AppsCustomizeTabHost.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.
 */

package com.android.launcher2;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.content.Context;
import android.content.res.Resources;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import android.widget.LinearLayout;
import android.widget.TabHost;
import android.widget.TabWidget;
import android.widget.TextView;

import com.android.launcher.R;

import java.util.ArrayList;

/**
 * “所有程序”界面的tabhost，事实上它也包含了content。换句话说，它就是实际上的“所有程序和widget”界面
 * 
 */
public class AppsCustomizeTabHost extends TabHost implements
		LauncherTransitionable, TabHost.OnTabChangeListener {
	static final String LOG_TAG = "AppsCustomizeTabHost";

	private static final String APPS_TAB_TAG = "APPS";
	private static final String WIDGETS_TAB_TAG = "WIDGETS";

	private final LayoutInflater mLayoutInflater;
	private ViewGroup mTabs;
	private ViewGroup mTabsContainer;
	private AppsCustomizePagedView mAppsCustomizePane;
	private FrameLayout mAnimationBuffer;
	private LinearLayout mContent;

	private boolean mInTransition;
	private boolean mTransitioningToWorkspace;
	private boolean mResetAfterTransition;
	private Runnable mRelayoutAndMakeVisible;

	public AppsCustomizeTabHost(Context context, AttributeSet attrs) {
		super(context, attrs);
		mLayoutInflater = LayoutInflater.from(context);
		mRelayoutAndMakeVisible = new Runnable() {
			public void run() {
				mTabs.requestLayout();
				mTabsContainer.setAlpha(1f);
			}
		};
	}

	/**
	 * Convenience methods to select specific tabs. We want to set the content
	 * type immediately in these cases, but we note that we still call
	 * setCurrentTabByTag() so that the tab view reflects the new content (but
	 * doesn't do the animation and logic associated with changing tabs
	 * manually). 无动画快速切换tab（其实是有点动画的）
	 */
	void setContentTypeImmediate(AppsCustomizePagedView.ContentType type) {
		setOnTabChangedListener(null);
		onTabChangedStart();
		onTabChangedEnd(type);
		setCurrentTabByTag(getTabTagForContentType(type));
		setOnTabChangedListener(this);
	}

	void selectAppsTab() {
		setContentTypeImmediate(AppsCustomizePagedView.ContentType.Applications);
	}

	void selectWidgetsTab() {
		setContentTypeImmediate(AppsCustomizePagedView.ContentType.Widgets);
	}

	/**
	 * 建立tab host，并创建必须的tab
	 */
	@Override
	protected void onFinishInflate() {
		// 建立tab host
		setup();

		final ViewGroup tabsContainer = (ViewGroup) findViewById(R.id.tabs_container);
		final TabWidget tabs = getTabWidget();
		final AppsCustomizePagedView appsCustomizePane = (AppsCustomizePagedView) findViewById(R.id.apps_customize_pane_content);
		mTabs = tabs;
		mTabsContainer = tabsContainer;
		mAppsCustomizePane = appsCustomizePane;
		mAnimationBuffer = (FrameLayout) findViewById(R.id.animation_buffer);
		mContent = (LinearLayout) findViewById(R.id.apps_customize_content);
		if (tabs == null || mAppsCustomizePane == null)
			throw new Resources.NotFoundException();

		// Configure the tabs content factory to return the same paged view
		// (that we change the content filter on)
		TabContentFactory contentFactory = new TabContentFactory() {
			public View createTabContent(String tag) {
				return appsCustomizePane;
			}
		};

		// Create the tabs
		TextView tabView;
		String label;
		label = getContext().getString(R.string.all_apps_button_label);
		tabView = (TextView) mLayoutInflater.inflate(
				R.layout.tab_widget_indicator, tabs, false);
		tabView.setText(label);
		tabView.setContentDescription(label);
		addTab(newTabSpec(APPS_TAB_TAG).setIndicator(tabView).setContent(
				contentFactory));
		label = getContext().getString(R.string.widgets_tab_label);
		tabView = (TextView) mLayoutInflater.inflate(
				R.layout.tab_widget_indicator, tabs, false);
		tabView.setText(label);
		tabView.setContentDescription(label);
		addTab(newTabSpec(WIDGETS_TAB_TAG).setIndicator(tabView).setContent(
				contentFactory));
		setOnTabChangedListener(this);

		// 市场和tab内容间跳转的键盘侦听
		AppsCustomizeTabKeyEventListener keyListener = new AppsCustomizeTabKeyEventListener();
		View lastTab = tabs.getChildTabViewAt(tabs.getTabCount() - 1);
		lastTab.setOnKeyListener(keyListener);
		View shopButton = findViewById(R.id.market_button);
		shopButton.setOnKeyListener(keyListener);

		// Hide the tab bar until we measure
		mTabsContainer.setAlpha(0f);
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		boolean remeasureTabWidth = (mTabs.getLayoutParams().width <= 0);
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);

		// Set the width of the tab list to the content width
		if (remeasureTabWidth) {
			int contentWidth = mAppsCustomizePane.getPageContentWidth();
			if (contentWidth > 0
					&& mTabs.getLayoutParams().width != contentWidth) {
				// Set the width and show the tab bar
				mTabs.getLayoutParams().width = contentWidth;
				mRelayoutAndMakeVisible.run();
			}

			super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		}
	}

	public boolean onInterceptTouchEvent(MotionEvent ev) {
		// 如果正在执行动画，直接拦截动作
		if (mInTransition && mTransitioningToWorkspace) {
			return true;
		}
		return super.onInterceptTouchEvent(ev);
	};

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		// 如果正在执行动画，什么也不做
		if (mInTransition && mTransitioningToWorkspace) {
			return super.onTouchEvent(event);
		}

		// 触摸点在AppsCustomizePane底部以上的都要拦截，防止进入workspace界面
		if (event.getY() < mAppsCustomizePane.getBottom()) {
			return true;
		}
		return super.onTouchEvent(event);
	}

	private void onTabChangedStart() {
		mAppsCustomizePane.hideScrollingIndicator(false);
	}

	private void reloadCurrentPage() {
		if (!LauncherApplication.isScreenLarge()) {
			mAppsCustomizePane.flashScrollingIndicator(true);
		}
		mAppsCustomizePane.loadAssociatedPages(mAppsCustomizePane
				.getCurrentPage());
		mAppsCustomizePane.requestFocus();
	}

	private void onTabChangedEnd(AppsCustomizePagedView.ContentType type) {
		mAppsCustomizePane.setContentType(type);
	}

	@Override
	public void onTabChanged(String tabId) {
		final AppsCustomizePagedView.ContentType type = getContentTypeForTabTag(tabId);

		// Animate the changing of the tab content by fading pages in and out
		final Resources res = getResources();
		final int duration = res
				.getInteger(R.integer.config_tabTransitionDuration);

		// We post a runnable here because there is a delay while the first page
		// is loading and
		// the feedback from having changed the tab almost feels better than
		// having it stick
		post(new Runnable() {
			@Override
			public void run() {
				if (mAppsCustomizePane.getMeasuredWidth() <= 0
						|| mAppsCustomizePane.getMeasuredHeight() <= 0) {
					reloadCurrentPage();
					return;
				}

				// Take the visible pages and re-parent them temporarily to
				// mAnimatorBuffer
				// and then cross fade to the new pages
				int[] visiblePageRange = new int[2];
				mAppsCustomizePane.getVisiblePages(visiblePageRange);
				if (visiblePageRange[0] == -1 && visiblePageRange[1] == -1) {
					// If we can't get the visible page ranges, then just skip
					// the animation
					reloadCurrentPage();
					return;
				}
				ArrayList<View> visiblePages = new ArrayList<View>();
				for (int i = visiblePageRange[0]; i <= visiblePageRange[1]; i++) {
					visiblePages.add(mAppsCustomizePane.getPageAt(i));
				}

				// We want the pages to be rendered in exactly the same way as
				// they were when
				// their parent was mAppsCustomizePane -- so set the scroll on
				// mAnimationBuffer
				// to be exactly the same as mAppsCustomizePane, and below, set
				// the left/top
				// parameters to be correct for each of the pages
				mAnimationBuffer.scrollTo(mAppsCustomizePane.getScrollX(), 0);

				// mAppsCustomizePane renders its children in reverse order, so
				// add the pages to mAnimationBuffer in reverse order to match
				// that behavior
				for (int i = visiblePages.size() - 1; i >= 0; i--) {
					View child = visiblePages.get(i);
					if (child instanceof PagedViewCellLayout) {
						((PagedViewCellLayout) child)
								.resetChildrenOnKeyListeners();
					} else if (child instanceof PagedViewGridLayout) {
						((PagedViewGridLayout) child)
								.resetChildrenOnKeyListeners();
					}
					PagedViewWidget
							.setDeletePreviewsWhenDetachedFromWindow(false);
					mAppsCustomizePane.removeView(child);
					PagedViewWidget
							.setDeletePreviewsWhenDetachedFromWindow(true);
					mAnimationBuffer.setAlpha(1f);
					mAnimationBuffer.setVisibility(View.VISIBLE);
					LayoutParams p = new FrameLayout.LayoutParams(
							child.getMeasuredWidth(), child.getMeasuredHeight());
					p.setMargins((int) child.getLeft(), (int) child.getTop(),
							0, 0);
					mAnimationBuffer.addView(child, p);
				}

				// Toggle the new content
				onTabChangedStart();
				onTabChangedEnd(type);

				// Animate the transition
				ObjectAnimator outAnim = LauncherAnimUtils.ofFloat(
						mAnimationBuffer, "alpha", 0f);
				outAnim.addListener(new AnimatorListenerAdapter() {
					@Override
					public void onAnimationEnd(Animator animation) {
						mAnimationBuffer.setVisibility(View.GONE);
						mAnimationBuffer.removeAllViews();
					}

					@Override
					public void onAnimationCancel(Animator animation) {
						mAnimationBuffer.setVisibility(View.GONE);
						mAnimationBuffer.removeAllViews();
					}
				});
				ObjectAnimator inAnim = LauncherAnimUtils.ofFloat(
						mAppsCustomizePane, "alpha", 1f);
				inAnim.addListener(new AnimatorListenerAdapter() {
					@Override
					public void onAnimationEnd(Animator animation) {
						reloadCurrentPage();
					}
				});

				final AnimatorSet animSet = LauncherAnimUtils
						.createAnimatorSet();
				animSet.playTogether(outAnim, inAnim);
				animSet.setDuration(duration);
				post(new Runnable() {
					public void run() {
						animSet.start();
					}
				});
			}
		});
	}

	public void setCurrentTabFromContent(AppsCustomizePagedView.ContentType type) {
		setOnTabChangedListener(null);
		setCurrentTabByTag(getTabTagForContentType(type));
		setOnTabChangedListener(this);
	}

	/**
	 * Returns the content type for the specified tab tag.
	 */
	public AppsCustomizePagedView.ContentType getContentTypeForTabTag(String tag) {
		if (tag.equals(APPS_TAB_TAG)) {
			return AppsCustomizePagedView.ContentType.Applications;
		} else if (tag.equals(WIDGETS_TAB_TAG)) {
			return AppsCustomizePagedView.ContentType.Widgets;
		}
		return AppsCustomizePagedView.ContentType.Applications;
	}

	/**
	 * Returns the tab tag for a given content type.
	 */
	public String getTabTagForContentType(
			AppsCustomizePagedView.ContentType type) {
		if (type == AppsCustomizePagedView.ContentType.Applications) {
			return APPS_TAB_TAG;
		} else if (type == AppsCustomizePagedView.ContentType.Widgets) {
			return WIDGETS_TAB_TAG;
		}
		return APPS_TAB_TAG;
	}

	/**
	 * 若不可见，则所有子控件都不可获得焦点
	 */
	@Override
	public int getDescendantFocusability() {
		if (getVisibility() != View.VISIBLE) {
			return ViewGroup.FOCUS_BLOCK_DESCENDANTS;
		}
		return super.getDescendantFocusability();
	}

	void reset() {
		if (mInTransition) {
			// Defer to after the transition to reset
			mResetAfterTransition = true;
		} else {
			// Reset immediately
			mAppsCustomizePane.reset();
		}
	}

	private void enableAndBuildHardwareLayer() {
		// isHardwareAccelerated() checks if we're attached to a window and if
		// that
		// window is HW accelerated-- we were sometimes not attached to a window
		// and buildLayer was throwing an IllegalStateException
		if (isHardwareAccelerated()) {
			// Turn on hardware layers for performance
			setLayerType(LAYER_TYPE_HARDWARE, null);

			// force building the layer, so you don't get a blip early in an
			// animation
			// when the layer is created layer
			buildLayer();
		}
	}

	@Override
	public View getContent() {
		return mContent;
	}

	/* LauncherTransitionable overrides */
	@Override
	public void onLauncherTransitionPrepare(Launcher l, boolean animated,
			boolean toWorkspace) {
		mAppsCustomizePane
				.onLauncherTransitionPrepare(l, animated, toWorkspace);
		mInTransition = true;
		mTransitioningToWorkspace = toWorkspace;

		if (toWorkspace) {
			// Going from All Apps -> Workspace
			setVisibilityOfSiblingsWithLowerZOrder(VISIBLE);
			// Stop the scrolling indicator - we don't want All Apps to be
			// invalidating itself
			// during the transition, especially since it has a hardware layer
			// set on it
			mAppsCustomizePane.cancelScrollingIndicatorAnimations();
		} else {
			// Going from Workspace -> All Apps
			mContent.setVisibility(VISIBLE);

			// Make sure the current page is loaded (we start loading the side
			// pages after the
			// transition to prevent slowing down the animation)
			mAppsCustomizePane.loadAssociatedPages(
					mAppsCustomizePane.getCurrentPage(), true);

			if (!LauncherApplication.isScreenLarge()) {
				mAppsCustomizePane.showScrollingIndicator(true);
			}
		}

		if (mResetAfterTransition) {
			mAppsCustomizePane.reset();
			mResetAfterTransition = false;
		}
	}

	@Override
	public void onLauncherTransitionStart(Launcher l, boolean animated,
			boolean toWorkspace) {
		if (animated) {
			enableAndBuildHardwareLayer();
		}
	}

	@Override
	public void onLauncherTransitionStep(Launcher l, float t) {
		// Do nothing
	}

	@Override
	public void onLauncherTransitionEnd(Launcher l, boolean animated,
			boolean toWorkspace) {
		mAppsCustomizePane.onLauncherTransitionEnd(l, animated, toWorkspace);
		mInTransition = false;
		if (animated) {
			setLayerType(LAYER_TYPE_NONE, null);
		}

		if (!toWorkspace) {
			// Dismiss the workspace cling
			l.dismissWorkspaceCling(null);
			// Show the all apps cling (if not already shown)
			mAppsCustomizePane.showAllAppsCling();
			// Make sure adjacent pages are loaded (we wait until after the
			// transition to
			// prevent slowing down the animation)
			mAppsCustomizePane.loadAssociatedPages(mAppsCustomizePane
					.getCurrentPage());

			if (!LauncherApplication.isScreenLarge()) {
				mAppsCustomizePane.hideScrollingIndicator(false);
			}

			// Going from Workspace -> All Apps
			// NOTE: We should do this at the end since we check visibility
			// state in some of the
			// cling initialization/dismiss code above.
			setVisibilityOfSiblingsWithLowerZOrder(INVISIBLE);
		}
	}

	private void setVisibilityOfSiblingsWithLowerZOrder(int visibility) {
		ViewGroup parent = (ViewGroup) getParent();
		if (parent == null)
			return;

		final int count = parent.getChildCount();
		if (!isChildrenDrawingOrderEnabled()) {
			for (int i = 0; i < count; i++) {
				final View child = parent.getChildAt(i);
				if (child == this) {
					break;
				} else {
					if (child.getVisibility() == GONE) {
						continue;
					}
					child.setVisibility(visibility);
				}
			}
		} else {
			throw new RuntimeException("Failed; can't get z-order of views");
		}
	}

	/**
	 * 不可见时会卸载数据，在可见时就要加载数据
	 */
	public void onWindowVisible() {
		if (getVisibility() == VISIBLE) {
			mContent.setVisibility(VISIBLE);
			// We unload the widget previews when the UI is hidden, so need to
			// reload pages
			// 同步加载当前页，异步加载相信页
			mAppsCustomizePane.loadAssociatedPages(
					mAppsCustomizePane.getCurrentPage(), true);
			mAppsCustomizePane.loadAssociatedPages(
					mAppsCustomizePane.getCurrentPage(), false);
		}
	}

	/**
	 * 合适的时候清理后台view
	 */
	public void onTrimMemory() {
		mContent.setVisibility(GONE);
		// Clear the widget pages of all their subviews - this will trigger the
		// widget previews
		// to delete their bitmaps
		mAppsCustomizePane.clearAllWidgetPages();
	}

	boolean isTransitioning() {
		return mInTransition;
	}
}