Cuustom slidng tabs more material

SlidingTabLayout.java

package com.alorma.github.ui.view;

import android.content.Context;
import android.graphics.Color;
import android.graphics.Typeface;
import android.os.Build;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.HorizontalScrollView;
import android.widget.TextView;

/**
 * To be used with ViewPager to provide a tab indicator component which give constant feedback as to
 * the user's scroll progress.
 * <p>
 * To use the component, simply add it to your view hierarchy. Then in your
 * {@link android.app.Activity} or {@link android.support.v4.app.Fragment} call
 * {@link #setViewPager(ViewPager)} providing it the ViewPager this layout is being used for.
 * <p>
 * The colors can be customized in two ways. The first and simplest is to provide an array of colors
 * via {@link #setSelectedIndicatorColors(int...)} and {@link #setDividerColors(int...)}. The
 * alternative is via the {@link TabColorizer} interface which provides you complete control over
 * which color is used for any individual position.
 * <p>
 * The views used as tabs can be customized by calling {@link #setCustomTabView(int, int)},
 * providing the layout ID of your custom layout.
 */
public class SlidingTabLayout extends HorizontalScrollView {

	/**
	 * Allows complete control over the colors drawn in the tab layout. Set with
	 * {@link #setCustomTabColorizer(TabColorizer)}.
	 */
	public interface TabColorizer {

		/**
		 * @return return the color of the indicator used when {@code position} is selected.
		 */
		int getIndicatorColor(int position);

		/**
		 * @return return the color of the divider drawn to the right of {@code position}.
		 */
		int getDividerColor(int position);

	}

	private static final int TITLE_OFFSET_DIPS = 24;
	private static final int TAB_VIEW_PADDING_DIPS = 16;
	private static final int TAB_VIEW_TEXT_SIZE_SP = 12;

	private int mTitleOffset;

	private int mTabViewLayoutId;
	private int mTabViewTextViewId;

	private ViewPager mViewPager;
	private ViewPager.OnPageChangeListener mViewPagerPageChangeListener;

	private final SlidingTabStrip mTabStrip;

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

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

	public SlidingTabLayout(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);

		// Disable the Scroll Bar
		setHorizontalScrollBarEnabled(false);
		// Make sure that the Tab Strips fills this View
		setFillViewport(true);

		mTitleOffset = (int) (TITLE_OFFSET_DIPS * getResources().getDisplayMetrics().density);

		mTabStrip = new SlidingTabStrip(context);
		addView(mTabStrip, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
	}

	/**
	 * Set the custom {@link TabColorizer} to be used.
	 *
	 * If you only require simple custmisation then you can use
	 * {@link #setSelectedIndicatorColors(int...)} and {@link #setDividerColors(int...)} to achieve
	 * similar effects.
	 */
	public void setCustomTabColorizer(TabColorizer tabColorizer) {
		mTabStrip.setCustomTabColorizer(tabColorizer);
	}

	/**
	 * Sets the colors to be used for indicating the selected tab. These colors are treated as a
	 * circular array. Providing one color will mean that all tabs are indicated with the same color.
	 */
	public void setSelectedIndicatorColors(int... colors) {
		mTabStrip.setSelectedIndicatorColors(colors);
	}

	/**
	 * Sets the colors to be used for tab dividers. These colors are treated as a circular array.
	 * Providing one color will mean that all tabs are indicated with the same color.
	 */
	public void setDividerColors(int... colors) {
		mTabStrip.setDividerColors(colors);
	}

	/**
	 * Set the {@link ViewPager.OnPageChangeListener}. When using {@link SlidingTabLayout} you are
	 * required to set any {@link ViewPager.OnPageChangeListener} through this method. This is so
	 * that the layout can update it's scroll position correctly.
	 *
	 * @see ViewPager#setOnPageChangeListener(ViewPager.OnPageChangeListener)
	 */
	public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) {
		mViewPagerPageChangeListener = listener;
	}

	/**
	 * Set the custom layout to be inflated for the tab views.
	 *
	 * @param layoutResId Layout id to be inflated
	 * @param textViewId id of the {@link TextView} in the inflated view
	 */
	public void setCustomTabView(int layoutResId, int textViewId) {
		mTabViewLayoutId = layoutResId;
		mTabViewTextViewId = textViewId;
	}

	/**
	 * Sets the associated view pager. Note that the assumption here is that the pager content
	 * (number of tabs and tab titles) does not change after this call has been made.
	 */
	public void setViewPager(ViewPager viewPager) {
		mTabStrip.removeAllViews();

		mViewPager = viewPager;
		if (viewPager != null) {
			viewPager.setOnPageChangeListener(new InternalViewPagerListener());
			populateTabStrip();
		}
	}

	/**
	 * Create a default view to be used for tabs. This is called if a custom tab view is not set via
	 * {@link #setCustomTabView(int, int)}.
	 */
	protected TextView createDefaultTabView(Context context) {
		TextView textView = new TextView(context);
		textView.setGravity(Gravity.CENTER);
		textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, TAB_VIEW_TEXT_SIZE_SP);
		textView.setTypeface(Typeface.DEFAULT_BOLD);

		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
			// If we're running on Honeycomb or newer, then we can use the Theme's
			// selectableItemBackground to ensure that the View has a pressed state
			TypedValue outValue = new TypedValue();
			getContext().getTheme().resolveAttribute(android.R.attr.selectableItemBackground,
					outValue, true);
			textView.setBackgroundResource(outValue.resourceId);
		}

		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
			// If we're running on ICS or newer, enable all-caps to match the Action Bar tab style
			textView.setAllCaps(true);
		}

		textView.setTextColor(Color.WHITE);

		int padding = (int) (TAB_VIEW_PADDING_DIPS * getResources().getDisplayMetrics().density);
		textView.setPadding(padding, padding, padding, padding);

		return textView;
	}

	private void populateTabStrip() {
		final PagerAdapter adapter = mViewPager.getAdapter();
		final View.OnClickListener tabClickListener = new TabClickListener();

		for (int i = 0; i < adapter.getCount(); i++) {
			View tabView = null;
			TextView tabTitleView = null;

			if (mTabViewLayoutId != 0) {
				// If there is a custom tab view layout id set, try and inflate it
				tabView = LayoutInflater.from(getContext()).inflate(mTabViewLayoutId, mTabStrip,
						false);
				tabTitleView = (TextView) tabView.findViewById(mTabViewTextViewId);
			}

			if (tabView == null) {
				tabView = createDefaultTabView(getContext());
			}

			if (tabTitleView == null && TextView.class.isInstance(tabView)) {
				tabTitleView = (TextView) tabView;
			}

			if (tabTitleView != null) {
				tabTitleView.setText(adapter.getPageTitle(i));
			}
			tabView.setOnClickListener(tabClickListener);

			mTabStrip.addView(tabView);
		}
	}

	@Override
	protected void onAttachedToWindow() {
		super.onAttachedToWindow();

		if (mViewPager != null) {
			scrollToTab(mViewPager.getCurrentItem(), 0);
		}
	}

	private void scrollToTab(int tabIndex, int positionOffset) {
		final int tabStripChildCount = mTabStrip.getChildCount();
		if (tabStripChildCount == 0 || tabIndex < 0 || tabIndex >= tabStripChildCount) {
			return;
		}

		View selectedChild = mTabStrip.getChildAt(tabIndex);
		if (selectedChild != null) {
			int targetScrollX = selectedChild.getLeft() + positionOffset;

			if (tabIndex > 0 || positionOffset > 0) {
				// If we're not at the first child and are mid-scroll, make sure we obey the offset
				targetScrollX -= mTitleOffset;
			}

			scrollTo(targetScrollX, 0);
		}
	}

	private class InternalViewPagerListener implements ViewPager.OnPageChangeListener {
		private int mScrollState;

		@Override
		public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
			int tabStripChildCount = mTabStrip.getChildCount();
			if ((tabStripChildCount == 0) || (position < 0) || (position >= tabStripChildCount)) {
				return;
			}

			mTabStrip.onViewPagerPageChanged(position, positionOffset);

			View selectedTitle = mTabStrip.getChildAt(position);
			int extraOffset = (selectedTitle != null)
					? (int) (positionOffset * selectedTitle.getWidth())
					: 0;
			scrollToTab(position, extraOffset);

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

		@Override
		public void onPageScrollStateChanged(int state) {
			mScrollState = state;

			if (mViewPagerPageChangeListener != null) {
				mViewPagerPageChangeListener.onPageScrollStateChanged(state);
			}
		}

		@Override
		public void onPageSelected(int position) {
			if (mScrollState == ViewPager.SCROLL_STATE_IDLE) {
				mTabStrip.onViewPagerPageChanged(position, 0f);
				scrollToTab(position, 0);
			}

			if (mViewPagerPageChangeListener != null) {
				mViewPagerPageChangeListener.onPageSelected(position);
			}
		}

	}

	private class TabClickListener implements View.OnClickListener {
		@Override
		public void onClick(View v) {
			for (int i = 0; i < mTabStrip.getChildCount(); i++) {
				if (v == mTabStrip.getChildAt(i)) {
					mViewPager.setCurrentItem(i);
					return;
				}
			}
		}
	}

}

SlidingTabStrip.java

package com.alorma.github.ui.view;

import android.R;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.View;
import android.widget.LinearLayout;

class SlidingTabStrip extends LinearLayout {

	private static final int DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS = 2;
	private static final byte DEFAULT_BOTTOM_BORDER_COLOR_ALPHA = 0x26;
	private static final int SELECTED_INDICATOR_THICKNESS_DIPS = 3;
	private static final int DEFAULT_SELECTED_INDICATOR_COLOR = 0xFF33B5E5;

	private static final int DEFAULT_DIVIDER_THICKNESS_DIPS = 1;
	private static final byte DEFAULT_DIVIDER_COLOR_ALPHA = 0x20;
	private static final float DEFAULT_DIVIDER_HEIGHT = 0.5f;

	private final int mBottomBorderThickness;
	private final Paint mBottomBorderPaint;

	private final int mSelectedIndicatorThickness;
	private final Paint mSelectedIndicatorPaint;

	private final int mDefaultBottomBorderColor;

	private final Paint mDividerPaint;
	private final float mDividerHeight;

	private int mSelectedPosition;
	private float mSelectionOffset;

	private SlidingTabLayout.TabColorizer mCustomTabColorizer;
	private final SimpleTabColorizer mDefaultTabColorizer;

	SlidingTabStrip(Context context) {
		this(context, null);
	}

	SlidingTabStrip(Context context, AttributeSet attrs) {
		super(context, attrs);
		setWillNotDraw(false);

		final float density = getResources().getDisplayMetrics().density;

		TypedValue outValue = new TypedValue();
		context.getTheme().resolveAttribute(R.attr.colorForeground, outValue, true);
		final int themeForegroundColor =  outValue.data;

		mDefaultBottomBorderColor = setColorAlpha(themeForegroundColor,
				DEFAULT_BOTTOM_BORDER_COLOR_ALPHA);

		mDefaultTabColorizer = new SimpleTabColorizer();
		mDefaultTabColorizer.setIndicatorColors(DEFAULT_SELECTED_INDICATOR_COLOR);
		mDefaultTabColorizer.setDividerColors(setColorAlpha(themeForegroundColor,
				DEFAULT_DIVIDER_COLOR_ALPHA));

		mBottomBorderThickness = (int) (DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS * density);
		mBottomBorderPaint = new Paint();
		mBottomBorderPaint.setColor(mDefaultBottomBorderColor);

		mSelectedIndicatorThickness = (int) (SELECTED_INDICATOR_THICKNESS_DIPS * density);
		mSelectedIndicatorPaint = new Paint();

		mDividerHeight = DEFAULT_DIVIDER_HEIGHT;
		mDividerPaint = new Paint();
		mDividerPaint.setStrokeWidth((int) (DEFAULT_DIVIDER_THICKNESS_DIPS * density));
	}

	void setCustomTabColorizer(SlidingTabLayout.TabColorizer customTabColorizer) {
		mCustomTabColorizer = customTabColorizer;
		invalidate();
	}

	void setSelectedIndicatorColors(int... colors) {
		// Make sure that the custom colorizer is removed
		mCustomTabColorizer = null;
		mDefaultTabColorizer.setIndicatorColors(colors);
		invalidate();
	}

	void setDividerColors(int... colors) {
		// Make sure that the custom colorizer is removed
		mCustomTabColorizer = null;
		mDefaultTabColorizer.setDividerColors(colors);
		invalidate();
	}

	void onViewPagerPageChanged(int position, float positionOffset) {
		mSelectedPosition = position;
		mSelectionOffset = positionOffset;
		invalidate();
	}

	@Override
	protected void onDraw(Canvas canvas) {
		final int height = getHeight();
		final int childCount = getChildCount();
		final int dividerHeightPx = (int) (Math.min(Math.max(0f, mDividerHeight), 1f) * height);
		final SlidingTabLayout.TabColorizer tabColorizer = mCustomTabColorizer != null
				? mCustomTabColorizer
				: mDefaultTabColorizer;

		// Thick colored underline below the current selection
		if (childCount > 0) {
			View selectedTitle = getChildAt(mSelectedPosition);
			int left = selectedTitle.getLeft();
			int right = selectedTitle.getRight();
			int color = tabColorizer.getIndicatorColor(mSelectedPosition);

			if (mSelectionOffset > 0f && mSelectedPosition < (getChildCount() - 1)) {
				int nextColor = tabColorizer.getIndicatorColor(mSelectedPosition + 1);
				if (color != nextColor) {
					color = blendColors(nextColor, color, mSelectionOffset);
				}

				// Draw the selection partway between the tabs
				View nextTitle = getChildAt(mSelectedPosition + 1);
				left = (int) (mSelectionOffset * nextTitle.getLeft() +
						(1.0f - mSelectionOffset) * left);
				right = (int) (mSelectionOffset * nextTitle.getRight() +
						(1.0f - mSelectionOffset) * right);
			}

			mSelectedIndicatorPaint.setColor(color);

			canvas.drawRect(left, height - mSelectedIndicatorThickness, right,
					height, mSelectedIndicatorPaint);
		}

		// Thin underline along the entire bottom edge
		//canvas.drawRect(0, height - mBottomBorderThickness, getWidth(), height, mBottomBorderPaint);

		// Vertical separators between the titles
		int separatorTop = (height - dividerHeightPx) / 2;
		for (int i = 0; i < childCount - 1; i++) {
			View child = getChildAt(i);
			mDividerPaint.setColor(tabColorizer.getDividerColor(i));
			canvas.drawLine(child.getRight(), separatorTop, child.getRight(),
					separatorTop + dividerHeightPx, mDividerPaint);
		}
	}

	/**
	 * Set the alpha value of the {@code color} to be the given {@code alpha} value.
	 */
	private static int setColorAlpha(int color, byte alpha) {
		return Color.argb(alpha, Color.red(color), Color.green(color), Color.blue(color));
	}

	/**
	 * Blend {@code color1} and {@code color2} using the given ratio.
	 *
	 * @param ratio of which to blend. 1.0 will return {@code color1}, 0.5 will give an even blend,
	 *              0.0 will return {@code color2}.
	 */
	private static int blendColors(int color1, int color2, float ratio) {
		final float inverseRation = 1f - ratio;
		float r = (Color.red(color1) * ratio) + (Color.red(color2) * inverseRation);
		float g = (Color.green(color1) * ratio) + (Color.green(color2) * inverseRation);
		float b = (Color.blue(color1) * ratio) + (Color.blue(color2) * inverseRation);
		return Color.rgb((int) r, (int) g, (int) b);
	}

	private static class SimpleTabColorizer implements SlidingTabLayout.TabColorizer {
		private int[] mIndicatorColors;
		private int[] mDividerColors;

		@Override
		public final int getIndicatorColor(int position) {
			return mIndicatorColors[position % mIndicatorColors.length];
		}

		@Override
		public final int getDividerColor(int position) {
			return mDividerColors[position % mDividerColors.length];
		}

		void setIndicatorColors(int... colors) {
			mIndicatorColors = colors;
		}

		void setDividerColors(int... colors) {
			mDividerColors = colors;
		}
	}
}