1.0f - positions[0] * 2;      }      positions[positions.length - 1] = 1.0f;      LinearGradient shader = new LinearGradient(3, 3, (mWidth - 3)          * section, mHeight - 3, colors, null,          Shader.TileMode.MIRROR);      mPaint.setShader(shader);    }    canvas.drawArc(rectBlackBg, 180, section * 360, false, mPaint);  }  private void initPaint() {    mPaint.setAntiAlias(true);    mPaint.setStrokeWidth((float) 40.0);    mPaint.setStyle(Style.STROKE);    mPaint.setStrokeCap(Cap.ROUND);    mPaint.setColor(Color.TRANSPARENT);    mTextPaint.setAntiAlias(true);    mTextPaint.setStrokeWidth((float) 3.0);    mTextPaint.setTextAlign(Paint.Align.CENTER);    mTextPaint.setTextSize(50);    mTextPaint.setColor(Color.BLACK);  }  private int dipToPx(int dip) {    float scale = getContext().getResources().getDisplayMetrics().density;    return (int) (dip * scale + 0.5f * (dip >= 0 ? 1 : -1));  }  public int getScore() {    return score;  }  public String getCrrentLevel() {    return crrentLevel;  }  public void setCrrentLevel(String crrentLevel) {    this.crrentLevel = crrentLevel;  }  public float getMaxCount() {    return maxCount;  }  public float getCurrentCount() {    return currentCount;  }  public void setScore(int score) {    this.score = score;    if (score == 100) {      this.crrentLevel = ALARM_LEVEL[0];    } else if (score >= 70 && score < 100) {      this.crrentLevel = ALARM_LEVEL[1];    } else if (score >= 30 && score < 70) {      this.crrentLevel = ALARM_LEVEL[2];    } else {      this.crrentLevel = ALARM_LEVEL[3];    }    invalidate();  }  /***   * 设置最大的进度值   *   * @param maxCount   */  public void setMaxCount(float maxCount) {    this.maxCount = maxCount;  }  /***   * 设置当前的进度值   *   * @param currentCount   */  public void setCurrentCount(float currentCount) {    this.currentCount = currentCount > maxCount ? maxCount : currentCount;    invalidate();  }  @Override  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {    int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);    int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);    int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);    int heightSpecSize = MeasureSpec.getSize(heightMeasureSpec);    if (widthSpecMode == MeasureSpec.EXACTLY        || widthSpecMode == MeasureSpec.AT_MOST) {      mWidth = widthSpecSize;    } else {      mWidth = 0;    }    if (heightSpecMode == MeasureSpec.AT_MOST        || heightSpecMode == MeasureSpec.UNSPECIFIED) {      mHeight = dipToPx(15);    } else {      mHeight = heightSpecSize;    }    setMeasuredDimension(mWidth, mHeight);  }}

 Demo:http://files.cnblogs.com/files/liujingg/ProgressViewDemo.rar