Android Custom View

Custom controls, Video tutorials

Http://www.jikexueyuan.com/course/1748.html

1. Writing the Custom view

2. Join Logical Threads

3. Extracting and encapsulating a custom view

4. Use XML to define styles to influence display effects

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1. Writing the Custom view

Define MyView

 Public classMyViewextendsView { PublicMyView (Context context, AttributeSet attrs) {Super(context, attrs); }     PublicMyView (Context context) {Super(context); } @Overrideprotected voidOnDraw (canvas canvas) {//adding drawing elementsPaint paint =NewPaint (); Paint.settextsize (30); Canvas.drawtext ("Hello Carloz", 0, +, paint);//default left bottom align            }}

Use in Layout file, green background

< Com.carloz.diycontrols.MyView      Android:layout_width = "Match_parent"     android:layout_height= "Match_parent"    android:background= "#00ff00"  />

Run effect

Drawing geometry

Canvas.drawline (0, Max, max, paint);  // Draw a line  New//parm:int//  Draw Rectangle  new// parm:float // Draw a rectangle

Drawing pictures

 Public classMyViewextendsView {Bitmap Bitmap;  PublicMyView (Context context, AttributeSet attrs) {Super(context, attrs); Bitmap=Bitmapfactory.decoderesource (Getresources (), r.drawable.ic_launcher); }     PublicMyView (Context context) {Super(context); Bitmap=Bitmapfactory.decoderesource (Getresources (), r.drawable.ic_launcher); } @Overrideprotected voidOnDraw (canvas canvas) {//adding drawing elementsPaint paint =NewPaint (); Paint.settextsize (30); Canvas.drawtext ("Hello Carloz", 0, +, paint);//default left bottom alignRECTF R=NewRECTF (10, 90, 110, 190);//Parm:intCanvas.drawroundrect (R, ten, G, paint);//Draw rounded rectanglesPaint.setcolor (color.red);//Change the color of a graphicCanvas.drawcircle (max., +, +, paint);//Draw Circle, center, RadiusPaint.setstyle (Style.stroke); //draw a hollow elementcanvas.drawbitmap (Bitmap,(+), and paint);//Drawing    }}

As a contentview, you can see that the background color in the layout file has been removed

 Public class extends Activity {    @Override    protectedvoid  onCreate (Bundle savedinstancestate) {         Super . OnCreate (savedinstancestate);         // Setcontentview (r.layout.activity_main);        Setcontentview (new MyView (this));}    }

2. Join Logical Threads

Purpose: To make the drawing elements move.

2.1 The text of the marquee effect

 Public classLogicviewextendsView {Paint Paint=NewPaint (); String text= "Carloz Logic View"; Private floatRx = 0;        MyThread thread;  PublicLogicview (Context context, AttributeSet attrs) {Super(context, attrs); //TODO auto-generated Constructor stub    }     PublicLogicview (Context context) {Super(context); //TODO auto-generated Constructor stub} @Overrideprotected voidOnDraw (canvas canvas) {paint.settextsize (30); Canvas.drawtext (text, RX,30, paint); if(Thread = =NULL) {Thread=NewMyThread ();        Thread.Start (); }    }        classMyThreadextendsThread {@Override Public voidrun () {//TODO auto-generated Method Stub            Super. Run ();  while(true) {Rx+ = 5; if(Rx > GetWidth ())//Let it go when it's out of the screen.Rx = 0-paint.measuretext (text); Postinvalidate (); //The thread updates the drawing and calls the OnDraw method again                Try{Thread.Sleep (50);//It's too fast for the naked eye to see, to sleep.}Catch(interruptedexception e) {//TODO auto-generated Catch blockE.printstacktrace (); }            }        }    }}

The effect is as follows, the picture does not do well (????)

2.2. Fan Forming Circle

3. Extracting and encapsulating a custom view

4. Use XML to define styles to influence display effects

Android Custom View