下拉刷新之高仿京东头部快递小哥（1）

先看主页面布局文件activity_main.xml--有一个SeekBar、还有一个缩放快递小哥的自定义控件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent" >    <SeekBar        android:id="@+id/seekbar"        android:layout_width="match_parent"        android:layout_height="wrap_content" />    <com.example.jingdong.FirstSetpView        android:id="@+id/firstview"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@+id/seekbar"        android:layout_centerInParent="true" /></RelativeLayout>

看主页面布局代码实现把MainActivity

package com.example.jingdong;import android.app.Activity;import android.os.Bundle;import android.widget.SeekBar;import android.widget.SeekBar.OnSeekBarChangeListener;public class MainActivity extends Activity {private SeekBar sb;private FirstSetpView mFirstStepView;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        sb = (SeekBar) findViewById(R.id.seekbar);        mFirstStepView = (FirstSetpView) findViewById(R.id.firstview);        //设置监听事件        sb.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {@Overridepublic void onStopTrackingTouch(SeekBar seekBar) {}@Overridepublic void onStartTrackingTouch(SeekBar seekBar) {}@Overridepublic void onProgressChanged(SeekBar seekBar, int progress,boolean fromUser) {float currentProgress = (float)seekBar.getProgress()/(float)seekBar.getMax();mFirstStepView.setCurrentProgress(currentProgress);mFirstStepView.invalidate();}});    }  }

接下来看自定义控件代码FirstSetpView

package com.example.jingdong;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Paint;import android.util.AttributeSet;import android.view.View;public class FirstSetpView extends View {private Bitmap people;private Bitmap peopleWithGoods;private float mCurrentProgress;private int mCurrentAlpha;private Paint mPaint;private int widthResult;private int heightResult;/** * 构造函数 *  * @param context * @param attrs * @param defStyle */public FirstSetpView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);init();}public FirstSetpView(Context context, AttributeSet attrs) {super(context, attrs);init();}public FirstSetpView(Context context) {super(context);init();}/** * 1、获取包裹、快递小哥的图片资源 2、获取动画系类的最后一张图片（测量宽高） 3、初始化画笔，初始化透明度为0 */private void init() {people = BitmapFactory.decodeResource(getResources(),R.drawable.app_refresh_people_3);peopleWithGoods = BitmapFactory.decodeResource(getResources(),R.drawable.app_refresh_people_3);mPaint = new Paint();mPaint.setAlpha(0);}/** * 测量方法 *  * @param widthMeasureSpec * @param heightMeasureSpec *            MeasureSpec类中的三个Mode常量值的意义，其中UNSPECIFIED表示未指定，爹不会对儿子作任何的束缚， *            儿子想要多大都可以 *            ；EXACTLY表示完全的，意为儿子多大爹心里有数，爹早已算好了；AT_MOST表示至多，爹已经为儿子设置好了一个最大限制 *            ，儿子你不能比这个值大，不能再多了 *  *            MeasureSpec.EXACTLY是精确尺寸， *            当我们将控件的layout_width或layout_height指定为具体数值时如andorid *            :layout_width="50dip"，或者为FILL_PARENT是，都是控件大小已经确定的情况，都是精确尺寸。 *  *            MeasureSpec.AT_MOST是最大尺寸， *            当控件的layout_width或layout_height指定为WRAP_CONTENT时 *            ，控件大小一般随着控件的子空间或内容进行变化 *            ，此时控件尺寸只要不超过父控件允许的最大尺寸即可。因此，此时的mode是AT_MOST，size给出了父控件允许的最大尺寸。 */@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {setMeasuredDimension(measureWidth(widthMeasureSpec),measureHeight(heightMeasureSpec));}// 测量宽度private int measureWidth(int widthMeasureSpec) {widthResult = 0;int size = MeasureSpec.getSize(widthMeasureSpec);int mode = MeasureSpec.getMode(widthMeasureSpec);if (MeasureSpec.EXACTLY == mode) {widthResult = size;} else {widthResult = peopleWithGoods.getWidth();if (MeasureSpec.AT_MOST == mode) {widthResult = Math.min(widthResult, size);}}return widthResult;}// 测量高度private int measureHeight(int heightMeasureSpec) {heightResult = 0;int size = MeasureSpec.getSize(heightMeasureSpec);int mode = MeasureSpec.getMode(heightMeasureSpec);if (MeasureSpec.EXACTLY == mode) {heightResult = size;} else {heightResult = peopleWithGoods.getHeight();if (MeasureSpec.AT_MOST == mode) {heightResult = Math.min(heightResult, size);}}return heightResult;}/** * 绘制方法 *  * @param canvas */@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);canvas.scale(mCurrentProgress, mCurrentProgress);mPaint.setAlpha(mCurrentAlpha);canvas.drawBitmap(people, 0, 0, mPaint);}/** * 根据进度来对小哥和包裹进行缩放 *  * @param currentProgress */public void setCurrentProgress(float currentProgress) {this.mCurrentProgress = currentProgress;this.mCurrentAlpha = (int) (currentProgress * 255);}}