Android simple to implement drawing function _android

How do you draw on the picture? Here has written a demo, for everyone to refer to
first, take a look at the structure of the project
Engineering Structure:

Two, custom view
This custom view implements the function of preserving the trajectory, as follows

Package Picturegame.view; 
Import Android.content.Context; 
Import Android.graphics.Bitmap; 
Import Android.graphics.BitmapFactory; 
Import Android.graphics.Canvas; 
Import Android.graphics.Color; 
Import Android.graphics.Paint; 
Import Android.graphics.Paint.Style; 
Import Android.util.AttributeSet; 
Import android.view.MotionEvent; 
Import Android.view.View; 
 
Import COM.WINTON.PICTUREGAME.R; public class Gameview extends view{private Paint Paint = null;//private Bitmap Originalbitmap = null;//Original 
   
  Figure private Bitmap new1bitmap = null; 
   
  Private Bitmap new2bitmap = null; 
   
  private float Clickx = 0; 
   
  private float clicky=0; 
   
  private float startx=0; 
   
  private float starty=0; 
   
  Private Boolean ismove = true; 
   
  Private Boolean isclear = false; private int color =color.red;//default brush color is red private float strokewidth =2.0f;//default brush bold public Gameview (Cont 
    Ext context) {this (context,null); TODO auto-generated constructor stub} public Gameview (context Context,attributeset Atts) {this (context,atts,0); TODO auto-generated Constructor stub} public Gameview (context Context,attributeset Atts,int Defstyle) {sup 
    ER (context,atts,defstyle); TODO auto-generated constructor stub originalbitmap = Bitmapfactory.decoderesource (Getresources (), R.DRAWABL e.default_pic). Copy (Bitmap.Config.ARGB_8888, true);//Load a background new1bitmap=originalbitmap.createbitmap ( 
  ORIGINALBITMAP); 
    }//Purge function public void clear () {isclear =true; 
    New2bitmap=originalbitmap.createbitmap (ORIGINALBITMAP); 
    Invalidate ()//overload} public void Setstrokewidth (float width) {this.strokewidth=width; 
  Initpaint (); @Override protected void OnDraw (Canvas Canvas) {//TODO auto-generated Method Stub Super.ondraw (Canvas) 
    ; 
     
  Canvas.drawbitmap (writer (new1bitmap), 0,0, NULL); @Override public Boolean Ontouchevent(Motionevent event) 
     
    {//TODO auto-generated method Stub Clickx =event.getx (); 
     
    Clicky=event.gety (); 
      if (Event.getaction () ==motionevent.action_down) {Ismove =false; 
      Invalidate (); 
    return true; 
      else if (event.getaction () ==motionevent.action_move) {Ismove =true; 
      Invalidate (); 
    return true; 
  Return Super.ontouchevent (event); /** * @Title: Writer * @Description: TODO (Generate bitmap) * @param @param pic * @param settings file * @ 
     
    return Bitmap type * @throws/public Bitmap writer (Bitmap pic) {initpaint (); 
    Canvas Canvas =null; 
    if (isclear) {canvas=new canvas (new2bitmap); 
    }else{canvas=new canvas (pic); 
     
    } if (Ismove) {canvas.drawline (StartX, Starty, Clickx, clicky, paint);/dash} startx = Clickx; 
    Starty =clicky; 
    if (isclear) {return new2bitmap; } rEturn pic; 
     
    private void Initpaint () {paint = new paint ();//New Brush Paint.setstyle (Style.stroke);//set to draw line Paint.setantialias (TRUE);//You can make the line smooth some paint.setcolor (color);/Set the brush color Paint.setstrokewidth (s Trokewidth)//Set the thickness of the brush line}/** * @Title: SetColor * @Description: TODO (Set the external interface for line color) * @param @param colo 
    R Set File * @return void return type * @throws */public void setcolor (int color) {this.color=color; 
  Initpaint ();  } 
   
   
}

Three, home page layout file
Home page layout file

<linearlayout xmlns:android= "http://schemas.android.com/apk/res/android" android:layout_width= "Fill_parent" android:layout_height= "Fill_parent" android:gravity= "center_horizontal" android:orientation= "vertical" > & Lt LinearLayout android:layout_width= "match_parent" android:layout_height= "50DP" android:orientation= "Horizo" 
      Ntal "> <linearlayout android:layout_width=" 0dp "android:layout_height=" Match_parent " android:layout_weight= "1" android:gravity= "center" > <textview android:id= "@+id/ Tv_30 "android:layout_width=" 30DP "android:layout_height=" 30DP "android:background=" @drawable/b 
      G_notifaction "/> </LinearLayout> <linearlayout android:layout_width=" 0DP " 
      android:layout_height= "Match_parent" android:layout_weight= "1" android:gravity= "Center" >  
       <textview Android:id= "@+id/tv_25" android:layout_width= "25DP" android:layout_height= "25DP" android:backg round= "@drawable/bg_notifaction"/> </LinearLayout> <linearlayout Android:lay Out_width= "0DP" android:layout_height= "Match_parent" android:layout_weight= "1" android:gravity= "Cente R "> <textview android:id=" @+id/tv_20 "android:layout_width=" 20DP "Android 
     
    : layout_height= "20DP" android:background= "@drawable/bg_notifaction"/> </LinearLayout> <linearlayout android:layout_width= "0DP" android:layout_height= "Match_parent" Android:lay 
        out_weight= "1" android:gravity= "center" > <textview android:id= "@+id/tv_15" 
        Android:layout_width= "15DP" android:layout_height= "15DP" android:background= "@drawable/bg_notifaction" /> </linearlayout> <linearlayout android:layout_width= "0DP" android:layout_height= "Match_paren T "android:layout_weight=" 1 "android:gravity=" center "> <textview android:id=" @+id/tv_10 "android:layout_width=" 10DP "android:layout_height=" 10DP "android:background=" @drawa 
      Ble/bg_notifaction "/> </LinearLayout> <linearlayout android:layout_width=" 0DP " 
      android:layout_height= "Match_parent" android:layout_weight= "1" android:gravity= "Center" > 
        <textview android:id= "@+id/tv_5" android:layout_width= "5DP" android:layout_height= "5DP" android:background= "@drawable/bg_notifaction"/> </LinearLayout> <linearlay 
      Out android:layout_width= "0DP" android:layout_height= "Match_parent" android:layout_weight= "1" android:gravity= "Center"> <textview android:id=" @+id/tv_2 "android:layout_width=" 2DP "Android:la yout_height= "2DP" android:background= "@drawable/bg_notifaction"/> </LinearLayout> < /linearlayout> <picturegame.view.gameview android:layout_width= "Match_parent" Android:layout_heigh 
    t= "300DP" android:id= "@+id/gameview"/> <button android:layout_width= "200DP" android:layout_height= "80DP" android:text= "clear" android:textcolor= "@color/black" android:id= "@+id/btn_cl  Ear "/> </LinearLayout>

Four, main activity code

Package com.winton.picturegame; 
Import Picturegame.view.GameView; 
Import Android.os.Bundle; 
Import Android.view.View; 
Import Android.view.View.OnClickListener; 
Import Android.widget.Button; 
 
Import Android.widget.TextView; 
 
Import com.winton.basemodule.BaseActivity; 
  public class Mainactivity extends Baseactivity implements Onclicklistener {private Gameview gameview = null; 
   
  Private Button clear = null; 
 
  Private TextView TV30,TV25,TV20,TV15,TV10,TV5,TV2; @Override protected void OnCreate (Bundle savedinstancestate) {//TODO auto-generated method stub Super.oncre 
  Ate (savedinstancestate); @Override public void Initview () {//TODO auto-generated Method stub Setcontentview (r.layout.activity 
     
    _main); 
    gameview= (Gameview) Findviewbyid (R.id.gameview); 
    Clear = (Button) Findviewbyid (r.id.btn_clear); 
    tv30= (TextView) Findviewbyid (r.id.tv_30); 
    tv25= (TextView) Findviewbyid (r.id.tv_25); tv20= (TextView) FINDVIEWBYid (R.ID.TV_20); 
    tv15= (TextView) Findviewbyid (r.id.tv_15); 
    tv10= (TextView) Findviewbyid (R.ID.TV_10); 
    tv5= (TextView) Findviewbyid (r.id.tv_5); 
  Tv2= (TextView) Findviewbyid (r.id.tv_2); @Override public void Initlistener () {//TODO auto-generated method stub clear.setonclicklistener (thi 
    s); 
    Tv30.setonclicklistener (this); 
    Tv25.setonclicklistener (this); 
    Tv20.setonclicklistener (this); 
    Tv15.setonclicklistener (this); 
    Tv10.setonclicklistener (this); 
    Tv5.setonclicklistener (this); 
     
  Tv2.setonclicklistener (this); @Override public void InitData () {//TODO auto-generated a stub} @Override public Voi 
      D OnClick (View v) {//TODO auto-generated Method stub if (v==clear) {gameview.clear (); 
    Return 
      } if (V==TV30) {gameview.setstrokewidth (30f); 
    Return 
      } if (v==tv25) {gameview.setstrokewidth (25f); 
    Return } if (V==TV{gameview.setstrokewidth (20f); 
    Return 
      } if (v==tv15) {gameview.setstrokewidth (15f); 
    Return 
      } if (V==TV10) {gameview.setstrokewidth (10f); 
    Return 
      } if (V==TV5) {gameview.setstrokewidth (5f); 
    Return 
      } if (V==TV2) {gameview.setstrokewidth (2f); 
    Return  } 
     
  } 
    
}

Five, the effect
The Operation effect chart is as follows

Vi. questions
When the line becomes thicker, the line appears as a discontinuity in the above image. May I ask the master how to deal with this? I guess I should run the algorithm, but I don't know how to run it yet.

The article for everyone to introduce to this, in fact, there are many knowledge points small series is not very clear, I hope you can carry out the expansion of common progress.