android - ImageView 中的图像消失

Question

在MainActivtiy中，我们使用Glide将URL图片加载到imgSignature中。

当点击 imgSignature 时，会弹出一个自定义对话框，它将在 imgSign 中显示图像。我们的问题是，当我们在自定义对话框中单击完成按钮时，imgSignature 中的图像变为空，并收到此 toast 消息 bgDrawable null。

为什么 imgSignature 中的图片会消失？

      lateinit var signDialog: Dialog

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
            super.onViewCreated(view, savedInstanceState)

            signDialog = Util().dialogSignature(getActivity())

            var mSignature = signature(activity, null)
            signDialog.relativeLayout2.addView(mSignature)

            var image: Bitmap? = null

            if (obj?.signature_image?.url != null) {
                Glide.with(activity)
                    .load(obj?.signature_image?.url.toString())
                    .into(imgSignature)
            }

            imgSignature.setOnClickListener {
                signDialog.show()
                if (obj?.signature_image?.url != " ") {
                    Glide.with(activity)
                        .load(obj?.signature_image?.url.toString())
                        .into(signDialog.imgSign);
                }
            }

            signDialog.doneTxt.setOnClickListener {
                signDialog.dismiss()
                imgSignature.setImageBitmap(getBitmapFromView(mSignature))
            }
    }

 fun getBitmapFromView(view: View): Bitmap {
        //Define a bitmap with the same size as the view
        val returnedBitmap = Bitmap.createBitmap(250, 250, Bitmap.Config.ARGB_8888)
        //Bind a canvas to it
        val canvas = Canvas(returnedBitmap)
        //Get the view's background
        val bgDrawable = view.background
        if (bgDrawable != null) {
            longToast("bgDrawable not null")
            //has background drawable, then draw it on the canvas
            bgDrawable.draw(canvas)
        }
        else {
            //does not have background drawable, then draw white background on the canvas
            canvas.drawColor(Color.WHITE)
            // draw the view on the canvas
            view.draw(canvas)
            longToast("bgDrawable null")
        }
        //return the bitmap
        return returnedBitmap
    }
}

效用

 fun dialogSignature(context: Context?):Dialog{

        var dialog = Dialog(context)
        dialog.requestWindowFeature(Window.FEATURE_NO_TITLE)
        dialog.setContentView(R.layout.dialog_signature)
        dialog.getWindow().setLayout(ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.WRAP_CONTENT);
        return dialog
    }

dialog_signature

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
                                             xmlns:app="http://schemas.android.com/apk/res-auto"
                                             xmlns:tools="http://schemas.android.com/tools"
                                             android:id="@+id/relativeLayout1"
                                             android:layout_width="match_parent"
                                             android:layout_height="230dp"
                                             android:orientation="vertical"
                                             android:background="@android:color/white">

    <LinearLayout android:layout_width="0dp" android:layout_height="wrap_content"
                  android:background="@color/colorPrimaryShadow"
                  android:orientation="horizontal"
                  android:id="@+id/linearLayout1"
                  android:gravity="center"
                  android:layout_marginBottom="2dp" app:layout_constraintEnd_toEndOf="parent"
                  app:layout_constraintBottom_toTopOf="@+id/relativeLayout2" app:layout_constraintTop_toTopOf="parent"
                  app:layout_constraintStart_toStartOf="parent">

        <TextView
                android:layout_marginLeft="10dp"
                android:layout_weight="0.4"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:text="Place Signature"
                android:textSize="17sp"
                android:layout_gravity="right"/>

        <TextView android:layout_width="wrap_content" android:layout_height="wrap_content"
                  android:layout_marginRight="10dp"
                  android:id="@+id/doneTxt"
                  android:text="Done"
                  android:textColor="@color/colorDarkBlue"/>

    </LinearLayout>

    <RelativeLayout android:layout_width="0dp" android:layout_height="0dp"
                    android:id="@+id/relativeLayout2"
                    android:background="@color/colorWhite"
                    app:layout_constraintTop_toBottomOf="@+id/linearLayout1" app:layout_constraintEnd_toEndOf="parent"
                    app:layout_constraintStart_toStartOf="parent" app:layout_constraintBottom_toBottomOf="parent"
                    app:layout_constraintHorizontal_bias="1.0">

        <ImageView android:layout_width="match_parent" android:layout_height="match_parent"
                   android:id="@+id/imgSign"/>
    </RelativeLayout>


    <TextView android:layout_width="wrap_content" android:layout_height="wrap_content"
              android:layout_below="@+id/linearLayout1"
              android:textColor="@color/colorDarkBlue"
              android:text="Clear" app:layout_constraintStart_toStartOf="parent"
              android:layout_marginStart="8dp" app:layout_constraintEnd_toEndOf="parent"
              android:layout_marginEnd="8dp" app:layout_constraintHorizontal_bias="1.0"
              android:layout_marginBottom="16dp" app:layout_constraintBottom_toBottomOf="parent"
              android:id="@+id/clearTxt"/>

</android.support.constraint.ConstraintLayout>

祝所有华人新年快乐

编辑

我尝试了@rafa 的回答，但得到了这个异常

cannot be cast to android.widget.ImageView  

在线

val bgDrawable = (view as ImageView).drawable

签名

inner class signature(context: Context, attrs: AttributeSet?) : View(context, attrs) {
        private val paint = Paint()
        private val path = Path()

        private var lastTouchX: Float = 0.toFloat()
        private var lastTouchY: Float = 0.toFloat()
        private val dirtyRect = RectF()

        private val STROKE_WIDTH = 5f
        private val HALF_STROKE_WIDTH = STROKE_WIDTH / 2

        init {
            paint.setAntiAlias(true)
            paint.setColor(Color.BLACK)
            paint.setStyle(Paint.Style.STROKE)
            paint.setStrokeJoin(Paint.Join.ROUND)
            paint.setStrokeWidth(STROKE_WIDTH)
        }

        override fun onDraw(canvas: Canvas) {
            canvas.drawPath(path, paint)
        }

        override fun onTouchEvent(event: MotionEvent): Boolean {
            val eventX = event.x
            val eventY = event.y
//            mGetSign.setEnabled(true)

            when (event.action) {
                MotionEvent.ACTION_DOWN -> {
                    path.moveTo(eventX, eventY)
                    lastTouchX = eventX
                    lastTouchY = eventY
                    return true
                }

                MotionEvent.ACTION_MOVE,

                MotionEvent.ACTION_UP -> {
                    resetDirtyRect(eventX, eventY)
                    val historySize = event.historySize
                    for (i in 0 until historySize) {
                        val historicalX = event.getHistoricalX(i)
                        val historicalY = event.getHistoricalY(i)
                        expandDirtyRect(historicalX, historicalY)
                        path.lineTo(historicalX, historicalY)
                    }
                    path.lineTo(eventX, eventY)
                }
                else -> {
                    debug("Ignored touch event: $event")
                    return false
                }
            }

            invalidate(
                (dirtyRect.left - HALF_STROKE_WIDTH).toInt(),
                (dirtyRect.top - HALF_STROKE_WIDTH).toInt(),
                (dirtyRect.right + HALF_STROKE_WIDTH).toInt(),
                (dirtyRect.bottom + HALF_STROKE_WIDTH).toInt()
            )

            lastTouchX = eventX
            lastTouchY = eventY

            return true
        }

        private fun debug(string: String) {
//            Log.v("log_tag", string)
        }

        private fun expandDirtyRect(historicalX: Float, historicalY: Float) {
            if (historicalX < dirtyRect.left) {
                dirtyRect.left = historicalX
            } else if (historicalX > dirtyRect.right) {
                dirtyRect.right = historicalX
            }

            if (historicalY < dirtyRect.top) {
                dirtyRect.top = historicalY
            } else if (historicalY > dirtyRect.bottom) {
                dirtyRect.bottom = historicalY
            }
        }

        private fun resetDirtyRect(eventX: Float, eventY: Float) {
            dirtyRect.left = Math.min(lastTouchX, eventX)
            dirtyRect.right = Math.max(lastTouchX, eventX)
            dirtyRect.top = Math.min(lastTouchY, eventY)
            dirtyRect.bottom = Math.max(lastTouchY, eventY)
        }

    }

Answer 1

首先，您的 mSignature 不包含任何图像，因此当您尝试从中检索图像(或背景)时返回 null。使用 imgSignature 删除 mSignature 应该可以。但仍然不确定为什么需要签名类。

lateinit var signDialog: Dialog

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        signDialog = Util().dialogSignature(getActivity())

        //var mSignature = signature(activity, null)
        //signDialog.relativeLayout2.addView(mSignature)

        var image: Bitmap? = null

        if (obj?.signature_image?.url != null) {
            Glide.with(activity)
                .load(obj?.signature_image?.url.toString())
                .into(imgSignature)
        }

        imgSignature.setOnClickListener {
            signDialog.show()
            if (obj?.signature_image?.url != " ") {
                Glide.with(activity)
                    .load(obj?.signature_image?.url.toString())
                    .into(signDialog.imgSign);
            }
        }

        signDialog.doneTxt.setOnClickListener {
            signDialog.dismiss()



            // code change goes here imgSignature
            imgSignature.setImageBitmap(getBitmapFromView(imgSignature))
        }
}

您正在使用 view.background 而不是 view.drawable 因为 Imageview 是通过 glide 设置的 src 属性。而且您必须为可绘制对象设置边界。请在下面找到更改。

fun getBitmapFromView(view: View): Bitmap {
        //Define a bitmap with the same size as the view
        val returnedBitmap = Bitmap.createBitmap(250, 250, Bitmap.Config.ARGB_8888)
        //Bind a canvas to it
        val canvas = Canvas(returnedBitmap)


        //Get the Imageview's src drawable
        val bgDrawable = (view as ImageView).drawable


        if (bgDrawable != null) {
            bgDrawable.setbounds(10,10,240,240); // setting bounds with padding of 10

            longToast("bgDrawable not null")
            //has background drawable, then draw it on the canvas
            bgDrawable.draw(canvas)
        }
        else {
            //does not have background drawable, then draw white background on the canvas
            canvas.drawColor(Color.WHITE)
            // draw the view on the canvas
            view.draw(canvas)
            longToast("bgDrawable null")
        }
        //return the bitmap
        return returnedBitmap
    }
}

新年快乐:)