start adding hover info

src/render.cpp

@@ -33,6 +33,9 @@ u32 mem_edit_bg_color_fn(const u8 *, u64 off, void *user_data)
   App_State *app = reinterpret_cast<App_State *>(user_data);
   off += app->base_display_addr;
 
+  if (app->viewer.hovered_range.start <= off && off < app->viewer.hovered_range.end())
+    return imcol(app->viewer.col_highlight);
+
   i64 hilite_cluster = app->viewer.highlight_cluster ? app->viewer.highlighted_cluster : -1;
   Section section = find_section(*app, off, hilite_cluster);
   
@@ -46,6 +49,9 @@ u32 mem_edit_bg_color_fn(const u8 *, u64 off, void *user_data)
 internal
 void mem_edit_interact_fn(const u8 *, u64 off, void *user_data)
 {
+  App_State *app = reinterpret_cast<App_State *>(user_data);
+  off += app->base_display_addr;
+  app->viewer.hovered_off = off;
 }
 
 internal
@@ -219,6 +225,10 @@ void update_and_render(Arena *arena, App_State &app, f32 delta_time_ms)
       }
 
       // Repeated sections: allow jumping to the N-th
+      ImGui::ColorEdit3("_TKey Header", app.viewer.col_key, flags);
+      ImGui::SameLine(); 
+      if (ImGui::Button("TKey Header")) {} // TODO: jump to next key
+
       ImGui::ColorEdit3("_Page Start", app.viewer.col_page_start, flags);
       ImGui::SameLine(); 
       if (ImGui::Button("Page Start"))
@@ -282,6 +292,26 @@ void update_and_render(Arena *arena, App_State &app, f32 delta_time_ms)
         ImGui::Checkbox("Highlight cluster", &app.viewer.highlight_cluster);
       }
 
+      // ---------------------------------
+      ImGui::Separator();
+
+      {
+        Section hovered_section = find_section(app, app.viewer.hovered_off);
+        Sec_Hover_Info hover_info = get_section_hover_info(scratch.arena, hovered_section, app.viewer.hovered_off, app.inspected_file.mem);
+        u8 indent = 0;
+        for (String8_Node *node = hover_info.desc; node; node = node->next) {
+          String8 fmt = str8("%s");
+          if (indent) {
+            // create indent
+            fmt = push_str8f(scratch.arena, "%%%ds", indent + node->str.size);
+          }
+
+          ImGui::Text(fmt.c(), node->str.c());
+          indent += 2;
+        }
+        app.viewer.hovered_range = hover_info.rng;
+      }
+
       ImGui::EndTable();
     }
 

src/render.h

@@ -17,6 +17,10 @@ struct Viewer {
   u64 latest_key_gone_to;
   u64 latest_checksum_gone_to;
   u64 latest_page_list_gone_to;
+
+  // Absolute byte offset into inspected_file.mem that has been hovered last.
+  u64 hovered_off;
+  Byte_Range hovered_range;
 };
 
 struct Edit_Bg_Color_Data {

src/render_term.cpp

@@ -39,11 +39,7 @@ String8 render_legend_to_string(Arena *arena, const Term_Viewer &viewer, const A
   Temp scratch = scratch_begin(&arena, 1);
   defer { scratch_end(scratch); };
   
-  struct String8_Node {
-    String8_Node *next;
-    String8 str;
-  } *head = nullptr, *tail = nullptr;
-  
+  String8_Node *head = nullptr, *tail = nullptr;
   String8 color_none = ansi_color_table[ACol_None];
   u64 tot_len = 0;
   for (u64 section = 1; section < Sec_COUNT; ++section) {

src/rntuple.cpp

@@ -439,3 +439,57 @@ Section find_section(App_State &app, u64 off, i64 hilite_cluster = -1)
 
   return {};
 }
+
+struct Sec_Hover_Info {
+  Byte_Range rng;
+  String8_Node *desc;
+};
+
+// `off` is the absolute offset into `data`.
+internal
+Sec_Hover_Info get_section_hover_info(Arena *arena, Section section, u64 off, const u8 *data)
+{
+  Sec_Hover_Info info {};
+
+  printf("off: 0x%lX, sec start: 0x%lX\n", off, section.range.start);
+  // assert(off >= section.range.start);
+  if (off < section.range.start) {
+    printf("WRONG\n"); // TODO: fix TKey Header case
+  }
+  
+  u64 start = section.range.start;
+  u64 roff = off - start; // offset relative to `section`
+  
+  if (section.id == Sec_RNTuple_Anchor) {
+    info.desc = push_str8_node(arena, nullptr, "RNTuple Anchor");
+    // TODO: dry
+    if (roff < sizeof(u32)) {
+      info.rng = { start, sizeof(u32) };
+      u32 val;
+      memcpy(&val, data + info.rng.start, info.rng.len);
+      val = bswap_32(val);
+      val -= 0x40000000;
+      push_str8_node(arena, info.desc, "Object len: %u", val);
+    } else if (roff < sizeof(u32) + sizeof(u16)) {
+      info.rng = { start + sizeof(u32), sizeof(u16) };
+      u32 val;
+      memcpy(&val, data + info.rng.start, info.rng.len);
+      val = bswap_16(val);
+      push_str8_node(arena, info.desc, "Class version: %u", val);
+    } else if (roff < sizeof(u32) + sizeof(u16) + sizeof(u16)) {
+      info.rng = { start + sizeof(u32) + sizeof(u16), sizeof(u16) };
+      u16 val;
+      memcpy(&val, data + info.rng.start, info.rng.len);
+      val = bswap_16(val);
+      push_str8_node(arena, info.desc, "Version Epoch: %u", val);
+    } else if (roff < sizeof(u32) + sizeof(u16) + sizeof(u16) + sizeof(u16)) {
+      info.rng = { start + sizeof(u32) + sizeof(u16) + sizeof(u16), sizeof(u16) };
+      u16 val;
+      memcpy(&val, data + info.rng.start, info.rng.len);
+      val = bswap_16(val);
+      push_str8_node(arena, info.desc, "Version Major: %u", val);
+    }
+  }
+ 
+  return info;
+}

src/str.cpp

@@ -36,3 +36,19 @@ String8 to_pretty_size(Arena *arena, u64 bytes)
 	return push_str8f(arena, "%zu B", bytes);
 }
 
+
+internal
+String8_Node *push_str8_node(Arena *arena, String8_Node *prev, const char *fmt, ...)
+{
+  String8_Node *snode = arena_push<String8_Node>(arena);
+
+  va_list args;
+  va_start(args, fmt);
+  snode->str = push_str8fv(arena, fmt, args);
+  va_end(args);
+
+  if (prev)
+    prev->next = snode;
+
+  return snode;
+}

src/str.h

@@ -10,3 +10,10 @@ struct String8 {
 
 String8 str8_from_c(const char *str);
 String8 push_str8f(Arena *arena, char *fmt, ...);
+
+
+struct String8_Node {
+  String8_Node *next;
+  String8 str;
+};
+