stb_textedit: subsequent fixes for next/prev word impl (not used by imgui) + PageUp/Home/End (no side effect but more correct) (#8635, #7925)

imstb_textedit.h

@@ -667,9 +667,9 @@ static int is_word_boundary( IMSTB_TEXTEDIT_STRING *str, int idx )
 #ifndef STB_TEXTEDIT_MOVEWORDLEFT
 static int stb_textedit_move_to_word_previous( IMSTB_TEXTEDIT_STRING *str, int c )
 {
-   --c; // always move at least one character
-   while( c >= 0 && !is_word_boundary( str, c ) )
-      --c;
+   c = IMSTB_TEXTEDIT_GETPREVCHARINDEX( str, c ); // always move at least one character
+   while (c >= 0 && !is_word_boundary(str, c))
+      c = IMSTB_TEXTEDIT_GETPREVCHARINDEX(str, c);
 
    if( c < 0 )
       c = 0;
@@ -683,9 +683,9 @@ static int stb_textedit_move_to_word_previous( IMSTB_TEXTEDIT_STRING *str, int c
 static int stb_textedit_move_to_word_next( IMSTB_TEXTEDIT_STRING *str, int c )
 {
    const int len = STB_TEXTEDIT_STRINGLEN(str);
-   ++c; // always move at least one character
+   c = IMSTB_TEXTEDIT_GETNEXTCHARINDEX(str, c); // always move at least one character
    while( c < len && !is_word_boundary( str, c ) )
-      ++c;
+      c = IMSTB_TEXTEDIT_GETNEXTCHARINDEX(str, c);
 
    if( c > len )
       c = len;
@@ -1005,8 +1005,13 @@ retry:
             // go to previous line
             // (we need to scan previous line the hard way. maybe we could expose this as a new API function?)
             prev_scan = find.prev_first > 0 ? find.prev_first - 1 : 0;
-            while (prev_scan > 0 && STB_TEXTEDIT_GETCHAR(str, prev_scan - 1) != STB_TEXTEDIT_NEWLINE)
-               --prev_scan;
+            while (prev_scan > 0)
+            {
+               int prev = IMSTB_TEXTEDIT_GETPREVCHARINDEX(str, prev_scan);
+               if (STB_TEXTEDIT_GETCHAR(str, prev) == STB_TEXTEDIT_NEWLINE)
+                  break;
+               prev_scan = prev;
+            }
             find.first_char = find.prev_first;
             find.prev_first = prev_scan;
          }
@@ -1085,7 +1090,7 @@ retry:
          if (state->single_line)
             state->cursor = 0;
          else while (state->cursor > 0 && STB_TEXTEDIT_GETCHAR(str, state->cursor-1) != STB_TEXTEDIT_NEWLINE)
-            --state->cursor;
+            state->cursor = IMSTB_TEXTEDIT_GETPREVCHARINDEX(str, state->cursor);
          state->has_preferred_x = 0;
          break;
 
@@ -1097,9 +1102,9 @@ retry:
          stb_textedit_clamp(str, state);
          stb_textedit_move_to_first(state);
          if (state->single_line)
-             state->cursor = n;
+            state->cursor = n;
          else while (state->cursor < n && STB_TEXTEDIT_GETCHAR(str, state->cursor) != STB_TEXTEDIT_NEWLINE)
-             ++state->cursor;
+            state->cursor = IMSTB_TEXTEDIT_GETNEXTCHARINDEX(str, state->cursor);
          state->has_preferred_x = 0;
          break;
       }
@@ -1113,7 +1118,7 @@ retry:
          if (state->single_line)
             state->cursor = 0;
          else while (state->cursor > 0 && STB_TEXTEDIT_GETCHAR(str, state->cursor-1) != STB_TEXTEDIT_NEWLINE)
-            --state->cursor;
+            state->cursor = IMSTB_TEXTEDIT_GETPREVCHARINDEX(str, state->cursor);
          state->select_end = state->cursor;
          state->has_preferred_x = 0;
          break;
@@ -1128,7 +1133,7 @@ retry:
          if (state->single_line)
              state->cursor = n;
          else while (state->cursor < n && STB_TEXTEDIT_GETCHAR(str, state->cursor) != STB_TEXTEDIT_NEWLINE)
-            ++state->cursor;
+            state->cursor = IMSTB_TEXTEDIT_GETNEXTCHARINDEX(str, state->cursor);
          state->select_end = state->cursor;
          state->has_preferred_x = 0;
          break;