java - 在imageview android上绘制

Question

在我的应用程序中，我想通过徒手绘制来选择 ImageView 上的一个区域。为此，我已将该类扩展为 ImageView，然后附加 OntouchListener。当我运行该应用程序时，ImageView 上没有任何内容。任何人都可以解决这个问题吗？问候 代码:

    public class MainActivity_ extends Activity {
    ImageView im;
    public static List<Point> points;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
 im=(DrawView) findViewById(R.id.imageView1);  
    }
    }

public class DrawView extends ImageView implements View.OnTouchListener{
    public static List<Point> points;
    Bitmap resultingImage;
    private Paint paint;

    int DIST = 2;
    boolean flgPathDraw = true;

    Point mfirstpoint = null;
    boolean bfirstpoint = false;

    Point mlastpoint = null;

    Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
            R.drawable.gallery_12);// convert image to bitmap
    Context mContext;


    public Bitmap get(){
    return resultingImage;
    }

    public DrawView(Context c) {
        super(c);

        mContext = c;
        setFocusable(true);
        setFocusableInTouchMode(true);

        paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        paint.setStyle(Paint.Style.STROKE);
        paint.setPathEffect(new DashPathEffect(new float[] { 10, 20 }, 0));
        paint.setStrokeWidth(5);
        paint.setColor(Color.WHITE);

        this.setOnTouchListener(this);
        points = new ArrayList<Point>();

        bfirstpoint = false;
    }

    public DrawView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mContext = context;
        setFocusable(true);
        setFocusableInTouchMode(true);

        paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        paint.setStyle(Paint.Style.STROKE);
        paint.setPathEffect(new DashPathEffect(new float[] { 10, 20 }, 0));
        paint.setStrokeWidth(15);
        paint.setColor(Color.WHITE);

        this.setOnTouchListener(this);
        points = new ArrayList<Point>();
        bfirstpoint = false;

    }

    public void onDraw(Canvas canvas) {
         canvas.drawBitmap(bitmap, 0, 0, null);

        Path path = new Path();
        boolean first = true;

        for (int i = 0; i < points.size(); i += 2) {
            Point point = points.get(i);
            if (first) {
                first = false;
                path.moveTo(point.x, point.y);
            } else if (i < points.size() - 1) {
                Point next = points.get(i + 1);
                path.quadTo(point.x, point.y, next.x, next.y);
            } else {
                mlastpoint = points.get(i);
                path.lineTo(point.x, point.y);
            }
        }
        canvas.drawPath(path, paint);
    }

    public boolean onTouch(View view, MotionEvent event) {
        /// if(event.getAction() != MotionEvent.ACTION_DOWN)
        // return super.onTouchEvent(event);
//Toast.makeText(getApplicationContext(), "On touch is working",Toast.LENGTH_LONG).show();
        Point point = new Point();
    //    point.x=(int) View.getLocationOnScreen

        point.x = (int) event.getX();
        point.y = (int) event.getY();

        int[] pp={point.x,point.y};
      view.getLocationOnScreen(pp);


view.getLocationOnScreen(pp);
point.x=pp[0];
point.y=pp[1];

        if (flgPathDraw) {

            if (bfirstpoint) {

                if (comparepoint(mfirstpoint, point)) {
                    // points.add(point);
                    points.add(mfirstpoint);
                        flgPathDraw = false;
                                        showcropdialog();
                } else {
                    points.add(point);
                }
            } else {
                points.add(point);
            }

            if (!(bfirstpoint)) {

                mfirstpoint = point;
                bfirstpoint = true;
            }
        }

        invalidate();
        Log.e("Hi  ==>", "Size: " + point.x + " " + point.y);

        if (event.getAction() == MotionEvent.ACTION_UP) {
            Log.d("Action up*******~~~~~~~>>>>", "called");
            mlastpoint = point;
            if (flgPathDraw) {
                if (points.size() > 12) {
                    if (!comparepoint(mfirstpoint, mlastpoint)) {
                        flgPathDraw = false;
                        points.add(mfirstpoint);
                        showcropdialog();
                    }
                }
            }
        }

        return true;
    }

    private boolean comparepoint(Point first, Point current) {
        int left_range_x = (int) (current.x - 3);
        int left_range_y = (int) (current.y - 3);

        int right_range_x = (int) (current.x + 3);
        int right_range_y = (int) (current.y + 3);

        if ((left_range_x < first.x && first.x < right_range_x)
                && (left_range_y < first.y && first.y < right_range_y)) {
            if (points.size() < 10) {
                return false;
            } else {
                return true;
            }
        } else {
            return false;
        }

    }

    public void fillinPartofPath() {
        Point point = new Point();
        point.x = points.get(0).x;
        point.y = points.get(0).y;

        points.add(point);
        invalidate();
    }

    public void resetView() {
        points.clear();
        paint.setColor(Color.WHITE);
        paint.setStyle(Style.STROKE);
        flgPathDraw = true;
        invalidate();
    }

    private void showcropdialog() {
}

}

xml代码:

<com.example.crop4.DrawView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/textView1"
        android:layout_marginTop="46dp"
        android:src="@drawable/gallery_12" />

Answer 1

问题很少。

首先，您根本不使用 DrawView。您可以在 onCreate 中创建一个，但不将其添加到 View 树中。我认为您想在布局 XML 中将 ImageView 替换为 DrawView。

然后，event.getX 返回绝对位置(从屏幕的左边缘开始)，但要绘制，您需要相对位置(从 Canvas 的左边缘开始)。 Y 轴也是如此。使用View.getLocationOnScreen获取 View 在屏幕上的位置。