tornadofx拖拽显示文本文件和图片文件

class DragFile : View("drag and drop") {
    val dragFileModel = DragFileModel(this)
    lateinit var ap: FlowPane
    override val root = vbox {
        label("drop txt file to the left and image file to the right and View") {
            addClass(DragStyles.heading)
        }
        label(dragFileModel.lineCountProperty)
        scrollpane {
            minHeight = 320.0
            hbox {
                textarea(dragFileModel.fileLinesProperty) {
                    minHeight = 320.0
                    promptText = "Drop file here"
                    setOnDragOver { event -> dragFileModel.handleDragOver(event) }
                    setOnDragEntered { event -> dragFileModel.handleDragEntered(event) }
                    setOnDragExited { event -> dragFileModel.handleDragExited(event) }
                    setOnDragDropped { event -> dragFileModel.handleDragDropped(event) }
                }
                scrollpane {
                    ap = flowpane {
                        vgap = 10.0
                        hgap = 10.0
                        prefHeight = 600.0
                        prefWidth = 800.0
                        setOnDragOver { event -> dragFileModel.handleDragOver(event) }
                        setOnDragEntered { event -> dragFileModel.handleDragEntered(event) }
                        setOnDragExited { event -> dragFileModel.handleDragExited(event) }
                        setOnDragDropped { event -> dragFileModel.handleImgDropped(event) }
                    }
                }
            }
        }
    }
}

class DragFileModel(dragView: DragFile) {
    val dragView=dragView
    var lineList: List<String> = emptyList()
    val fileLinesProperty = SimpleStringProperty(this, "leftLines", "initial")
    var lines by fileLinesProperty
    val lineCountProperty = SimpleIntegerProperty(this, "leftLineCount", 0)
    var lineCount by lineCountProperty

    fun handleDragOver(event: DragEvent) {
        event.acceptTransferModes(TransferMode.MOVE)
        event.consume()
    }

    fun handleDragEntered(event: DragEvent) {
        println("Entered ${event.source}")
        event.consume()
    }

    fun handleDragExited(event: DragEvent) {
        println("Exited  ${event.source}")
        event.consume()
    }

    fun handleDragDropped(event: DragEvent) {
        println("Dropped  ${event.source}")
        val db = event.dragboard
        if (db.hasFiles()) {
            db.files.map { processFile(it.absolutePath) }
        }
        event.consume()
    }
    fun handleImgDropped(event: DragEvent) {
        println("Dropped  ${event.source}")
        val db = event.dragboard
        if (db.hasFiles()) {
            dragView.ap.add(ImageView(Image(File(db.files.first().toString()).inputStream())))
        }
        event.consume()
    }

    private fun processFile(filename: String) {
        lineList = FileService.getFileLines(filename)
        lines = lineList.joinToString(separator = "\n")
        lineCount = lineList.count()
    }
}

class FileService {
    companion object {
        fun getFileLines(filename: String): List<String> {
            val lineList = mutableListOf<String>()
            File(filename).useLines { lines -> lines.forEach { lineList.add(it) } }
            return lineList
        }
    }
}

class DragStyles : Stylesheet() {
    companion object {
        val heading by cssclass()
        val dropzone by cssclass()
    }

    init {
        label and heading {
            padding = box(10.px)
            fontSize = 20.px
            fontWeight = FontWeight.BOLD
        }
        dropzone {
            borderColor += box(
                top = Color.RED,
                right = Color.DARKGREEN,
                left = Color.ORANGE,
                bottom = Color.RED
            )
            padding = box(40.px)
        }
    }
}