Question

我正在尝试绘制一个我触摸的圆圈，所以我使用OnTouchListener来获取x，y坐标。但是当我在模拟器上运行代码时，我没有在单击的位置绘制圆圈。

public class MainActivity extends AppCompatActivity {
    Canvas canvas;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //------------------

        DisplayMetrics displaymetrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getRealMetrics(displaymetrics);
        int screenWidth = displaymetrics.widthPixels;//480
        int screenHeight = displaymetrics.heightPixels;//1920

        Bitmap bg = Bitmap.createBitmap(screenWidth, screenHeight, Bitmap.Config.ARGB_8888);

         canvas = new Canvas(bg);
        RelativeLayout ll = (RelativeLayout) findViewById(R.id.RelativeLayoutCells);
        ll.setBackgroundDrawable(new BitmapDrawable(bg));

        ll.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {

                if (event.getAction() == MotionEvent.ACTION_DOWN) {
                    float  xf =  event.getRawX();
                    float  yf =  event.getRawY();
                    Log.d("=", String.valueOf(x) + " " + String.valueOf(xf));
                    Paint fillpaint= new Paint();;
                    fillpaint.setColor(Color.RED);
                    fillpaint.setStyle(Paint.Style.FILL);
                    canvas.drawCircle(xf, yf, 5, fillpaint);
                    canvas.drawCircle(x, y, 15, fillpaint);
                }
                Button button = (Button) findViewById(R.id.button);
                button.setText("ghj");
                return false;
            }
        });
    }
}

Answer 1

您不应该使用event.getRawX()。返回的值是完全原始的，不会根据您的视图进行调整。如果未缩放画布，请改用event.getX()。它因为它的回归而有所不同。 getX返回x调整为自定义视图，但getRawX基于导致不准确的屏幕。

从OnTouchListener得到错误

1 个答案: