fix: differentiate style presets with wider font/line/paragraph spacing values, apply paragraph_spacing

src/reader.rs

@@ -205,7 +205,7 @@ pub fn reading_view(
                 let start = section.pages[*current_page];
                 let end = section.pages[*current_page + 1];
                 let raw_text: String = section.content.chars().skip(start).take(end - start).collect();
-                let indented = crate::style::apply_indent(&raw_text, style.first_line_indent);
+                let indented = style.apply_to_text(&raw_text);
 
                 let align = match style.alignment {
                     TextAlignment::Left => egui::Align::LEFT,

src/style.rs

@@ -31,18 +31,18 @@ impl StyleProfile {
             StyleProfile {
                 name: "紧凑".into(),
                 alignment: TextAlignment::Left,
-                line_spacing: 1.4,
+                line_spacing: 1.2,
-                paragraph_spacing: 0.5,
+                paragraph_spacing: 0.3,
                 first_line_indent: 2.0,
-                font_size: 18.0,
+                font_size: 16.0,
             },
             StyleProfile {
                 name: "宽松".into(),
                 alignment: TextAlignment::Left,
-                line_spacing: 2.2,
+                line_spacing: 2.4,
-                paragraph_spacing: 1.5,
+                paragraph_spacing: 1.8,
                 first_line_indent: 2.0,
-                font_size: 22.0,
+                font_size: 24.0,
             },
             StyleProfile {
                 name: "居中".into(),
@@ -59,6 +59,21 @@ impl StyleProfile {
         self.font_size * self.line_spacing
     }
 
+    pub fn apply_to_text(&self, text: &str) -> String {
+        let indented = apply_indent(text, self.first_line_indent);
+        apply_para_spacing(&indented, self.paragraph_spacing)
+    }
+
+}
+
+fn apply_para_spacing(text: &str, spacing: f32) -> String {
+    if spacing <= 0.5 {
+        return text.to_string();
+    }
+    // Each unit of paragraph_spacing adds one extra blank line
+    let extra_nls = (spacing * 2.0).round() as usize;
+    let sep = "\n".repeat(extra_nls);
+    text.replace("\n\n", &sep)
 }
 
 pub fn apply_indent(text: &str, indent_chars: f32) -> String {