Custom ViewGroup Control (ii)-----> Flow Layout Advanced (ii)

Main.xml

<?xml version= "1.0" encoding= "Utf-8"? ><com.example.simplelayout.mylinlayout xmlns:android= "/http Schemas.android.com/apk/res/android "xmlns:tools=" Http://schemas.android.com/tools "android:layout_width=" Match_ The parent "android:layout_height=" wrap_content "android:background=" #ff00ff "tools:context=".        Mainactivity "><!--add layout_margin parameters to the XML--<textview android:layout_width=" Wrap_content " android:layout_height= "Wrap_content" android:layout_margintop= "10DP" android:background= "#ff0000" an droid:text= "First View"/> <textview android:layout_width= "wrap_content" android:layout_height= "Wrap_c    Ontent "android:layout_margintop=" 20DP "android:background=" #00ff00 "android:text=" Second View "/> <textview android:layout_width= "wrap_content" android:layout_height= "Wrap_content" Android:layout_ margintop= "30DP" android:background= "#0000ff" AndroiD:text= "A third view"/></com.example.simplelayout.mylinlayout> 

Mainactivity

Package Com.example.simplelayout;import Android.app.activity;import Android.os.bundle;public class MainActivity Extends Activity {    @Override public    void OnCreate (Bundle savedinstancestate) {        super.oncreate ( Savedinstancestate);        Setcontentview (R.layout.main);    }}

Mylinlayout

Package Com.example.simplelayout;import Android.content.context;import Android.util.attributeset;import Android.view.view;import android.view.viewgroup;/** */** onmeasure (): Measure your size, your size, and provide recommendations for a formal layout. (note, just suggest, as to use not, to see OnLayout); * OnLayout (): Use the layout () function to lay out all child controls; OnDraw (): Draw according to the location of the layout; * */public class Mylinlayout extends ViewGroup {/** * constructor--apart, straight Then write out three to * * @param context */public mylinlayout (context) {super ';} Public Mylinlayout (context context, AttributeSet Attrs) {Super (context, attrs);} Public Mylinlayout (context context, AttributeSet attrs, int defstyleattr) {Super (context, attrs, defstyleattr);} /** * If you want to customize ViewGroup supports Layout_margin parameters for child controls, the custom ViewGroup class must overload the Generatelayoutparams * () function, and returns a Viewgroup.marginlayoutparams derived class object in the function in order to use the margin parameter. */@Overrideprotected Layoutparams generatelayoutparams (Layoutparams p) {return new Marginlayoutparams (p);} /** * Gets the corresponding layout_width and layout_height values from the specified XML */// If we still need margin-related parameters, we can only rewrite the Generatelayoutparams () function: @Overridepublic LAyoutparams generatelayoutparams (AttributeSet attrs) {return new Marginlayoutparams (GetContext (), attrs);} /** * Generatedefaultlayoutparams () function. Returns an instance of the corresponding marginlayoutparams () directly *//** * generates Layout_width= "Wrap_content", layout_height= "wrap_content" If you want to use the default constructor method * The corresponding parameter *//** * Why the Generatelayoutparams () function must be overridden, because the default generatelayoutparams () * function extracts only the values of Layout_width *, Layout_height, Only Marginlayoutparams () has the ability to extract margin spacing!!!! */@Overrideprotected Layoutparams generatedefaultlayoutparams () {return new Marginlayoutparams (LAYOUTPARAMS.WRAP_ content,layoutparams.wrap_content);} /** * This viewgroup's wide-height attribute android:layout_width= "match_parent"--exactly (OK) * android:layout_height= "wrap_content"--AT_ Most (indeterminate) * * They are the parent class passed over to the current view of a suggested value, the recommended value, that is, to set the current view size to wide widthmeasurespec, * High Heightmeasurespec * *②, exactly (full), The parent element determines the exact size of the element, and the child element is scoped to the given boundary and ignores its size, *③, At_most (at most), and the child element reaches a value of at most the specified size. */@Overrideprotected void onmeasure (int widthmeasurespec, int heightmeasurespec) {super.onmeasure (Widthmeasurespec, Heightmeasurespec);//width, height int measurewidth = measurespec.getsize (widthmeasurespec); int measureheight = Measurespec.getsize ( HEIGHTMEASURESPEC);//measurement mode int measurewidthmode = Measurespec.getmode (widthmeasurespec); int measureheightmode = Measurespec.getmode (HEIGHTMEASURESPEC);//Initialize viewgroup wide, high int viewgroupheight = 0;int Viewgroupwidth = 0;// Get each child in ViewGroup view, traverse int count = Getchildcount (); for (int i = 0; i < count; i++) {//Get each child view object in turn view children = ge Tchildat (i);//measure each child's view, pass the pattern of the parent class into it------------------------click on the source Measurechild Get marginlayoutparams Layout Parameters!!!!!!!!!!!!!!!!!!!!!!! /** * Because the return value of Generatelayoutparams () is a layoutparams instance, * and Marginlayoutparams is derived from Layoutparam *; so depending on the polymorphic nature of the class, You can directly convert the Layoutparams instance at this time directly to marginlayoutparams instance; * So the following sentence here is not error: */marginlayoutparams LP = (marginlayoutparams) Child.getlayoutparams (); int childheight = Child.getmeasuredheight () + lp.topmargin+ lp.bottommargin;int childWidth = Child.getmeasuredwidth () + lp.leftmargin+ lp.rightmargin;//ViewgrouP height Increment viewgroupheight + = childheight;//viewgroup width take maximum viewgroupwidth = Math.max (Childwidth, viewgroupwidth);} The width of the viewgroup does not need to be measured directly "match_parent"--exactly//High is "wrap_content"--at_most, need to accumulate to get the height/** *②, exactly (full), the parent element determines the exact size of the element , the child element is limited to a given boundary and ignores its size, *③, At_most (at most), and the child element reaches a value of at most the specified size. */setmeasureddimension (Measurewidthmode = = measurespec.exactly)? measurewidth:viewgroupwidth, (MeasureHeightMode = = measurespec.exactly)? Measureheight:viewgroupheight);}  @Overrideprotected void OnLayout (Boolean changed, int l, int t, int r, int b) {int top = 0;int count = Getchildcount (); for (int i = 0; i < count; i++) {View child = Getchildat (i);//Get marginlayoutparams layout parameters!!!!!!!!!!!!!!!!!!!! Marginlayoutparams LP = (marginlayoutparams) child.getlayoutparams (); int childheight = Child.getmeasuredheight () + lp.topmargin+ Lp.bottommargin;int childwidth = child.getmeasuredwidth () + lp.leftmargin+ lp.rightMargin;child.layout ( 0, top, childwidth, top + childheight); top + + Childheight;}}}

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

Custom ViewGroup Control (ii)-----> Flow Layout Advanced (ii)