Add layout modes to grid panel

src/main/kotlin/ru/dbotthepony/mc/otm/client/screen/panels/util/GridPanel.kt

@@ -21,21 +21,79 @@ open class GridPanel<out S : Screen>(
 ) : EditablePanel<S>(screen, parent, x, y, width, height) {
 	var columns: Int = columns
 		set(value) {
+			if (field != value) {
 				field = value
 				invalidateLayout()
 			}
+		}
 
 	var rows: Int = rows
 		set(value) {
+			if (field != value) {
 				field = value
 				invalidateLayout()
 			}
+		}
 
 	var gravity: RenderGravity = RenderGravity.CENTER_CENTER
 		set(value) {
+			if (field != value) {
 				field = value
 				invalidateLayout()
 			}
+		}
+
+	var layout: Layout = Layout.TOP_LEFT
+		set(value) {
+			if (field != value) {
+				field = value
+				invalidateLayout()
+			}
+		}
+
+	enum class Layout {
+		TOP_LEFT {
+			override fun rows(last: Int): IntIterator {
+				return (0 until last).iterator()
+			}
+
+			override fun columns(last: Int): IntIterator {
+				return (0 until last).iterator()
+			}
+		},
+
+		TOP_RIGHT {
+			override fun rows(last: Int): IntIterator {
+				return (0 until last).iterator()
+			}
+
+			override fun columns(last: Int): IntIterator {
+				return (last - 1 downTo 1).iterator()
+			}
+		},
+		BOTTOM_LEFT {
+			override fun rows(last: Int): IntIterator {
+				return (last - 1 downTo 1).iterator()
+			}
+
+			override fun columns(last: Int): IntIterator {
+				return (0 until last).iterator()
+			}
+		},
+
+		BOTTOM_RIGHT {
+			override fun rows(last: Int): IntIterator {
+				return (last - 1 downTo 1).iterator()
+			}
+
+			override fun columns(last: Int): IntIterator {
+				return (last - 1 downTo 1).iterator()
+			}
+		};
+
+		abstract fun rows(last: Int): IntIterator
+		abstract fun columns(last: Int): IntIterator
+	}
 
 	override fun sizeToContents() {
 		if (visibleChildren.isEmpty()) {
@@ -50,11 +108,11 @@ open class GridPanel<out S : Screen>(
 
 		val children = visibleChildren.iterator().filter { it.dock == Dock.NONE }
 
-		for (row in 0 until rows) {
+		for (row in layout.rows(rows)) {
 			var maxHeight = 0f
 			var rowWidth = 0f
 
-			for (column in 0 until columns) {
+			for (column in layout.columns(columns)) {
 				val nextChild = children.maybe() ?: break
 				rowWidth += nextChild.width + nextChild.dockMargin.horizontal
 				maxHeight = max(maxHeight, nextChild.height + nextChild.dockMargin.vertical)
@@ -75,11 +133,11 @@ open class GridPanel<out S : Screen>(
 		var totalWidth = 0f
 		var totalHeight = 0f
 
-		for (row in 0 until rows) {
+		for (row in layout.rows(rows)) {
 			var maxHeight = 0f
 			var width = 0f
 
-			for (column in 0 until columns) {
+			for (column in layout.columns(columns)) {
 				val child = children.maybe() ?: break
 				width += child.dockedWidth
 				maxHeight = maxHeight.coerceAtLeast(child.dockedHeight)
@@ -96,11 +154,11 @@ open class GridPanel<out S : Screen>(
 		totalWidth = 0f
 		totalHeight = 0f
 
-		for (row in 0 until rows) {
+		for (row in layout.rows(rows)) {
 			var maxHeight = 0f
 			var width = 0f
 
-			for (column in 0 until columns) {
+			for (column in layout.columns(columns)) {
 				val child = children.maybe() ?: break
 				child.x = alignX + width
 				child.y = alignY + totalHeight