android自定义进度条渐变色View的实例代码

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Shader;
import android.util.AttributeSet;
import android.view.View;

/***
 * 自定义进度条
 * @author spring sky
 * Email:vipa1888@163.com
 * 创建时间：2014-1-6下午3:28:51
 */
public class SpringProgressView extends View {

 /**分段颜色*/
 private static final int[] SECTION_COLORS = {Color.GREEN,Color.YELLOW,Color.RED};
 /**进度条最大值*/
 private float maxCount;
 /**进度条当前值*/
 private float currentCount;
 /**画笔*/
 private Paint mPaint;
 private int mWidth,mHeight;

 public SpringProgressView(Context context, AttributeSet attrs,
   int defStyleAttr) {
  super(context, attrs, defStyleAttr);
  initView(context);
 }

 public SpringProgressView(Context context, AttributeSet attrs) {
  super(context, attrs);
  initView(context);
 }

 public SpringProgressView(Context context) {
  super(context);
  initView(context);
 }

 private void initView(Context context) {
 }

 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  mPaint = new Paint();
  mPaint.setAntiAlias(true);
  int round = mHeight/2;
  System.out.println("max="+maxCount + "  current="+currentCount);
  mPaint.setColor(Color.rgb(71, 76, 80));
  RectF rectBg = new RectF(0, 0, mWidth, mHeight);
  canvas.drawRoundRect(rectBg, round, round, mPaint);
  mPaint.setColor(Color.BLACK);
  RectF rectBlackBg = new RectF(2, 2, mWidth-2, mHeight-2);
  canvas.drawRoundRect(rectBlackBg, round, round, mPaint);

  float section = currentCount/maxCount;
  RectF rectProgressBg = new RectF(3, 3, (mWidth-3)*section, mHeight-3);
  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.drawRoundRect(rectProgressBg, round, round, mPaint);
 }

 private int dipToPx(int dip) {
  float scale = getContext().getResources().getDisplayMetrics().density;
  return (int) (dip * scale + 0.5f * (dip >= 0 ? 1 : -1));
 }

 /***
  * 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();
 }

 public float getMaxCount() {
  return maxCount;
 }

 public float getCurrentCount() {
  return currentCount;
 }

 @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);
 }
 

}