上一次我們試驗(yàn)了有彈性的ScrollView。詳情

這一次，我們來試驗(yàn)有彈性的ScrollView。

國際慣例，效果圖：

?

主要代碼：

?

[java]?view plaincopy

import?android.content.Context;??

import?android.graphics.Rect;??

import?android.util.AttributeSet;??

import?android.view.MotionEvent;??

import?android.view.animation.Animation;??

import?android.view.animation.Animation.AnimationListener;??

import?android.view.animation.TranslateAnimation;??

import?android.widget.AbsListView;??

import?android.widget.ListView;??

??

/**?

?*?ElasticScrollView有彈性的ListView?

?*/??

public?class?ElasticListView?extends?ListView?{??

????private?float?y;??

????private?Rect?normal?=?new?Rect();??

????private?boolean?animationFinish?=?true;??

??

????public?ElasticListView(Context?context)?{??

????????super(context);??

????????init();??

????}??

??

????public?ElasticListView(Context?context,?AttributeSet?attrs)?{??

????????super(context,?attrs);??

????????init();??

????}??

??

????protected?void?onScrollChanged(int?l,?int?t,?int?oldl,?int?oldt)?{??

??

????}??

??

????boolean?overScrolled?=?false;??

????private?void?init()?{??

????????setOnScrollListener(new?OnScrollListener()?{??

????????????@Override??

????????????public?void?onScrollStateChanged(AbsListView?view,?int?scrollState)?{??

????????????}??

??

????????????@Override??

????????????public?void?onScroll(AbsListView?view,?int?firstVisibleItem,?int?visibleItemCount,?int?totalItemCount)?{??

????????????????overScrolled?=?false;??

????????????}??

????????});??

????}??

??????

????@Override??

????protected?void?onOverScrolled(int?scrollX,?int?scrollY,?boolean?clampedX,?boolean?clampedY)?{??

????????overScrolled?=?true;??

????}??

??

????@Override??

????public?boolean?onTouchEvent(MotionEvent?ev)?{??

????????commOnTouchEvent(ev);??

????????return?super.onTouchEvent(ev);??

????}??

??

????public?void?commOnTouchEvent(MotionEvent?ev)?{??

????????if?(animationFinish)?{??

????????????int?action?=?ev.getAction();??

????????????switch?(action)?{??

????????????case?MotionEvent.ACTION_DOWN:??

????????????????y?=?ev.getY();??

????????????????break;??

????????????case?MotionEvent.ACTION_UP:??

????????????????y?=?0;??

????????????????if?(isNeedAnimation())?{??

????????????????????animation();??

????????????????}??

????????????????break;??

????????????case?MotionEvent.ACTION_MOVE:??

????????????????final?float?preY?=?y?==?0???ev.getY()?:?y;??

????????????????float?nowY?=?ev.getY();??

????????????????int?deltaY?=?(int)?(preY?-?nowY);??

??

????????????????y?=?nowY;??

????????????????//?當(dāng)滾動到最上或者最下時就不會再滾動，這時移動布局??

????????????????if?(isNeedMove(deltaY))?{??

????????????????????if?(normal.isEmpty())?{??

????????????????????????//?保存正常的布局位置??

????????????????????????normal.set(getLeft(),?getTop(),?getRight(),?getBottom());??

????????????????????}??

????????????????????//?移動布局??

????????????????????layout(getLeft(),?getTop()?-?deltaY?/?2,?getRight(),?getBottom()?-?deltaY?/?2);??

????????????????}??

????????????????break;??

????????????default:??

????????????????break;??

????????????}??

????????}??

????}??

??

????//?開啟動畫移動??

????public?void?animation()?{??

????????//?開啟移動動畫??

????????TranslateAnimation?ta?=?new?TranslateAnimation(0,?0,?0,?normal.top?-?getTop());??

????????ta.setDuration(200);??

????????ta.setAnimationListener(new?AnimationListener()?{??

????????????@Override??

????????????public?void?onAnimationStart(Animation?animation)?{??

????????????????animationFinish?=?false;??

??

????????????}??

??

????????????@Override??

????????????public?void?onAnimationRepeat(Animation?animation)?{??

??

????????????}??

??

????????????@Override??

????????????public?void?onAnimationEnd(Animation?animation)?{??

????????????????clearAnimation();??

????????????????//?設(shè)置回到正常的布局位置??

????????????????layout(normal.left,?normal.top,?normal.right,?normal.bottom);??

????????????????normal.setEmpty();??

????????????????animationFinish?=?true;??

????????????}??

????????});??

????????startAnimation(ta);??

????}??

??

????//?是否需要開啟動畫??

????public?boolean?isNeedAnimation()?{??

????????return?!normal.isEmpty();??

????}??

??

????//?是否需要移動布局??

????public?boolean?isNeedMove(float?deltaY)?{??

????????if?(overScrolled?&&?getChildCount()?>?0)?{??

????????????if?(getLastVisiblePosition()?==?getCount()?-?1?&&?deltaY?>?0)?{??

????????????????return?true;??

????????????}??

????????????if?(getFirstVisiblePosition()?==?0?&&?deltaY?<?0)?{??

????????????????return?true;??

????????????}??

????????}??

????????return?false;??

????}??

}??

測試代碼：

?

?

[java]?view plaincopy

public?class?MainActivity?extends?Activity?{??

????ElasticListView?listView;??

????@Override??

????protected?void?onCreate(Bundle?savedInstanceState)?{??

????????super.onCreate(savedInstanceState);??

????????setContentView(R.layout.activity_main);??

??????????

????????listView?=?(ElasticListView)?findViewById(R.id.listview);??

??????????

????????String[]?listValues?=?new?String[20];??

????????for?(int?i=0;i<listValues.length;i++)?{??

????????????listValues[i]?=?"TextView"?+?i;??

????????}??

????????listView.setAdapter(new?ArrayAdapter<String>(this,?android.R.layout.simple_list_item_1,?listValues));??

????}??

}??

?

[html]?view plaincopy

public?class?MainActivity?extends?Activity?{??

????ElasticListView?listView;??

????@Override??

????protected?void?onCreate(Bundle?savedInstanceState)?{??

????????super.onCreate(savedInstanceState);??

????????setContentView(R.layout.activity_main);??

??????????

????????listView?=?(ElasticListView)?findViewById(R.id.listview);??

??????????

????????String[]?listValues?=?new?String[20];??

????????for?(int?i=0;i<listValues.length;i++)?{??

????????????listValues[i]?=?"TextView"?+?i;??

????????}??

????????listView.setAdapter(new?ArrayAdapter<String>(this,?android.R.layout.simple_list_item_1,?listValues));??

????}??

}?

總結(jié)

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