Custom View one (Inherit view override OnDraw method)

Item: Custom view with rounded effect

First, inherit the view and rewrite the OnDraw method

 Public classCircleviewextendsview{Private Static Final intCOLOR =color.red; PrivatePaint Mpaint =NewPaint (Paint.anti_alias_flag); Private intMwidth = 0; Private intMheight = 0;  PublicCircleview (Context context, AttributeSet attrs) {Super(context, attrs);    Init (); }     PublicCircleview (Context context) {Super(context);    Init (); }     PublicCircleview (context context, AttributeSet attrs,intdefstyleattr) {        Super(context, attrs, defstyleattr);    Init (); }    Private voidinit () {mpaint.setcolor (COLOR); } @Overrideprotected voidOnDraw (canvas canvas) {Super. OnDraw (canvas); //Gets the width/height of the current viewMwidth =getmeasuredwidth (); Mheight=getmeasuredheight (); //Get Radius        intRadium = Math.min (mwidth,mheight)/2; //Draw a circleCanvas.drawcircle (MWIDTH/2,MHEIGHT/2, Radium,mpaint); }}

Circleview

Testing margin discovery in XML can be used to show that margin is controlled by the parent container (think Measurechildmarginlayout source)

But wrap_content and padding are not effective.

Second, let the wrap_content enter into force

According to the previous Chapter view works: ①, rewrite the Onmeasure method ②, set a fixed width to the Circleview

//set the width of the wrap_content timePrivate Static Final intAt_width = 30;Private Static Final intAt_height = 30;//overriding the Onmeasure () method@Overrideprotected voidOnmeasure (intWidthmeasurespec,intHeightmeasurespec) {        //get the scope of a child view        intWidthsize =measurespec.getsize (WIDTHMEASURESPEC); intWidthmode =Measurespec.getmode (WIDTHMEASURESPEC); intHeightsize =measurespec.getsize (HEIGHTMEASURESPEC); intHeightmode =Measurespec.getmode (HEIGHTMEASURESPEC); //Judging when the attribute is wrap_content        if(Widthmode = = Measurespec.at_most && Heightmode = =measurespec.at_most)        {setmeasureddimension (at_width,at_height); }        Else if(Widthmode = =measurespec.at_most)        {setmeasureddimension (at_width,heightsize); }        Else if(Heightmode = =measurespec.at_most)        {setmeasureddimension (widthsize,at_height); }        Else {            Super. Onmeasure (WIDTHMEASURESPEC,HEIGHTMEASURESPEC); }    }    

Iii. solving problems that cannot be padding

Principle: Only need to be in the OnDraw, get padding parameters can be

//overriding the OnDraw method protected voidOnDraw (canvas canvas) {Super. OnDraw (canvas); //Get padding        intPaddingleft =Getpaddingleft (); intPaddingright =getpaddingright (); intPaddingtop =Getpaddingtop (); intPaddingbottom =Getpaddingbottom (); //Gets the width/height minus padding of the current viewMwidth = Getmeasuredwidth ()-Paddingleft-paddingright; Mheight= Getmeasuredheight ()-Paddingtop-Paddingbottom; //Get Radius        intRadium = Math.min (mwidth,mheight)/2; //Draw a circleCanvas.drawcircle (PADDINGLEFT+MWIDTH/2,PADDINGTOP-MHEIGHT/2, Radium,mpaint); }

CircleviewIv. Custom Attributes

Step: ①, create the XML file name in the values directory, the file name must start with Attr_. ②, contents of the:<declare-styleadable> tag: name represents a custom attribute (the Circleview Class)

The name in the <attr> tag represents the property name (Circle_color) that is used after, and format is represented by the formatting (color)

<resources>    <declare-styleable name= "Circleview" >        <attr name= "color_circle" format= "Color" />    </declare-styleable></resources>

Attr_circleview

Step ③, using custom attributes in the layout file must be declared in schemas: xmlns:app= "Http://schemas.android.com/apk/res-auto" where the app name can be replaced casually.

But the prefix for custom attribute names in Circleview must be the same as here (the app is generally used)

<LinearLayoutxmlns:android= "Http://schemas.android.com/apk/res/android"//This paragraph must be added to the app name can be replaced
Xmlns:app= "Http://schemas.android.com/apk/res-auto"Xmlns:tools= "Http://schemas.android.com/tools"Android:layout_width= "Match_parent"Android:layout_height= "Match_parent"Tools:context= "Com.maikefengchao.circleview.MainActivity">    <Com.maikefengchao.circleview.CircleViewAndroid:layout_width= "80DP"Android:layout_height= "80DP"
        The prefix is consistent with the added declaration prefix
app:color_circle= "#9999"/></LinearLayout>

Step ④: Get custom attribute parameters in Circleview

          public int defstyleattr) {Super (context, Attrs,   DEFSTYLEATTR);         // Load Custom Properties collection Circleview        TypedArray a = context.obtainstyledattributes (attrs,r.styleable.circleview);         // resolves circle_circle in the collection, sets the default color        Mcolor = A.getcolor (r.styleable.circleview_color_circle,color.red);        Init ();    }

All code: (P209①)

Custom View one (Inherit view override OnDraw method)