如何在 kotlin 的滚动视图中实现人类签名视图？

Question

我需要在 滚动视图 中实现 自定义签名视图 。我的 xml 文件的结构是这样的

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
>
    <ScrollView>
        <androidx.constraintlayout.widget.ConstraintLayout>
          //bunch of linear layouts and textviews
            <LinearLayout
                android:id="@+id/linearLayoutSignature"
                android:layout_width="match_parent"
                android:layout_height="200dp"
                android:layout_marginTop="10dp"
                android:orientation="vertical"
                app:layout_constraintTop_toBottomOf="@+id/imageView3"
                tools:ignore="MissingConstraints">
            </LinearLayout>
         //some buttons and textfields
 </androidx.constraintlayout.widget.ConstraintLayout>
    </ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>

现在，当我在签名视图中向右或向左移动时 canvas，一切都很好。但是当我上下移动时，卷轴移动，我无法绘制。有没有办法在不将我的签名视图移出滚动视图的情况下实现这一点？有没有一种方法可以在签名布局处于活动状态时冻结签名布局，以便在我绘制签名时不会向上或向下滚动？

CaptureSignature.java

package com.example.app_ptt.services;

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 android.view.View;

import java.io.ByteArrayOutputStream;

public class CaptureSignature extends View {

    private Bitmap _Bitmap;
    private Canvas _Canvas;
    private Path _Path;
    private Paint _BitmapPaint;
    private Paint _paint;
    private float _mX;
    private float _mY;
    private float TouchTolerance = 4;
    private float LineThickness = 4;

    public CaptureSignature(Context context, AttributeSet attr) {
        super(context, attr);
        _Path = new Path();
        _BitmapPaint = new Paint(Paint.DITHER_FLAG);
        _paint = new Paint();
        _paint.setAntiAlias(true);
        _paint.setDither(true);
        _paint.setColor(Color.argb(255, 0, 0, 0));
        _paint.setStyle(Paint.Style.STROKE);
        _paint.setStrokeJoin(Paint.Join.ROUND);
        _paint.setStrokeCap(Paint.Cap.ROUND);
        _paint.setStrokeWidth(LineThickness);
    }

    public CaptureSignature(Context context) {
        super(context);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        _Bitmap = Bitmap.createBitmap(w, (h > 0 ? h : ((View) this.getParent()).getHeight()), Bitmap.Config.ARGB_8888);
        _Canvas = new Canvas(_Bitmap);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawColor(Color.WHITE);
        canvas.drawBitmap(_Bitmap, 0, 0, _BitmapPaint);
        canvas.drawPath(_Path, _paint);
    }

    private void TouchStart(float x, float y) {
        _Path.reset();
        _Path.moveTo(x, y);
        _mX = x;
        _mY = y;
    }

    private void TouchMove(float x, float y) {
        float dx = Math.abs(x - _mX);
        float dy = Math.abs(y - _mY);

        if (dx >= TouchTolerance || dy >= TouchTolerance) {
            _Path.quadTo(_mX, _mY, (x + _mX) / 2, (y + _mY) / 2);
            _mX = x;
            _mY = y;
        }
    }

    private void TouchUp() {
        if (!_Path.isEmpty()) {
            _Path.lineTo(_mX, _mY);
            _Canvas.drawPath(_Path, _paint);
        } else {
            _Canvas.drawPoint(_mX, _mY, _paint);
        }

        _Path.reset();
    }

    @Override
    public boolean onTouchEvent(MotionEvent e) {
        super.onTouchEvent(e);
        float x = e.getX();
        float y = e.getY();

        switch (e.getAction()) {
            case MotionEvent.ACTION_DOWN:
                TouchStart(x, y);
                invalidate();
                break;
            case MotionEvent.ACTION_MOVE:
                TouchMove(x, y);
                invalidate();
                break;
            case MotionEvent.ACTION_UP:
                TouchUp();
                invalidate();
                break;
        }

        return true;
    }

    public void ClearCanvas() {
        _Canvas.drawColor(Color.WHITE);
        invalidate();
    }

    public byte[] getBytes() {
        Bitmap b = getBitmap();

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        b.compress(Bitmap.CompressFormat.PNG, 100, baos);
        return baos.toByteArray();
    }

    public Bitmap getBitmap() {
        View v = (View) this.getParent();
        Bitmap b = Bitmap.createBitmap(v.getWidth(), v.getHeight(), Bitmap.Config.ARGB_8888);
        Canvas c = new Canvas(b);
        v.layout(v.getLeft(), v.getTop(), v.getRight(), v.getBottom());
        v.draw(c);

        return b;
    }
}

Answer 1

尝试在您的 CaptureSignature 中复制此覆盖方法 class 并检查

@Override
    public boolean onTouchEvent(final MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:

                getParent().getParent().requestDisallowInterceptTouchEvent(true);

                break;
            case MotionEvent.ACTION_UP:

                getParent().getParent().requestDisallowInterceptTouchEvent(false);


                break;
            default:
                break;
        }

        return super.onTouchEvent(event);
    }

如何在 kotlin 的滚动视图中实现人类签名视图？

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