From e75c083ac979beda09716774a6c80ae943c84149 Mon Sep 17 00:00:00 2001
From: Martin Rys <martin@rys.rs>
Date: Sat, 28 Sep 2024 13:37:08 +0200
Subject: [PATCH] Try to keep text highlighting with highlighted processes

This tries to keep special markup like large numbers and
other special markup inside a process row even when such
a line has been highlighted by being selected, followed,
or otherwise marked in the list view.

Alternate take on PR #434.
---
 Panel.c      |  2 +-
 RichString.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 RichString.h |  4 +++
 3 files changed, 79 insertions(+), 1 deletion(-)

diff --git a/Panel.c b/Panel.c
index 4784a6585..05e009403 100644
--- a/Panel.c
+++ b/Panel.c
@@ -289,7 +289,7 @@ void Panel_draw(Panel* this, bool force_redraw, bool focus, bool highlightSelect
          }
          if (item.highlightAttr) {
             attrset(item.highlightAttr);
-            RichString_setAttr(&item, item.highlightAttr);
+            RichString_setAttr_preserveWithStandout(&item, item.highlightAttr);
             this->selectedLen = itemLen;
          }
          mvhline(y + line, x, ' ', this->w);
diff --git a/RichString.c b/RichString.c
index 390beb073..4fbea1cdd 100644
--- a/RichString.c
+++ b/RichString.c
@@ -62,6 +62,10 @@ void RichString_rewind(RichString* this, int count) {
    RichString_setLen(this, this->chlen - count);
 }
 
+void RichString_setAttr_preserveWithStandout(RichString* this, int attrs) {
+   RichString_setAttrn_preserveWithStandout(this, attrs, 0, this->chlen - 1);
+}
+
 #ifdef HAVE_LIBNCURSESW
 
 static size_t mbstowcs_nonfatal(wchar_t* restrict dest, const char* restrict src, size_t n) {
@@ -160,6 +164,41 @@ inline void RichString_setAttrn(RichString* this, int attrs, int start, int char
    }
 }
 
+void RichString_setAttrn_preserveWithStandout(RichString* this, int attrs, int start, int finish) {
+   finish = CLAMP(finish, 0, this->chlen - 1);
+
+   // Extract the foreground and background color indexes from the passed attrs
+   short passed_color_pair_number = (short)PAIR_NUMBER(attrs);
+   short passed_fg_color = -1, passed_bg_color = -1;
+   if (passed_color_pair_number != 0) {
+      pair_content(passed_color_pair_number, &passed_fg_color, &passed_bg_color);
+   }
+
+   cchar_t* ch = this->chptr + start;
+   for (int i = start; i <= finish; i++) {
+      // Extract foreground and background color indexes from the current char
+      short currentCharPairNum = (short)PAIR_NUMBER(ch->attr);
+      short before_fg_color = -1, before_bg_color = -1;
+      if (currentCharPairNum != 0) {
+         pair_content(currentCharPairNum, &before_fg_color, &before_bg_color);
+      }
+
+      // TODO: When text color matches higlight, the resulting STANDOUT is the same as on default text,
+      //       so we at least set italics
+      chtype attrToPass = A_STANDOUT;
+      if (before_fg_color == passed_bg_color) {
+         attrToPass |= A_ITALIC;
+      }
+      // If current char is not a space and its ColorPair Index is not the default 0,
+      //    apply our own attrToPass with STANDOUT + optionally ITALICS,
+      //    instead of the passed attrs, which has the BG highlight color
+      ch->attr = (ch->chars[0] != L' ' && currentCharPairNum != 0)
+                  ? (ch->attr | attrToPass)
+                  : (unsigned int)attrs;
+      ch++;
+   }
+}
+
 void RichString_appendChr(RichString* this, int attrs, char c, int count) {
    int from = this->chlen;
    int newLen = from + count;
@@ -210,6 +249,41 @@ void RichString_setAttrn(RichString* this, int attrs, int start, int charcount)
    }
 }
 
+void RichString_setAttrn_preserveWithStandout(RichString* this, int attrs, int start, int finish) {
+   finish = CLAMP(finish, 0, this->chlen - 1);
+
+   // Extract the foreground and background color indexes from the passed attrs
+   short passed_color_pair_number = (short)PAIR_NUMBER(attrs);
+   short passed_fg_color = -1, passed_bg_color = -1;
+   if (passed_color_pair_number != 0) {
+      pair_content(passed_color_pair_number, &passed_fg_color, &passed_bg_color);
+   }
+
+   chtype* ch = this->chptr + start;
+   for (int i = start; i <= finish; i++) {
+      // Extract foreground and background color indexes from the current char
+      short currentCharPairNum = (short)PAIR_NUMBER(*ch);
+      short before_fg_color = -1, before_bg_color = -1;
+      if (currentCharPairNum != 0) {
+         pair_content(currentCharPairNum, &before_fg_color, &before_bg_color);
+      }
+
+      // TODO: When text color matches higlight, the resulting STANDOUT is the same as on default text,
+      //       so we at least set italics
+      chtype attrToPass = A_STANDOUT;
+      if (before_fg_color == passed_bg_color) {
+         attrToPass |= A_ITALIC;
+      }
+      // If current char is not a space and its ColorPair Index is not the default 0,
+      //    apply our own attrToPass with STANDOUT + optionally ITALICS,
+      //    instead of the passed attrs, which has the BG highlight color
+      *ch = ((*ch & A_CHARTEXT) != L' ' && currentCharPairNum != 0)
+            ? *ch | attrToPass
+            : (*ch & A_CHARTEXT) | (unsigned int)attrs;
+      ch++;
+   }
+}
+
 void RichString_appendChr(RichString* this, int attrs, char c, int count) {
    int from = this->chlen;
    int newLen = from + count;
diff --git a/RichString.h b/RichString.h
index 7783378bc..12e68fded 100644
--- a/RichString.h
+++ b/RichString.h
@@ -52,10 +52,14 @@ void RichString_rewind(RichString* this, int count);
 
 void RichString_setAttrn(RichString* this, int attrs, int start, int charcount);
 
+void RichString_setAttrn_preserveWithStandout(RichString* this, int attrs, int start, int finish);
+
 int RichString_findChar(const RichString* this, char c, int start);
 
 void RichString_setAttr(RichString* this, int attrs);
 
+void RichString_setAttr_preserveWithStandout(RichString* this, int attrs);
+
 void RichString_appendChr(RichString* this, int attrs, char c, int count);
 
 /* All appending and writing functions return the number of written characters (not columns). */