From 6d7892cfc4354008dba3f09f0edbf04e0b746830 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Thu, 17 Dec 2020 20:17:29 +0100
Subject: [PATCH] LibWeb: Whitespace that causes a line to wrap should be
 hidden

We were only pruning trailing whitespace on lines. This patch makes it
so we also don't add whitespace as the leading line box fragment on new
lines.

This logic is pretty crufty and I think we can do better, but for now
I've just made it handle this extra case so we can stop having lines
that start with a space character. :^)
---
 Libraries/LibWeb/Layout/LineBox.cpp  | 4 ++--
 Libraries/LibWeb/Layout/LineBox.h    | 2 +-
 Libraries/LibWeb/Layout/TextNode.cpp | 9 ++++++---
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/Libraries/LibWeb/Layout/LineBox.cpp b/Libraries/LibWeb/Layout/LineBox.cpp
index b4415ae11b..cf2a127755 100644
--- a/Libraries/LibWeb/Layout/LineBox.cpp
+++ b/Libraries/LibWeb/Layout/LineBox.cpp
@@ -73,10 +73,10 @@ void LineBox::trim_trailing_whitespace()
     }
 }
 
-bool LineBox::ends_in_whitespace() const
+bool LineBox::is_empty_or_ends_in_whitespace() const
 {
     if (m_fragments.is_empty())
-        return false;
+        return true;
     return m_fragments.last().ends_in_whitespace();
 }
 
diff --git a/Libraries/LibWeb/Layout/LineBox.h b/Libraries/LibWeb/Layout/LineBox.h
index cc821d9d6e..dcf1efd081 100644
--- a/Libraries/LibWeb/Layout/LineBox.h
+++ b/Libraries/LibWeb/Layout/LineBox.h
@@ -45,7 +45,7 @@ public:
 
     void trim_trailing_whitespace();
 
-    bool ends_in_whitespace() const;
+    bool is_empty_or_ends_in_whitespace() const;
 
 private:
     friend class BlockBox;
diff --git a/Libraries/LibWeb/Layout/TextNode.cpp b/Libraries/LibWeb/Layout/TextNode.cpp
index 06b9093269..f3b1d7cbe8 100644
--- a/Libraries/LibWeb/Layout/TextNode.cpp
+++ b/Libraries/LibWeb/Layout/TextNode.cpp
@@ -210,7 +210,7 @@ void TextNode::split_into_lines_by_rules(InlineFormattingContext& context, Layou
             }
             it = prev;
         };
-        if (line_boxes.last().ends_in_whitespace())
+        if (line_boxes.last().is_empty_or_ends_in_whitespace())
             skip_over_whitespace();
         for (; it != utf8_view.end(); ++it) {
             if (!isspace(*it)) {
@@ -246,13 +246,13 @@ void TextNode::split_into_lines_by_rules(InlineFormattingContext& context, Layou
         auto& chunk = chunks[i];
 
         // Collapse entire fragment into non-existence if previous fragment on line ended in whitespace.
-        if (do_collapse && line_boxes.last().ends_in_whitespace() && chunk.is_all_whitespace)
+        if (do_collapse && line_boxes.last().is_empty_or_ends_in_whitespace() && chunk.is_all_whitespace)
             continue;
 
         float chunk_width;
         bool need_collapse = false;
         if (do_wrap_lines) {
-            need_collapse = do_collapse && isspace(*chunk.view.begin()) && line_boxes.last().ends_in_whitespace();
+            need_collapse = do_collapse && isspace(*chunk.view.begin()) && line_boxes.last().is_empty_or_ends_in_whitespace();
 
             if (need_collapse)
                 chunk_width = space_width;
@@ -262,6 +262,9 @@ void TextNode::split_into_lines_by_rules(InlineFormattingContext& context, Layou
             if (line_boxes.last().width() > 0 && chunk_width > available_width) {
                 containing_block.add_line_box();
                 available_width = context.available_width_at_line(line_boxes.size() - 1);
+
+                if (do_collapse && chunk.is_all_whitespace)
+                    continue;
             }
             if (need_collapse & line_boxes.last().fragments().is_empty())
                 continue;