安卓自定义进度条

具体思路：

1.进度条，其实就是一个最大值和最小值的比例值，这个比例就是 当前值/最大值;

2.自定义的圆角问题，只要还是用到了Canvar的画板的drawRoundRect ;

3.渐变色：LinearGradient对象渲染，具体渲染的比例要自己计算，目前我的程序提供3中颜色渲染，具体规则是：

(1)当进度条占最大值的三分之一以下，则提供一种颜色

(2)当最大值超过三分之一话，就区分是否超过三分之二，如果超过则用三种，否则用两种颜色，因为三种颜色各占总进度条的三分之一，这是一个初中数据的问题，自己慢慢画图吧！

4.怎么把进度条放在一个有圆角背景的上面，这个就是绘制两个圆角长方形：第一个作为背景，第二个作为进度条的实体，具体第二个进度的实体占多长，就是当前 currentCount/maxCount*自定义View的长度 ;

这个自定义的view，完全脱离了android自带的ProgressView，并且没使用一张图片，这样就能更好的降低程序代码上的耦合性！

下面我贴出代码 ，大概讲解一下实现思路吧！

复制代码 代码如下:

package com.spring.progressview;
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);

}

}