1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.messaging.ui; 18 19 import android.content.Context; 20 import android.content.res.Resources; 21 import android.graphics.Canvas; 22 import android.graphics.Paint; 23 import android.util.AttributeSet; 24 import android.view.View; 25 import android.widget.LinearLayout; 26 27 import com.android.messaging.R; 28 import com.android.messaging.util.OsUtil; 29 30 public class ViewPagerTabStrip extends LinearLayout { 31 private int mSelectedUnderlineThickness; 32 private final Paint mSelectedUnderlinePaint; 33 34 private int mIndexForSelection; 35 private float mSelectionOffset; 36 ViewPagerTabStrip(Context context)37 public ViewPagerTabStrip(Context context) { 38 this(context, null); 39 } 40 ViewPagerTabStrip(Context context, AttributeSet attrs)41 public ViewPagerTabStrip(Context context, AttributeSet attrs) { 42 super(context, attrs); 43 44 final Resources res = context.getResources(); 45 46 mSelectedUnderlineThickness = 47 res.getDimensionPixelSize(R.dimen.pager_tab_underline_selected); 48 int underlineColor = res.getColor(R.color.contact_picker_tab_underline); 49 int backgroundColor = res.getColor(R.color.action_bar_background_color); 50 51 mSelectedUnderlinePaint = new Paint(); 52 mSelectedUnderlinePaint.setColor(underlineColor); 53 54 setBackgroundColor(backgroundColor); 55 setWillNotDraw(false); 56 } 57 58 /** 59 * Notifies this view that view pager has been scrolled. We save the tab index 60 * and selection offset for interpolating the position and width of selection 61 * underline. 62 */ onPageScrolled(int position, float positionOffset, int positionOffsetPixels)63 void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { 64 mIndexForSelection = position; 65 mSelectionOffset = positionOffset; 66 invalidate(); 67 } 68 69 @Override onDraw(Canvas canvas)70 protected void onDraw(Canvas canvas) { 71 int childCount = getChildCount(); 72 73 // Thick colored underline below the current selection 74 if (childCount > 0) { 75 View selectedTitle = getChildAt(mIndexForSelection); 76 int selectedLeft = selectedTitle.getLeft(); 77 int selectedRight = selectedTitle.getRight(); 78 final boolean isRtl = isRtl(); 79 final boolean hasNextTab = isRtl ? mIndexForSelection > 0 80 : (mIndexForSelection < (getChildCount() - 1)); 81 if ((mSelectionOffset > 0.0f) && hasNextTab) { 82 // Draw the selection partway between the tabs 83 View nextTitle = getChildAt(mIndexForSelection + (isRtl ? -1 : 1)); 84 int nextLeft = nextTitle.getLeft(); 85 int nextRight = nextTitle.getRight(); 86 87 selectedLeft = (int) (mSelectionOffset * nextLeft + 88 (1.0f - mSelectionOffset) * selectedLeft); 89 selectedRight = (int) (mSelectionOffset * nextRight + 90 (1.0f - mSelectionOffset) * selectedRight); 91 } 92 93 int height = getHeight(); 94 canvas.drawRect(selectedLeft, height - mSelectedUnderlineThickness, 95 selectedRight, height, mSelectedUnderlinePaint); 96 } 97 } 98 isRtl()99 private boolean isRtl() { 100 return OsUtil.isAtLeastJB_MR2() ? getLayoutDirection() == View.LAYOUT_DIRECTION_RTL : false; 101 } 102 }