英文:
android - Canvas draw path on canvas without touch direction
问题
以下是翻译好的代码部分:
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.MotionEvent;
import androidx.appcompat.widget.AppCompatImageView;
public class RachetBasic extends AppCompatImageView {
    private Canvas canvas;
    private Bitmap bitmap;
    private Paint bitmapPaint = new Paint(Paint.DITHER_FLAG);
    private Path squarePath = new Path();
    private Paint squarePaint = new Paint();
    public RachetBasic(Context context) {
        super(context);
    }
    public RachetBasic(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
    public RachetBasic(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }
    @Override
    protected void onSizeChanged(int width, int height, int oldw, int oldh) {
        super.onSizeChanged(width, height, oldw, oldh);
        squarePaint.setAntiAlias(true);
        squarePaint.setDither(true);
        squarePaint.setStyle(Paint.Style.STROKE);
        squarePaint.setStrokeCap(Paint.Cap.SQUARE);
        squarePaint.setStrokeWidth(80);
        squarePaint.setColor(Color.BLUE);
        bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        canvas = new Canvas(bitmap);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawBitmap(bitmap, 0, 0, bitmapPaint);
        canvas.drawPath(squarePath, squarePaint);
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX();
        float y = event.getY();
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            squarePath.moveTo(x, y);
        } else if (event.getAction() == MotionEvent.ACTION_MOVE) {
            squarePath.lineTo(x, y);
        } else if (event.getAction() == MotionEvent.ACTION_UP) {
            squarePath.lineTo(x, y);
            canvas.drawPath(squarePath, squarePaint);
            squarePath.reset();
        }
        invalidate();
        return true;
    }
}
public class MainActivity extends androidx.appcompat.app.AppCompatActivity {
   public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
       setContentView(new RachetBasic(MainActivity.this));
    }
}
英文:
I build this class to draw on screen to implement some brushes created via differents Paints and paths.
Currently is drawing a square based on user touch movement, but the draw path is being rotated by the draw direction of the touch. I tried to apply a rect without no luck and I don't found any related info about this phenom
EDIT :
This image is from current result
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.MotionEvent;
public class RachetBasic extends androidx.appcompat.widget.AppCompatImageView {
    private Canvas canvas;
    private Bitmap bitmap;
    private Paint bitmapPaint = new Paint(Paint.DITHER_FLAG);
    private Path squarePath = new Path();
    private Paint squarePaint = new Paint();
    public RachetBasic(Context context) {
        super(context);
    }
    public RachetBasic(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
    public RachetBasic(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }
    @Override
    protected void onSizeChanged(int width, int height, int oldw, int oldh) {
        super.onSizeChanged(width, height, oldw, oldh);
        squarePaint.setAntiAlias(true);
        squarePaint.setDither(true);
        squarePaint.setStyle(Paint.Style.STROKE);
        squarePaint.setStrokeCap(Paint.Cap.SQUARE);
        squarePaint.setStrokeWidth(80);
        squarePaint.setColor(Color.BLUE);
        bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        canvas = new Canvas(bitmap);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawBitmap(bitmap, 0, 0, bitmapPaint);
        canvas.drawPath(squarePath, squarePaint);
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX();
        float y = event.getY();
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            squarePath.moveTo(x, y);
        } else if (event.getAction() == MotionEvent.ACTION_MOVE) {
            squarePath.lineTo(x, y);
        } else if (event.getAction() == MotionEvent.ACTION_UP) {
            squarePath.lineTo(x, y);
            canvas.drawPath(squarePath, squarePaint);
            squarePath.reset();
        }
        invalidate();
        return true;
    }
}
public class MainActivity extends androidx.appcompat.app.AppCompatActivity {
   public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
       setContentView(new RachetBasic(MainActivity.this));
    }
}
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