info.papdt.blacklight.ui.common.LinearViewPagerIndicator.java Source code

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Here is the source code for info.papdt.blacklight.ui.common.LinearViewPagerIndicator.java

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/* 
 * Copyright (C) 2014 Peter Cai
 *
 * This file is part of BlackLight
 *
 * BlackLight is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * BlackLight is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with BlackLight.  If not, see <http://www.gnu.org/licenses/>.
 */

package info.papdt.blacklight.ui.common;

import android.content.Context;
import android.content.res.Resources.NotFoundException;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.util.Log;
import android.view.Gravity;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.TextView;

import info.papdt.blacklight.R;

import static info.papdt.blacklight.BuildConfig.DEBUG;

/*
 * A pager indicator implemented by extending LinearLayout
 * Creates TextViews to display pager titles
 * Draws a line to indicate the current tab
 */
public class LinearViewPagerIndicator extends LinearLayout
        implements ViewPager.OnPageChangeListener, View.OnClickListener {
    private static final String TAG = LinearViewPagerIndicator.class.getSimpleName();

    private int mForeground = Color.WHITE;
    private boolean mMeasured = false;
    private Context mContext;
    private int mWidth, mHeight, mTabWidth;
    private ViewPager mPager;
    private float mOffset = 0.0f;
    private int mCurrentPage = 0;
    private ViewPager.OnPageChangeListener mListener;

    public LinearViewPagerIndicator(Context context) {
        this(context, null);
    }

    public LinearViewPagerIndicator(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public LinearViewPagerIndicator(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        mContext = context;

        try {
            TypedArray array = context.obtainStyledAttributes(R.styleable.BlackLight);
            mForeground = array.getColor(R.styleable.BlackLight_IndicatorForeground, Color.WHITE);
            array.recycle();
        } catch (NotFoundException e) {
            mForeground = Color.WHITE;
        }

        // Make it draw
        setWillNotDraw(false);
    }

    /*
     * Adds a tab to the indicator
     * You can only do this before the view is measured
     */
    public void addTab(String title) {
        if (mMeasured) {
            throw new IllegalStateException("Cannot add tabs when measured");
        }

        TextView tv = new TextView(mContext);
        tv.setText(title);
        tv.setTextColor(mForeground);
        tv.setGravity(Gravity.CENTER);
        tv.setTag(getChildCount());
        tv.setOnClickListener(this);
        LayoutParams params = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
        params.weight = 1.0f;
        addView(tv, params);
    }

    /*
     * Bind this view with a ViewPager
     */
    public void setViewPager(ViewPager pager) {
        mPager = pager;
        pager.setOnPageChangeListener(this);
    }

    /*
     * Set color
     */
    public void setForeground(int color) {
        mForeground = color;
        for (int i = 0; i < getChildCount(); i++) {
            TextView tv = (TextView) getChildAt(i);
            tv.setTextColor(mForeground);
        }
        invalidate();
    }

    /*
     * Set listener
     */
    public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) {
        mListener = listener;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        mWidth = getMeasuredWidth();
        mHeight = getMeasuredHeight();
        mTabWidth = getChildAt(0).getMeasuredWidth();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        // Draw the indicator line
        int position = mCurrentPage * mTabWidth + (int) (mOffset * mTabWidth);

        Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        paint.setColor(mForeground);

        canvas.drawRect(position, (mHeight - mHeight / 18), position + mTabWidth, mHeight, paint);

        if (DEBUG) {
            Log.d(TAG, "mWidth = " + mWidth + "; mHeight = " + mHeight + "; mTabWidth = " + mTabWidth);
            Log.d(TAG, "mCurrentPage = " + mCurrentPage);
        }
    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        mCurrentPage = position;
        mOffset = positionOffset;
        invalidate();

        if (mListener != null) {
            mListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
        }
    }

    @Override
    public void onPageSelected(int position) {
        if (mListener != null) {
            mListener.onPageSelected(position);
        }
    }

    @Override
    public void onPageScrollStateChanged(int state) {
        if (mListener != null) {
            mListener.onPageScrollStateChanged(state);
        }
    }

    @Override
    public void onClick(View v) {
        TextView tv = (TextView) v;
        mPager.setCurrentItem(Integer.valueOf(tv.getTag().toString()));
    }
}