Java tutorial
/* * Copyright 2014 Google Inc. All rights reserved. * * 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 org.nativescript.widgets; import android.content.Context; import android.graphics.Typeface; import android.support.v4.view.PagerAdapter; import android.support.v4.view.ViewPager; import android.text.TextUtils; import android.util.AttributeSet; import android.util.SparseArray; import android.util.TypedValue; import android.view.Gravity; import android.view.View; import android.view.ViewGroup; import android.widget.HorizontalScrollView; import android.widget.ImageView; import android.widget.ImageView.ScaleType; import android.widget.LinearLayout; 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...)}. * The alternative is via the {@link TabColorizer} interface which provides you * complete control over which color is used for any individual position. * <p> */ public class TabLayout extends HorizontalScrollView { /** * 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); } 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 static final int TEXT_MAX_WIDTH = 180; private static final int SMALL_MIN_HEIGHT = 48; private static final int LARGE_MIN_HEIGHT = 72; private int mTitleOffset; private boolean mDistributeEvenly = true; private TabItemSpec[] mTabItems; private ViewPager mViewPager; private SparseArray<String> mContentDescriptions = new SparseArray<String>(); private ViewPager.OnPageChangeListener mViewPagerPageChangeListener; private final TabStrip mTabStrip; public TabLayout(Context context) { this(context, null); } public TabLayout(Context context, AttributeSet attrs) { this(context, attrs, 0); } public TabLayout(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 TabStrip(context); addView(mTabStrip, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT); } /** * Set the custom {@link TabColorizer} to be used. * * If you only require simple customisation then you can use * {@link #setSelectedIndicatorColors(int...)} to achieve similar effects. */ public void setCustomTabColorizer(TabColorizer tabColorizer) { mTabStrip.setCustomTabColorizer(tabColorizer); } public void setDistributeEvenly(boolean distributeEvenly) { mDistributeEvenly = distributeEvenly; } /** * 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); this.mSelectedIndicatorColors = colors; } private int[] mSelectedIndicatorColors; public int[] getSelectedIndicatorColors() { return this.mSelectedIndicatorColors; } public void setTabTextColor(int color) { mTabStrip.setTabTextColor(color); } public int getTabTextColor() { return mTabStrip.getTabTextColor(); } public void setSelectedTabTextColor(int color) { mTabStrip.setSelectedTabTextColor(color); } public int getSelectedTabTextColor() { return mTabStrip.getSelectedTabTextColor(); } public void setTabTextFontSize(float fontSize) { mTabStrip.setTabTextFontSize(fontSize); } public float getTabTextFontSize() { return mTabStrip.getTabTextFontSize(); } /** * Set the {@link ViewPager.OnPageChangeListener}. When using * {@link TabLayout} 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; } /** * 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) { this.setItems(null, viewPager); } public void setItems(TabItemSpec[] items, ViewPager viewPager) { mTabStrip.removeAllViews(); mViewPager = viewPager; mTabItems = items; if (viewPager != null) { viewPager.addOnPageChangeListener(new InternalViewPagerListener()); populateTabStrip(); } } /** * Updates the UI of an item at specified index */ public void updateItemAt(int position, TabItemSpec tabItem) { LinearLayout ll = (LinearLayout) mTabStrip.getChildAt(position); ImageView imgView = (ImageView) ll.getChildAt(0); TextView textView = (TextView) ll.getChildAt(1); this.setupItem(ll, textView, imgView, tabItem); } /** * Gets the TextView for tab item at index */ public TextView getTextViewForItemAt(int index) { LinearLayout ll = this.getViewForItemAt(index); return (ll != null) ? (TextView) ll.getChildAt(1) : null; } /** * Gets the LinearLayout container for tab item at index */ public LinearLayout getViewForItemAt(int index) { LinearLayout result = null; if (this.mTabStrip.getChildCount() > index) { result = (LinearLayout) this.mTabStrip.getChildAt(index); } return result; } /** * Gets the number of realized tabs. */ public int getItemCount() { return this.mTabStrip.getChildCount(); } /** * Create a default view to be used for tabs. */ protected View createDefaultTabView(Context context, TabItemSpec tabItem) { float density = getResources().getDisplayMetrics().density; int padding = (int) (TAB_VIEW_PADDING_DIPS * density); LinearLayout ll = new LinearLayout(context); ll.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.MATCH_PARENT)); ll.setGravity(Gravity.CENTER); ll.setOrientation(LinearLayout.VERTICAL); TypedValue outValue = new TypedValue(); getContext().getTheme().resolveAttribute(android.R.attr.selectableItemBackground, outValue, true); ll.setBackgroundResource(outValue.resourceId); ImageView imgView = new ImageView(context); imgView.setScaleType(ScaleType.FIT_CENTER); LinearLayout.LayoutParams imgLP = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT); imgLP.gravity = Gravity.CENTER; imgView.setLayoutParams(imgLP); TextView textView = new TextView(context); textView.setGravity(Gravity.CENTER); textView.setMaxWidth((int) (TEXT_MAX_WIDTH * density)); textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, TAB_VIEW_TEXT_SIZE_SP); textView.setTypeface(Typeface.DEFAULT_BOLD); textView.setEllipsize(TextUtils.TruncateAt.END); textView.setAllCaps(true); textView.setMaxLines(2); textView.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT)); textView.setPadding(padding, 0, padding, 0); this.setupItem(ll, textView, imgView, tabItem); ll.addView(imgView); ll.addView(textView); return ll; } private void setupItem(LinearLayout ll, TextView textView, ImageView imgView, TabItemSpec tabItem) { float density = getResources().getDisplayMetrics().density; if (tabItem.iconId != 0) { imgView.setImageResource(tabItem.iconId); imgView.setVisibility(VISIBLE); } else if (tabItem.iconDrawable != null) { imgView.setImageDrawable(tabItem.iconDrawable); imgView.setVisibility(VISIBLE); } else { imgView.setVisibility(GONE); } if (tabItem.title != null && !tabItem.title.isEmpty()) { textView.setText(tabItem.title); textView.setVisibility(VISIBLE); } else { textView.setVisibility(GONE); } if (imgView.getVisibility() == VISIBLE && textView.getVisibility() == VISIBLE) { ll.setMinimumHeight((int) (LARGE_MIN_HEIGHT * density)); } else { ll.setMinimumHeight((int) (SMALL_MIN_HEIGHT * density)); } if (mDistributeEvenly) { LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) ll.getLayoutParams(); lp.width = 0; lp.weight = 1; } } private void populateTabStrip() { final PagerAdapter adapter = mViewPager.getAdapter(); final OnClickListener tabClickListener = new TabClickListener(); for (int i = 0; i < adapter.getCount(); i++) { View tabView = null; TabItemSpec tabItem; if (this.mTabItems != null && this.mTabItems.length > i) { tabItem = this.mTabItems[i]; } else { tabItem = new TabItemSpec(); tabItem.title = adapter.getPageTitle(i).toString(); } tabView = createDefaultTabView(getContext(), tabItem); tabView.setOnClickListener(tabClickListener); String desc = mContentDescriptions.get(i, null); if (desc != null) { tabView.setContentDescription(desc); } mTabStrip.addView(tabView); if (i == mViewPager.getCurrentItem()) { tabView.setSelected(true); } } } public void setContentDescription(int i, String desc) { mContentDescriptions.put(i, desc); } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); if (mViewPager != null) { 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); } } 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 (mViewPagerPageChangeListener != null) { mViewPagerPageChangeListener.onPageScrollStateChanged(state); } } @Override public void onPageSelected(int position) { if (mScrollState == ViewPager.SCROLL_STATE_IDLE) { mTabStrip.onViewPagerPageChanged(position, 0f); scrollToTab(position, 0); } for (int i = 0; i < mTabStrip.getChildCount(); i++) { mTabStrip.getChildAt(i).setSelected(position == i); } 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; } } } } }