Android 自定义滚动视图

MainActivity

package org.wp.activity;

import android.app.Activity;
import android.os.Bundle;
import android.widget.ImageView;

publicclass MainActivity extends Activity {
 private ImageScrollView imageScrollView = null;
 private PageControlView pageControlView = null;

 @Override
 publicvoid onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.main);

 imageScrollView = (ImageScrollView) this.findViewById(R.id.myImageScrollView);

 ImageView imageView = new ImageView(this);
 imageView.setImageResource(R.drawable.a1);
 imageScrollView.addView(imageView);

 imageView = new ImageView(this);
 imageView.setImageResource(R.drawable.a2);
 imageScrollView.addView(imageView);

 imageView = new ImageView(this);
 imageView.setImageResource(R.drawable.a3);
 imageScrollView.addView(imageView);

 imageView = new ImageView(this);
 imageView.setImageResource(R.drawable.a4);
 imageScrollView.addView(imageView);

 imageView = new ImageView(this);
 imageView.setImageResource(R.drawable.a5);
 imageScrollView.addView(imageView);

 imageView = new ImageView(this);
 imageView.setImageResource(R.drawable.a6);
 imageScrollView.addView(imageView);

 pageControlView = (PageControlView) this.findViewById(R.id.myPageControlView);
 /** 设置圆圈的数量 **/
 pageControlView.setCount(imageScrollView.getChildCount());
 /** 初始化圆圈 **/
 pageControlView.generatePageControl(0);
 /** 设置视图切换回调函数实现 **/
 imageScrollView.setScrollToScreenCallback(pageControlView);
 }
}

ImageScrollView

package org.wp.activity;

import android.content.Context;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.Scroller;

publicclass ImageScrollView extends ViewGroup {
 /** 滚动对象Scroller **/
 private Scroller scroller = null;
 /** 手势识别对象GestureDetector **/
 private GestureDetector gestureDetector = null;
 /** 当前屏幕索引 **/
 privateint currentScreenIndex = 0;
 /** 设置一个标志位，防止底层的onTouch事件重复处理UP事件 **/
 privateboolean fling = false;

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

 @Override
 protectedvoid onLayout(boolean changed, int left, int top, int right,
 int bottom) {
 /** 设置布局，将子视图顺序横屏排列 **/
 for (int i = 0; i < getChildCount(); i++) {
 View child = getChildAt(i);
 child.setVisibility(View.VISIBLE);
 child.measure(right - left, bottom - top);
 child.layout(i * getWidth(), 0, (i + 1) * getWidth(), getHeight());
 }
 }

 /** 初始化 **/
 privatevoid initView(final Context context) {
 this.scroller = new Scroller(context);

 this.gestureDetector = new GestureDetector(new OnGestureListener() {
 @Override
 publicboolean onSingleTapUp(MotionEvent e) {
 returnfalse;
 }

 @Override
 publicvoid onShowPress(MotionEvent e) {
 }

 @Override
 publicboolean onScroll(MotionEvent e1, MotionEvent e2,
 float distanceX, float distanceY) {
 // 防止移动过最后一页
 if ((distanceX > 0 && getScrollX() < getWidth() * (getChildCount() - 1))
 || (distanceX < 0 && getScrollX() > 0)) {// 防止向第一页之前移动
 scrollBy((int) distanceX, 0);
 }
 returntrue;
 }

 @Override
 publicvoid onLongPress(MotionEvent e) {
 }

 @Override
 publicboolean onFling(MotionEvent e1, MotionEvent e2,
 float velocityX, float velocityY) {
 // 判断是否达到最小轻松速度，取绝对值的
 if (Math.abs(velocityX) > ViewConfiguration.get(context)
 .getScaledMinimumFlingVelocity()) {
 if (velocityX > 0 && currentScreenIndex > 0) {
 fling = true;
 scrollToScreen(currentScreenIndex - 1);
 } elseif (velocityX < 0 && currentScreenIndex < getChildCount() - 1) {
 fling = true;
 scrollToScreen(currentScreenIndex + 1);
 }
 }
 returntrue;
 }

 @Override
 publicboolean onDown(MotionEvent e) {
 returnfalse;
 }
 });
 }

 /** 切换到指定屏 **/
 publicvoid scrollToScreen(int whichScreen) {
 if (whichScreen != currentScreenIndex && getFocusedChild() != null
 && getFocusedChild() == getChildAt(currentScreenIndex)) {
 getFocusedChild().clearFocus(); // 清除焦点
 }

 finalint delta = whichScreen * getWidth() - getScrollX();
 scroller.startScroll(getScrollX(), 0, delta, 0, Math.abs(delta) * 2);
 invalidate();

 currentScreenIndex = whichScreen; // 设置当前屏幕索引
 if (scrollToScreenCallback != null) { // 刷新圆圈
 scrollToScreenCallback.callback(currentScreenIndex);
 }
 }

 @Override
 publicvoid computeScroll() {
 // 当滚动没有完成
 if (scroller.computeScrollOffset()) {
 scrollTo(scroller.getCurrX(), 0);
 postInvalidate();
 }
 }

 @Override
 publicboolean onTouchEvent(MotionEvent event) {
 gestureDetector.onTouchEvent(event);

 if (event.getAction() == MotionEvent.ACTION_UP) {
 if (!fling) {
 // 当用户停止拖动
 snapToDestination();
 }
 fling = false;
 }
 returntrue;
 }

 /** 根据当前x坐标位置确定切换到第几屏 **/
 privatevoid snapToDestination() {
 scrollToScreen((getScrollX() + (getWidth() / 2)) / getWidth());
 }

 /** 底部圆圈显示回调接口 **/
 interface ScrollToScreenCallback {
 publicvoid callback(int currentIndex);
 }

 /** ScrollToScreenCallback回调对象 **/
 private ScrollToScreenCallback scrollToScreenCallback;

 /** 设置回调函数对象 **/
 publicvoid setScrollToScreenCallback(ScrollToScreenCallback scrollToScreenCallback) {
 this.scrollToScreenCallback = scrollToScreenCallback;
 }
}

 

PageControlView

package org.wp.activity;

import org.wp.activity.ImageScrollView.ScrollToScreenCallback;

import android.content.Context;
import android.util.AttributeSet;
import android.widget.ImageView;
import android.widget.LinearLayout;

publicclass PageControlView extends LinearLayout implements
 ScrollToScreenCallback {
 /** Context对象 **/
 private Context context;
 /** 圆圈的数量 **/
 privateint count;

 public PageControlView(Context context, AttributeSet attrs) {
 super(context, attrs);
 this.context = context;
 }

 /** 回调函数 **/
 @Override
 publicvoid callback(int currentIndex) {
 generatePageControl(currentIndex);
 }

 /** 设置选中圆圈 **/
 publicvoid generatePageControl(int currentIndex) {
 this.removeAllViews();

 for (int i = 0; i < this.count; i++) {
 ImageView iv = new ImageView(context);
 if (currentIndex == i) {
 iv.setImageResource(R.drawable.page_indicator_focused);
 } else {
 iv.setImageResource(R.drawable.page_indicator);
 }
 this.addView(iv);
 }
 }

 /** 设置圆圈数量 **/
 publicvoid setCount(int count) {
 this.count = count;
 }
}

main.xml

<?xmlversion="1.0"encoding="utf-8"?>
<RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent">
 <org.wp.activity.ImageScrollViewandroid:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:id="@+id/myImageScrollView"/>
 <org.wp.activity.PageControlViewandroid:layout_width="fill_parent"
 android:layout_height="40dip"
 android:layout_alignParentBottom="true"
 android:background="#8f00000f"
 android:gravity="center"
 android:id="@+id/myPageControlView"/>
</RelativeLayout>