Java tutorial
/* * Copyright (C) 2013 The Android Open Source Project * * 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/liceses/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.simplecity.amp_library.ui.views; import android.content.Context; import android.graphics.Color; import android.support.v4.view.PagerAdapter; import android.support.v4.view.ViewPager; import android.util.AttributeSet; import android.util.TypedValue; import android.view.Gravity; import android.view.LayoutInflater; import android.view.View; import android.widget.HorizontalScrollView; import android.widget.LinearLayout; import android.widget.TextView; import com.simplecity.amp_library.R; import com.simplecity.amp_library.utils.ColorUtils; import com.simplecity.amp_library.utils.ResourceUtils; import com.simplecity.amp_library.utils.TypefaceManager; import java.util.ArrayList; /** * To be used with ViewPager to provide a tab indicator component which give constant feedback as to * the user's scroll progress. * <p/> * To use the component, simply add it to your view hierarchy. Then in your * {@link android.app.Activity} or {@link android.support.v4.app.Fragment} call * {@link #setViewPager(android.support.v4.view.ViewPager)} providing it the ViewPager this layout is being used for. * <p/> * The views used as tabs can be customized by calling {@link #setCustomTabView(int, int)}, * providing the layout ID of your custom layout. */ public class SlidingTabLayout extends HorizontalScrollView { private static final int TITLE_OFFSET_DIPS = 24; private static final int TAB_VIEW_PADDING_DIPS = 16; private static final int TAB_VIEW_TEXT_SIZE_SP = 13; private int mTitleOffset; private int mTabViewLayoutId; private int mTabViewTextViewId; ArrayList<View> mTabViews = new ArrayList<>(); ViewPager mViewPager; ViewPager.OnPageChangeListener mViewPagerPageChangeListener; final SlidingTabStrip mTabStrip; private boolean mShouldExpand = false; int mTextColor = Color.WHITE; public SlidingTabLayout(Context context) { this(context, null); } public SlidingTabLayout(Context context, AttributeSet attrs) { this(context, attrs, 0); } public SlidingTabLayout(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); // Disable the Scroll Bar setHorizontalScrollBarEnabled(false); mTitleOffset = (int) (TITLE_OFFSET_DIPS * getResources().getDisplayMetrics().density); mTabStrip = new SlidingTabStrip(context); mTabStrip.setIndicatorColor(ColorUtils.getAccentColor()); addView(mTabStrip, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT); } public void setTextColor(int color) { mTextColor = color; } public void setIndicatorColor(int color) { mTabStrip.setIndicatorColor(color); } /** * Set the {@link android.support.v4.view.ViewPager.OnPageChangeListener}. When using {@link SlidingTabLayout} you are * required to set any {@link android.support.v4.view.ViewPager.OnPageChangeListener} through this method. This is so * that the layout can update it's scroll position correctly. * * @see android.support.v4.view.ViewPager#setOnPageChangeListener(android.support.v4.view.ViewPager.OnPageChangeListener) */ public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) { mViewPagerPageChangeListener = listener; } /** * Set the custom layout to be inflated for the tab views. * * @param layoutResId Layout id to be inflated * @param textViewId id of the {@link android.widget.TextView} in the inflated view */ public void setCustomTabView(int layoutResId, int textViewId) { mTabViewLayoutId = layoutResId; mTabViewTextViewId = textViewId; } /** * Sets the associated view pager. Note that the assumption here is that the pager content * (number of tabs and tab titles) does not change after this call has been made. */ public void setViewPager(ViewPager viewPager) { mTabStrip.removeAllViews(); mViewPager = viewPager; if (viewPager != null) { viewPager.addOnPageChangeListener(new InternalViewPagerListener()); populateTabStrip(); } } /** * If true, causes the tabs to expand such that their widths are of equal weight, evenly distributed across the * width of the screen, rather than aligned left and only as wide as required by the text they contain * * @param shouldExpand whether to expand the tabs */ public void setShouldExpand(boolean shouldExpand) { mShouldExpand = shouldExpand; } /** * Create a default view to be used for tabs. This is called if a custom tab view is not set via * {@link #setCustomTabView(int, int)}. */ protected TextView createDefaultTabView(Context context) { TextView textView = new TextView(context); textView.setTypeface(TypefaceManager.getInstance().getTypeface(TypefaceManager.SANS_SERIF_MEDIUM)); textView.setGravity(Gravity.CENTER); textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, TAB_VIEW_TEXT_SIZE_SP); textView.setMinWidth(ResourceUtils.toPixels(72)); textView.setSingleLine(true); // If we're running on Honeycomb or newer, then we can use the Theme's // selectableItemBackground to ensure that the View has a pressed state TypedValue outValue = new TypedValue(); getContext().getTheme().resolveAttribute(R.attr.list_selector, outValue, true); textView.setBackgroundResource(outValue.resourceId); // Enable all-caps to match the Action Bar tab style textView.setAllCaps(true); int padding = (int) (TAB_VIEW_PADDING_DIPS * getResources().getDisplayMetrics().density); textView.setPadding(padding, padding, padding, padding); return textView; } private void populateTabStrip() { final PagerAdapter adapter = mViewPager.getAdapter(); final OnClickListener tabClickListener = new TabClickListener(); for (int i = 0; i < adapter.getCount(); i++) { View tabView = null; TextView tabTitleView = null; if (mTabViewLayoutId != 0) { // If there is a custom tab view layout id set, try and inflate it tabView = LayoutInflater.from(getContext()).inflate(mTabViewLayoutId, mTabStrip, false); tabTitleView = (TextView) tabView.findViewById(mTabViewTextViewId); } if (tabView == null) { tabView = createDefaultTabView(getContext()); mTabViews.add(tabView); } if (tabTitleView == null && TextView.class.isInstance(tabView)) { tabTitleView = (TextView) tabView; } if (tabView instanceof TextView) { ((TextView) tabView).setTextColor(mTextColor); } if (i == mViewPager.getCurrentItem()) { if (tabView instanceof TextView) { tabView.setAlpha(1.0f); } } else { if (tabView instanceof TextView) { tabView.setAlpha(0.7f); } } tabTitleView.setText(adapter.getPageTitle(i)); tabView.setOnClickListener(tabClickListener); if (mShouldExpand) { mTabStrip.addView(tabView, new LinearLayout.LayoutParams(0, LayoutParams.MATCH_PARENT, 1.0f)); } else { mTabStrip.addView(tabView); } } } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); if (mViewPager != null) { scrollToTab(mViewPager.getCurrentItem(), 0); } } void scrollToTab(int tabIndex, int positionOffset) { final int tabStripChildCount = mTabStrip.getChildCount(); if (tabStripChildCount == 0 || tabIndex < 0 || tabIndex >= tabStripChildCount) { return; } View selectedChild = mTabStrip.getChildAt(tabIndex); if (selectedChild != null) { int targetScrollX = selectedChild.getLeft() + positionOffset; if (tabIndex > 0 || positionOffset > 0) { // If we're not at the first child and are mid-scroll, make sure we obey the offset targetScrollX -= mTitleOffset; } scrollTo(targetScrollX, 0); } } private class InternalViewPagerListener implements ViewPager.OnPageChangeListener { private int mScrollState; InternalViewPagerListener() { } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { int tabStripChildCount = mTabStrip.getChildCount(); if ((tabStripChildCount == 0) || (position < 0) || (position >= tabStripChildCount)) { return; } mTabStrip.onViewPagerPageChanged(position, positionOffset); View selectedTitle = mTabStrip.getChildAt(position); int extraOffset = (selectedTitle != null) ? (int) (positionOffset * selectedTitle.getWidth()) : 0; scrollToTab(position, extraOffset); if (mViewPagerPageChangeListener != null) { mViewPagerPageChangeListener.onPageScrolled(position, positionOffset, positionOffsetPixels); } } @Override public void onPageScrollStateChanged(int state) { mScrollState = state; if (mViewPagerPageChangeListener != null) { mViewPagerPageChangeListener.onPageScrollStateChanged(state); } } @Override public void onPageSelected(int position) { if (mScrollState == ViewPager.SCROLL_STATE_IDLE) { mTabStrip.onViewPagerPageChanged(position, 0f); scrollToTab(position, 0); } if (mViewPagerPageChangeListener != null) { mViewPagerPageChangeListener.onPageSelected(position); } for (int i = 0; i < mTabViews.size(); i++) { ((TextView) mTabViews.get(i)).setTextColor(mTextColor); if (i == position) { mTabViews.get(i).setAlpha(1.0f); } else { mTabViews.get(i).setAlpha(0.7f); } } } } private class TabClickListener implements OnClickListener { TabClickListener() { } @Override public void onClick(View v) { for (int i = 0; i < mTabStrip.getChildCount(); i++) { if (v == mTabStrip.getChildAt(i)) { mViewPager.setCurrentItem(i); return; } } } } }