Step-by-step implementation of GIF animation drop-down (ii)

http://blog.csdn.net/yoyo_newbie/article/details/47167933

The second step, hide the head file Headerview, this step is crucial for the novice.

The principle is to hide it by setting a negative number of the total height of his margintop. However, we call through direct

View. Getmeasuredheight ()

Direct access to a height of 0! So we need to solve this problem. We can measure the total height by notifying the parent layout, as follows

    /*** Measure the true height of the view and return     */    private intMeasureview(View view) {Linearlayout.layoutparams params = (layoutparams) view.getlayoutparams ();intwidth = linearlayout.Getchildmeasurespec(0, 0, Params.width);intTempheight = params.Height;intHeight = tempheight>0? Measurespec.Makemeasurespec(Tempheight, Measurespec.exactly): Measurespec.Makemeasurespec(0, Measurespec.UNSPECIFIED);    View.measure (width, Height;returnView.getmeasuredheight ();}

Some of the knowledge I will not talk about, their own to check, won't be is unable to parse, more abstract, need to understand their own hands, do it for the year.

Then we define a height variable, hide the header file method and set the method of Headerview MarginTop

/** * Height of head file  */  headerviewheight;  /**  * Hide Headerview *  /  privatehideheaderview() {    //Set MarginTop to a negative total height can hide it      directly setheaderviewmargintop (-headerviewheight );}

/*** Set header file Magrintop */private voidSetheaderviewmargintop(intTop) {Linearlayout.layoutparams params = (layoutparams)Heanderview. Getlayoutparams ();    Params.setmargins (0,Top, 0, 0);    Heanderview. Setlayoutparams (params);}

So we completed the method of hiding the Headerview.

The code after stitching. As follows

/*** with GIF drop -down * @authorSam */Public abstract classbasegifrefresh<VextendsView>extendslinearlayout{/*** Content Section     */    PrivateVChilderview;    /*** Implementation Content Section     * @paramContext     * @return     */    protected AbstractVGetconvertview(Context context); PublicBasegifrefresh (Context Context, AttributeSet attrs) {Super(Context, ATTRS);        Init (context);    }/*** Refresh time, show the head     */    PrivateViewHeanderview;    /*** Initialize UI     * @paramContext     */    private voidInit(Context context) {//Set Vertical layout        SetOrientation (LinearLayout.VERTICAL);        //Add head        Heanderview= Newheaderview (context);        AddView (Heanderview);        //Add Content section        Childerview= Newchildview (context);        AddView (Childerview);        //Second step, height, hide Headerview//Get the height of the head///Direct access to the height of the view, the result is 0. So first measure the height of the head.        Headerviewheight= Measureview (Heanderview);        //Hide Headerview        Hideheaderview ();    }/*** Height of head file     */    private intHeaderviewheight;    /*** Hide Headerview     */    private voidHideheaderview()    {//Set the total height of the margintop to a negative number to hide it directly        Setheaderviewmargintop (-Headerviewheight);    }/*** Set header file Magrintop     */    private voidSetheaderviewmargintop(intTop) {Linearlayout.layoutparams params = (layoutparams)Heanderview. Getlayoutparams ();        Params.setmargins (0,Top, 0, 0);        Heanderview. Setlayoutparams (params);    }/*** Construct a head header     * @paramContext     * @return     */    PrivateViewNewheaderview(Context context) {View Heanderview = Layoutinflater. from(context). Inflate (r.layout.Refresh_list_header, NULL);        Linearlayout.layoutparams Headerviewparams =NewLinearlayout.layoutparams (Layoutparams.match_parent,  Layoutparams.wrap_content);        Heanderview.setlayoutparams (Headerviewparams);returnHeanderview;    }/*** Component Content Section     * @paramContext     * @return     */    PrivateVNewchildview(Context context) {Linearlayout.layoutparams Convertviewparams =NewLinearlayout.layoutparams (Layoutparams.match_parent,  Layoutparams.match_parent);        Convertviewparams.Weight=1;        VChildview = Getconvertview (context);        Childview.setbackgroundcolor (Color.RED);//TODO to see the effect, test it.        Childview.setlayoutparams (Convertviewparams);returnChildview;    }/*** Measure the true height of the view and return */private intMeasureview(View view) {Linearlayout.layoutparams params = (layoutparams) view.getlayoutparams ();intwidth = linearlayout.Getchildmeasurespec(0, 0, Params.width);intTempheight = params.Height;intHeight = tempheight>0? Measurespec.Makemeasurespec(Tempheight, Measurespec.exactly): Measurespec.Makemeasurespec(0, Measurespec.UNSPECIFIED);    View.measure (width, Height;returnView.getmeasuredheight ();}}

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Step-by-step implementation of GIF animation drop-down (ii)