at least some of the new UIs are working

src/net/torvald/terrarum/UIItemInventoryCatBar.kt

@@ -0,0 +1,157 @@
+package net.torvald.terrarum
+
+import com.badlogic.gdx.graphics.Camera
+import com.badlogic.gdx.graphics.Color
+import com.badlogic.gdx.graphics.Pixmap
+import com.badlogic.gdx.graphics.Texture
+import com.badlogic.gdx.graphics.g2d.SpriteBatch
+import net.torvald.terrarum.gameactors.Second
+import net.torvald.terrarum.gameactors.floorInt
+import net.torvald.terrarum.gameactors.roundInt
+import net.torvald.terrarum.ui.*
+import net.torvald.terrarumsansbitmap.gdx.TextureRegionPack
+
+/**
+ * Created by minjaesong on 2017-10-20.
+ */
+class UIItemInventoryCatBar(
+        parentUI: UICanvas,
+        override var posX: Int,
+        override var posY: Int,
+        override val width: Int,
+        val catIcons: TextureRegionPack = TextureRegionPack("./assets/graphics/gui/inventory/category.tga", 20, 20),
+        val catArrangement: IntArray = intArrayOf(9,6,7,1,0,2,3,4,5,8)
+) : UIItem(parentUI) {
+
+    private val inventoryUI = parentUI
+    override val height = catIcons.tileH + 5
+    
+
+    private val buttons: Array<UIItemImageButton>
+    private val buttonGapSize = (width.toFloat() - (catArrangement.size * catIcons.tileW)) / (catArrangement.size + 1f)
+    var selectedIndex = 0 // default to ALL
+        private set
+    val selectedIcon: Int
+        get() = catArrangement[selectedIndex]
+    private val catSelectionOld = 0 // default to ALL
+
+    // set up buttons
+    init {
+        // place sub UIs: Image Buttons
+        buttons = Array(catArrangement.size, { index ->
+            val iconPosX = (buttonGapSize + catIcons.tileW).roundInt()
+            val iconPosY = 0
+
+            UIItemImageButton(
+                    inventoryUI,
+                    catIcons.get(catArrangement[index], 0),
+                    activeBackCol = Color(0),
+                    activeBackBlendMode = BlendMode.NORMAL,
+                    posX = posX + iconPosX,
+                    posY = posY + iconPosY,
+                    highlightable = true
+            )
+        })
+    }
+
+
+    private val underlineIndTex: Texture
+    private val underlineColour = Color(0xeaeaea_40.toInt())
+    private val underlineHighlightColour = buttons[0].highlightCol
+    private var highlighterXStart = 0.0 // left-end position
+    private var highlighterXEnd = 0.0 // left-end position
+    private var highlighterXPos = 0.0 // left-end position
+    private val highlighterYPos = catIcons.tileH + 5f
+    private var highlighterMoving = false
+    private val highlighterMoveDuration: Second = 0.1f
+    private var highlighterMoveTimer: Second = 0f
+
+    // set up underlined indicator
+    init {
+        // procedurally generate texture
+        val pixmap = Pixmap(catIcons.tileW + buttonGapSize.floorInt(), 1, Pixmap.Format.RGBA8888)
+        for (x in 0 until pixmap.width.plus(1).ushr(1)) { // eqv. of ceiling the half-int
+            val col = if      (x == 0) 0xffffff_80.toInt()
+                      else if (x == 1) 0xffffff_c0.toInt()
+                      else             0xffffff_ff.toInt()
+
+            pixmap.drawPixel(x, 0, col)
+            pixmap.drawPixel(pixmap.width - (x + 1), 0, col)
+        }
+        underlineIndTex = Texture(pixmap)
+        underlineIndTex.setFilter(Texture.TextureFilter.Nearest, Texture.TextureFilter.Nearest)
+        pixmap.dispose() // FIXME is this how it's supposed to work? (still a noob)
+    }
+
+
+    /** (oldIndex: Int?, newIndex: Int) -> Unit */
+    var selectionChangeListener: ((Int?, Int) -> Unit)? = null
+
+    override fun update(delta: Float) {
+        super.update(delta)
+        
+
+        if (highlighterMoving) {
+            highlighterMoveTimer += delta
+
+            if (selectedIndex != null) {
+                highlighterXPos = UIUtils.moveQuick(
+                        highlighterXStart,
+                        highlighterXEnd,
+                        highlighterMoveTimer.toDouble(),
+                        highlighterMoveDuration.toDouble()
+                )
+            }
+
+            if (highlighterMoveTimer > highlighterMoveDuration) {
+                highlighterMoveTimer = 0f
+                highlighterXStart = highlighterXEnd
+                highlighterXPos = highlighterXEnd
+                highlighterMoving = false
+            }
+        }
+
+
+        buttons.forEachIndexed { index, btn ->
+            btn.update(delta)
+
+
+            if (btn.mousePushed && index != selectedIndex) {
+                val oldIndex = selectedIndex
+
+                highlighterXStart = buttons[selectedIndex].posY.toDouble()
+                selectedIndex = index
+                highlighterMoving = true
+                highlighterXEnd = buttons[selectedIndex].posY.toDouble()
+
+                selectionChangeListener?.invoke(oldIndex, index)
+            }
+            btn.highlighted = (index == selectedIndex) // forcibly highlight if this.highlighted != null
+
+        }
+    }
+
+    override fun render(batch: SpriteBatch, camera: Camera) {
+        super.render(batch, camera)
+
+        // button
+        // colour determined by UI items themselves
+        buttons.forEach { it.render(batch, camera) }
+
+        // underline
+        batch.color = underlineColour
+        batch.drawStraightLine(posX.toFloat(), posY + height - 1f, width.toFloat(), 1f, false)
+
+        // indicator
+        batch.color = underlineHighlightColour
+        batch.draw(underlineIndTex, (posX + highlighterXPos).toFloat().round(), posY + highlighterYPos)
+    }
+
+
+
+
+    override fun dispose() {
+        underlineIndTex.dispose()
+        catIcons.dispose()
+    }
+}