android canvas 지우개

지우개를 사용하는 예제입니다.

canvas를 bitmap으로 나누고 setXfermode를 통해서 지우개 기능을 추가하는 내용인데..

너무 단순하면 허전해서 몇 가지 기능을 넣었습니다.

1. option menu를 통해 pen <-> eraser 간 전환

2. 이미지를 가져와서 canvas 에 그리기

2-1. Manifest.Permission을 가져오는 기능

2-2. ACTION_PICK으로 image Uri를 얻어오는 기능

2-3. image uri에서 bitmap을 가져와서 canvas에 그리는 기능

사진이 안올라가네요. 사진을 올릴 때 TestView에 Paint 내용을 설명하겠습니다.

MainActivity.java

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "paul";

    private static final int REQ_CODE_SELECT_IMAGE=200;

    private static final int REQUEST_EXTERNAL_STORAGE = 201;

    private static final int PICK_IMAGE_ID = Menu.FIRST;

    private static final int SET_TO_PEN_ID = Menu.FIRST+1;

    private static final int SET_TO_ERASER_ID = Menu.FIRST+2;

    TestView testView;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        testView = new TestView(this);

        setContentView(testView);

    }

    @Override

    public boolean onCreateOptionsMenu(Menu menu) {

        super.onCreateOptionsMenu(menu);

        menu.add(0, PICK_IMAGE_ID,0, "pick image");

        menu.add(0, SET_TO_PEN_ID,0, "set to pen");

        menu.add(0, SET_TO_ERASER_ID,0, "set to eraser");

        return true;

    }

    @Override

    public boolean onOptionsItemSelected(MenuItem item) {

        switch (item.getItemId()){

            case PICK_IMAGE_ID:

                verifyStoragePermission();

                break;

            case SET_TO_PEN_ID:

                testView.setToPen();

                break;

            case SET_TO_ERASER_ID:

                testView.setToEraser();

                break;

        }

        return super.onOptionsItemSelected(item);

    }

    //// 이미지가져오는 코드 그냥 사용하자..///////////

    String[] PERMISSIONS_STOARGE = {

            Manifest.permission.READ_EXTERNAL_STORAGE,

            Manifest.permission.WRITE_EXTERNAL_STORAGE

    };

    private void verifyStoragePermission(){

        int readPermission = ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE);

        if(readPermission != PackageManager.PERMISSION_GRANTED){

            ActivityCompat.requestPermissions(this, PERMISSIONS_STOARGE, REQUEST_EXTERNAL_STORAGE );

        }else{

            pickImageFromGallery();

        }

    }

    @Override

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {

        if(requestCode == REQUEST_EXTERNAL_STORAGE){

            if(resultCode == RESULT_OK){

                pickImageFromGallery();

            }

        }else if(requestCode == REQ_CODE_SELECT_IMAGE){

            if(resultCode == RESULT_OK){

                try{

                    Bitmap bitmap = MediaStore.Images.Media.getBitmap(getContentResolver(), data.getData());

                    testView.setBitmp(bitmap);

                }catch (Exception e){

                }

            }

        }

    }

    private void pickImageFromGallery(){

        Intent intent = new Intent(Intent.ACTION_PICK);

        intent.setType(MediaStore.Images.Media.CONTENT_TYPE);

        intent.setData(MediaStore.Images.Media.EXTERNAL_CONTENT_URI);

        startActivityForResult(intent, REQ_CODE_SELECT_IMAGE);

    }

}

TestView.java

public class TestView extends View {

    private static final String TAG = "paul";

    Paint mPenPaint;

    Paint mTransPaint;

    PorterDuffXfermode clear = new PorterDuffXfermode(PorterDuff.Mode.CLEAR);

    Bitmap mBitmap1;

    Canvas mCanvas1;

    Bitmap mBitmap2;

    Canvas mCanvas2;

    Paint mBitmapPaint;

    float x;

    float y;

    Path mPath = new Path();

    public TestView(Context context) {

        super(context);

        this.mPenPaint = new Paint(Paint.DEV_KERN_TEXT_FLAG);

        this.mPenPaint.setAntiAlias(true);

        this.mPenPaint.setColor(Color.BLUE);

        this.mPenPaint.setStrokeWidth(5f);

        this.mPenPaint.setStyle(Paint.Style.STROKE);

        this.mTransPaint = new Paint(Paint.DEV_KERN_TEXT_FLAG);

        this.mTransPaint.setAntiAlias(true);

        this.mTransPaint.setColor(Color.TRANSPARENT);

        this.mTransPaint.setStrokeWidth(5f);

        this.mTransPaint.setStyle(Paint.Style.STROKE);

        mPath = new Path();

    }

    @Override

    protected void onSizeChanged(int w, int h, int oldw, int oldh) {

        super.onSizeChanged(w, h, oldw, oldh);

        mBitmap1 = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);

        mBitmap2 = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);

        mCanvas1 = new Canvas(mBitmap1);

        mCanvas2 = new Canvas(mBitmap2);

    }

    public void setToPen(){

        mPenPaint.setXfermode(null);

    }

    public void setToEraser(){

        mPenPaint.setXfermode(clear);

    }

    @Override

    protected void onDraw(Canvas canvas) {

        canvas.drawBitmap(mBitmap2,0,0, mBitmapPaint);

        canvas.drawBitmap(mBitmap1,0,0, mBitmapPaint);

        canvas.drawPath(mPath,mTransPaint );

    }

    @Override

    public boolean onTouchEvent(MotionEvent event) {

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

            x = event.getX(0);

            y = event.getY(0);

            mPath.moveTo(x, y);

            return true;

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

            x = event.getX(0);

            y = event.getY(0);

            mPath.lineTo(x, y);

            mCanvas1.drawPath(mPath, mPenPaint);

            invalidate();

        }else if(event.getAction() == MotionEvent.ACTION_UP){

            mCanvas1.drawPath(mPath, mPenPaint);

            mPath.reset();

            invalidate();

        }

        return super.onTouchEvent(event);

    }

    public void setBitmp(Bitmap bitmap){

        mCanvas2.drawBitmap(bitmap,0,0,null );

    }

}