zooming properly with z key (with some async artefacts)

src/net/torvald/terrarum/modulebasegame/ui/UIScreenZoom.kt

@@ -0,0 +1,66 @@
+package net.torvald.terrarum.modulebasegame.ui
+
+import com.badlogic.gdx.graphics.Camera
+import com.badlogic.gdx.graphics.g2d.SpriteBatch
+import net.torvald.EMDASH
+import net.torvald.terrarum.AppLoader
+import net.torvald.terrarum.Terrarum
+import net.torvald.terrarum.keyToIcon
+import net.torvald.terrarum.ui.Movement
+import net.torvald.terrarum.ui.UICanvas
+
+/**
+ * Created by minjaesong on 2019-08-11.
+ */
+class UIScreenZoom : UICanvas(
+        AppLoader.getConfigInt("keyzoom")
+) {
+
+    val zoomText = "${keyToIcon(handler.toggleKeyLiteral!!)} $EMDASH Zoom Out"
+
+    override var width = AppLoader.fontGame.getWidth(zoomText)
+    override var height = AppLoader.fontGame.lineHeight.toInt()
+
+    override var openCloseTime = 0.3f
+
+    override val mouseUp = false
+
+    private val zoomMin = 1f
+    private val zoomMax = 2f
+
+    override fun updateUI(delta: Float) {
+    }
+
+    override fun renderUI(batch: SpriteBatch, camera: Camera) {
+        batch.color = handler.opacityColour
+
+        AppLoader.fontGame.draw(
+                batch, zoomText,
+                (AppLoader.screenW * AppLoader.TV_SAFE_GRAPHICS + 1).toInt().toFloat(),
+                (AppLoader.screenH - height - AppLoader.getTvSafeGraphicsHeight()).toFloat()
+        )
+    }
+
+    override fun dispose() {
+    }
+
+    override fun doOpening(delta: Float) {
+        Terrarum.ingame?.screenZoom = Movement.fastPullOut(handler.openCloseCounter / openCloseTime, zoomMin, zoomMax)
+        handler.opacity = Terrarum.ingame?.screenZoom!! - zoomMin
+    }
+
+    override fun doClosing(delta: Float) {
+        Terrarum.ingame?.screenZoom = Movement.fastPullOut(handler.openCloseCounter / openCloseTime, zoomMax, zoomMin)
+        handler.opacity = Terrarum.ingame?.screenZoom!! - zoomMin
+    }
+
+    override fun endOpening(delta: Float) {
+        Terrarum.ingame?.screenZoom = zoomMax
+        handler.opacity = 1f
+    }
+
+    override fun endClosing(delta: Float) {
+        Terrarum.ingame?.screenZoom = zoomMin
+        handler.opacity = 0f
+    }
+}