From 2ba48f8784fec27b01da616329c9a2d6d0b1ba3e Mon Sep 17 00:00:00 2001
From: silverweed <silverweed14@proton.me>
Date: Tue, 30 Jul 2024 11:34:08 +0200
Subject: [PATCH] brighten color on hover instead of using col_highlight

---
 src/render.cpp                | 59 +++++++++++++++++++++++++++++------
 src/root/RMicroFileReader.hxx |  2 ++
 2 files changed, 51 insertions(+), 10 deletions(-)

diff --git a/src/render.cpp b/src/render.cpp
index 0eb452a..ebd552f 100644
--- a/src/render.cpp
+++ b/src/render.cpp
@@ -1,3 +1,38 @@
+constexpr f32 max3(f32 a, f32 b, f32 c)
+{
+  return (a > b) ? (a > c) ? a : (b > c) ? b : c : (b > c) ? b : c; 
+}
+
+struct Color_Rgb { f32 r, g, b; };
+
+// https://stackoverflow.com/questions/141855/programmatically-lighten-a-color
+internal
+Color_Rgb redist_rgb(Color_Rgb c)
+{
+  f32 r = c.r;
+  f32 g = c.g;
+  f32 b = c.b;
+  f32 threshold = 255.999;
+  f32 m = max3(r, g, b);
+  if (m <= threshold)
+      return { r, g, b };
+  f32 total = r + g + b;
+  if (total >= 3 * threshold)
+      return { threshold, threshold, threshold };
+  f32 x = (3 * threshold - total) / (3 * m - total);
+  f32 gray = threshold - x * m;
+  return { gray + x * r, gray + x * g, gray + x * b };
+}
+
+internal
+Color_Rgb brighten(Color_Rgb c, f32 amt)
+{
+  f32 a = 1.f + amt;
+  Color_Rgb cb = { c.r * a, c.g * a, c.b * a };
+  cb = redist_rgb(cb);
+  return cb;  
+}
+
 internal
 void accum_dt_ms(Delta_Time_Accum &accum, f32 dt)
 {
@@ -22,9 +57,13 @@ f32 calc_avg_dt_ms(const Delta_Time_Accum &accum)
 }
 
 internal
-ImColor imcol(const f32 col[3])
+ImColor imcol(const f32 col[3], f32 brighten_amt = 0)
 {
-  return ImColor(col[0], col[1], col[2]);
+  Color_Rgb c = { col[0], col[1], col[2] };
+  if (brighten_amt != 0)
+    c = brighten(c, brighten_amt);
+  
+  return ImColor(c.r, c.g, c.b);
 }
 
 internal
@@ -33,17 +72,18 @@ 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;
 
+  f32 brighten = 0;
   if (app->viewer.hovered_range.start <= off && off < app->viewer.hovered_range.end())
-    return imcol(app->viewer.col_highlight);
+    brighten = 0.3;
 
   i64 hilite_cluster = app->viewer.highlight_cluster ? app->viewer.highlighted_cluster : -1;
   Section section = find_section(*app, off, hilite_cluster);
   
-  if (section.highlighted) return imcol(app->viewer.col_highlight);
-  if (section.id == Sec_Page && off == section.range.start) return imcol(app->viewer.col_page_start);
-  if (off < section.range.start) return imcol(app->viewer.col_key);
-  if (section.range.end() - section.post_size <= off && off < section.range.end()) return imcol(app->viewer.col_checksum);
-  return imcol(app->viewer.col_section[section.id]);
+  if (section.highlighted) return imcol(app->viewer.col_highlight, brighten);
+  if (section.id == Sec_Page && off == section.range.start) return imcol(app->viewer.col_page_start, brighten);
+  if (off < section.range.start) return imcol(app->viewer.col_key, brighten);
+  if (section.range.end() - section.post_size <= off && off < section.range.end()) return imcol(app->viewer.col_checksum, brighten);
+  return imcol(app->viewer.col_section[section.id], brighten);
 }
 
 internal
@@ -101,8 +141,7 @@ void make_viewer(App_State &app, u16 n_cols)
 internal
 void viewer_jump_to(App_State &app, u64 addr)
 {
-  app.base_display_addr = addr;
-  app.viewer.mem_edit.GotoAddr = 0;
+  app.viewer.mem_edit.GotoAddr = addr;
 }
 
 internal
diff --git a/src/root/RMicroFileReader.hxx b/src/root/RMicroFileReader.hxx
index d8f7328..d68f48c 100644
--- a/src/root/RMicroFileReader.hxx
+++ b/src/root/RMicroFileReader.hxx
@@ -2,6 +2,8 @@
 
 #include <cstdint>
 
+// We are forced to use our own RNTuple anchor struct because we cannot
+// write into the private members of the real RNTuple class from RMicroFileReader.
 struct RNTuple_Anchor {
    /// Version of the RNTuple binary format that the writer supports (see specification).
    /// Changing the epoch indicates backward-incompatible changes