看到有人在問如何實現(xiàn)淘寶商品詳情頁效果，獻上效果圖
大致梳理一下思路，這里不提供源碼
狀態(tài)欄透明使用開源庫StatusBarCompat，為了兼容手機4.4
dependencies { compile ('com.github.niorgai:StatusBarCompat:2.1.4', { exclude group: 'com.android.support' }) }allprojects { repositories { ... maven { url "https://jitpack.io" } } }標題欄圖標透明度變化參考Api setAlpha()已過時
icon.setImageAlpha(0);
Banner控件為ViewPager,淘寶顯示為正方形，這里需要修改ViewPager measure函數(shù)
public class IdeaViewPager extends ViewPager { private Point point; public IdeaViewPager(Context context) { this(context,null); } public IdeaViewPager(Context context, AttributeSet attrs) { super(context, attrs); WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE); point = new Point(); windowManager.getDefaultDisplay().getSize(point); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); setMeasuredDimension(point.x,point.x); }}測量View高度，獲取到高度集合綁定到ScrollView,根據(jù)ScrollView滑動距離判斷是屬于哪一個Tab選項
public int getMeasureHeight(View view){ int width = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED); int height = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED); view.measure(width, height); return view.getMeasuredHeight(); }重新onScrollChanged函數(shù)，實現(xiàn)ViewPager滑動速度比其他View慢
@Override protected void onScrollChanged(int l, int t, int oldl, int oldt) { super.onScrollChanged(l, t, oldl, oldt); if (viewPager != null && t != oldt) { viewPager.setTranslationY(t/2); } }根據(jù)限定距離（Banner）計算百分比偏移量，實現(xiàn)顏色漸變、透明度漸變（淘寶商品詳情頁有二次顏色漸變）
@Override protected void onScrollChanged(int l, int t, int oldl, int oldt) { super.onScrollChanged(l, t, oldl, oldt); if(viewPager!=null&&t<=point.x-headerHeight&&getOnScrollChangedColorListener()!=null){ getOnScrollChangedColorListener().onChanged(Math.abs(t)/Float.valueOf(point.x-headerHeight)); if(t<=(point.x-headerHeight)/2){ getOnScrollChangedColorListener().onChangedFirstColor(t/(point.x-headerHeight)/2); }else{ getOnScrollChangedColorListener().onChangedSecondColor((t-(point.x-headerHeight)/2)/(point.x-headerHeight)/2); } } int currentPosition = getCurrentPosition(t,arrayDistance); if(currentPosition!=position&&getOnSelectedIndicateChangedListener()!=null){ getOnSelectedIndicateChangedListener().onSelectedChanged(currentPosition); } this.position = currentPosition; }單一顏色漸變透明度，還原argb通道，修改a值
ideaScrollView.setOnScrollChangedColorListener(new IdeaScrollView.OnScrollChangedColorListener() { @Override public void onChanged(float percentage) { int color = getAlphaColor(percentage>0.9f?1.0f:percentage); header.setBackgroundDrawable(new ColorDrawable(color)); radioGroup.setBackgroundDrawable(new ColorDrawable(color)); icon.setImageAlpha((int) ((percentage>0.9f?1.0f:percentage)*255)); radioGroup.setAlpha((percentage>0.9f?1.0f:percentage)*255); setRadioButtonTextColor(percentage); } @Override public void onChangedFirstColor(float percentage) { } @Override public void onChangedSecondColor(float percentage) { } }); ideaScrollView.setOnSelectedIndicateChangedListener(new IdeaScrollView.OnSelectedIndicateChangedListener() { @Override public void onSelectedChanged(int position) { isNeedScrollTo = false; radioGroup.check(radioGroup.getChildAt(position).getId()); isNeedScrollTo = true; } }); public int getAlphaColor(float f){ return Color.argb((int) (f*255),0x09,0xc1,0xf4); }Tab選項屬性不能太頻繁，會有顏色值閃爍情況出現(xiàn)，這里需要策略
public void setRadioButtonTextColor(float percentage){ if(Math.abs(percentage-currentPercentage)>=0.1f){ for(int i=0;i<radioGroup.getChildCount();i++){ RadioButton radioButton = (RadioButton) radioGroup.getChildAt(i); radioButton.setTextColor(radioButton.isChecked()?getRadioCheckedAlphaColor(percentage):getRadioAlphaColor(percentage)); } this.currentPercentage = percentage; } }判斷當前屬于哪個選項，根據(jù)滑動距離與傳入綁定的View高度集合來計算
private int getCurrentPosition(int t, ArrayList<Integer> arrayDistance) { int index = 0; for (int i=0;i<arrayDistance.size();i++){ if(i==arrayDistance.size()-1){ index = i; }else { if(t>=arrayDistance.get(i)&&t<arrayDistance.get(i+1)){ index = i; break; } } } return index; }切換選項卡以及回到頂部按鈕的具體實現(xiàn)參考scrollTo函數(shù)
private void scrollToPosition(int position){ scrollTo(0,arrayDistance.get(position)); }以上代碼實現(xiàn)了上圖效果，當然也可以使用RecyclerView AbsListView做容器。
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