Java tutorial
/* * Copyright (C) 2013 Charon Chui <charon.chui@gmail.com> * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.charon.materialsample.view; import android.content.Context; import android.support.v4.view.ViewPager; import android.support.v4.view.ViewPager.OnPageChangeListener; import android.util.AttributeSet; import android.util.DisplayMetrics; import android.view.View; import android.view.ViewGroup; import android.view.WindowManager; import android.widget.HorizontalScrollView; import android.widget.LinearLayout; public class ScrollingTabs extends HorizontalScrollView implements OnPageChangeListener { protected LinearLayout mContainer; protected ViewPager mViewPager; protected TabAdapter mTabAdapter; protected int mWindowWidth; /** * True if have segmentation view between two tab view. */ protected boolean isUseSeperator; protected TabClickListener mTabClickListener; protected PageSelectedListener mPageSelectedListener; /** * The width of the tab view, usually it may be 0. */ protected int tabWidth; /** * True if you want to make make all the tabs equals the width when the total width is less than the window width */ protected boolean mEqualWidth; public ScrollingTabs(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); init(context); } public ScrollingTabs(Context context, AttributeSet attrs) { super(context, attrs); init(context); } public ScrollingTabs(Context context) { super(context); init(context); } protected void init(Context context) { this.setHorizontalScrollBarEnabled(false); this.setHorizontalFadingEdgeEnabled(false); mContainer = new LinearLayout(context); LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT); mContainer.setLayoutParams(params); mContainer.setOrientation(LinearLayout.HORIZONTAL); addView(mContainer); mWindowWidth = getWindowWidth(context); } public static int getWindowWidth(Context context) { WindowManager manager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE); DisplayMetrics outMetrics = new DisplayMetrics(); manager.getDefaultDisplay().getMetrics(outMetrics); return outMetrics.widthPixels; } public void setTabAdapter(TabAdapter adapter) { this.mTabAdapter = adapter; initTabView(); } public void setViewPager(ViewPager pager) { this.mViewPager = pager; mViewPager.setOnPageChangeListener(this); initTabView(); } /** * Add tab view. */ private void initTabView() { int totalWidth = 0; if (mViewPager != null && mTabAdapter != null) { mContainer.removeAllViews(); if (mEqualWidth) { for (int i = 0; i < mViewPager.getAdapter().getCount(); i++) { View tab = mTabAdapter.getView(i); measureView(tab); totalWidth += tab.getWidth(); if (tab.getLayoutParams() != null) { // int width = tab.getLayoutParams().width; // int height = tab.getLayoutParams().height; } else { tab.setLayoutParams(new LinearLayout.LayoutParams(0, LayoutParams.MATCH_PARENT, 100f)); } if (mTabAdapter.getSeparator() != null && i != mViewPager.getAdapter().getCount() - 1) { isUseSeperator = true; measureView(mTabAdapter.getSeparator()); totalWidth += mTabAdapter.getSeparator().getWidth(); } } if (totalWidth < mWindowWidth) { int count = mViewPager.getAdapter().getCount(); if (isUseSeperator) { tabWidth = (mWindowWidth - (count - 1) * mTabAdapter.getSeparator().getWidth()) / count; } else { tabWidth = mWindowWidth / count; } } } for (int i = 0; i < mViewPager.getAdapter().getCount(); i++) { final View tab = mTabAdapter.getView(i); tab.setTag(i); if (tabWidth != 0) { mContainer.addView(tab, new LinearLayout.LayoutParams(tabWidth, LinearLayout.LayoutParams.MATCH_PARENT)); } else { mContainer.addView(tab, new LinearLayout.LayoutParams(0, LinearLayout.LayoutParams.MATCH_PARENT, 100f)); } // Segmentation view if (mTabAdapter.getSeparator() != null && i != mViewPager.getAdapter().getCount() - 1) { isUseSeperator = true; mContainer.addView(mTabAdapter.getSeparator()); } // Set click listener on tab. tab.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { int index = (Integer) tab.getTag(); if (mTabClickListener != null) { mTabClickListener.onClick(index); } else { if (mViewPager.getCurrentItem() == index) { selectTab(index); } else { // If ViewPager change the page, the listener // will call selectTab method mViewPager.setCurrentItem(index, true); } } } }); } // Set the current selected tab when first coming. selectTab(mViewPager.getCurrentItem()); } } /** * Select the tab, and move the tab to the middle position * * @param position Position of the tab. */ protected void selectTab(int position) { if (!isUseSeperator) { for (int i = 0; i < mContainer.getChildCount(); i++) { View tab = mContainer.getChildAt(i); // Make the current tab selected, others unselected. tab.setSelected(i == position); if (mTabAdapter != null) { if (i == position) { mTabAdapter.onTabSelected(position, mContainer); } else { mTabAdapter.onTabUnSelected(i, mContainer); } } } } else { // pos is the position of the tab. for (int i = 0, pos = 0; i < mContainer.getChildCount(); i += 2, pos++) { View tab = mContainer.getChildAt(i); tab.setSelected(pos == position); if (mTabAdapter != null) { if (pos == position) { mTabAdapter.onTabSelected(i, mContainer); } else { mTabAdapter.onTabUnSelected(i, mContainer); } } } } View selectedView = null; if (!isUseSeperator) { selectedView = mContainer.getChildAt(position); } else { selectedView = mContainer.getChildAt(position * 2); } int tabWidth = selectedView.getMeasuredWidth(); int tabLeft = selectedView.getLeft(); // (tabLeft + tabWidth / 2) is the distance from current tab's middle to // the left of the screen int distance = (tabLeft + tabWidth / 2) - mWindowWidth / 2; smoothScrollTo(distance, this.getScrollY()); } protected View getSelectedView(int position) { View selectedView = null; if (!isUseSeperator) { selectedView = mContainer.getChildAt(position); } else { selectedView = mContainer.getChildAt(position * 2); } return selectedView; } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { super.onLayout(changed, l, t, r, b); if (changed) { selectTab(mViewPager.getCurrentItem()); } } @Override public void onPageScrollStateChanged(int arg0) { } @Override public void onPageScrolled(int arg0, float arg1, int arg2) { } @Override public void onPageSelected(int position) { selectTab(position); if (mPageSelectedListener != null) { mPageSelectedListener.onPageSelected(position); } } /** * Set the tab width be all equals when all the tab width is less than the window width<br> * <font color=red>Note</font>This must be used before setTabAdapter and setViewPager * * @param flag */ public void setEqualWidth(boolean flag) { mEqualWidth = flag; } public void setTabClickListener(TabClickListener listener) { this.mTabClickListener = listener; } public void setPageSelectedListener(PageSelectedListener pageSelectedListener) { this.mPageSelectedListener = pageSelectedListener; } public static void measureView(View view) { ViewGroup.LayoutParams lp = view.getLayoutParams(); if (lp == null) { lp = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT); } int childMeasureWidth = ViewGroup.getChildMeasureSpec(0, 0, lp.width); int childMeasureHeight; if (lp.height > 0) { childMeasureHeight = MeasureSpec.makeMeasureSpec(lp.height, MeasureSpec.EXACTLY); } else { // Measure specification mode: The parent has not imposed any // constraint on the child. It can be whatever size it wants. childMeasureHeight = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); } view.measure(childMeasureWidth, childMeasureHeight); } /** * On click Listener of the tab. */ public interface TabClickListener { public void onClick(int position); } /** * Callback when ViewPager change Pager.To avoid use setOnPageChangeListener more times will override. */ public interface PageSelectedListener { public void onPageSelected(int position); } /** * Interface to get the tab view. * * @author Charon Chui */ public interface TabAdapter { /** * Tab View * * @param position Position of the tab view. * @return View View of the tab. */ public View getView(int position); /** * Segmentation view between two tab. * * @return View, If don't use you this may return null. */ public View getSeparator(); /** * Callback when the tab is selected. * * @param position Selected tab postion * @param mContainer The parent of all the tab. */ public void onTabSelected(int position, ViewGroup mContainer); /** * Callback when the tab is unselected. * * @param position Unselected tab postion * @param mContainer The parent of all the tab. */ public void onTabUnSelected(int position, ViewGroup mContainer); } }