Launcher知識點整理（三）

一、增加牆紙

圖片放入/packages/apps/Launcher2/res/drawable-mdpi

/packages/apps/Launcher2/res/values-mdpi/wallpapers.xml 

<resources>
    <string-array name="wallpapers" translatable="false">
        <item>wallpaper_lake</item>
        <item>wallpaper_sunset</item>
        <item>wallpaper_beach</item>
        <item>wallpaper_snow_leopard</item>
        <item>wallpaper_path</item>
        <item>wallpaper_sunrise</item>
        <item>wallpaper_mountain</item>
        <item>wallpaper_road</item>
        <item>wallpaper_jellyfish</item>
        <item>wallpaper_zanzibar</item>
        <item>wallpaper_blue</item>
        <item>wallpaper_grey</item>
        <item>wallpaper_green</item>
        <item>wallpaper_pink</item>
    </string-array>
</resources>

設置默認牆紙

frameworks\base\core\res\res\drawable中default_wallpaper.jpg這個是默認的牆紙

二、源代碼中設置wallpaper

在launcher.java中

public boolean onCreateOptionsMenu(Menu menu) {
    if (isWorkspaceLocked()) {
        return false;
    }
    super.onCreateOptionsMenu(menu);

    menu.add(MENU_GROUP_ADD, MENU_ADD, 0, R.string.menu_add)
            .setIcon(android.R.drawable.ic_menu_add)
            .setAlphabeticShortcut('A');
    menu.add(0, MENU_MANAGE_APPS, 0, R.string.menu_manage_apps)
            .setIcon(android.R.drawable.ic_menu_manage)
            .setAlphabeticShortcut('M');
    menu.add(MENU_GROUP_WALLPAPER, MENU_WALLPAPER_SETTINGS, 0, R.string.menu_wallpaper)
             .setIcon(android.R.drawable.ic_menu_gallery)
             .setAlphabeticShortcut('W');
 … …

點擊wallpaper後會調用

public boolean onOptionsItemSelected(MenuItem item) {
       switch (item.getItemId()) {
           case MENU_ADD:
               addItems();
               return true;
           case MENU_MANAGE_APPS:
               manageApps();
               return true;
           case MENU_WALLPAPER_SETTINGS:
               startWallpaper();
               return true;
           case MENU_SEARCH:
               onSearchRequested();
               return true;
           case MENU_NOTIFICATIONS:
               showNotifications();
               return true;
       }

       return super.onOptionsItemSelected(item);
   }

將進入

private void startWallpaper() {
    closeAllApps(true);
    final Intent pickWallpaper = new Intent(Intent.ACTION_SET_WALLPAPER);
    Intent chooser = Intent.createChooser(pickWallpaper,
            getText(R.string.chooser_wallpaper));
    startActivityForResult(chooser, REQUEST_PICK_WALLPAPER);
}

三、launcher中launcher的搜索框和ProtipWidget（widget修改）

 Launcher2/res/xml/default_workspace.xml

<!--  Middle screen [2] <search>爲添加google搜索框；-->
<search
    launcher:screen="2"
    launcher:x="0"
    launcher:y="0" />
!--  <appwidget>爲添加相應的widget； -->
<appwidget
    launcher:packageName="com.android.protips"
    launcher:className="com.android.protips.ProtipWidget"
    launcher:screen="2"
    launcher:x="0"
    launcher:y="1"
    launcher:spanX="4"
    launcher:spanY="1" />

此xml解析在Launcherprovider.java文件loadFavorites方法中

 

 

四、launcher屏數和默認屏

在launcher.java的Launcher類中有

    static final int SCREEN_COUNT = 5;  //屏數

    static final int DEFAULT_SCREEN = 2;  //默認顯示的第幾屏（從0屏開始）。

 

修改屏數還需要修改

Launcher2/res/layout-port/Launcher.xml

<!-- The workspace contains 3 screens of cells -->
<com.android.launcher2.Workspace
    android:id="@+id/workspace"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:scrollbars="horizontal"
    android:fadeScrollbars="true"
    launcher:defaultScreen="2">

    <include android:id="@+id/cell1" layout="@layout/workspace_screen" />
    <include android:id="@+id/cell2" layout="@layout/workspace_screen" />
    <include android:id="@+id/cell3" layout="@layout/workspace_screen" />
    <include android:id="@+id/cell4" layout="@layout/workspace_screen" />
    <include android:id="@+id/cell5" layout="@layout/workspace_screen" />

</com.android.launcher2.Workspace>

修改默認屏同時需要修改workspace.java中

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

    … …
    mDefaultScreen = a.getInt(R.styleable.Workspace_defaultScreen, 1);
    a.recycle();

    setHapticFeedbackEnabled(false);
    initWorkspace();

五、頁面標記實現原理

Launcher2/res/drawable/ home_arrows_left.xml

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true" android:drawable="@drawable/all_apps_button_pressed" />
    <item android:state_focused="true" android:state_window_focused="true" android:drawable="@drawable/all_apps_button_focused" />
    <item android:state_focused="true" android:state_window_focused="false" android:drawable="@drawable/all_apps_button_normal" />
    <item android:drawable="@drawable/all_apps_button_normal" />
</selector>

Launcher2/res/layout-port/Launcher.xml

<ImageView
    android:id="@+id/previous_screen"
    android:layout_width="93dip"
    android:layout_height="@dimen/button_bar_height"
    android:layout_gravity="bottom|left"
    android:layout_marginLeft="6dip"

    android:scaleType="center"
    android:src="@drawable/home_arrows_left"

    android:onClick="previousScreen"    <!—點擊事件處理-->

    android:focusable="true"
    android:clickable="true" />

在launcher.java中實現

private void setupViews() {

… …
        mPreviousView = (ImageView) dragLayer.findViewById(R.id.previous_screen);
        mNextView = (ImageView) dragLayer.findViewById(R.id.next_screen);

        Drawable previous = mPreviousView.getDrawable();
        Drawable next = mNextView.getDrawable();
        mWorkspace.setIndicators(previous, next);
    … …
}

獲取這個兩旁的圖片設置到mCurrentScreen屏幕上

Workspace.java

void setIndicators(Drawable previous, Drawable next) {
    mPreviousIndicator = previous;
    mNextIndicator = next;
    previous.setLevel(mCurrentScreen);
    next.setLevel(mCurrentScreen);

在launcher.xml中定義

android:onClick="previousScreen"    <!—點擊事件處理-->

在launcher.java中的處理爲

@SuppressWarnings({"UnusedDeclaration"})
public void previousScreen(View v) {
    if (!isAllAppsVisible()) {
        mWorkspace.scrollLeft();
    }
}

@SuppressWarnings({"UnusedDeclaration"})
public void nextScreen(View v) {
    if (!isAllAppsVisible()) {
        mWorkspace.scrollRight();
    }
}

進入到workspace中

public void scrollLeft() {
        clearVacantCache();
        if (mScroller.isFinished()) {
            if (mCurrentScreen > 0) snapToScreen(mCurrentScreen - 1);
        } else {
            if (mNextScreen > 0) snapToScreen(mNextScreen - 1);
        }
    }

    public void scrollRight() {
        clearVacantCache();
        if (mScroller.isFinished()) {
            if (mCurrentScreen < getChildCount() -1) snapToScreen(mCurrentScreen + 1);
        } else {
            if (mNextScreen < getChildCount() -1) snapToScreen(mNextScreen + 1);
        }
    }

先判斷滑動是否完成，然後跳轉到目標屏。

void snapToScreen(int whichScreen) {
        snapToScreen(whichScreen, 0, false);
    }

    private void snapToScreen(int whichScreen, int velocity, boolean settle) {
        //if (!mScroller.isFinished()) return;

        whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));

        clearVacantCache();
        enableChildrenCache(mCurrentScreen, whichScreen);

        mNextScreen = whichScreen;

        mPreviousIndicator.setLevel(mNextScreen);
        mNextIndicator.setLevel(mNextScreen);

        View focusedChild = getFocusedChild();
        if (focusedChild != null && whichScreen != mCurrentScreen &&
                focusedChild == getChildAt(mCurrentScreen)) {
            focusedChild.clearFocus();
        }

        final int screenDelta = Math.max(1, Math.abs(whichScreen - mCurrentScreen));
        final int newX = whichScreen * getWidth();
        final int delta = newX - mScrollX;
        int duration = (screenDelta + 1) * 100;

        if (!mScroller.isFinished()) {
            mScroller.abortAnimation();
        }

        if (settle) {
            mScrollInterpolator.setDistance(screenDelta);
        } else {
            mScrollInterpolator.disableSettle();
        }

        velocity = Math.abs(velocity);
        if (velocity > 0) {
            duration += (duration / (velocity / BASELINE_FLING_VELOCITY))
                    * FLING_VELOCITY_INFLUENCE;
        } else {
            duration += 100;
        }

        awakenScrollBars(duration);
        mScroller.startScroll(mScrollX, 0, delta, 0, duration);
        invalidate();
    }

六、左右滑動切換屏幕

在workspace中實現屏幕切換主要重寫了以下幾個方法：onMeasure（）、onLayout（）、onInterceptTouchEvent（）、onTouchEvent（）方法。

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

    final int width = MeasureSpec.getSize(widthMeasureSpec);
    final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
    if (widthMode != MeasureSpec.EXACTLY) {
        throw new IllegalStateException("Workspace can only be used in EXACTLY mode.");
    }

    final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
    if (heightMode != MeasureSpec.EXACTLY) {
        throw new IllegalStateException("Workspace can only be used in EXACTLY mode.");
    }

    // The children are given the same width and height as the workspace
    final int count = getChildCount();
    for (int i = 0; i < count; i++) {
        getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
    }


    if (mFirstLayout) {
        setHorizontalScrollBarEnabled(false);
        scrollTo(mCurrentScreen * width, 0);
        setHorizontalScrollBarEnabled(true);
        updateWallpaperOffset(width * (getChildCount() - 1));
        mFirstLayout = false;
    }
}

onInterceptTouchEvent（）方法和onTouchEvent（）主要是來響應手指按下划動時所需要捕獲的消息，例如划動的速度，划動的距離等。當手指起來時，根據划動的速度與跨度來判斷是向左滑動一頁還是向右滑動一頁，確保每次用戶操作結束之後顯示的都是整體的一個子view.

 

在View.java中framework\base\core\java\android\view

將當前視圖內容偏移至(x , y)座標處，即顯示(可視)區域位於(x , y)座標

public void scrollTo(int x, int y) {
    if (mScrollX != x || mScrollY != y) {
        int oldX = mScrollX;
        int oldY = mScrollY;
        mScrollX = x;
        mScrollY = y;
        onScrollChanged(mScrollX, mScrollY, oldX, oldY);
        if (!awakenScrollBars()) {
            invalidate();
        }
    }
}

在當前視圖內容繼續偏移(x , y)個單位，顯示(可視)區域也跟着偏移(x,y)個單位

public void scrollBy(int x, int y) {
    scrollTo(mScrollX + x, mScrollY + y);
}

mScrollX 與 mScrollY 代表我們當前偏移的位置 ， 在當前位置繼續偏移(x ,y)個單位 

七、獲取應用列表（相當於mainmenu）

在launcher.java中

Launcher 佈局文件初始化方法中

private void setupViews() {
… …
mHandleView = (HandleView) findViewById(R.id.all_apps_button);
mHandleView.setLauncher(this);
mHandleView.setOnClickListener(this);
mHandleView.setOnLongClickListener(this);
… …
}

點擊中間button

public void onClick(View v) {
    Object tag = v.getTag();
    if (tag instanceof ShortcutInfo) {
…
    } else if (tag instanceof FolderInfo) {
        handleFolderClick((FolderInfo) tag);
    } else if (v == mHandleView) {
        if (isAllAppsVisible()) {
            closeAllApps(true);
        } else {
            showAllApps(true);
        }
    }

進入到showAllApps()方法

void showAllApps(boolean animated) {
    mAllAppsGrid.zoom(1.0f, animated);

    ((View) mAllAppsGrid).setFocusable(true);
    ((View) mAllAppsGrid).requestFocus();

    // TODO: fade these two too
    mDeleteZone.setVisibility(View.GONE);
}

在上面使用到了mAllAppsGrid

 privateAllAppsView mAllAppsGrid; //聲明

在setupViews（）方法中

private void setupViews() {
… …
        mAllAppsGrid = (AllAppsView)dragLayer.findViewById(R.id.all_apps_view);
        mAllAppsGrid.setLauncher(this);
        mAllAppsGrid.setDragController(dragController);
        ((View) mAllAppsGrid).setWillNotDraw(false); // We don't want a hole punched in our window.
        // Manage focusability manually since this thing is always visible
        ((View) mAllAppsGrid).setFocusable(false);
        … …
}

all_apps_view是在all_app_2d.xml中定義

位於res/layout-port中

故找到AllApps2D.java可以找到addApps，removeApps，zoom這幾個方法。

public void zoom(float zoom, boolean animate) {
      Log.d(TAG, "zooming " + ((zoom == 1.0) ? "open" : "closed"));
    cancelLongPress();

    mZoom = zoom;

    if (isVisible()) {
        getParent().bringChildToFront(this);
        setVisibility(View.VISIBLE);
        mGrid.setAdapter(mAppsAdapter);
        if (animate) {
            startAnimation(AnimationUtils.loadAnimation(getContext(), R.anim.all_apps_2d_fade_in));
        } else {
            onAnimationEnd();
        }
    } else {
        if (animate) {
            startAnimation(AnimationUtils.loadAnimation(getContext(), R.anim.all_apps_2d_fade_out));
        } else {
            onAnimationEnd();
        }
    }
}

在zoom()方法裏面有mGrid.setAdapter(mAppsAdapter)，在構造方法中，給adapter已經賦值。

public AllApps2D(Context context, AttributeSet attrs) {
    super(context, attrs);
    setVisibility(View.GONE);
    setSoundEffectsEnabled(false);

    mAppsAdapter = new AppsAdapter(getContext(), mAllAppsList);
    mAppsAdapter.setNotifyOnChange(false);
}

在launcher.java函數中

private void loadHotseats() {
… …
PackageManager pm = getPackageManager();
… …
ResolveInfo bestMatch = pm.resolveActivity(intent, PackageManager.MATCH_DEFAULT_ONLY);
List<ResolveInfo> allMatches = pm.queryIntentActivities(intent, PackageManager.MATCH_DEFAULT_ONLY);
… …
}

如此獲取了應用列表