michael@0: /* -*- Mode: Java; c-basic-offset: 4; tab-width: 4; indent-tabs-mode: nil; -*-
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: package org.mozilla.gecko.home;
michael@0: 
michael@0: import org.mozilla.gecko.R;
michael@0: 
michael@0: import android.content.Context;
michael@0: import android.content.res.TypedArray;
michael@0: import android.graphics.Canvas;
michael@0: import android.graphics.drawable.Drawable;
michael@0: import android.util.AttributeSet;
michael@0: import android.view.LayoutInflater;
michael@0: import android.view.View;
michael@0: import android.view.ViewTreeObserver;
michael@0: import android.view.accessibility.AccessibilityEvent;
michael@0: import android.widget.LinearLayout;
michael@0: import android.widget.TextView;
michael@0: 
michael@0: /**
michael@0:  * {@code TabMenuStripLayout} is the view that draws the {@code HomePager}
michael@0:  * tabs that are displayed in {@code TabMenuStrip}.
michael@0:  */
michael@0: class TabMenuStripLayout extends LinearLayout
michael@0:                          implements View.OnFocusChangeListener {
michael@0: 
michael@0:     private HomePager.OnTitleClickListener onTitleClickListener;
michael@0:     private Drawable strip;
michael@0:     private View selectedView;
michael@0: 
michael@0:     // Data associated with the scrolling of the strip drawable.
michael@0:     private View toTab;
michael@0:     private View fromTab;
michael@0:     private float progress;
michael@0: 
michael@0:     // This variable is used to predict the direction of scroll.
michael@0:     private float prevProgress;
michael@0: 
michael@0:     TabMenuStripLayout(Context context, AttributeSet attrs) {
michael@0:         super(context, attrs);
michael@0: 
michael@0:         TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TabMenuStrip);
michael@0:         final int stripResId = a.getResourceId(R.styleable.TabMenuStrip_strip, -1);
michael@0:         a.recycle();
michael@0: 
michael@0:         if (stripResId != -1) {
michael@0:             strip = getResources().getDrawable(stripResId);
michael@0:         }
michael@0: 
michael@0:         setWillNotDraw(false);
michael@0:     }
michael@0: 
michael@0:     void onAddPagerView(String title) {
michael@0:         final TextView button = (TextView) LayoutInflater.from(getContext()).inflate(R.layout.tab_menu_strip, this, false);
michael@0:         button.setText(title.toUpperCase());
michael@0: 
michael@0:         addView(button);
michael@0:         button.setOnClickListener(new ViewClickListener(getChildCount() - 1));
michael@0:         button.setOnFocusChangeListener(this);
michael@0:     }
michael@0: 
michael@0:     void onPageSelected(final int position) {
michael@0:         selectedView = getChildAt(position);
michael@0: 
michael@0:         // Callback to measure and draw the strip after the view is visible.
michael@0:         ViewTreeObserver vto = selectedView.getViewTreeObserver();
michael@0:         if (vto.isAlive()) {
michael@0:             vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
michael@0:                 @Override
michael@0:                 public void onGlobalLayout() {
michael@0:                     selectedView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
michael@0: 
michael@0:                     if (strip != null) {
michael@0:                         strip.setBounds(selectedView.getLeft(),
michael@0:                                         selectedView.getTop(),
michael@0:                                         selectedView.getRight(),
michael@0:                                         selectedView.getBottom());
michael@0:                     }
michael@0: 
michael@0:                     prevProgress = position;
michael@0:                 }
michael@0:             });
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     // Page scroll animates the drawable and its bounds from the previous to next child view.
michael@0:     void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
michael@0:         if (strip == null) {
michael@0:             return;
michael@0:         }
michael@0: 
michael@0:         setScrollingData(position, positionOffset);
michael@0: 
michael@0:         if (fromTab == null || toTab == null) {
michael@0:             return;
michael@0:         }
michael@0: 
michael@0:         final int fromTabLeft =  fromTab.getLeft();
michael@0:         final int fromTabRight = fromTab.getRight();
michael@0: 
michael@0:         final int toTabLeft =  toTab.getLeft();
michael@0:         final int toTabRight = toTab.getRight();
michael@0: 
michael@0:         strip.setBounds((int) (fromTabLeft + ((toTabLeft - fromTabLeft) * progress)),
michael@0:                          0,
michael@0:                          (int) (fromTabRight + ((toTabRight - fromTabRight) * progress)),
michael@0:                          getHeight());
michael@0:         invalidate();
michael@0:     }
michael@0: 
michael@0:     /*
michael@0:      * position + positionOffset goes from 0 to 2 as we scroll from page 1 to 3.
michael@0:      * Normalized progress is relative to the the direction the page is being scrolled towards.
michael@0:      * For this, we maintain direction of scroll with a state, and the child view we are moving towards and away from.
michael@0:      */
michael@0:     void setScrollingData(int position, float positionOffset) {
michael@0:         if (position >= getChildCount() - 1) {
michael@0:             return;
michael@0:         }
michael@0: 
michael@0:         final float currProgress = position + positionOffset;
michael@0: 
michael@0:         if (prevProgress > currProgress) {
michael@0:             toTab = getChildAt(position);
michael@0:             fromTab = getChildAt(position + 1);
michael@0:             progress = 1 - positionOffset;
michael@0:         } else {
michael@0:             toTab = getChildAt(position + 1);
michael@0:             fromTab = getChildAt(position);
michael@0:             progress = positionOffset;
michael@0:         }
michael@0: 
michael@0:         prevProgress = currProgress;
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     public void onDraw(Canvas canvas) {
michael@0:         super.onDraw(canvas);
michael@0: 
michael@0:         if (strip != null) {
michael@0:             strip.draw(canvas);
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     public void onFocusChange(View v, boolean hasFocus) {
michael@0:         if (v == this && hasFocus && getChildCount() > 0) {
michael@0:             selectedView.requestFocus();
michael@0:             return;
michael@0:         }
michael@0: 
michael@0:         if (!hasFocus) {
michael@0:             return;
michael@0:         }
michael@0: 
michael@0:         int i = 0;
michael@0:         final int numTabs = getChildCount();
michael@0: 
michael@0:         while (i < numTabs) {
michael@0:             View view = getChildAt(i);
michael@0:             if (view == v) {
michael@0:                 view.requestFocus();
michael@0:                 if (isShown()) {
michael@0:                     // A view is focused so send an event to announce the menu strip state.
michael@0:                     sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_FOCUSED);
michael@0:                 }
michael@0:                 break;
michael@0:             }
michael@0: 
michael@0:             i++;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     void setOnTitleClickListener(HomePager.OnTitleClickListener onTitleClickListener) {
michael@0:         this.onTitleClickListener = onTitleClickListener;
michael@0:     }
michael@0: 
michael@0:     private class ViewClickListener implements OnClickListener {
michael@0:         private final int mIndex;
michael@0: 
michael@0:         public ViewClickListener(int index) {
michael@0:             mIndex = index;
michael@0:         }
michael@0: 
michael@0:         @Override
michael@0:         public void onClick(View view) {
michael@0:             if (onTitleClickListener != null) {
michael@0:                 onTitleClickListener.onTitleClicked(mIndex);
michael@0:             }
michael@0:         }
michael@0:     }
michael@0: }