applicationsstacklayout.java

android first home screen

/*
 * Copyright (C) 2007 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.example.android.home;

import android.content.Context;
import android.content.Intent;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.view.LayoutInflater;
import android.widget.TextView;
import android.*;

import java.util.List;
import java.util.Map;

/**
 * The ApplicationsStackLayout is a specialized layout used for the purpose of the home screen only. This layout stacks various icons in three distinct areas: the recents, the favorites (or faves) and the button.
 * 
 * This layout supports two different orientations: vertical and horizontal. When horizontal, the areas are laid out this way:
 * 
 * [RECENTS][FAVES][BUTTON]
 * 
 * When vertical, the layout is the following:
 * 
 * [RECENTS] [FAVES] [BUTTON]
 * 
 * The layout operates from the "bottom up" (or from right to left.) This means that the button area will first be laid out, then the faves area, then the recents. When there are too many favorites, the recents area is not displayed.
 * 
 * The following attributes can be set in XML:
 * 
 * orientation: horizontal or vertical marginLeft: the left margin of each element in the stack marginTop: the top margin of each element in the stack marginRight: the right margin of each element in the stack marginBottom: the bottom margin of each element in the stack
 */
public class ApplicationsStackLayout extends ViewGroup implements View.OnClickListener
{
	public static final int HORIZONTAL = 0;
	public static final int VERTICAL = 1;

	private View mButton;
	private LayoutInflater mInflater;

	private int mFavoritesEnd;
	private int mFavoritesStart;

	private List<ApplicationInfo> mFavorites;
	private List<ApplicationInfo> mRecents;

	private int mOrientation = VERTICAL;

	private int mMarginLeft;
	private int mMarginTop;
	private int mMarginRight;
	private int mMarginBottom;

	private Rect mDrawRect = new Rect();

	private Drawable mBackground;
	private int mIconSize;

	public ApplicationsStackLayout(Context context)
	{
		super(context);
		initLayout();
	}

	public ApplicationsStackLayout(Context context, AttributeSet attrs)
	{
		super(context, attrs);

		TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ApplicationsStackLayout);

		mOrientation = a.getInt(R.styleable.ApplicationsStackLayout_stackOrientation, VERTICAL);

		mMarginLeft = a.getDimensionPixelSize(R.styleable.ApplicationsStackLayout_marginLeft, 0);
		mMarginTop = a.getDimensionPixelSize(R.styleable.ApplicationsStackLayout_marginTop, 0);
		mMarginRight = a.getDimensionPixelSize(R.styleable.ApplicationsStackLayout_marginRight, 0);
		mMarginBottom = a.getDimensionPixelSize(R.styleable.ApplicationsStackLayout_marginBottom, 0);

		a.recycle();

		mIconSize = (int) getResources().getDimension(android.R.dimen.app_icon_size);

		initLayout();
	}

	private void initLayout()
	{
		mInflater = LayoutInflater.from(getContext());
		mButton = mInflater.inflate(R.layout.all_applications_button, this, false);
		addView(mButton);

		mBackground = getBackground();
		setBackgroundDrawable(null);
		setWillNotDraw(false);
	}

	/**
	 * Return the current orientation, either VERTICAL (default) or HORIZONTAL.
	 * 
	 * @return the stack orientation
	 */
	public int getOrientation()
	{
		return mOrientation;
	}

	@Override
	protected void onDraw(Canvas canvas)
	{
		final Drawable background = mBackground;

		final int right = getWidth();
		final int bottom = getHeight();

		// Draw behind recents
		if (mOrientation == VERTICAL)
		{
			mDrawRect.set(0, 0, right, mFavoritesStart);
		}
		else
		{
			mDrawRect.set(0, 0, mFavoritesStart, bottom);
		}
		background.setBounds(mDrawRect);
		background.draw(canvas);

		// Draw behind favorites
		if (mFavoritesStart > -1)
		{
			if (mOrientation == VERTICAL)
			{
				mDrawRect.set(0, mFavoritesStart, right, mFavoritesEnd);
			}
			else
			{
				mDrawRect.set(mFavoritesStart, 0, mFavoritesEnd, bottom);
			}
			background.setBounds(mDrawRect);
			background.draw(canvas);
		}

		super.onDraw(canvas);
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
	{
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);

		final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
		final int widthSize = MeasureSpec.getSize(widthMeasureSpec);

		final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
		final int heightSize = MeasureSpec.getSize(heightMeasureSpec);

		if (widthMode != MeasureSpec.EXACTLY || heightMode != MeasureSpec.EXACTLY)
		{
			throw new IllegalStateException("ApplicationsStackLayout can only be used with " + "measure spec mode=EXACTLY");
		}

		setMeasuredDimension(widthSize, heightSize);
	}

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b)
	{
		removeAllApplications();

		LayoutParams layoutParams = mButton.getLayoutParams();
		final int widthSpec = MeasureSpec.makeMeasureSpec(layoutParams.width, MeasureSpec.EXACTLY);
		final int heightSpec = MeasureSpec.makeMeasureSpec(layoutParams.height, MeasureSpec.EXACTLY);
		mButton.measure(widthSpec, heightSpec);

		if (mOrientation == VERTICAL)
		{
			layoutVertical();
		}
		else
		{
			layoutHorizontal();
		}
	}

	private void layoutVertical()
	{
		int childLeft = 0;
		int childTop = getHeight();

		int childWidth = mButton.getMeasuredWidth();
		int childHeight = mButton.getMeasuredHeight();

		childTop -= childHeight + mMarginBottom;
		mButton.layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight);
		childTop -= mMarginTop;
		mFavoritesEnd = childTop - mMarginBottom;

		int oldChildTop = childTop;
		childTop = stackApplications(mFavorites, childLeft, childTop);
		if (childTop != oldChildTop)
		{
			mFavoritesStart = childTop + mMarginTop;
		}
		else
		{
			mFavoritesStart = -1;
		}

		stackApplications(mRecents, childLeft, childTop);
	}

	private void layoutHorizontal()
	{
		int childLeft = getWidth();
		int childTop = 0;

		int childWidth = mButton.getMeasuredWidth();
		int childHeight = mButton.getMeasuredHeight();

		childLeft -= childWidth;
		mButton.layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight);
		childLeft -= mMarginLeft;
		mFavoritesEnd = childLeft - mMarginRight;

		int oldChildLeft = childLeft;
		childLeft = stackApplications(mFavorites, childLeft, childTop);
		if (childLeft != oldChildLeft)
		{
			mFavoritesStart = childLeft + mMarginLeft;
		}
		else
		{
			mFavoritesStart = -1;
		}

		stackApplications(mRecents, childLeft, childTop);
	}

	private int stackApplications(List<ApplicationInfo> applications, int childLeft, int childTop)
	{
		LayoutParams layoutParams;
		int widthSpec;
		int heightSpec;
		int childWidth;
		int childHeight;

		final boolean isVertical = mOrientation == VERTICAL;

		final int count = applications.size();
		for (int i = count - 1; i >= 0; i--)
		{
			final ApplicationInfo info = applications.get(i);
			final View view = createApplicationIcon(mInflater, this, info);

			layoutParams = view.getLayoutParams();
			widthSpec = MeasureSpec.makeMeasureSpec(layoutParams.width, MeasureSpec.EXACTLY);
			heightSpec = MeasureSpec.makeMeasureSpec(layoutParams.height, MeasureSpec.EXACTLY);
			view.measure(widthSpec, heightSpec);

			childWidth = view.getMeasuredWidth();
			childHeight = view.getMeasuredHeight();

			if (isVertical)
			{
				childTop -= childHeight + mMarginBottom;

				if (childTop < 0)
				{
					childTop += childHeight + mMarginBottom;
					break;
				}
			}
			else
			{
				childLeft -= childWidth + mMarginRight;

				if (childLeft < 0)
				{
					childLeft += childWidth + mMarginRight;
					break;
				}
			}

			addViewInLayout(view, -1, layoutParams);

			view.layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight);

			if (isVertical)
			{
				childTop -= mMarginTop;
			}
			else
			{
				childLeft -= mMarginLeft;
			}
		}

		return isVertical ? childTop : childLeft;
	}

	private void removeAllApplications()
	{
		final int count = getChildCount();
		for (int i = count - 1; i >= 0; i--)
		{
			final View view = getChildAt(i);
			if (view != mButton)
			{
				removeViewAt(i);
			}
		}
	}

	private View createApplicationIcon(LayoutInflater inflater, ViewGroup group, ApplicationInfo info)
	{

		TextView textView = (TextView) inflater.inflate(R.layout.favorite, group, false);

		info.icon.setBounds(0, 0, mIconSize, mIconSize);
		textView.setCompoundDrawables(null, info.icon, null, null);
		textView.setText(info.title);

		textView.setTag(info.intent);
		textView.setOnClickListener(this);

		return textView;
	}

	/**
	 * Sets the list of favorites.
	 * 
	 * @param applications
	 *            the applications to put in the favorites area
	 */
	public void setFavorites(List<ApplicationInfo> applications)
	{
		mFavorites = applications;
		requestLayout();
	}

	/**
	 * Sets the list of recents.
	 * 
	 * @param applications
	 *            the applications to put in the recents area
	 */
	public void setRecents(List<ApplicationInfo> applications)
	{
		mRecents = applications;
		requestLayout();
	}

	public void onClick(View v)
	{
		getContext().startActivity((Intent) v.getTag());
	}
}