From ef677ae441ee7c9ebc648083ef6f5a8be2210ca9 Mon Sep 17 00:00:00 2001
From: Ellpeck <megamaximal@gmail.com>
Date: Sun, 18 Aug 2019 18:32:34 +0200
Subject: [PATCH] added some useful querying functions

---
 Demos/UiDemo.cs             | 14 ++++++++++++++
 MLEM.Ui/Elements/Element.cs | 27 +++++++++++++++++++++++++--
 2 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/Demos/UiDemo.cs b/Demos/UiDemo.cs
index badb355..65e7ff9 100644
--- a/Demos/UiDemo.cs
+++ b/Demos/UiDemo.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Coroutine;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
@@ -132,6 +133,19 @@ namespace Demos {
             var slider = new Slider(Anchor.AutoLeft, new Vector2(1, 10), 5, 1);
             root.AddChild(new Paragraph(Anchor.AutoLeft, 1, paragraph => "Slider is at " + (slider.CurrentValue * 100).Floor() + "%") {PositionOffset = new Vector2(0, 1)});
             root.AddChild(slider);
+
+            // Below are some querying examples that help you find certain elements easily
+
+            var textFields = root.GetChildren<TextField>();
+            Console.WriteLine($"The root has {textFields.Count()} text fields");
+
+            var paragraphs = root.GetChildren<Paragraph>();
+            var totalParagraphs = root.GetChildren<Paragraph>(regardChildrensChildren: true);
+            Console.WriteLine($"The root has {paragraphs.Count()} paragraphs, but there are {totalParagraphs.Count()} when regarding children's children");
+
+            var autoWidthChildren = root.GetChildren(e => e.Size.X == 1);
+            var autoWidthButtons = root.GetChildren<Button>(e => e.Size.X == 1);
+            Console.WriteLine($"The root has {autoWidthChildren.Count()} auto-width children, {autoWidthButtons.Count()} of which are buttons");
         }
 
         protected override void DoDraw(GameTime gameTime) {
diff --git a/MLEM.Ui/Elements/Element.cs b/MLEM.Ui/Elements/Element.cs
index afdb8df..2ce05f2 100644
--- a/MLEM.Ui/Elements/Element.cs
+++ b/MLEM.Ui/Elements/Element.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Linq;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
 using Microsoft.Xna.Framework.Input;
@@ -329,7 +330,7 @@ namespace MLEM.Ui.Elements {
             return this.Area;
         }
 
-        protected Element GetPreviousChild(bool hiddenAlso) {
+        public Element GetPreviousChild(bool hiddenAlso) {
             if (this.Parent == null)
                 return null;
 
@@ -344,7 +345,7 @@ namespace MLEM.Ui.Elements {
             return lastChild;
         }
 
-        protected IEnumerable<Element> GetSiblings(bool hiddenAlso) {
+        public IEnumerable<Element> GetSiblings(bool hiddenAlso) {
             if (this.Parent == null)
                 yield break;
             foreach (var child in this.Parent.Children) {
@@ -355,6 +356,28 @@ namespace MLEM.Ui.Elements {
             }
         }
 
+        public IEnumerable<Element> GetChildren(Func<Element, bool> condition = null, bool regardChildrensChildren = false) {
+            foreach (var child in this.Children) {
+                if (condition == null || condition(child))
+                    yield return child;
+                if (regardChildrensChildren) {
+                    foreach (var cc in child.GetChildren(condition, true))
+                        yield return cc;
+                }
+            }
+        }
+
+        public IEnumerable<T> GetChildren<T>(Func<T, bool> condition = null, bool regardChildrensChildren = false) where T : Element {
+            foreach (var child in this.Children) {
+                if (child is T t && (condition == null || condition(t)))
+                    yield return t;
+                if (regardChildrensChildren) {
+                    foreach (var cc in child.GetChildren(condition, true))
+                        yield return cc;
+                }
+            }
+        }
+
         public virtual void Update(GameTime time) {
             foreach (var child in this.SortedChildren)
                 child.Update(time);