我有一个包含JFrame的JPanel。此JPanel中还有更多组件，例如JLabel，JTextField，JLabel和JFileChooser。这些组件将正确显示在应有的位置，但它们也将显示在窗口中应位于其下的位置(0, 0)处。在上方显示的是最后一个关注的对象：(Image) The JFileChooser is displayed as a separate window, but also displayed underneath what is supposed to be displayed at (0, 0)
如何防止这种情况发生？
代码：（省略了一些方法以使代码更短。这些与发布无关。）
(0, 0)对Kotlin一无所知，但我想问题是：
package com.kasad.pathfinder.mapmaker.graphics.components
import com.kasad.pathfinder.mapmaker.grid.Node
import java.awt.Color
import java.awt.FlowLayout
import java.awt.Graphics
import java.awt.event.*
import javax.swing.JButton
import javax.swing.JFileChooser
import javax.swing.JLabel
import javax.swing.JPanel
import javax.swing.filechooser.FileNameExtensionFilter
class DisplaySO : JPanel() {
companion object {
val WALKABLE_TILE_COLOR: Color = Color.WHITE
val WALL_TILE_COLOR: Color = Color.BLACK
val START_TILE_COLOR: Color = Color.GREEN
val END_TILE_COLOR: Color = Color.RED
val TILE_BORDER_COLOR: Color = Color.BLACK
const val GRID_MARGIN: Int = 50
}
private var nodes = arrayOf( // Start with a 3x3 grid of walkable nodes
... // Not relevant to issue (omitted)
)
// These variables (nodeSize, centerOffset[X/Y], grid[Height/Width]) are referred to as "draw sizes"
private var nodeSize = 0 // Size of each node
private var centerOffsetX = 0 // X offset to center grid
private var centerOffsetY = 0 // Y offset to center grid
private var gridWidth = 0 // The total width of the grid
private var gridHeight = 0 // The total height of the grid
private var previousWidth = 0 // Previous width of window
private var previousHeight = 0 // Previous height of window
private var startNode: Node? = null
private var endNode: Node? = null
private lateinit var prevMousedNode: Node // Previous node selected by mouse
private var currentKeyPressed: Char? = null
private var currentMouseButton: Int? = null
private val widthBox = JNumberField(6) // Create text boxes for grid width & height input
private val heightBox = JNumberField(6) // |
private val widthBoxLabel = JLabel("Rows:") // Text box labels
private val heightBoxLabel = JLabel("Columns:") // |
private val resizeButton = JButton("Resize") // Button to resize grid/process inputs
private val fileChooser = JFileChooser()
private val saveButton = JButton("Save to File")
fun init() {
isDoubleBuffered = true
isVisible = true
isFocusable = true
layout = FlowLayout(FlowLayout.LEFT)
add(widthBoxLabel)
add(widthBox)
add(heightBoxLabel)
add(heightBox)
add(resizeButton)
add(saveButton)
resizeButton.addActionListener {
[email protected]()
val newWidth: Int
val newHeight: Int
try {
newWidth = widthBox.value
newHeight = heightBox.value
} catch (e: NumberFormatException) {
println("Error: Invalid number")
return@addActionListener
}
resizeGrid(newWidth, newHeight)
}
saveButton.addActionListener { // When the save button is pressed,
saveGrid() // Save the grid to a file
}
resizeButton.isFocusable = false // Set buttons as unfocusable (forces keystrokes to be processed by window)
saveButton.isFocusable = false // |
fileChooser.apply {
dialogTitle = "Choose file to save to..." // Window title
addChoosableFileFilter(FileNameExtensionFilter("Grid Map Files", "gmap")) // Add a file extension filter and
fileFilter = choosableFileFilters[1] // set it as the default
isMultiSelectionEnabled = false // Only allow selecting one file
}
addKeyListener(object : KeyListener {
override fun keyPressed(e: KeyEvent) {
if ((e.keyChar in 'A'..'Z' || e.keyChar in 'a'..'z') && currentKeyPressed != e.keyChar) {
currentKeyPressed = e.keyChar
println(e.keyChar)
}
}
override fun keyReleased(e: KeyEvent) {
if (currentKeyPressed == e.keyChar)
currentKeyPressed = null
}
override fun keyTyped(e: KeyEvent?) {}
})
addMouseListener(object : MouseListener {
override fun mousePressed(e: MouseEvent) {
if ([email protected])
[email protected]()
currentMouseButton = e.button
processMouseDown(e)
}
override fun mouseReleased(e: MouseEvent) {
if (currentMouseButton == e.button)
currentMouseButton = null
}
override fun mouseEntered(e: MouseEvent?) {}
override fun mouseExited(e: MouseEvent?) {}
override fun mouseClicked(e: MouseEvent?) {}
})
addMouseMotionListener(object : MouseMotionListener {
override fun mouseMoved(e: MouseEvent?) {}
override fun mouseDragged(e: MouseEvent) {
processMouseDown(e)
}
})
nodeSize = (height - 2 * GRID_MARGIN) / nodes.size
repaint()
}
private fun resizeGrid(newGridWidth: Int, newGridHeight: Int) {
... // Not relevant to issue (omitted)
}
private fun computeDrawSizes() {
... // Not relevant to issue (omitted)
}
private fun drawGrid(g: Graphics) {
var nodePositionX: Int
var nodePositionY: Int
for (row in nodes) {
for (node in row) {
nodePositionX = node.gridX * nodeSize + centerOffsetX
nodePositionY = node.gridY * nodeSize + centerOffsetY
with(g) {
color = when (true) {
node.walkable -> when {
node.isStartNode -> START_TILE_COLOR
node.isEndNode -> END_TILE_COLOR
else -> WALKABLE_TILE_COLOR
}
else -> WALL_TILE_COLOR
}
fillRect(
nodePositionX,
nodePositionY,
nodeSize,
nodeSize
)
color = TILE_BORDER_COLOR
drawRect(
nodePositionX,
nodePositionY,
nodeSize,
nodeSize
)
}
}
}
}
private fun processMouseDown(e: MouseEvent) {
... // Not relevant to issue (omitted)
}
private fun getNodeByPosition(x: Int, y: Int): Node? {
... // Not relevant to issue (omitted)
}
@Throws(IllegalArgumentException::class)
private fun updateNode(node: Node, newStatus: Int) {
... // Not relevant to issue (omitted)
}
private fun saveGrid() {
if (startNode == null || endNode == null) {
println("Error: must choose a start node and an end node")
return
}
if (fileChooser.showSaveDialog(this) != JFileChooser.APPROVE_OPTION)
return
fileChooser.selectedFile.writeText(
gridToString()
)
}
private fun gridToString(): String {
... // Not relevant to issue (omitted)
}
override fun paintComponent(g: Graphics) {
if (width != previousWidth || height != previousHeight) // If window has been resized,
computeDrawSizes() // recalculate the draw sizes
drawGrid(g) // Draw the grid
}
}
在Swing中重写paintComponent（...）时的第一条语句应该是：
override fun paintComponent(g: Graphics) {
if (width != previousWidth || height != previousHeight)
为了确保清除背景，所以没有绘画痕迹。