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我可以通过将其转换为位图并使用以下代码将其设置在画布中来擦除图像。但我无法设置撤消和重做功能。以下代码更改了源位图，那么我如何保存路径并执行撤消和重做功能？

public class MyCustomView extends View
    {
        private Bitmap sourceBitmap;
        ImageButton undo, redo;
        private Canvas sourceCanvas = new Canvas();
        private Paint destPaint = new Paint();
        private Path destPath = new Path();

        Boolean IsEraserSet = false;

        public MyCustomView(Context context, Bitmap rawBitmap)
        {
            super(context);

            //converting drawable resource file into bitmap
           // Bitmap rawBitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.attire);

            //converting bitmap into mutable bitmap
            this.undo = undo;
            this.redo = redo;
            sourceBitmap = Bitmap.createBitmap(rawBitmap.getWidth(), rawBitmap.getHeight(), Bitmap.Config.ARGB_8888);

            sourceCanvas.setBitmap(sourceBitmap);
            sourceCanvas.drawBitmap(rawBitmap, 0, 0, null);

            destPaint.setAlpha(0);
            destPaint.setAntiAlias(true);
            destPaint.setStyle(Paint.Style.STROKE);
            destPaint.setStrokeJoin(Paint.Join.ROUND);
            destPaint.setStrokeCap(Paint.Cap.ROUND);
            //change this value as per your need
            destPaint.setStrokeWidth(50);
            destPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));


        }




        @Override
        protected void onDraw(Canvas canvas) {
            super.onDraw(canvas);

                 sourceCanvas.drawPath(destPath, destPaint);
                 canvas.drawBitmap(sourceBitmap, 0, 0, null);

           // sourceCanvas.drawPath(destPath, destPaint);
           // canvas.drawBitmap(sourceBitmap, 0, 0, null);

        }

        public void setEraser(Boolean value){

            IsEraserSet = value;
        }



        @Override
        public boolean onTouchEvent(MotionEvent event)
        {

            if(!IsEraserSet){

               return true;
            }
            float xPos = event.getX();
            float yPos = event.getY();

            switch (event.getAction())
            {
                case MotionEvent.ACTION_DOWN:

                    destPath.moveTo(xPos, yPos);

                    break;

                case MotionEvent.ACTION_MOVE:
                    destPath.lineTo(xPos, yPos);
                    break;

                case MotionEvent.ACTION_UP:
                    upTouch();

                    break;
            }

            invalidate();
            return true;
        }
    }

擦除图像后如下所示。我在擦除图像下方添加了背景图像。所以实际上我必须删除我的顶部图像以显示背景图像。但是我如何添加撤消和重做功能？任何帮助将永远感激。 一个

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1 回答 1

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你应该有一个java.util.LinkedList<Path>而不是一个Path。迭代该列表onDraw并将这些路径绘制到画布。当用户单击撤消时，您只需从列表中删除最后一个路径，当用户单击重做时，您添加最近删除的路径，这将在备份java.util.Stack<Path>中。

于 2018-11-15T03:57:37.620 回答