06-2. 이벤트를 이용한 드로잉

※ 화면을 터치하여 앱의 기능을 구현해 보자

 - 레이아웃에서 TextView나 Button 등은 모두 클래스이다. 그래서 우리가 CustomView 클래스를

   만들어서 레이아웃에 적용시킬 수 있다(패키지명+클래스이름)

   그렇기 때문에 MainActivity에서 인스턴스화 해서 아이디를 설정해 주면 그 위젯에 대한 인스턴스가 된다.

CustomView

public class CustomView extends View{

      

      public final static int CURRENT_CANVAS =0;

      public final static int NEW_CANVAS =1;

      

      private Context mContext;

      ArrayList<Dot> dots = new ArrayList<Dot>();

      private Paint paint;

      public CustomView(Context context) {

            super(context);

            initPaint(CURRENT_CANVAS);

      }

      

      public CustomView(Context context, AttributeSet attrs) {

            super(context, attrs);

            initPaint(CURRENT_CANVAS);

      }

      public CustomView(Context context, AttributeSet attrs, int defStyleAttr) {

            super(context, attrs, defStyleAttr);

            initPaint(CURRENT_CANVAS);

      }

      

      public void SetContext(Context context){

            this.mContext = context;

      }

      @Override

      protected void onDraw(Canvas canvas) {

            //super.onDraw(canvas);

            

            //캔버스 배경색 설정

            canvas.drawColor(Color.WHITE);

            

            for(int i =0; i< dots.size(); i++){

                  

                  if(dots.get(i).isMovState()){

                        canvas.drawLine(dots.get(i-1).getX(), dots.get(i-1).getY(), dots.get(i).getX(), dots.get(i).getY(), paint);

                  }

            }

      }

      

      public void initPaint(int i){

            

            dots.clear();

            paint = null;

            paint = new Paint();

            paint.setColor(Color.GREEN);

            //선굵기 설정

            paint.setStrokeWidth(2);

            //곡선 부드럽게 설정

            paint.setAntiAlias(true);

            

            if(i == NEW_CANVAS){

                  /*onDraw 호출 함수 : onDraw를 바로 호출해도 되지만 여러가지 문제로 발생할 수 있으므로

                   * invalidate() 호출해서 onDraw를 콜하는게 정석

                   */

                  invalidate();

            }

      }

      

      @Override

      public boolean onTouchEvent ( MotionEvent event) {

            // TODO Auto-generated method stub

            if(event.getAction() == MotionEvent.ACTION_DOWN){

                  dots.add(new Dot(event.getX(),event.getY(),false));

                  return true;

            }

            if(event.getAction() == MotionEvent.ACTION_MOVE){

                  dots.add(new Dot(event.getX(),event.getY(),true));

                  invalidate();

                  return true;

            }

            return false;

      }

}

MainActivity

public class MainActivity extends Activity {

      

      CustomView customView;

      Button button;

      

      @Override

      protected void onCreate(Bundle savedInstanceState) {

            super.onCreate(savedInstanceState);

            setContentView(R.layout.activity_main);   

            

            customView = (CustomView) findViewById(R.id.customView);

            customView.SetContext(MainActivity.this);

            

            button = (Button) findViewById(R.id.bt_new_canvas);

            button.setOnClickListener(onclick);

            

      }

      

      OnClickListener onclick = new OnClickListener() {

            

            @Override

            public void onClick(View v) {

                  switch(v.getId()){

                  case R.id.bt_new_canvas:

                        customView.initPaint(CustomView.NEW_CANVAS);

                        break;

                        

                  default :

                        break;

                        

                  }

            }

      };

}

Dot

public class Dot {

      

      private float x,y;

      private boolean movState;

      

      public Dot(float x, float y, boolean movState) {

            // TODO Auto-generated constructor stub

            this.x = x;

            this.y = y;

            this.movState = movState;

      }

      public float getX() {

            return x;

      }

      public void setX(float x) {

            this.x = x;

      }

      public float getY() {

            return y;

      }

      public void setY(float y) {

            this.y = y;

      }

      public boolean isMovState() {

            return movState;

      }

      public void setMovState(boolean movState) {

            this.movState = movState;

      }

      

}

Acitvity_MAin

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:id="@+id/ll"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

      android:orientation="vertical"

    tools:context="com.example.androidex.MainActivity" >

        

    <com.example.androidex.CustomView

        android:id="@+id/customView"

        android:layout_width="match_parent"

        android:layout_height="0px"

        android:layout_weight="9"

        />

   

    <LinearLayout

        android:orientation="horizontal"

        android:layout_width="match_parent"

        android:layout_height="0px"

        android:layout_weight="1">

       

        <Button

            android:id="@+id/bt_new_canvas"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:text="New Canvas"

            />

       

    </LinearLayout>

</LinearLayout>