Рисование по внутренней структуре макета?

Question

Моя активность:

public class myMainActivity extends AppCompatActivity { 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.MyLayout); 

    } 
} 

Я хочу рисовать пальцем на фоне моего макета, как так:

Answer 1

Вы должны иметь класс краски первый

paint = new Paint(); 
paint.setColor(Color.BLACK); 
paint.setStrokeWidth(5); 
paint.setStyle(Paint.Style.STROKE); 
paint.setPathEffect(new DashPathEffect(new float[]{15.0f, 15.0f}, 0)); 

и осуществить следующее onTouchListener

public boolean onTouch(View v, MotionEvent event) { 
int action = event.getAction(); 

switch (action) { 
    case MotionEvent.ACTION_DOWN: 


    downx = event.getX(); 
    downy = event.getY(); 
    clipPath = new Path(); 
    clipPath.moveTo(downx, downy); 
    tdownx = downx; 
    tdowny = downy; 
    smallx = downx; 
    smally = downy; 
    largex = downx; 
    largey = downy; 
    lastTouchDown = System.currentTimeMillis(); 
    break; 

    case MotionEvent.ACTION_MOVE: 
    upx = event.getX(); 
    upy = event.getY(); 
cropModelArrayList.add(new CropModel(upx, upy)); 
clipPath = new Path(); 
clipPath.moveTo(tdownx,tdowny); 
    for(int i = 0; i<cropModelArrayList.size();i++){ clipPath.lineTo(cropModelArrayList.get(i).getY(),cropModelArrayList.get(i).getX( )); 
    } 
    canvas.drawPath(clipPath, paint); 
    im_crop_image_view.invalidate(); 
    downx = upx; 
    downy = upy; 
    break; 
    case MotionEvent.ACTION_UP: 
if (System.currentTimeMillis() - lastTouchDown < CLICK_ACTION_THRESHHOLD) { 

cropModelArrayList.clear(); 
initcanvas(); 

int cx = (screen_width - bmp.getWidth()) >> 1; 
int cy = (screen_height - bmp.getHeight()) >> 1; 
canvas.drawBitmap(bmp, cx, cy, null); 
im_crop_image_view.setImageBitmap(alteredBitmap); 

} else { 
if (upx != upy) { 
upx = event.getX(); 
upy = event.getY(); 


canvas.drawLine(downx, downy, upx, upy, paint); 
clipPath.lineTo(upx, upy); 
yourview.invalidate(); 

    } 

    } 
    break; 
    return true; 
    } 

Вы можете найти полную реализацию here(ignore the crop method)