如何将 android.graphics.path 保存在数据库中并从数据库中重绘它们

Question

我正在开发一个具有绘图功能的安卓应用程序。 我想保存那些绘图路径，这样当我从历史中重新打开活动时，我可以重绘它们。 我只想将所有内容保存在画布上，无论是路径还是自定义形状。

private val drawShapes = Stack<ShapeAndPaint?>()
private val redoShapes = Stack<ShapeAndPaint?>()
private var currentShape: ShapeAndPaint? = null
var isDrawingEnabled = false
    private set
private var viewChangeListener: BrushViewChangeListener? = null
var currentShapeBuilder: ShapeBuilder? = null

// eraser parameters
private var isErasing = false

var serializablePath = SerializablePath()
var customPath = CustomPath()

// endregion
@SuppressLint("Range")
private fun createPaint(): Paint {
    val paint = Paint()
    paint.isAntiAlias = true
    paint.isDither = true
    paint.style = Paint.Style.STROKE
    paint.strokeJoin = Paint.Join.ROUND
    paint.strokeCap = Paint.Cap.ROUND
    paint.xfermode = PorterDuffXfermode(PorterDuff.Mode.SRC_OVER)

    // apply shape builder parameters
    currentShapeBuilder?.apply {
        paint.strokeWidth = this.shapeSize
        paint.alpha = this.shapeOpacity
        paint.color = this.shapeColor
    }

    if (WhiteBoardActivity.dullPenSelected){
        paint.alpha = 40
    }


    return paint
}

private fun createEraserPaint(): Paint {
    val paint = createPaint()
    paint.xfermode = PorterDuffXfermode(PorterDuff.Mode.CLEAR)
    return paint
}

private fun setupBrushDrawing() {
    //Caution: This line is to disable hardware acceleration to make eraser feature work properly
    setLayerType(LAYER_TYPE_HARDWARE, null)
    visibility = GONE
    currentShapeBuilder = ShapeBuilder()
}

fun clearAll() {
    drawShapes.clear()
    redoShapes.clear()
    invalidate()
}

fun setBrushViewChangeListener(brushViewChangeListener: BrushViewChangeListener?) {
    viewChangeListener = brushViewChangeListener
}

public override fun onDraw(canvas: Canvas) {
    for (shape in drawShapes) {
        shape?.shape?.draw(canvas, shape.paint)
    }
}


@SuppressLint("ClickableViewAccessibility")
override fun onTouchEvent(event: MotionEvent): Boolean {
    return if (isDrawingEnabled) {
        val touchX = event.x
        val touchY = event.y
        when (event.action) {
            MotionEvent.ACTION_DOWN -> onTouchEventDown(touchX, touchY)
            MotionEvent.ACTION_MOVE -> onTouchEventMove(touchX, touchY)
            MotionEvent.ACTION_UP -> onTouchEventUp(touchX, touchY)
        }
        invalidate()
        true
    } else {
        false
    }


}

private fun onTouchEventDown(touchX: Float, touchY: Float) {
    createShape()
    currentShape?.shape?.startShape(touchX, touchY)
    customPath.ActionLine(touchX,touchY)
}

private fun onTouchEventMove(touchX: Float, touchY: Float) {
    currentShape?.shape?.moveShape(touchX, touchY)
    customPath.ActionMove(touchX,touchY)
}

private fun onTouchEventUp(touchX: Float, touchY: Float) {
    currentShape?.apply {
        shape.stopShape()
        endShape(touchX, touchY)

    }

}

private fun createShape() {
    var paint = createPaint()
    var shape: AbstractShape = BrushShape()

    if (isErasing) {
        paint = createEraserPaint()
    } else {
        when(currentShapeBuilder?.shapeType){
            
            ShapeType.BRUSH -> {
                shape = BrushShape()
            }

            else -> {}
        }
    }

    currentShape = ShapeAndPaint(shape, paint)
    drawShapes.push(currentShape)
    viewChangeListener?.onStartDrawing()
}

private fun endShape(touchX: Float, touchY: Float) {
    if (currentShape?.shape?.hasBeenTapped() == true) {
        // just a tap, this is not a shape, so remove it
        drawShapes.remove(currentShape)
        //handleTap(touchX, touchY);
    }
    viewChangeListener?.apply {
        onStopDrawing()
        onViewAdd(this@DrawingView)
    }
}

fun undo(): Boolean {
    if (!drawShapes.empty()) {
        redoShapes.push(drawShapes.pop())
        invalidate()
    }
    viewChangeListener?.onViewRemoved(this)
    return !drawShapes.empty()
}

fun redo(): Boolean {
    if (!redoShapes.empty()) {
        drawShapes.push(redoShapes.pop())
        invalidate()
    }
    viewChangeListener?.onViewAdd(this)
    return !redoShapes.empty()
}

// region eraser
fun brushEraser() {
    isDrawingEnabled = true
    isErasing = true
}

// endregion
// region Setters/Getters

fun enableDrawing(brushDrawMode: Boolean) {
    isDrawingEnabled = brushDrawMode
    isErasing = !brushDrawMode
    if (brushDrawMode) {
        visibility = VISIBLE
    }
}

fun getBitmap(): Bitmap? {
    destroyDrawingCache()
    this.buildDrawingCache()
    return this.drawingCache
}

fun setPaintAlpha(i: Int) {
    createPaint().alpha = i
}

// endregion
val drawingPath: Pair<Stack<ShapeAndPaint?>, Stack<ShapeAndPaint?>>
    get() = Pair(drawShapes, redoShapes)

companion object {
    private const val DEFAULT_ERASER_SIZE = 50.0f
    var eraserSize = DEFAULT_ERASER_SIZE
}

// region constructors
init {
    setupBrushDrawing()
}

}

这是我的 DrawingView 课程。

有没有可能的解决方案？ 提前致谢。