Center images when they are the only contents in a paragraph.

default_environment/stylesheet/main.css

@@ -9,8 +9,9 @@
 
   --blog-post-background-color: #0a0a0a;
 
-  --src-font-family: ui-monospace, "Cascadia Code", "Source Code Pro", Menlo,
-    Consolas, "DejaVu Sans Mono", monospace;
+  --src-font-family:
+    ui-monospace, "Cascadia Code", "Source Code Pro", Menlo, Consolas,
+    "DejaVu Sans Mono", monospace;
 
   --src-block-background-color: #141414;
   --src-block-border-color: #84828f;
@@ -55,8 +56,9 @@
 body {
   color: var(--site-text-color);
   background-color: var(--site-background-color);
-  font-family: source-sans-pro, Seravek, "Gill Sans Nova", Ubuntu, Calibri,
-    "DejaVu Sans", sans-serif;
+  font-family:
+    source-sans-pro, Seravek, "Gill Sans Nova", Ubuntu, Calibri, "DejaVu Sans",
+    sans-serif;
 
   a:link,
   a:visited {
@@ -146,6 +148,10 @@ body {
 
   p {
     margin: 1rem 0;
+
+    &.image {
+      text-align: center;
+    }
   }
 
   .src_block {

default_environment/templates/html/paragraph.dust

@@ -1,3 +1,3 @@
-<p>{#.children}
+<p class="{?.is_single_image}image{/.is_single_image}">{#.children}
   {>object/}
 {/.children}</p>

src/context/paragraph.rs

@@ -12,6 +12,7 @@ use super::RenderObject;
 #[serde(rename = "paragraph")]
 pub(crate) struct RenderParagraph {
     children: Vec<RenderObject>,
+    is_single_image: bool,
     post_blank: organic::types::PostBlank,
 }
 
@@ -26,6 +27,7 @@ render!(RenderParagraph, IParagraph, original, render_context, {
 
     Ok(RenderParagraph {
         children,
+        is_single_image: original.is_single_image(),
         post_blank: original.post_blank,
     })
 });

src/intermediate/paragraph.rs

@@ -1,3 +1,5 @@
+use std::any::Any;
+
 use super::macros::intermediate;
 use super::IObject;
 use crate::error::CustomError;
@@ -41,4 +43,32 @@ impl IParagraph {
             post_blank,
         })
     }
+
+    /// Checks if the paragraph contains nothing but a single image.
+    ///
+    /// When this happens, we want to center the image.
+    pub(crate) fn is_single_image(&self) -> bool {
+        let num_images = self
+            .children
+            .iter()
+            .filter(|c| match c {
+                IObject::RegularLink(iregular_link) => match &iregular_link.target {
+                    super::LinkTarget::Image { src, alt } => true,
+                    _ => false,
+                },
+                _ => false,
+            })
+            .count();
+        num_images == 1
+            && self.children.iter().all(|c| match c {
+                IObject::RegularLink(iregular_link) => match &iregular_link.target {
+                    super::LinkTarget::Image { src, alt } => true,
+                    _ => false,
+                },
+                IObject::PlainText(iplain_text) => {
+                    iplain_text.source.chars().all(|c| c.is_ascii_whitespace())
+                }
+                _ => false,
+            })
+    }
 }