Android標題欄TitleBar全攻略

很多細心的網友發現Android浏覽器的標題欄TitleBar的功能比較多，細心的網友在查看Browser時會發現，從左到右依次為網站圖標(favicon)、標題、最右邊的動畫進度條(圓圈)、背景進度條(和前面的不在一層)，今天我們就一起來看看android標題欄高級實現方法。

  在android Browser程序中標題欄是自繪的，TitleBar類繼承於線性布局LinearLayout類，通過LayoutInflater調用layout中的XML布局文件實現相關方法

public class TitleBar extends LinearLayout {
    private TextVIEw        mTitle; //標題文字
    private Drawable        mCloseDrawable;
    private ImageVIEw       mRtButton;
    private Drawable        mCircularProgress; //圓圈進度指示
    private ProgressBar     mHorizontalProgress; //水平進度條
    private ImageVIEw       mFavicon; //網站圖標
    private ImageVIEw       mLockIcon;
    private Drawable        mStopDrawable; //停止狀態的圖標
    private Drawable        mBookmarkDrawable; //是一個書簽的圖標
    private boolean         mInLoad;
    private BrowserActivity mBrowserActivity;
    private Drawable        mGenericFavicon; //如果站點沒有favicon.ico時顯示的默認圖標
    private int             mIconDimension; 
    private VIEw            mTitleBg; //文字的背景
    private MyHandler       mHandler;

    private static int LONG_PRESS = 1;

    public TitleBar(BrowserActivity context) {
        super(context, null);
        mHandler = new MyHandler();
        LayoutInflater factory = LayoutInflater.from(context);
        factory.inflate(R.layout.title_bar, this); //從XML文件創建，android123提示大家，該文件的詳細內容在本段代碼最下方。
        mBrowserActivity = context;

        mTitle = (TextView) findVIEwById(R.id.title);
        mTitle.setCompoundDrawablePadding(5); 

        mTitleBg = findVIEwById(R.id.title_bg);
        mLockIcon = (ImageView) findVIEwById(R.id.lock);
        mFavicon = (ImageView) findVIEwById(R.id.favicon);

        mRtButton = (ImageView) findVIEwById(R.id.rt_btn);

        Resources resources = context.getResources();
        mCircularProgress = (Drawable) resources.getDrawable(com.android.internal.R.drawable.search_spinner);
        mIconDimension = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 20f,resources.getDisplayMetrics());
        mCircularProgress.setBounds(0, 0, mIconDimension, mIconDimension);
        mHorizontalProgress = (ProgressBar) findVIEwById(R.id.progress_horizontal);
        mGenericFavicon = context.getResources().getDrawable(R.drawable.app_web_browser_sm);
    }

    private class MyHandler extends Handler {
        public void handleMessage(Message msg) {
            if (msg.what == LONG_PRESS) {
                            mTitleBg.setPressed(false);
                             mBrowserActivity.showTitleBarContextMenu();
            }
        }
    };

    @Override
    protected void onCreateContextMenu(ContextMenu menu) { //創建上下文菜單，相關的XML代碼在本文最後
        MenuInflater inflater = mBrowserActivity.getMenuInflater();
        inflater.inflate(R.menu.title_context, menu);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
               if ((int) event.getX() > mTitleBg.getRight()) {
                    mRtButton.setPressed(true);
                } else {
                    mTitleBg.setPressed(true);
                    mHandler.sendMessageDelayed(mHandler.obtainMessage(
                            LONG_PRESS),
                            VIEwConfiguration.getLongPressTimeout());
                }
                break;
            case MotionEvent.ACTION_MOVE:
                int slop = VIEwConfiguration.get(mBrowserActivity)
                        .getScaledTouchSlop();
                if ((int) event.getY() > getHeight() + slop) {
                     mTitleBg.setPressed(false);
                    mRtButton.setPressed(false);
                    mHandler.removeMessages(LONG_PRESS);
                    break;
                }
                int x = (int) event.getX();
                int titleRight = mTitleBg.getRight();
                if (mTitleBg.isPressed() && x > titleRight + slop) {
                    mTitleBg.setPressed(false);
                    mHandler.removeMessages(LONG_PRESS);
                } else if (mRtButton.isPressed() && x < titleRight - slop) {
                    mRtButton.setPressed(false);
                }
                break;
            case MotionEvent.ACTION_CANCEL:
                mRtButton.setPressed(false);
                mTitleBg.setPressed(false);
                mHandler.removeMessages(LONG_PRESS);
                break;
            case MotionEvent.ACTION_UP:
                if (mRtButton.isPressed()) {
                    if (mInLoad) {
                        mBrowserActivity.stopLoading();
                    } else {
                        mBrowserActivity.bookmarksOrHistoryPicker(false);
                    }
                    mRtButton.setPressed(false);
                } else if (mTitleBg.isPressed()) {
                    mHandler.removeMessages(LONG_PRESS);
                    mBrowserActivity.onSearchRequested();
                    mTitleBg.setPressed(false);
                }
                break;
            default:
                break;
        }
        return true;
    }

boolean isInLoad() {
        return mInLoad;
    }

void setFavicon(Bitmap icon) {
        Drawable[] array = new Drawable[3];
        array[0] = new PaintDrawable(Color.BLACK);
        PaintDrawable p = new PaintDrawable(Color.WHITE);
        array[1] = p;
        if (icon == null) {
            array[2] = mGenericFavicon;
        } else {
            array[2] = new BitmapDrawable(icon);
        }
        LayerDrawable d = new LayerDrawable(array);
        d.setLayerInset(1, 1, 1, 1, 1);
        d.setLayerInset(2, 2, 2, 2, 2);
        mFavicon.setImageDrawable(d);
    }

 void setLock(Drawable d) {
        if (null == d) {
            mLockIcon.setVisibility(VIEw.GONE);
        } else {
            mLockIcon.setImageDrawable(d);
            mLockIcon.setVisibility(VIEw.VISIBLE);
        }
    }

 void setProgress(int newProgress) {
        if (newProgress >= mHorizontalProgress.getMax()) {
            mTitle.setCompoundDrawables(null, null, null, null);
            ((Animatable) mCircularProgress).stop();
            mHorizontalProgress.setVisibility(VIEw.INVISIBLE);
            if (mBookmarkDrawable != null) {
                mRtButton.setImageDrawable(mBookmarkDrawable);
            }
            mInLoad = false;
        } else {
            mHorizontalProgress.setProgress(newProgress);
            if (!mInLoad && getWindowToken() != null) {

                mTitle.setCompoundDrawables(null, null, mCircularProgress,
                        null);
                ((Animatable) mCircularProgress).start();
                mHorizontalProgress.setVisibility(VIEw.VISIBLE);
                if (mBookmarkDrawable == null) {
                    mBookmarkDrawable = mRtButton.getDrawable();
                }
                if (mStopDrawable == null) {
                    mRtButton.setImageResource(R.drawable.ic_btn_stop_v2);
                    mStopDrawable = mRtButton.getDrawable();
                } else {
                    mRtButton.setImageDrawable(mStopDrawable);
                }
                mInLoad = true;
            }
        }
    }

void setTitleAndUrl(CharSequence title, CharSequence url) {
        if (url == null) {
            mTitle.setText(R.string.title_bar_loading);
        } else {
            mTitle.setText(url.toString());
        }
    }

void setToTabPicker() {
        mTitle.setText(R.string.tab_picker_title);
        setFavicon(null);
        setLock(null);
        mHorizontalProgress.setVisibility(VIEw.GONE);
    }
}

 本文的相關的title_bar.XML布局文件內容，其中大家可以理解下部分圖標在創建時使用隱藏GONE的visibility顯示屬性，通過條件來設置其顯示

  <LinearLayout XMLns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orIEntation="vertical"
    android:paddingLeft="8dip"
    android:paddingRight="12dip"
    android:paddingTop="2dip"
    android:paddingBottom="1dip"
    android:background="@drawable/search_plate_browser" >

    <ProgressBar android:id="@+id/progress_horizontal"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="fill_parent"
        android:layout_height="5dip"
        android:max="100"
        />

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orIEntation="horizontal"
        >

        <LinearLayout android:id="@+id/title_bg"
            android:background="@drawable/title_text"
            android:layout_width="0dip"
            android:layout_weight="1.0"
            android:layout_height="wrap_content"
            android:gravity="center_vertical"
            android:orIEntation="horizontal"
            >
                <ImageVIEw android:id="@+id/favicon"
                    android:layout_width="20dip"
                    android:layout_height="20dip"
                    android:layout_marginLeft="3dip"
                    />
                <ImageVIEw android:id="@+id/lock"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginLeft="6dip"
                    android:visibility="gone"
                    />
                <TextVIEw
                    android:id="@+id/title"
                    android:layout_height="wrap_content"
                    android:layout_width="0dip"
                    android:layout_weight="1.0"
                    android:paddingLeft="8dip"
                    android:paddingRight="6dip"
                    android:textAppearance="?android:attr/textAppearanceMedium"
                    android:textColor="@color/black"
                    android:gravity="center_vertical"
                    android:singleLine="true"
                    android:ellipsize="end"
                />
        </LinearLayout>
        <ImageVIEw
            android:id="@+id/rt_btn"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:layout_marginLeft="6dip"
            android:scaleType="center"
            android:layout_marginBottom="4dip"
            android:background="@drawable/btn_bookmark"
            android:src="@drawable/ic_btn_bookmarks"
        />
    </LinearLayout>
</LinearLayout>

以下為 title_context.XML，裡面僅有兩條一個為分享該頁和復制本頁的URL

<menu XMLns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/title_bar_share_page_url"
        android:title="@string/share_page"/>
    <item android:id="@+id/title_bar_copy_page_url"
        android:title="@string/copy_page_url"/>
</menu>