Java tutorial
/* * Copyright (C) 2011 The Android Open Source Project * Copyright (C) 2012 Jake Wharton * * 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. * * Modifications: * - use normal LinearLayout instead of IcsLinearLayout * - remove dependency on PageIndicator interface * - notifyDataSetChanged(): * - use actionButtonStyle to give icons button-like padding and selector * - add click listener (and tag) and onClick update the view pager * - constructor: initialize the indicator stuff * - onDraw(): draw indicator below the selected item */ package com.quran.labs.androidquran.widgets; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.support.v4.view.PagerAdapter; import android.support.v4.view.ViewPager; import android.support.v4.view.ViewPager.OnPageChangeListener; import android.util.AttributeSet; import android.view.View; import android.widget.HorizontalScrollView; import android.widget.ImageView; import android.widget.LinearLayout; import com.quran.labs.androidquran.R; import static android.view.ViewGroup.LayoutParams.MATCH_PARENT; import static android.view.ViewGroup.LayoutParams.WRAP_CONTENT; /** * This widget implements the dynamic action bar tab behavior that can change * across different configurations or circumstances. */ public class IconPageIndicator extends HorizontalScrollView implements ViewPager.OnPageChangeListener, View.OnClickListener { private static final int DEF_INDICATOR_HEIGHT = 3; // dp private static final int DEF_INDICATOR_COLOR = Color.WHITE; private final LinearLayout mIconsLayout; private ViewPager mViewPager; private OnPageChangeListener mListener; private OnClickListener mClickListener; private Runnable mIconSelector; private int mSelectedIndex; private float mSelectionOffset; private int mIndicatorColor; private int mIndicatorHeight; private final Paint mIndicatorPaint = new Paint(); public IconPageIndicator(Context context) { this(context, null); } public IconPageIndicator(Context context, AttributeSet attrs) { super(context, attrs); setHorizontalScrollBarEnabled(false); mIconsLayout = new LeftToRightLinearLayout(context); addView(mIconsLayout, new LayoutParams(WRAP_CONTENT, MATCH_PARENT)); // Set indicator attributes (to defaults) final float density = context.getResources().getDisplayMetrics().density; mIndicatorHeight = (int) (DEF_INDICATOR_HEIGHT * density + 0.5f); mIndicatorColor = DEF_INDICATOR_COLOR; // Read the user-specified values if set, otherwise use defaults if (attrs != null) { TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.IconPageIndicator); mIndicatorHeight = ta.getDimensionPixelSize(R.styleable.IconPageIndicator_indicatorHeight, mIndicatorHeight); mIndicatorColor = ta.getColor(R.styleable.IconPageIndicator_indicatorColor, mIndicatorColor); ta.recycle(); } mIndicatorPaint.setColor(mIndicatorColor); } private void animateToIcon(final int position) { final View iconView = mIconsLayout.getChildAt(position); if (mIconSelector != null) { removeCallbacks(mIconSelector); } mIconSelector = new Runnable() { public void run() { final int scrollPos = iconView.getLeft() - (getWidth() - iconView.getWidth()) / 2; smoothScrollTo(scrollPos, 0); mIconSelector = null; } }; post(mIconSelector); } @Override public void onAttachedToWindow() { super.onAttachedToWindow(); if (mIconSelector != null) { // Re-post the selector we saved post(mIconSelector); } } @Override public void onDetachedFromWindow() { super.onDetachedFromWindow(); if (mIconSelector != null) { removeCallbacks(mIconSelector); } } @Override public void onPageScrollStateChanged(int state) { if (mListener != null) { mListener.onPageScrollStateChanged(state); } } @Override public void onPageScrolled(int position, float offset, int offsetPixels) { mSelectionOffset = offset; mSelectedIndex = position; invalidate(); if (mListener != null) { mListener.onPageScrolled(position, offset, offsetPixels); } } @Override public void onPageSelected(int position) { setCurrentItem(position); if (mListener != null) { mListener.onPageSelected(position); } } public void setViewPager(ViewPager view) { if (mViewPager == view) { return; } if (mViewPager != null) { mViewPager.addOnPageChangeListener(null); } PagerAdapter adapter = view.getAdapter(); if (adapter == null) { throw new IllegalStateException("ViewPager does not have adapter instance."); } mViewPager = view; view.addOnPageChangeListener(this); notifyDataSetChanged(); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); int count = mIconsLayout.getChildCount(); ImageView v = (ImageView) mIconsLayout.getChildAt(mSelectedIndex); final int bottom = v.getHeight(); final int top = bottom - mIndicatorHeight; int left = v.getLeft(); int right = v.getRight(); if (mSelectedIndex + 1 < count) { View nextIcon = mIconsLayout.getChildAt(mSelectedIndex + 1); left = (int) (mSelectionOffset * nextIcon.getLeft() + (1.0f - mSelectionOffset) * left); right = (int) (mSelectionOffset * nextIcon.getRight() + (1.0f - mSelectionOffset) * right); } mIndicatorPaint.setColor(mIndicatorColor); canvas.drawRect(left, top, right, bottom, mIndicatorPaint); } public void notifyDataSetChanged() { mIconsLayout.removeAllViews(); IconPagerAdapter iconAdapter = (IconPagerAdapter) mViewPager.getAdapter(); int count = iconAdapter.getCount(); for (int i = 0; i < count; i++) { ImageView view = new ImageView(getContext(), null, R.attr.actionButtonStyle); view.setImageResource(iconAdapter.getIconResId(i)); view.setTag(i); view.setOnClickListener(this); mIconsLayout.addView(view, new LayoutParams(WRAP_CONTENT, MATCH_PARENT)); } if (mSelectedIndex > count) { mSelectedIndex = count - 1; } setCurrentItem(mSelectedIndex); requestLayout(); } public void setViewPager(ViewPager view, int initialPosition) { setViewPager(view); setCurrentItem(initialPosition); } public void setCurrentItem(int item) { if (mViewPager == null) { throw new IllegalStateException("ViewPager has not been bound."); } mSelectedIndex = item; mViewPager.setCurrentItem(item); int tabCount = mIconsLayout.getChildCount(); for (int i = 0; i < tabCount; i++) { View child = mIconsLayout.getChildAt(i); boolean isSelected = (i == item); child.setSelected(isSelected); if (isSelected) { animateToIcon(item); } } } public void setOnPageChangeListener(OnPageChangeListener listener) { mListener = listener; } public void setOnClickListener(OnClickListener clickListener) { mClickListener = clickListener; } @Override public void onClick(View v) { if (mViewPager != null && v instanceof ImageView) { mViewPager.setCurrentItem((Integer) v.getTag()); } if (mClickListener != null) { mClickListener.onClick(v); } } public interface IconPagerAdapter { int getIconResId(int index); int getCount(); } }