The Tor Browser / file revision

 /* -*- Mode: Java; c-basic-offset: 4; tab-width: 4; indent-tabs-mode: nil; -*-

  * This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 package org.mozilla.gecko.home;

 import org.mozilla.gecko.R;

 import android.content.Context;

 import android.content.res.TypedArray;

 import android.graphics.Canvas;

 import android.graphics.drawable.Drawable;

 import android.util.AttributeSet;

 import android.view.LayoutInflater;

 import android.view.View;

 import android.view.ViewTreeObserver;

 import android.view.accessibility.AccessibilityEvent;

 import android.widget.LinearLayout;

 import android.widget.TextView;

 /**

  * {@code TabMenuStripLayout} is the view that draws the {@code HomePager}

  * tabs that are displayed in {@code TabMenuStrip}.

  */

 class TabMenuStripLayout extends LinearLayout

                          implements View.OnFocusChangeListener {

     private HomePager.OnTitleClickListener onTitleClickListener;

     private Drawable strip;

     private View selectedView;

     // Data associated with the scrolling of the strip drawable.

     private View toTab;

     private View fromTab;

     private float progress;

     // This variable is used to predict the direction of scroll.

     private float prevProgress;

     TabMenuStripLayout(Context context, AttributeSet attrs) {

         super(context, attrs);

         TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TabMenuStrip);

         final int stripResId = a.getResourceId(R.styleable.TabMenuStrip_strip, -1);

         a.recycle();

         if (stripResId != -1) {

             strip = getResources().getDrawable(stripResId);

         }

         setWillNotDraw(false);

     }

     void onAddPagerView(String title) {

         final TextView button = (TextView) LayoutInflater.from(getContext()).inflate(R.layout.tab_menu_strip, this, false);

         button.setText(title.toUpperCase());

         addView(button);

         button.setOnClickListener(new ViewClickListener(getChildCount() - 1));

         button.setOnFocusChangeListener(this);

     }

     void onPageSelected(final int position) {

         selectedView = getChildAt(position);

         // Callback to measure and draw the strip after the view is visible.

         ViewTreeObserver vto = selectedView.getViewTreeObserver();

         if (vto.isAlive()) {

             vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {

                 @Override

                 public void onGlobalLayout() {

                     selectedView.getViewTreeObserver().removeGlobalOnLayoutListener(this);

                     if (strip != null) {

                         strip.setBounds(selectedView.getLeft(),

                                         selectedView.getTop(),

                                         selectedView.getRight(),

                                         selectedView.getBottom());

                     }

                     prevProgress = position;

                 }

             });

         }

     }

     // Page scroll animates the drawable and its bounds from the previous to next child view.

     void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

         if (strip == null) {

             return;

         }

         setScrollingData(position, positionOffset);

         if (fromTab == null || toTab == null) {

             return;

         }

         final int fromTabLeft =  fromTab.getLeft();

         final int fromTabRight = fromTab.getRight();

         final int toTabLeft =  toTab.getLeft();

         final int toTabRight = toTab.getRight();

         strip.setBounds((int) (fromTabLeft + ((toTabLeft - fromTabLeft) * progress)),

                          0,

                          (int) (fromTabRight + ((toTabRight - fromTabRight) * progress)),

                          getHeight());

         invalidate();

     }

     /*

      * position + positionOffset goes from 0 to 2 as we scroll from page 1 to 3.

      * Normalized progress is relative to the the direction the page is being scrolled towards.

      * For this, we maintain direction of scroll with a state, and the child view we are moving towards and away from.

      */

     void setScrollingData(int position, float positionOffset) {

         if (position >= getChildCount() - 1) {

             return;

         }

         final float currProgress = position + positionOffset;

         if (prevProgress > currProgress) {

             toTab = getChildAt(position);

             fromTab = getChildAt(position + 1);

             progress = 1 - positionOffset;

         } else {

             toTab = getChildAt(position + 1);

             fromTab = getChildAt(position);

             progress = positionOffset;

         }

         prevProgress = currProgress;

     }

     @Override

     public void onDraw(Canvas canvas) {

         super.onDraw(canvas);

         if (strip != null) {

             strip.draw(canvas);

         }

     }

     @Override

     public void onFocusChange(View v, boolean hasFocus) {

         if (v == this && hasFocus && getChildCount() > 0) {

             selectedView.requestFocus();

             return;

         }

         if (!hasFocus) {

             return;

         }

         int i = 0;

         final int numTabs = getChildCount();

         while (i < numTabs) {

             View view = getChildAt(i);

             if (view == v) {

                 view.requestFocus();

                 if (isShown()) {

                     // A view is focused so send an event to announce the menu strip state.

                     sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_FOCUSED);

                 }

                 break;

             }

             i++;

         }

     }

     void setOnTitleClickListener(HomePager.OnTitleClickListener onTitleClickListener) {

         this.onTitleClickListener = onTitleClickListener;

     }

     private class ViewClickListener implements OnClickListener {

         private final int mIndex;

         public ViewClickListener(int index) {

             mIndex = index;

         }

         @Override

         public void onClick(View view) {

             if (onTitleClickListener != null) {

                 onTitleClickListener.onTitleClicked(mIndex);

             }

         }

     }

 }