From 82cec909a6120c5f2fb4de8c56486a14f1071392 Mon Sep 17 00:00:00 2001
From: linsy king <linsy_king@sjtu.edu.cn>
Date: Sun, 7 May 2023 22:35:53 +0800
Subject: [PATCH] feat: add empty renderable

---
 elm.json                       |  2 +-
 src/Canvas.elm                 | 18 ++++++++++++++++--
 src/Canvas/Internal/Canvas.elm |  1 +
 src/Canvas/Settings/Text.elm   |  4 ++++
 4 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/elm.json b/elm.json
index ce776f2..4dcfe07 100644
--- a/elm.json
+++ b/elm.json
@@ -3,7 +3,7 @@
     "name": "linsyking/elm-canvas",
     "summary": "2D drawing API based on DOM Canvas, but nicer",
     "license": "BSD-3-Clause",
-    "version": "3.0.0",
+    "version": "3.1.0",
     "exposed-modules": {
         "Main module": [
             "Canvas"
diff --git a/src/Canvas.elm b/src/Canvas.elm
index 52d3e3a..67fb4a8 100755
--- a/src/Canvas.elm
+++ b/src/Canvas.elm
@@ -1,7 +1,7 @@
 module Canvas exposing
     ( toHtml, toHtmlWith
     , Renderable, Point
-    , clear, shapes, text, texture, group
+    , clear, shapes, text, texture, group, empty
     , Shape
     , rect, roundRect, circle, arc, path
     , PathSegment, arcTo, bezierCurveTo, lineTo, moveTo, quadraticCurveTo
@@ -23,7 +23,7 @@ requires the `elm-canvas` web component to work.
 
 @docs Renderable, Point
 
-@docs clear, shapes, text, texture, group
+@docs clear, shapes, text, texture, group, empty
 
 
 # Drawing shapes
@@ -582,6 +582,17 @@ group settings entities =
         )
 
 
+{-| Empty renderable. Useful for creating an empty renderable instead of writing `group [] []`
+-}
+empty : Renderable
+empty =
+    Renderable
+        { commands = []
+        , drawOp = NotSpecified
+        , drawable = DrawableEmpty
+        }
+
+
 
 -- Rendering internals
 
@@ -619,6 +630,9 @@ renderDrawable drawable drawOp cmds =
         DrawableGroup renderables ->
             renderGroup drawOp renderables cmds
 
+        DrawableEmpty ->
+            cmds
+
 
 renderShape : Shape -> Commands -> Commands
 renderShape shape cmds =
diff --git a/src/Canvas/Internal/Canvas.elm b/src/Canvas/Internal/Canvas.elm
index 8f5416a..e447b72 100755
--- a/src/Canvas/Internal/Canvas.elm
+++ b/src/Canvas/Internal/Canvas.elm
@@ -37,6 +37,7 @@ type Drawable
     | DrawableTexture Point Texture
     | DrawableClear Point Float Float
     | DrawableGroup (List Renderable)
+    | DrawableEmpty
 
 
 type Renderable
diff --git a/src/Canvas/Settings/Text.elm b/src/Canvas/Settings/Text.elm
index 9546317..b31979b 100755
--- a/src/Canvas/Settings/Text.elm
+++ b/src/Canvas/Settings/Text.elm
@@ -50,6 +50,7 @@ type TextAlign
     | End
 
 
+textAlignToString : TextAlign -> String
 textAlignToString alignment =
     case alignment of
         Left ->
@@ -182,4 +183,7 @@ maxWidth width =
 
                 DrawableGroup _ ->
                     d
+
+                DrawableEmpty ->
+                    d
         )