Android的下拉刷新带进度条效果

首先看一下运行效果图，程序的下拉刷新参考了视频，在视频页面也提供了源码下载，

http://www.imooc.com/learn/135

本篇主要说在此基础上增加了进度条的快速旋转和递增递减处理，在文章最后也会给出源码，这里主要描述一下所用的一个类

RoundProgressBar

package com.cayden.listview;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.RectF;import android.os.Handler;import android.os.Message;import android.util.AttributeSet;import android.view.View;/** * 带进度的进度条，线程安全的View，可直接在线程中更新进度 * @author cuiran * */public class RoundProgressBar extends View {/** * 画笔对象的引用 */private Paint paint;/** * 圆环的颜色 */private int roundColor;/** * 圆环进度的颜色 */private int roundProgressColor;/** * 中间进度百分比的字符串的颜色 */private int textColor;/** * 中间进度百分比的字符串的字体 */private float textSize;/** * 圆环的宽度 */private float roundWidth;/** * 最大进度 */private int max;/** * 当前进度 */private int progress;/** * 是否显示中间的进度 */private boolean textIsDisplayable;/** * 进度的风格，实心或者空心 */private int style;public static final int STROKE = 0;public static final int FILL = 1;/**是否循环**/public  boolean isSpinning = false;public RoundProgressBar(Context context) {this(context, null);}public RoundProgressBar(Context context, AttributeSet attrs) {this(context, attrs, 0);}public RoundProgressBar(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);paint = new Paint();TypedArray mTypedArray = context.obtainStyledAttributes(attrs,R.styleable.RoundProgressBar);//获取自定义属性和默认值roundColor = mTypedArray.getColor(R.styleable.RoundProgressBar_roundColor, Color.RED);roundProgressColor = mTypedArray.getColor(R.styleable.RoundProgressBar_roundProgressColor, Color.GREEN);textColor = mTypedArray.getColor(R.styleable.RoundProgressBar_textColor, Color.GREEN);textSize = mTypedArray.getDimension(R.styleable.RoundProgressBar_textSize, 15);roundWidth = mTypedArray.getDimension(R.styleable.RoundProgressBar_roundWidth, 5);max = mTypedArray.getInteger(R.styleable.RoundProgressBar_max, 360);textIsDisplayable = mTypedArray.getBoolean(R.styleable.RoundProgressBar_textIsDisplayable, true);style = mTypedArray.getInt(R.styleable.RoundProgressBar_style, 0);mTypedArray.recycle();//必须Recycle}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);/** * 画最外层的大圆环 */int centre = getWidth()/2; //获取圆心的x坐标int radius = (int) (centre - roundWidth/2); //圆环的半径paint.setColor(roundColor); //设置圆环的颜色paint.setStyle(Paint.Style.STROKE); //设置空心paint.setStrokeWidth(roundWidth); //设置圆环的宽度paint.setAntiAlias(true);  //消除锯齿 canvas.drawCircle(centre, centre, radius, paint); //画出圆环/** * 画进度百分比 现已去掉改成画图片 *///paint.setStrokeWidth(0); //paint.setColor(textColor);//paint.setTextSize(textSize);//paint.setTypeface(Typeface.DEFAULT_BOLD); //设置字体//int percent = (int)(((float)progress / (float)max) * 100);  //中间的进度百分比，先转换成float在进行除法运算，不然都为0//float textWidth = paint.measureText(percent + "%");   //测量字体宽度，我们需要根据字体的宽度设置在圆环中间////if(textIsDisplayable && percent != 0 && style == STROKE){//canvas.drawText(percent + "%", centre - textWidth / 2, centre + textSize/2, paint); //画出进度百分比//}if(isSpinning){/** * 画图片 */Bitmap bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.loading02);int width=bitmap.getWidth();int height=bitmap.getHeight();canvas.drawBitmap(bitmap, centre-width/2, centre-height/2 , paint);bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.loading06);width=bitmap.getWidth();height=bitmap.getHeight();canvas.drawBitmap(bitmap, centre-width/2, centre-height/2 , paint);/** * 画圆弧 ，画圆环的进度 *///设置进度是实心还是空心paint.setStrokeWidth(roundWidth); //设置圆环的宽度paint.setColor(roundProgressColor);  //设置进度的颜色RectF oval = new RectF(centre - radius, centre - radius, centre+ radius, centre + radius);  //用于定义的圆弧的形状和大小的界限paint.setStyle(Paint.Style.STROKE);canvas.drawArc(oval, progress-90, 320 , false, paint);  //根据进度画圆弧}else{/** * 画图片 */Bitmap bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.loading02);int width=bitmap.getWidth();int height=bitmap.getHeight();canvas.drawBitmap(bitmap, centre-width/2, centre-height/2 , paint); bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.loading05); width=bitmap.getWidth(); height=bitmap.getHeight(); canvas.drawBitmap(bitmap, centre-width/2, centre-height/2 , paint);/** * 画圆弧 ，画圆环的进度 *///设置进度是实心还是空心paint.setStrokeWidth(roundWidth); //设置圆环的宽度paint.setColor(roundProgressColor);  //设置进度的颜色RectF oval = new RectF(centre - radius, centre - radius, centre+ radius, centre + radius);  //用于定义的圆弧的形状和大小的界限paint.setStyle(Paint.Style.STROKE);canvas.drawArc(oval, -90, progress , false, paint);  //根据进度画圆弧}}public synchronized int getMax() {return max;}/** * 设置进度的最大值 * @param max */public synchronized void setMax(int max) {if(max < 0){throw new IllegalArgumentException("max not less than 0");}this.max = max;}/** * 获取进度.需要同步 * @return */public synchronized int getProgress() {return progress;}  /**     * Reset the count (in increment mode)     */    public void resetCount() {        progress = 0;        invalidate();    }    /**     * Turn off spin mode     */    public void stopSpinning() {        isSpinning = false;        progress = 0;        spinHandler.removeMessages(0);    }    /**     * Puts the view on spin mode     */    public void spin() {        isSpinning = true;        spinHandler.sendEmptyMessage(0);    }    /**     * Increment the progress by 1 (of 360)     */    public void incrementProgress() {        isSpinning = false;        if (progress > 360)            progress = 0;        spinHandler.sendEmptyMessage(0);    } private Handler spinHandler = new Handler() {        /**         * This is the code that will increment the progress variable         * and so spin the wheel         */        @Override        public void handleMessage(Message msg) {        invalidate();        if(isSpinning){          progress += 10;                  if (progress > 360) {                      progress = 0;                  }                  spinHandler.sendEmptyMessageDelayed(0, 0);        }            //super.handleMessage(msg);        }    };/** * 设置进度，此为线程安全控件，由于考虑多线的问题，需要同步 * 刷新界面调用postInvalidate()能在非UI线程刷新 * @param progress */public synchronized void setProgress(int progress) {if(progress < 0){throw new IllegalArgumentException("progress not less than 0");}if(progress > max){progress = max;}if(progress <= max){this.progress = progress;postInvalidate();}}public int getCricleColor() {return roundColor;}public void setCricleColor(int cricleColor) {this.roundColor = cricleColor;}public int getCricleProgressColor() {return roundProgressColor;}public void setCricleProgressColor(int cricleProgressColor) {this.roundProgressColor = cricleProgressColor;}public int getTextColor() {return textColor;}public void setTextColor(int textColor) {this.textColor = textColor;}public float getTextSize() {return textSize;}public void setTextSize(float textSize) {this.textSize = textSize;}public float getRoundWidth() {return roundWidth;}public void setRoundWidth(float roundWidth) {this.roundWidth = roundWidth;}}

类中的主要绘图部分在

canvas.drawArc(oval, progress-90, 320 , false, paint); //根据进度画圆弧

canvas.drawArc(oval, -90, progress , false, paint); //根据进度画圆弧

可以看一下canvas.drawArc方法

public void drawArc(RectF oval, float startAngle, float sweepAngle, boolean useCenter, Paint paint)

oval :指定圆弧的外轮廓矩形区域。
startAngle: 圆弧起始角度，单位为度。
sweepAngle: 圆弧扫过的角度，顺时针方向，单位为度。
useCenter: 如果为True时，在绘制圆弧时将圆心包括在内，通常用来绘制扇形。
paint: 绘制圆弧的画板属性，如颜色，是否填充等

可以参考以下对此介绍的网站

http://blog.sina.com.cn/s/blog_783ede0301012im3.html

最后给出项目的源码:

https://github.com/cayden/ListViewDemo

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