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/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 de.egh.bikehist.ui.masterdata; import android.content.Context; import android.graphics.Typeface; import android.os.Build; 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.TextView; /** 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(ViewPager)} providing it the ViewPager this layout is being used for. <p/> The colors can be customized in two ways. The first and simplest is to provide an array of colors via {@link #setSelectedIndicatorColors(int...)} and {@link #setDividerColors(int...)}. The alternative is via the {@link TabColorizer} interface which provides you complete control over which color is used for any individual position. <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 { public static final String TAG = SlidingTabLayout.class.getSimpleName(); 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 = 12; private final SlidingTabStrip mTabStrip; private final int mTitleOffset; private int mTabViewLayoutId; private int mTabViewTextViewId; private ViewPager mViewPager; private ViewPager.OnPageChangeListener mViewPagerPageChangeListener; private Callbacks callbacks = null; 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); // Make sure that the Tab Strips fills this View setFillViewport(true); mTitleOffset = (int) (TITLE_OFFSET_DIPS * getResources().getDisplayMetrics().density); mTabStrip = new SlidingTabStrip(context); addView(mTabStrip, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT); setCallbacks(null); } /** Set the custom {@link TabColorizer} to be used. <p/> If you only require simple custmisation then you can use {@link #setSelectedIndicatorColors(int...)} and {@link #setDividerColors(int...)} to achieve similar effects. */ public void setCustomTabColorizer(TabColorizer tabColorizer) { mTabStrip.setCustomTabColorizer(tabColorizer); } /** Sets the colors to be used for indicating the selected tab. These colors are treated as a circular array. Providing one color will mean that all tabs are indicated with the same color. */ public void setSelectedIndicatorColors(int... colors) { mTabStrip.setSelectedIndicatorColors(colors); } /** Sets the colors to be used for tab dividers. These colors are treated as a circular array. Providing one color will mean that all tabs are indicated with the same color. */ public void setDividerColors(int... colors) { mTabStrip.setDividerColors(colors); } /** Set the {@link ViewPager.OnPageChangeListener}. When using {@link SlidingTabLayout} you are required to set any {@link ViewPager.OnPageChangeListener} through this method. This is so that the layout can update it's scroll position correctly. @see ViewPager#setOnPageChangeListener(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 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.setOnPageChangeListener(new InternalViewPagerListener()); populateTabStrip(); } } /** 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)}. */ private TextView createDefaultTabView(Context context) { TextView textView = new TextView(context); textView.setGravity(Gravity.CENTER); textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, TAB_VIEW_TEXT_SIZE_SP); textView.setTypeface(Typeface.DEFAULT_BOLD); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { // 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(android.R.attr.selectableItemBackground, outValue, true); textView.setBackgroundResource(outValue.resourceId); } if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) { // If we're running on ICS or newer, 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()); } if (tabTitleView == null && TextView.class.isInstance(tabView)) { tabTitleView = (TextView) tabView; } tabTitleView.setText(adapter.getPageTitle(i)); tabView.setOnClickListener(tabClickListener); mTabStrip.addView(tabView); } } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); if (mViewPager != null) { callbacks.onPageSet(mViewPager.getCurrentItem()); scrollToTab(mViewPager.getCurrentItem(), 0); } } private 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); } } public void setCallbacks(Callbacks callbacks) { if (callbacks != null) this.callbacks = callbacks; else this.callbacks = new Callbacks() { @Override public void onPageSet(int position) { } }; } /** Allows complete control over the colors drawn in the tab layout. Set with {@link #setCustomTabColorizer(TabColorizer)}. */ public interface TabColorizer { /** @return return the color of the indicator used when {@code position} is selected. */ int getIndicatorColor(int position); /** @return return the color of the divider drawn to the right of {@code position}. */ int getDividerColor(int position); } /** Callbacks for the Consumer */ public interface Callbacks { /** Called with the new position, after tab has changed. */ void onPageSet(int position); } private class InternalViewPagerListener implements ViewPager.OnPageChangeListener { private int mScrollState; @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 (mScrollState == ViewPager.SCROLL_STATE_SETTLING) { callbacks.onPageSet(mViewPager.getCurrentItem()); 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); } } } private class TabClickListener implements OnClickListener { @Override public void onClick(View v) { for (int i = 0; i < mTabStrip.getChildCount(); i++) { if (v == mTabStrip.getChildAt(i)) { mViewPager.setCurrentItem(i); return; } } } } }