绘制圆的触摸 [英] Draw Circle on touch

问题描述

我想在这里用户触摸屏幕上画一个圆。

 公共类MainActivity扩展活动实现OnTouchListener {

的LinearLayout布局;
浮X = 0;
浮动Y = 0;

@覆盖
公共无效的onCreate（包savedInstanceState）{
    super.onCreate（savedInstanceState）;
    的setContentView（R.layout.layout_main）;
    布局=（的LinearLayout）findViewById（R.id.layout）;
    layout.addView（新CustomView（MainActivity.this））;
}

公共类CustomView扩展视图{

    位图mBitmap;
    涂料粉刷;
    公共CustomView（上下文的背景下）{
        超（上下文）;
        mBitmap = Bitmap.createBitmap（400，800，Bitmap.Config.ARGB_8888）;
        油漆=新的油漆（）;
        paint.setColor（Color.RED）;
        paint.setStyle（Style.FILL）;
    }

    @覆盖
    保护无效的OnDraw（帆布油画）{
        super.onDraw（画布）;
        canvas.setBitmap（mBitmap）;
        canvas.drawCircle（X，Y，50，油漆）;
        Toast.makeText（MainActivity.this，DDD，1）.show（）;
    }
}

@覆盖
公共布尔onTouch（视图V，MotionEvent事件）{

    如果（event.getAction（）== MotionEvent.ACTION_DOWN）{
    layout.invalidate（）;

    }
    返回false;
}}
 

解决方案

我会做这种方式：

 公共类TestActivity延伸活动{

    @覆盖
    公共无效的onCreate（包savedInstanceState）{
        super.onCreate（savedInstanceState）;
        的setContentView（新DrawingView（本））;
    }

    类DrawingView扩展了SurfaceView {

        私人最终SurfaceHolder surfaceHolder;
        私人最终涂料粉刷=新的油漆（Paint.ANTI_ALIAS_FLAG）;

        公共DrawingView（上下文的背景下）{
            超（上下文）;
            surfaceHolder = getHolder（）;
            paint.setColor（Color.RED）;
            paint.setStyle（Style.FILL）;
        }

        @覆盖
        公共布尔的onTouchEvent（MotionEvent事件）{
            如果（event.getAction（）== MotionEvent.ACTION_DOWN）{
                如果（surfaceHolder.getSurface（）。参考isValid（））{
                    帆布帆布= surfaceHolder.lockCanvas（）;
                    canvas.drawColor（Color.BLACK）;
                    canvas.drawCircle（event.getX（），event.getY（），50，油漆）;
                    surfaceHolder.unlockCanvasAndPost（画布）;
                }
            }
            返回false;
        }
    }
}
 

I am trying to draw a circle where user touches screen .

public class MainActivity extends Activity implements OnTouchListener {

LinearLayout layout;
float x=0;
float y=0;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.layout_main);
    layout=(LinearLayout)findViewById(R.id.layout);
    layout.addView(new CustomView(MainActivity.this));
}

public class CustomView extends View {

    Bitmap mBitmap;
    Paint paint;
    public CustomView(Context context) {
        super(context);
        mBitmap = Bitmap.createBitmap(400, 800, Bitmap.Config.ARGB_8888);
        paint=new Paint();
        paint.setColor(Color.RED);
        paint.setStyle(Style.FILL);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.setBitmap(mBitmap);
        canvas.drawCircle(x, y, 50, paint);
        Toast.makeText(MainActivity.this, "DDD", 1).show();
    }
}

@Override
public boolean onTouch(View v, MotionEvent event) {

    if (event.getAction() == MotionEvent.ACTION_DOWN) {
    layout.invalidate();

    }
    return false;
}}

解决方案

I would do it this way:

public class TestActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new DrawingView(this));
    }

    class DrawingView extends SurfaceView {

        private final SurfaceHolder surfaceHolder;
        private final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);

        public DrawingView(Context context) {
            super(context);
            surfaceHolder = getHolder();
            paint.setColor(Color.RED);
            paint.setStyle(Style.FILL);
        }

        @Override
        public boolean onTouchEvent(MotionEvent event) {
            if(event.getAction() == MotionEvent.ACTION_DOWN) {
                if (surfaceHolder.getSurface().isValid()) {
                    Canvas canvas = surfaceHolder.lockCanvas();
                    canvas.drawColor(Color.BLACK);
                    canvas.drawCircle(event.getX(), event.getY(), 50, paint);
                    surfaceHolder.unlockCanvasAndPost(canvas);
                }
            }
            return false;
        }
    }
}

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