[ghex/gtk4-port] gtkhex: Initial impl of cursor rendering in insert mode

[Logan Rathbone <larathbone src gnome org>]

commit fc81256ada2d7f37d86c84a4be68b5adfccd8407
Author: Logan Rathbone <poprocks gmail com>
Date:   Sun Dec 5 14:18:02 2021 -0500

    gtkhex: Initial impl of cursor rendering in insert mode

 src/gtkhex.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 55 insertions(+), 10 deletions(-)
---
diff --git a/src/gtkhex.c b/src/gtkhex.c
index 7037833..1d4e085 100644
--- a/src/gtkhex.c
+++ b/src/gtkhex.c
@@ -535,12 +535,23 @@ render_cursor (GtkHex *gh,
        GtkStyleContext *context;
        cairo_region_t *region;
        double x1, x2, y1, y2;
+       gboolean at_file_end = FALSE;
+       gboolean at_new_row = FALSE;
 
        g_return_if_fail (gtk_widget_get_realized (widget));
 
        context = gtk_widget_get_style_context (widget);
        state = gtk_widget_get_state_flags (widget);
 
+       /* Find out if we're at the end of the row and/or the end of the file,
+        * since this will make a difference when in insert mode
+        */
+       if (gh->cursor_pos >= hex_document_get_file_size (gh->document))
+               at_file_end = TRUE;
+
+       if (gh->cursor_pos % gh->cpl == 0)
+               at_new_row = TRUE;
+
        if (cursor_type == VIEW_HEX)
        {
                int spaces;
@@ -557,19 +568,41 @@ render_cursor (GtkHex *gh,
                        range[1] = index + 1;
                }
        }
-       else
+       else    /* VIEW_ASCII */
        {
                index = gh->cursor_pos % gh->cpl;
                range[0] = index;
                range[1] = index + 1;
        }
 
+       if (gh->insert && at_file_end)
+       {
+               if (at_new_row)
+               {
+                       range[0] = 0;
+                       range[1] = 1;
+               }
+               else
+               {
+                       --range[0];
+                       --range[1];
+               }
+       }
+
        region = gdk_pango_layout_get_clip_region (layout,
                        0,      /* x */
                        y,
                        range,
                        1);
 
+       if (gh->insert && at_file_end && !at_new_row)
+       {
+               cairo_rectangle_int_t tmp_rect = { 0 };
+
+               cairo_region_get_extents (region, &tmp_rect);
+               cairo_region_translate (region, tmp_rect.width, 0);
+       }
+
        gdk_cairo_region (cr, region);
        cairo_save (cr);
        cairo_clip (cr);
@@ -578,7 +611,6 @@ render_cursor (GtkHex *gh,
        /* Render background - fill bg with default selection colour if we have
         * focus on the pane in question; otherwise, draw a solid black box.
         */
-
        if (gh->active_view == cursor_type)
        {
                gtk_style_context_save (context);
@@ -592,7 +624,13 @@ render_cursor (GtkHex *gh,
                                ABS(x2-x1), 
                                ABS(y2-y1));
 
-               gtk_render_layout (context, cr, 0, y, layout);
+               /* Don't render layout if we're in insert mode and at file end, since
+                * the cursor should be blank at that point.
+                */
+               if (at_file_end && gh->insert)
+                       ;
+               else
+                       gtk_render_layout (context, cr, 0, y, layout);
 
                gtk_style_context_restore (context);
        }
@@ -830,6 +868,10 @@ invalidate_offsets (GtkHex *gh,
  * [0 .. gh->vis_lines-1] AND NOT [0 .. gh->lines]!
  */
 
+#define DO_RENDER_CURSOR \
+                       render_cursor (gh, cr, widget, layout,                          \
+                                       cursor_line * gh->char_height,  /* y */         \
+                                       type);
 static void
 render_lines (GtkHex *gh,
                cairo_t *cr,
@@ -846,6 +888,8 @@ render_lines (GtkHex *gh,
        int frm_len;
        int cursor_line;
        int cpl;
+       gboolean cursor_drawn = FALSE;
+       int i;
 
        g_return_if_fail (gtk_widget_get_realized (GTK_WIDGET(gh)));
        g_return_if_fail (gh->cpl);
@@ -888,7 +932,7 @@ render_lines (GtkHex *gh,
                        MIN( (gh->top_line + max_lines + 1) * gh->cpl,
                                hex_document_get_file_size (gh->document) ));
        
-       for (int i = min_lines; i <= max_lines; i++)
+       for (i = min_lines; i <= max_lines; i++)
        {
                int tmp = frm_len - ((i - min_lines) * cpl);
 
@@ -908,14 +952,15 @@ render_lines (GtkHex *gh,
 
                if (i == cursor_line)
                {
-                       render_cursor (gh,
-                                       cr,
-                                       widget,
-                                       layout,
-                                       i * gh->char_height,
-                                       type);
+                       DO_RENDER_CURSOR
+                       cursor_drawn = TRUE;
                }
        }
+
+       if (! cursor_drawn)
+       {
+               DO_RENDER_CURSOR
+       }
 }
 
 static void