TabsScroller.java

/*
 * Copyright (C) 2011 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.
 */

/*
 * Class taken from the stock browser in AOSP.
 * Only slightly modified to meet Tint's needs.
 */

package com.seal.ui.views;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.annotation.SuppressLint;
import android.content.Context;
import android.database.DataSetObserver;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.DecelerateInterpolator;
import android.widget.BaseAdapter;
import android.widget.LinearLayout;

/**
 * custom view for displaying tabs in the nav screen
 */
public class TabsScroller extends ScrollerView {

	static final int INVALID_POSITION = -1;
	static final float[] PULL_FACTOR = { 2.5f, 0.9f };

	public interface OnRemoveListener {
		public void onRemovePosition(int position);
	}

	interface OnLayoutListener {
		public void onLayout(int l, int t, int r, int b);
	}

	private ContentLayout mContentView;
	private BaseAdapter mAdapter;
	private OnRemoveListener mRemoveListener;
	private OnLayoutListener mLayoutListener;
	private int mGap;
	private int mGapPosition;
	private ObjectAnimator mGapAnimator;

	// after drag animation velocity in pixels/sec
	private static final float MIN_VELOCITY = 1500;
	private AnimatorSet mAnimator;

	private float mFlingVelocity;
	private boolean mNeedsScroll;
	private int mScrollPosition;

	DecelerateInterpolator mCubic;
	int mPullValue;

	public TabsScroller(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		init(context);
	}

	public TabsScroller(Context context, AttributeSet attrs) {
		super(context, attrs);
		init(context);
	}

	public TabsScroller(Context context) {
		super(context);
		init(context);
	}

	private void init(Context ctx) {
		mCubic = new DecelerateInterpolator(1.5f);
		mGapPosition = INVALID_POSITION;
		setHorizontalScrollBarEnabled(false);
		setVerticalScrollBarEnabled(false);
		mContentView = new ContentLayout(ctx, this);
		mContentView.setOrientation(LinearLayout.VERTICAL);
		addView(mContentView);
		mContentView.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT));
		// ProGuard !
		setGap(getGap());
		mFlingVelocity = getContext().getResources().getDisplayMetrics().density * MIN_VELOCITY;
	}

	protected int getScrollValue() {
		return mHorizontal ? getScrollX() : getScrollY();
	}

	protected void setScrollValue(int value) {
		scrollTo(mHorizontal ? value : 0, mHorizontal ? 0 : value);
	}

	protected TabView getTabView(int pos) {
		return (TabView) mContentView.getChildAt(pos);
	}

	protected boolean isHorizontal() {
		return mHorizontal;
	}

	public void setOrientation(int orientation) {
		mContentView.setOrientation(orientation);
		if (orientation == LinearLayout.HORIZONTAL) {
			mContentView.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT));
		} else {
			mContentView.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));
		}
		super.setOrientation(orientation);
	}

	public void setAdapter(BaseAdapter adapter) {
		setAdapter(adapter, 0);
	}

	public void setOnRemoveListener(OnRemoveListener l) {
		mRemoveListener = l;
	}

	public void setOnLayoutListener(OnLayoutListener l) {
		mLayoutListener = l;
	}

	protected void setAdapter(BaseAdapter adapter, int selection) {
		mAdapter = adapter;
		mAdapter.registerDataSetObserver(new DataSetObserver() {

			@Override
			public void onChanged() {
				super.onChanged();
				handleDataChanged();
			}

			@Override
			public void onInvalidated() {
				super.onInvalidated();
			}
		});
		handleDataChanged(selection);
	}

	protected ViewGroup getContentView() {
		return mContentView;
	}

	protected int getRelativeChildTop(int ix) {
		return mContentView.getChildAt(ix).getTop() - getScrollY();
	}

	protected void handleDataChanged() {
		handleDataChanged(INVALID_POSITION);
	}

	void handleDataChanged(int newscroll) {
		int scroll = getScrollValue();
		if (mGapAnimator != null) {
			mGapAnimator.cancel();
		}
		mContentView.removeAllViews();
		for (int i = 0; i < mAdapter.getCount(); i++) {
			View v = mAdapter.getView(i, null, mContentView);
			LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
			lp.gravity = (mHorizontal ? Gravity.CENTER_VERTICAL : Gravity.CENTER_HORIZONTAL);
			mContentView.addView(v, lp);
			if (mGapPosition > INVALID_POSITION) {
				adjustViewGap(v, i);
			}
		}
		if (newscroll > INVALID_POSITION) {
			newscroll = Math.min(mAdapter.getCount() - 1, newscroll);
			mNeedsScroll = true;
			mScrollPosition = newscroll;
			requestLayout();
		} else {
			setScrollValue(scroll);
		}
	}

	protected void finishScroller() {
		mScroller.forceFinished(true);
	}

	@SuppressLint("WrongCall")
	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		super.onLayout(changed, l, t, r, b);
		if (mNeedsScroll) {
			mScroller.forceFinished(true);
			snapToSelected(mScrollPosition, false);
			mNeedsScroll = false;
		}
		if (mLayoutListener != null) {
			mLayoutListener.onLayout(l, t, r, b);
			mLayoutListener = null;
		}
	}

	void clearTabs() {
		mContentView.removeAllViews();
	}

	public void snapToSelected(int pos, boolean smooth) {
		if (pos < 0) return;
		View v = mContentView.getChildAt(pos);
		if (v == null) return;
		int sx = 0;
		int sy = 0;
		if (mHorizontal) {
			sx = (v.getLeft() + v.getRight() - getWidth()) / 2;
		} else {
			sy = (v.getTop() + v.getBottom() - getHeight()) / 2;
		}
		if ((sx != getScrollX()) || (sy != getScaleY())) {
			if (smooth) {
				smoothScrollTo(sx, sy);
			} else {
				scrollTo(sx, sy);
			}
		}
	}

	public void animateOut(View v) {
		if (v == null) return;
		animateOut(v, -mFlingVelocity);
	}

	private void animateOut(final View v, float velocity) {
		float start = mHorizontal ? v.getTranslationY() : v.getTranslationX();
		animateOut(v, velocity, start);
	}

	private void animateOut(final View v, float velocity, float start) {
		if ((v == null) || (mAnimator != null)) return;
		final int position = mContentView.indexOfChild(v);
		int target = 0;
		if (velocity < 0) {
			target = mHorizontal ? -getHeight() : -getWidth();
		} else {
			target = mHorizontal ? getHeight() : getWidth();
		}
		int distance = target - (mHorizontal ? v.getTop() : v.getLeft());
		long duration = (long) (Math.abs(distance) * 1000 / Math.abs(velocity));
		int scroll = 0;
		int translate = 0;
		int gap = mHorizontal ? v.getWidth() : v.getHeight();
		int centerView = getViewCenter(v);
		int centerScreen = getScreenCenter();
		int newpos = INVALID_POSITION;
		if (centerView < centerScreen - gap / 2) {
			// top view
			scroll = -(centerScreen - centerView - gap);
			translate = (position > 0) ? gap : 0;
			newpos = position;
		} else if (centerView > centerScreen + gap / 2) {
			// bottom view
			scroll = -(centerScreen + gap - centerView);
			if (position < mAdapter.getCount() - 1) {
				translate = -gap;
			}
		} else {
			// center view
			scroll = -(centerScreen - centerView);
			if (position < mAdapter.getCount() - 1) {
				translate = -gap;
			} else {
				scroll -= gap;
			}
		}
		mGapPosition = position;
		final int pos = newpos;
		ObjectAnimator trans = ObjectAnimator.ofFloat(v, (mHorizontal ? TRANSLATION_Y : TRANSLATION_X), start, target);
		ObjectAnimator alpha = ObjectAnimator.ofFloat(v, ALPHA, getAlpha(v, start), getAlpha(v, target));
		AnimatorSet set1 = new AnimatorSet();
		set1.playTogether(trans, alpha);
		set1.setDuration(duration);
		mAnimator = new AnimatorSet();
		ObjectAnimator trans2 = null;
		ObjectAnimator scroll1 = null;
		if (scroll != 0) {
			if (mHorizontal) {
				scroll1 = ObjectAnimator.ofInt(this, "scrollX", getScrollX(), getScrollX() + scroll);
			} else {
				scroll1 = ObjectAnimator.ofInt(this, "scrollY", getScrollY(), getScrollY() + scroll);
			}
		}
		if (translate != 0) {
			trans2 = ObjectAnimator.ofInt(this, "gap", 0, translate);
		}
		final int duration2 = 200;
		if (scroll1 != null) {
			if (trans2 != null) {
				AnimatorSet set2 = new AnimatorSet();
				set2.playTogether(scroll1, trans2);
				set2.setDuration(duration2);
				mAnimator.playSequentially(set1, set2);
			} else {
				scroll1.setDuration(duration2);
				mAnimator.playSequentially(set1, scroll1);
			}
		} else {
			if (trans2 != null) {
				trans2.setDuration(duration2);
				mAnimator.playSequentially(set1, trans2);
			}
		}
		mAnimator.addListener(new AnimatorListenerAdapter() {
			public void onAnimationEnd(Animator a) {
				if (mRemoveListener != null) {
					mRemoveListener.onRemovePosition(position);
					mAnimator = null;
					mGapPosition = INVALID_POSITION;
					mGap = 0;
					handleDataChanged(pos);
				}
			}
		});
		mAnimator.start();
	}

	public void setGap(int gap) {
		if (mGapPosition != INVALID_POSITION) {
			mGap = gap;
			postInvalidate();
		}
	}

	public int getGap() {
		return mGap;
	}

	void adjustGap() {
		for (int i = 0; i < mContentView.getChildCount(); i++) {
			final View child = mContentView.getChildAt(i);
			adjustViewGap(child, i);
		}
	}

	private void adjustViewGap(View view, int pos) {
		if ((mGap < 0 && pos > mGapPosition) || (mGap > 0 && pos < mGapPosition)) {
			if (mHorizontal) {
				view.setTranslationX(mGap);
			} else {
				view.setTranslationY(mGap);
			}
		}
	}

	private int getViewCenter(View v) {
		if (mHorizontal) {
			return v.getLeft() + v.getWidth() / 2;
		} else {
			return v.getTop() + v.getHeight() / 2;
		}
	}

	private int getScreenCenter() {
		if (mHorizontal) {
			return getScrollX() + getWidth() / 2;
		} else {
			return getScrollY() + getHeight() / 2;
		}
	}

	@Override
	public void draw(Canvas canvas) {
		if (mGapPosition > INVALID_POSITION) {
			adjustGap();
		}
		super.draw(canvas);
	}

	@Override
	protected View findViewAt(int x, int y) {
		x += getScrollX();
		y += getScrollY();
		final int count = mContentView.getChildCount();
		for (int i = count - 1; i >= 0; i--) {
			View child = mContentView.getChildAt(i);
			if (child.getVisibility() == View.VISIBLE) {
				if ((x >= child.getLeft()) && (x < child.getRight()) && (y >= child.getTop()) && (y < child.getBottom())) {
					return child;
				}
			}
		}
		return null;
	}

	@Override
	protected void onOrthoDrag(View v, float distance) {
		if ((v != null) && (mAnimator == null)) {
			offsetView(v, distance);
		}
	}

	@Override
	protected void onOrthoDragFinished(View downView) {
		if (mAnimator != null) return;
		if (mIsOrthoDragged && downView != null) {
			// offset
			float diff = mHorizontal ? downView.getTranslationY() : downView.getTranslationX();
			if (Math.abs(diff) > (mHorizontal ? downView.getHeight() : downView.getWidth()) / 2) {
				// remove it
				animateOut(downView, Math.signum(diff) * mFlingVelocity, diff);
			} else {
				// snap back
				offsetView(downView, 0);
			}
		}
	}

	@Override
	protected void onOrthoFling(View v, float velocity) {
		if (v == null) return;
		if (mAnimator == null && Math.abs(velocity) > mFlingVelocity / 2) {
			animateOut(v, velocity);
		} else {
			offsetView(v, 0);
		}
	}

	private void offsetView(View v, float distance) {
		v.setAlpha(getAlpha(v, distance));
		if (mHorizontal) {
			v.setTranslationY(distance);
		} else {
			v.setTranslationX(distance);
		}
	}

	private float getAlpha(View v, float distance) {
		return 1 - (float) Math.abs(distance) / (mHorizontal ? v.getHeight() : v.getWidth());
	}

	private float ease(DecelerateInterpolator inter, float value, float start, float dist, float duration) {
		return start + dist * inter.getInterpolation(value / duration);
	}

	@Override
	protected void onPull(int delta) {
		boolean layer = false;
		int count = 2;
		if (delta == 0 && mPullValue == 0) return;
		if (delta == 0 && mPullValue != 0) {
			// reset
			for (int i = 0; i < count; i++) {
				View child = mContentView.getChildAt((mPullValue < 0) ? i : mContentView.getChildCount() - 1 - i);
				if (child == null) break;
				ObjectAnimator trans = ObjectAnimator.ofFloat(child, mHorizontal ? "translationX" : "translationY", mHorizontal ? getTranslationX()
						: getTranslationY(), 0);
				ObjectAnimator rot = ObjectAnimator.ofFloat(child, mHorizontal ? "rotationY" : "rotationX", mHorizontal ? getRotationY() : getRotationX(), 0);
				AnimatorSet set = new AnimatorSet();
				set.playTogether(trans, rot);
				set.setDuration(100);
				set.start();
			}
			mPullValue = 0;
		} else {
			if (mPullValue == 0) {
				layer = true;
			}
			mPullValue += delta;
		}
		final int height = mHorizontal ? getWidth() : getHeight();
		int oscroll = Math.abs(mPullValue);
		int factor = (mPullValue <= 0) ? 1 : -1;
		for (int i = 0; i < count; i++) {
			View child = mContentView.getChildAt((mPullValue < 0) ? i : mContentView.getChildCount() - 1 - i);
			if (child == null) break;
			if (layer) {
			}
			float k = PULL_FACTOR[i];
			float rot = -factor * ease(mCubic, oscroll, 0, k * 2, height);
			int y = factor * (int) ease(mCubic, oscroll, 0, k * 20, height);
			if (mHorizontal) {
				child.setTranslationX(y);
			} else {
				child.setTranslationY(y);
			}
			if (mHorizontal) {
				child.setRotationY(-rot);
			} else {
				child.setRotationX(rot);
			}
		}
	}

	static class ContentLayout extends LinearLayout {

		TabsScroller mScroller;

		public ContentLayout(Context context, TabsScroller scroller) {
			super(context);
			mScroller = scroller;
		}

		@Override
		protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
			super.onMeasure(widthMeasureSpec, heightMeasureSpec);
			if (mScroller.getGap() != 0) {
				View v = getChildAt(0);
				if (v != null) {
					if (mScroller.isHorizontal()) {
						int total = v.getMeasuredWidth() + getMeasuredWidth();
						setMeasuredDimension(total, getMeasuredHeight());
					} else {
						int total = v.getMeasuredHeight() + getMeasuredHeight();
						setMeasuredDimension(getMeasuredWidth(), total);
					}
				}

			}
		}

	}

}