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/*
* Copyright (C) 2014 The Android Open Source Project
*
* 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 com.android.contacts.common.list;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;
import android.widget.LinearLayout;
import com.android.contacts.common.R;
public class ViewPagerTabStrip extends LinearLayout {
private int mSelectedUnderlineThickness;
private final Paint mSelectedUnderlinePaint;
private int mIndexForSelection;
private float mSelectionOffset;
public ViewPagerTabStrip(Context context) {
this(context, null);
}
public ViewPagerTabStrip(Context context, AttributeSet attrs) {
super(context, attrs);
final Resources res = context.getResources();
mSelectedUnderlineThickness =
res.getDimensionPixelSize(R.dimen.tab_selected_underline_height);
int underlineColor = res.getColor(R.color.tab_selected_underline_color);
int backgroundColor = res.getColor(R.color.actionbar_background_color);
mSelectedUnderlinePaint = new Paint();
mSelectedUnderlinePaint.setColor(underlineColor);
setBackgroundColor(backgroundColor);
setWillNotDraw(false);
}
/**
* Notifies this view that view pager has been scrolled. We save the tab index
* and selection offset for interpolating the position and width of selection
* underline.
*/
void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
mIndexForSelection = position;
mSelectionOffset = positionOffset;
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
int childCount = getChildCount();
// Thick colored underline below the current selection
if (childCount > 0) {
View selectedTitle = getChildAt(mIndexForSelection);
if (selectedTitle == null) {
// The view pager's tab count changed but we weren't notified yet. Ignore this draw
// pass, when we get a new selection we will update and draw the selection strip in
// the correct place.
return;
}
int selectedLeft = selectedTitle.getLeft();
int selectedRight = selectedTitle.getRight();
final boolean isRtl = isRtl();
final boolean hasNextTab = isRtl ? mIndexForSelection > 0
: (mIndexForSelection < (getChildCount() - 1));
if ((mSelectionOffset > 0.0f) && hasNextTab) {
// Draw the selection partway between the tabs
View nextTitle = getChildAt(mIndexForSelection + (isRtl ? -1 : 1));
int nextLeft = nextTitle.getLeft();
int nextRight = nextTitle.getRight();
selectedLeft = (int) (mSelectionOffset * nextLeft +
(1.0f - mSelectionOffset) * selectedLeft);
selectedRight = (int) (mSelectionOffset * nextRight +
(1.0f - mSelectionOffset) * selectedRight);
}
int height = getHeight();
canvas.drawRect(selectedLeft, height - mSelectedUnderlineThickness,
selectedRight, height, mSelectedUnderlinePaint);
}
}
private boolean isRtl() {
return getLayoutDirection() == View.LAYOUT_DIRECTION_RTL;
}
}
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