Android 每次我触摸屏幕时画一个圆圈

我的目标是每次触摸屏幕时画一个圆圈，而如果我想再触摸一次，上一个圆圈就会消失

现在发生的事情是，前面的圆圈并没有消失，所以每次我触摸屏幕时，它们就加起来了

这是我的密码：

科特林：

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)       

    var imageBody: ImageView = findViewById(R.id.imageViewBody)       

    imageBody.isDrawingCacheEnabled = true
    imageBody.buildDrawingCache(true)

    imageBody.setOnTouchListener(OnTouchListener { v, event ->

        if(event != null){
            if (event.action == MotionEvent.ACTION_DOWN) {
                val bitmap: Bitmap = imageBody.drawingCache
                val pixel: Int = bitmap.getPixel(event.getX().toInt(), event.getY().toInt())
                coordX = event.getX()
                coordY = event.getY()

                val Drawable = imageBody.drawable
                val ImageBounds = Drawable.bounds
                val scaledHeight = ImageBounds.height()
                val scaledWidth = ImageBounds.width()

                OrigX = coordX / scaledHeight
                OrigY = coordY / scaledWidth

                when (pixel) {
                    Color.rgb(241,241,241) -> {
                        val canvas = Canvas(bitmap)
                        val paint = Paint()
                        paint.color = Color.rgb(255,128,0)

                        canvas.drawCircle(coordX, coordY, 15F, paint) /**DRAW CIRCLE*/

                        imageBody.setImageBitmap(bitmap)
                        imageBody.Invalidate()
                    }
                }
            }
        }

        false
    })

}

---

试试这个。清除操作

action\u UP

中imageView的位图。下面是示例代码：

首先，将位图置于

onTouchListener

之外，如下所示：

private var bitmap: Bitmap? = null

然后，您的

onTouchListener

将如下所示：

imageBody.setOnTouchListener({ v, event ->

        if(event != null){
            if (event.action == MotionEvent.ACTION_DOWN) {
                bitmap = Bitmap.createBitmap(imageBody.drawingCache)
                val pixel: Int = bitmap.getPixel(event.getX().toInt(), event.getY().toInt())
                coordX = event.getX()
                coordY = event.getY()

                val Drawable = imageBody.drawable
                val ImageBounds = Drawable.bounds
                val scaledHeight = ImageBounds.height()
                val scaledWidth = ImageBounds.width()

                OrigX = coordX / scaledHeight
                OrigY = coordY / scaledWidth

                when (pixel) {
                    Color.rgb(241,241,241) -> {
                        val canvas = Canvas(bitmap)
                        val paint = Paint()
                        paint.color = Color.rgb(255,128,0)

                        canvas.drawCircle(coordX, coordY, 15F, paint) /**DRAW CIRCLE*/

                        imageBody.setImageBitmap(bitmap)
                        imageBody.Invalidate()
                    }
                }
            }

            if (event.action == MotionEvent.ACTION_UP) {
                if (bitmap != null && !bitmap!!.isRecycled) {
                    bitmap?.recycle()
                    bitmap = null
                }
            }
        }
        true
    })

---

在绘制圆之前，请尝试清除onclick中的imageBody位图。每次触摸并向上移动指针时，都必须绘制一个新视图action@Tepits我尝试了“imageBody.ClearFindViewByDCache（）”，但它不起作用。@Dr.aNdRO你能帮我吗？请查看关于如何在画布上绘制的链接非常感谢，你的解决方案解决了我的问题。欢迎你。请将此标记为正确答案，以便每个人都知道您的问题已解决。

imageBody.setOnTouchListener({ v, event ->

        if(event != null){
            if (event.action == MotionEvent.ACTION_DOWN) {
                bitmap = Bitmap.createBitmap(imageBody.drawingCache)
                val pixel: Int = bitmap.getPixel(event.getX().toInt(), event.getY().toInt())
                coordX = event.getX()
                coordY = event.getY()

                val Drawable = imageBody.drawable
                val ImageBounds = Drawable.bounds
                val scaledHeight = ImageBounds.height()
                val scaledWidth = ImageBounds.width()

                OrigX = coordX / scaledHeight
                OrigY = coordY / scaledWidth

                when (pixel) {
                    Color.rgb(241,241,241) -> {
                        val canvas = Canvas(bitmap)
                        val paint = Paint()
                        paint.color = Color.rgb(255,128,0)

                        canvas.drawCircle(coordX, coordY, 15F, paint) /**DRAW CIRCLE*/

                        imageBody.setImageBitmap(bitmap)
                        imageBody.Invalidate()
                    }
                }
            }

            if (event.action == MotionEvent.ACTION_UP) {
                if (bitmap != null && !bitmap!!.isRecycled) {
                    bitmap?.recycle()
                    bitmap = null
                }
            }
        }
        true
    })