(转)android UI进阶之仿iphone的tab效果（二）

上篇博客我们写了一个Itab类，介绍了背景的绘制和简单的一个图的贴图方法。我们继续来完成Itab这个类，同时把他放到 MainAcitvity（继承Activity）这个类内部，这样，整个程序只需一个类就可以了。（上篇博客例子运行需要再建一个Activity的子 类来作为lanucher）。废话不多说了，看看代码

public static class iTab extends View
    {
        private Paint                   mPaint;//背景画笔
        private Paint                   mActiveTextPaint;//选中
        private Paint                   mInactiveTextPaint;//未选中
        private ArrayList<TabMember>  mTabMembers;//tab成员
        private int                     mActiveTab;
        private OnTabClickListener      mOnTabClickListener = null;

        public iTab( Context context, AttributeSet attrs ) //构造器，在里面初始化画笔
        {
            super(context, attrs);

            mTabMembers = new ArrayList<MainActivity.iTab.TabMember>( );

            mPaint = new Paint( );
            mActiveTextPaint = new Paint( );
            mInactiveTextPaint = new Paint( );

            mPaint.setStyle( Paint.Style.FILL );
            mPaint.setColor( 0xFFFFFF00 );
            mPaint.setAntiAlias(true);

            mActiveTextPaint.setTextAlign( Align.CENTER );
            mActiveTextPaint.setTextSize( 12 );
            mActiveTextPaint.setColor( 0xFFFFFFFF );
            mActiveTextPaint.setAntiAlias(true);


            mInactiveTextPaint.setTextAlign( Align.CENTER );
            mInactiveTextPaint.setTextSize( 12 );
            mInactiveTextPaint.setColor( 0xFF999999 );
            mInactiveTextPaint.setAntiAlias(true);
            mActiveTab = 0;

        }

        @Override
        protected void onDraw( Canvas canvas )
        {
            super.onDraw( canvas );

            Rect r = new Rect( );
            this.getDrawingRect( r );

            // 计算每个标签能使用多少像素
            int singleTabWidth = r.right / ( mTabMembers.size( ) != 0 ? mTabMembers.size( ) : 1 );


            // 绘制背景
            canvas.drawColor( 0xFF000000 );
            mPaint.setColor( 0xFF434343 );
            canvas.drawLine( r.left, r.top + 1, r.right, r.top + 1, mPaint );

            int color = 46;

            for( int i = 0; i < 24; i++ )
            {
                mPaint.setARGB( 255, color, color, color );
                canvas.drawRect( r.left, r.top + i + 1, r.right, r.top + i + 2, mPaint );
                color--;
            }
            // 绘制每一个tab
            for( int i = 0; i < mTabMembers.size( ); i++ )
            {
                TabMember tabMember = mTabMembers.get( i );

                Bitmap icon = BitmapFactory.decodeResource( getResources( ), tabMember.getIconResourceId( ) );
                Bitmap iconColored = Bitmap.createBitmap( icon.getWidth(), icon.getHeight(), Bitmap.Config.ARGB_8888 );
                Paint p = new Paint( Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
                Canvas iconCanvas = new Canvas( );
                iconCanvas.setBitmap( iconColored );

                if( mActiveTab == i )//为已选中的tab绘制一个白蓝的渐变色，未选中的绘制一个白灰的渐变色
                {
                    p.setShader( new LinearGradient( 0, 0, icon.getWidth(), icon.getHeight(),
                            0xFFFFFFFF, 0xFF54C7E1, Shader.TileMode.CLAMP ) );
                }
                else {
                    p.setShader( new LinearGradient( 0, 0, icon.getWidth(), icon.getHeight(),
                            0xFFA2A2A2, 0xFF5F5F5F, Shader.TileMode.CLAMP ) );
                }

                iconCanvas.drawRect( 0, 0, icon.getWidth( ), icon.getHeight( ), p );

                for( int x = 0; x < icon.getWidth(); x++ )
                {
                    for( int y = 0; y < icon.getHeight(); y++ )
                    {
                        if( ( icon.getPixel(x, y) & 0xFF000000 ) == 0 )
                        {
                            iconColored.setPixel( x, y, 0x00000000 );
                        }
                    }
                }

                // 计算tab图片的位置
                int tabImgX = singleTabWidth * i + ( singleTabWidth / 2 - icon.getWidth( ) / 2 );

                // 绘制tab图片 选中的和未选中的
                if( mActiveTab == i )
                {
                    mPaint.setARGB( 37, 255, 255, 255 );
                    canvas.drawRoundRect(  new RectF( r.left + singleTabWidth * i + 3, r.top + 3,
                            r.left + singleTabWidth * ( i + 1 ) - 3, r.bottom - 2 ), 5, 5, mPaint );
                    canvas.drawBitmap( iconColored, tabImgX , r.top + 5, null );
                    canvas.drawText( tabMember.getText( ),
                            singleTabWidth * i + ( singleTabWidth / 2), r.bottom - 2, mActiveTextPaint );
                } else
                {
                    canvas.drawBitmap( iconColored, tabImgX , r.top + 5, null );
                    canvas.drawText( tabMember.getText( ),
                            singleTabWidth * i + ( singleTabWidth / 2), r.bottom - 2, mInactiveTextPaint );
                }
            }
        }
        /*
         * 触摸事件
         */
        @Override
        public boolean onTouchEvent( MotionEvent motionEvent )
        {
            Rect r = new Rect( );
            this.getDrawingRect( r );
            float singleTabWidth = r.right / ( mTabMembers.size( ) != 0 ? mTabMembers.size( ) : 1 );

            int pressedTab = (int) ( ( motionEvent.getX( ) / singleTabWidth ) - ( motionEvent.getX( ) / singleTabWidth ) % 1 );

            mActiveTab = pressedTab;

            if( this.mOnTabClickListener != null)
            {
                this.mOnTabClickListener.onTabClick( mTabMembers.get( pressedTab ).getId( ) );
            }

            this.invalidate();

            return super.onTouchEvent( motionEvent );
        }

        void addTabMember( TabMember tabMember )
        {
            mTabMembers.add( tabMember );
        }

        void setOnTabClickListener( OnTabClickListener onTabClickListener )
        {
            mOnTabClickListener = onTabClickListener;
        }

        public static class TabMember//处理tab成员
        {
            protected int       mId;
            protected String    mText;
            protected int       mIconResourceId;

            TabMember( int Id, String Text, int iconResourceId )
            {
                mId = Id;
                mIconResourceId = iconResourceId;
                mText = Text;
            }

            public int getId( )
            {
                return mId;
            }

            public String getText( )
            {
                return mText;
            }

            public int getIconResourceId( )
            {
                return mIconResourceId;
            }

            public void setText( String Text )
            {
                mText = Text;
            }

            public void setIconResourceId( int iconResourceId )
            {
                mIconResourceId = iconResourceId;
            }
        }

        public static interface OnTabClickListener
        {
            public abstract void onTabClick( int tabId );
        }
    }

 这是MainActivity这个类里面的两个static类，看我写的注释和上篇博客的内容应该都能理解。其中还定义了触摸事件，实现点击tab出现不同布局的效果。接下来我们只需要在我们的layout上添加就可以了，我们继续写一个内部类

public static class iRelativeLayout extends RelativeLayout//注意，还是声明为静态
    {
        private Paint   mPaint;
        private Rect    mRect;

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

            mRect = new Rect( );
            mPaint = new Paint( );

            mPaint.setStyle( Paint.Style.FILL_AND_STROKE );
            mPaint.setColor( 0xFFCBD2D8 );
        }

        @Override
        protected void onDraw( Canvas canvas )
        {
            super.onDraw( canvas );
            canvas.drawColor( 0xFFC5CCD4 );

            this.getDrawingRect( mRect );

            for( int i = 0; i < mRect.right; i += 7 )//绘制屏幕背景的纹理效果
            {
                canvas.drawRect( mRect.left + i, mRect.top, mRect.left + i + 2, mRect.bottom, mPaint );
            }
        }
    }

    private static final int TAB_HIGHLIGHT = 1;
    private static final int TAB_CHAT = 2;
    private static final int TAB_LOOPBACK = 3;
    private static final int TAB_REDO = 4;
    private iTab            mTabs;
    private LinearLayout    mTabLayout_One;
    private LinearLayout    mTabLayout_Two;
    private LinearLayout    mTabLayout_Three;
    private LinearLayout    mTabLayout_Four;
    private LinearLayout    mTabLayout_Five;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        mTabs = (iTab) this.findViewById( R.id.Tabs );
        mTabLayout_One = (LinearLayout) this.findViewById( R.id.TabLayout_One );
        mTabLayout_Two = (LinearLayout) this.findViewById( R.id.TabLayout_Two );
        mTabLayout_Three = (LinearLayout) this.findViewById( R.id.TabLayout_Three );
        mTabLayout_Four = (LinearLayout) this.findViewById( R.id.TabLayout_Four );
        mTabLayout_Five = (LinearLayout) this.findViewById( R.id.TabLayout_Four );//偷个懒，不写第五个界面啦

        mTabs.addTabMember( new TabMember( TAB_HIGHLIGHT, "精选", R.drawable.jingxuan ) );
        mTabs.addTabMember( new TabMember( TAB_CHAT, "类别", R.drawable.cat ) );
        mTabs.addTabMember( new TabMember( TAB_LOOPBACK, "25大排行榜", R.drawable.rank ) );
        mTabs.addTabMember( new TabMember( TAB_REDO, "搜索", R.drawable.search ) );
        mTabs.addTabMember( new TabMember( TAB_REDO, "更新", R.drawable.download ) );//添加tab

        /*初始显示第一个界面*/
        mTabLayout_One.setVisibility( View.VISIBLE );
        mTabLayout_Two.setVisibility( View.GONE );
        mTabLayout_Three.setVisibility( View.GONE );
        mTabLayout_Four.setVisibility( View.GONE );

        mTabs.setOnTabClickListener( new OnTabClickListener( ) {
            @Override
            public void onTabClick( int tabId )//实现点击事件
            {
                if( tabId == TAB_HIGHLIGHT )
                {
                    mTabLayout_One.setVisibility( View.VISIBLE );
                    mTabLayout_Two.setVisibility( View.GONE );
                    mTabLayout_Three.setVisibility( View.GONE );
                    mTabLayout_Four.setVisibility( View.GONE );
                } else if( tabId == TAB_CHAT )
                {
                    mTabLayout_One.setVisibility( View.GONE );
                    mTabLayout_Two.setVisibility( View.VISIBLE );
                    mTabLayout_Three.setVisibility( View.GONE );
                    mTabLayout_Four.setVisibility( View.GONE );
                } else if( tabId == TAB_LOOPBACK )
                {
                    mTabLayout_One.setVisibility( View.GONE );
                    mTabLayout_Two.setVisibility( View.GONE );
                    mTabLayout_Three.setVisibility( View.VISIBLE );
                    mTabLayout_Four.setVisibility( View.GONE );
                } else if( tabId == TAB_REDO )
                {
                    mTabLayout_One.setVisibility( View.GONE );
                    mTabLayout_Two.setVisibility( View.GONE );
                    mTabLayout_Three.setVisibility( View.GONE );
                    mTabLayout_Four.setVisibility( View.VISIBLE );
                }
            }
        });
    }

 其中onDraw()方法里面实现了背景的纹理效果，配合xml里面背景色的配置，实现了如下图所示的效果：

是不是非常漂亮呢，剩下的就是在xml里面配置了

<?xml version="1.0" encoding="utf-8"?>
<view xmlns:android="http://schemas.android.com/apk/res/android"
    class="com.notice520.MainActivity$iRelativeLayout"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background = "#C5CCD4FF"
    >
        <LinearLayout
            android:id = "@+id/TabLayout_One"
            android:layout_width = "fill_parent"
            android:layout_height = "fill_parent"
            android:layout_above = "@+id/Tabs"
            >
            <ScrollView android:layout_width="fill_parent" android:layout_height="wrap_content">
                <RelativeLayout
                    android:layout_width = "fill_parent"
                    android:layout_height = "fill_parent"
                    android:visibility = "visible"
                    >
                    <TextView
                        android:textColor="@android:color/black"
                        android:textSize="30sp"
                        android:layout_width = "wrap_content"
                        android:layout_height = "wrap_content"
                        android:text = "春节快乐!!"
                    />
                    </RelativeLayout>
                </ScrollView>
            </LinearLayout>

        <LinearLayout
            android:id = "@+id/TabLayout_Two"
            android:layout_width = "fill_parent"
            android:layout_height = "fill_parent"
            android:layout_above = "@+id/Tabs"
            >
            <ScrollView android:layout_width="fill_parent" android:layout_height="wrap_content">
                    <RelativeLayout
                        android:layout_width = "fill_parent"
                        android:layout_height = "fill_parent"
                        android:visibility = "visible"
                        android:layout_above = "@+id/Tabs"
                        >
                        <Button
                            android:layout_width = "wrap_content"
                            android:layout_height = "wrap_content"
                            android:text = "祝大家事业有成！"
                            android:textSize = "30sp"
                        />
                    </RelativeLayout>
            </ScrollView>
        </LinearLayout>
        <LinearLayout
            android:id = "@+id/TabLayout_Three"
            android:layout_width = "fill_parent"
            android:layout_height = "fill_parent"
            android:layout_above = "@+id/Tabs"
            >
            <ScrollView android:layout_width="fill_parent" android:layout_height="wrap_content">
                <RelativeLayout
                    android:layout_width = "fill_parent"
                    android:layout_height = "fill_parent"
                    android:visibility = "visible"
                    android:layout_above = "@+id/Tabs"
                    >
                    <ImageView

                        android:layout_width = "fill_parent"
                        android:layout_height = "fill_parent"
                        android:src="@drawable/newq"
                    />
                </RelativeLayout>
            </ScrollView>
        </LinearLayout>
        <LinearLayout
            android:id = "@+id/TabLayout_Four"
            android:layout_width = "fill_parent"
            android:layout_height = "fill_parent"
            android:layout_above = "@+id/Tabs"
            >
            <ScrollView android:layout_width="fill_parent" android:layout_height="wrap_content">
                <RelativeLayout
                    android:id = "@+id/TabLayout_Four"
                    android:layout_width = "fill_parent"
                    android:layout_height = "fill_parent"
                    android:visibility = "visible"
                    android:layout_above = "@+id/Tabs"
                    >
                    <TextView
                        android:textColor="@android:color/black"
                        android:layout_width = "wrap_content"
                        android:layout_height = "wrap_content"
                        android:text = "很简单，是么"
                    />
                </RelativeLayout>
            </ScrollView>
        </LinearLayout>
    <view
        class="com.notice520.MainActivity$iTab"
        android:id="@+id/Tabs"
        android:layout_width = "fill_parent"
        android:layout_height = "49px"
        android:layout_alignParentBottom = "true"
    />
</view>

来看看最终效果吧