Android Custom View (one)

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This content: Custom view (can be used multiple times in a layout file)

First, step:

1. Custom View Properties

2. get our custom properties in the View construction method

3, rewrite onmesure (optional, generally need to rewrite, no write default call system provided )

4. rewrite OnDraw

Attention:

second step: We have rewritten 3 constructor methods, the default layout file is called two parameters of the construction method, So remember to have all the constructor methods call our three-parameter construction method, and we get custom attributes in the construction of three parameters.

step three: system to help us measure the height and width are match_parnet, so do not rewrite we can not set Measurement of height and width. When we set it to wrap_content, it will also be shown as match_parnet.

< Span style= "Color:rgb (51,51,51); font-family:arial; line-height:26px ">measurespec of the Specmode, altogether three kinds:
exactly: Generally set an explicit value or Match_parent
At_most: Indicates that the sub-layout is limited to a maximum value, Typically warp_content
UNSPECIFIED: Indicates how large a child layout wants to be, rarely used

Example:

Here is the Res/layout/activity_main.xml layout file:

<relativelayout xmlns:android= "http://schemas.android.com/apk/res/android"    xmlns:tools= "http// Schemas.android.com/tools "    xmlns:custom=" Http://schemas.android.com/apk/res/com.example.customview1    " Android:layout_width= "Match_parent"    android:layout_height= "match_parent" >    < Com.view.CustomTitleView        android:layout_width= "wrap_content"        android:layout_height= "Wrap_content        " Android:layout_centerinparent= "true"        custom:titletext= "1314"        custom:titletextcolor= "#ff0000"        Custom:titletextsize= "50SP"/></relativelayout>

Be sure to introducexmlns:custom= "http://schemas.android.com/apk/res/com.example.customview01"Our namespace, followed by the package path, refers to the project's

Below is the Res/values/attrs.xml file: ( )

<?xml version= "1.0" encoding= "Utf-8"?><resources>    <attr name= "TitleText" format= "string"/>    <attr name= "titletextcolor" format= "color"/> <attr name=    "titletextsize" format= "Dimension"/>    <declare-styleable name= "Customtitleview" >        <attr name= "TitleText"/> <attr name=        " Titletextcolor "/>        <attr name=" titletextsize "/>    </declare-styleable></resources>

We define the font, font color, font size 3 properties, format is the value type of the property:
Altogether there are: String,color,demension,integer,enum,reference,float,boolean,fraction,flag


Here are the custom Customtitleview.java files:

/span>

public class Customtitleview extends View {//text private String mtitletext;//The color of the text private int mtitletextcolor;//the size of the text priv ate int mtitletextsize;//Controls the extent to which text is drawn when drawing the private Rect mbound;private Paint mpaint;public Customtitleview (context context) {  This (context, NULL); }public Customtitleview (Context context, AttributeSet Attrs) {This (context, attrs, 0);} Get my custom style properties Public Customtitleview (context context, AttributeSet attrs, int defstyle) {Super (context, attrs, Defstyle) ;//Get the custom style attributes that we defined typedarray a = Context.gettheme (). Obtainstyledattributes (Attrs,r.styleable.customtitleview, Defstyle, 0); int n = A.getindexcount (); for (int i = 0; i < n; i++) {int attr = A.getindex (i); switch (attr) {case R.styl Eable. Customtitleview_titletext:mtitletext = a.getstring (attr); Break;case r.styleable.customtitleview_titletextcolor:// The default color is set to black Mtitletextcolor = A.getcolor (attr, color.black); Break;case r.styleable.customtitleview_titletextsize:// The default setting is 16sp,typevalue can also convert sp to pxmtitletextsize = A.getdimensionpIxelsize (attr, (int) typedvalue.applydimension (typedvalue.complex_unit_sp, 16,getresources (). Getdisplaymetrics ()) ); break;}} A.recycle ();//Obtain the width and height of the drawn text Mpaint = new paint (); mpaint.settextsize (mtitletextsize);//Mpaint.setcolor (Mtitletextcolor ); mbound = new Rect (); Mpaint.gettextbounds (mtitletext, 0, Mtitletext.length (), mbound);// This custom view does not have much advantage over TextView, so add an event to the Custom view: This.setonclicklistener (New Onclicklistener () {public void OnClick (View arg0) {mtitletext = Randomtext ();p ostinvalidate ();}});} Private String Randomtext () {Random random = new random (); set<integer> set = new Hashset<integer> (), while (Set.size () < 4) {int randomint = Random.nextint; set.a DD (randomint);} StringBuffer sb = new StringBuffer (); for (Integer I:set) {sb.append ("" + i);} return sb.tostring ();} protected void onmeasure (int widthmeasurespec, int heightmeasurespec) {//Super.onmeasure (Widthmeasurespec, HEIGHTMEASURESPEC); int width = 0;int height = 0;//set width int specmode = Measurespec.getmode (widthMEASURESPEC); int specsize = Measurespec.getsize (widthmeasurespec); switch (specmode) {case measurespec.exactly:// Explicitly specified width = getpaddingleft () + getpaddingright () + specsize;break;case measurespec.at_most://generally warp_contentwidth = Getpaddingleft () + getpaddingright () + mbound.width (); break;} Set the height Specmode = measurespec.getmode (heightmeasurespec); specsize = Measurespec.getsize (heightmeasurespec); switch ( Specmode) {Case measurespec.exactly://explicitly specified height = getpaddingtop () + getpaddingbottom () + specsize;break;case measurespec.at_most://generally warp_contentheight = getpaddingtop () + getpaddingbottom () + mbound.height (); Setmeasureddimension (width, height);} protected void OnDraw (canvas canvas) {mpaint.setcolor (Color.yellow); canvas.drawrect (0, 0, getmeasuredwidth (), Getmeasuredheight (), mpaint); Mpaint.setcolor (Mtitletextcolor); Canvas.drawtext (Mtitletext, GetWidth ()/2- Mbound.width ()/2,getheight ()/2 + mbound.height ()/2, Mpaint);}}

We have added a click event, each time it randomly generates a random 4-bit number, you can add a bit of noise to the OnDraw and rewrite it as a captcha.

Here is the Mainactivity.java main interface file:

public class Mainactivity extends Activity {@Overrideprotected void onCreate (Bundle savedinstancestate) {super.oncreate (savedinstancestate); Setcontentview (R.layout.activity_main);}}

Take your time and enjoy it

Android Custom View (i)