Fixes for the button iconset inspectors (#9999)

Author: RogPodge

Assets/MRTK/SDK/Features/UX/Scripts/Buttons/ButtonIconSet.cs

@@ -205,6 +205,7 @@ public static string ConvertUInt32ToUnicodeCharString(uint unicode)
         private Texture[] spriteIconTextures = null;
         private static Material fontRenderMat;
 
+        private const string missingPreviewImagesMessage = "Not all icon previews were loaded. Check the settings of the icons included in your iconset.";
         private const string noIconFontMessage = "No icon font selected. Icon fonts will be unavailable.";
         private const string downloadIconFontMessage = "For instructions on how to install the HoloLens icon font, click the button below.";
         private const string hololensIconFontUrl = "https://docs.microsoft.com/windows/mixed-reality/mrtk-unity/features/ux-building-blocks/button";
@@ -344,8 +345,16 @@ public bool EditorDrawSpriteIconSelector(Sprite currentSprite, out bool foundSpr
             {
                 float height = maxButtonSize * ((float)spriteIcons.Length / maxButtonsPerColumn);
                 var maxHeight = GUILayout.MaxHeight(height);
+
+                bool allPreviewsLoaded;
+                var gridContent = GenerateGridContent(spriteIconTextures, out allPreviewsLoaded);
+
+                if(!allPreviewsLoaded)
+                {
+                    EditorGUILayout.HelpBox(missingPreviewImagesMessage, MessageType.Warning);
+                }
 #if UNITY_2019_3_OR_NEWER
-                int newSelection = GUILayout.SelectionGrid(currentSelection, spriteIconTextures, maxButtonsPerColumn, maxHeight);
+                int newSelection = GUILayout.SelectionGrid(currentSelection, gridContent, maxButtonsPerColumn, maxHeight);
 #else
                 var maxWidth = GUILayout.MaxWidth(maxButtonSize * maxButtonsPerColumn);
                 int newSelection = GUILayout.SelectionGrid(currentSelection, spriteIconTextures, maxButtonsPerColumn, maxHeight, maxWidth);
@@ -363,7 +372,6 @@ public bool EditorDrawSpriteIconSelector(Sprite currentSprite, out bool foundSpr
             return newSprite != null;
         }
 
-
         /// <summary>
         /// Updates the cached sprite icon textures to the latest textures in spriteIcons
         /// </summary>
@@ -420,8 +428,16 @@ public bool EditorDrawQuadIconSelector(Texture currentTexture, out bool foundTex
             {
                 float height = maxButtonSize * ((float)quadIcons.Length / maxButtonsPerColumn);
                 var maxHeight = GUILayout.MaxHeight(height);
+
+                bool allPreviewsLoaded;
+                var gridContent = GenerateGridContent(quadIcons, out allPreviewsLoaded);
+
+                if (!allPreviewsLoaded)
+                {
+                    EditorGUILayout.HelpBox(missingPreviewImagesMessage, MessageType.Warning);
+                }
 #if UNITY_2019_3_OR_NEWER
-                int newSelection = GUILayout.SelectionGrid(currentSelection, quadIcons, maxButtonsPerColumn, maxHeight);
+                int newSelection = GUILayout.SelectionGrid(currentSelection, gridContent, maxButtonsPerColumn, maxHeight);
 #else
                 var maxWidth = GUILayout.MaxWidth(maxButtonSize * maxButtonsPerColumn);
                 int newSelection = GUILayout.SelectionGrid(currentSelection, quadIcons, maxButtonsPerColumn, maxHeight, maxWidth);
@@ -544,6 +560,27 @@ public bool EditorAddCustomQuadIcon(Texture customQuadIcon)
             return true;
         }
 
+        public GUIContent[] GenerateGridContent(Texture[] previewTextures, out bool allPreviewsLoaded)
+        {
+            GUIContent[] gridContent = new GUIContent[previewTextures.Length];
+            allPreviewsLoaded = true;
+
+            for (int i = 0; i < previewTextures.Length; i++)
+            {
+                if (previewTextures[i] != null)
+                {
+                    gridContent[i] = new GUIContent(previewTextures[i]);
+                }
+                else
+                {
+                    gridContent[i] = new GUIContent("N/A");
+                    allPreviewsLoaded = false;
+                }
+            }
+
+            return gridContent;
+        }
+
         [CustomEditor(typeof(ButtonIconSet))]
         private class ButtonIconSetInspector : UnityEditor.Editor
         {
@@ -578,6 +615,7 @@ public override void OnInspectorGUI()
 
 #if UNITY_2019_3_OR_NEWER
                 showQuadIconFoldout = EditorGUILayout.BeginFoldoutHeaderGroup(showQuadIconFoldout, "Quad Icons");
+                EditorGUILayout.EndFoldoutHeaderGroup();
 #else
                 showQuadIconFoldout = EditorGUILayout.Foldout(showQuadIconFoldout, "Quad Icons");
 #endif
@@ -589,12 +627,10 @@ public override void OnInspectorGUI()
                         EditorGUILayout.PropertyField(quadIconsProp, true);
                     }
                 }
-#if UNITY_2019_3_OR_NEWER
-                EditorGUILayout.EndFoldoutHeaderGroup();
-#endif
 
 #if UNITY_2019_3_OR_NEWER
                 showSpriteIconFoldout = EditorGUILayout.BeginFoldoutHeaderGroup(showSpriteIconFoldout, "Sprite Icons");
+                EditorGUILayout.EndFoldoutHeaderGroup();
 #else
                 showSpriteIconFoldout = EditorGUILayout.Foldout(showSpriteIconFoldout, "Sprite Icons");
 #endif
@@ -615,21 +651,14 @@ public override void OnInspectorGUI()
                         }
                     }
                 }
-#if UNITY_2019_3_OR_NEWER
-                EditorGUILayout.EndFoldoutHeaderGroup();
-#endif
 
 #if UNITY_2019_3_OR_NEWER
                 showCharIconFoldout = EditorGUILayout.BeginFoldoutHeaderGroup(showCharIconFoldout, "Font Icons");
+                EditorGUILayout.EndFoldoutHeaderGroup();
 #else
                 showCharIconFoldout = EditorGUILayout.Foldout(showCharIconFoldout, "Font Icons");
 #endif
 
-
-#if UNITY_2019_3_OR_NEWER
-                EditorGUILayout.EndFoldoutHeaderGroup();
-#endif
-
                 if (showCharIconFoldout)
                 {
                     EditorGUILayout.PropertyField(charIconFontProp);
@@ -823,6 +852,11 @@ private bool CheckIfHololensIconFontExists()
 
         Texture2D GetTextureFromSprite(Sprite sprite)
         {
+            if (sprite == null || sprite.texture == null)
+            {
+                return null;
+            }
+
             var rect = sprite.rect;
             var tex = new Texture2D((int)rect.width, (int)rect.height);
             var data = sprite.texture.GetPixels((int)rect.x, (int)rect.y, (int)rect.width, (int)rect.height);