proper cursor rendering

edit.jai

@@ -77,24 +77,47 @@ main :: () {
 }
 
 render_edit_buffer :: () {
-    num_lines_in_screen := window_height / line_height - 1;
-    viewable_lines := array_view(lines, first_line, num_lines_in_screen);
-    for line_buffer: viewable_lines {
+    visible_lines := get_visible_lines();
+    for line_buffer: visible_lines {
         Simp.set_shader_for_text();
 
-        line := builder_to_line(*line_buffer);
+        line_str := builder_to_string(*line_buffer, do_reset = false,, temp);
 
-        Simp.prepare_text(my_font, line);
-        top_of_line := window_height - (it_index + 1) * line_height;
-        Simp.draw_prepared_text(my_font, 5, top_of_line, White);
+        prefix: string;
+        suffix: string;
 
-        if it_index == cursor_y {
-            Simp.set_shader_for_color();
-            Simp.immediate_quad(
-                5., cast(float) top_of_line + line_height,
-                6., cast(float) top_of_line,
-                White);
+        has_cursor_on_line := it_index == cursor_y;
+
+        if has_cursor_on_line {
+            prefix, suffix = string_to_line(line_str, cursor_x);
+        } else {
+            prefix, suffix = string_to_line(line_str);
         }
+
+        prefix_width := Simp.prepare_text(my_font, prefix);
+        top_of_line := window_height - (it_index + 1) * line_height;
+
+        Left_Max :: 5;
+        Simp.draw_prepared_text(my_font, Left_Max, top_of_line, White);
+
+        if has_cursor_on_line {
+            Simp.set_shader_for_color();
+            start := ifx suffix.count == 0 then Left_Max else prefix_width + Left_Max;
+            Simp.immediate_quad(
+                cast(float) start,     cast(float) top_of_line + line_height,
+                cast(float) start + 1, cast(float) top_of_line,
+                White);
+
+
+            print("----------------\n");
+            print("cursor_x: %\n", cursor_x);
+            print("Prefix width: %\n", prefix_width);
+            print("Suffix: %\n", suffix);
+            Simp.set_shader_for_text();
+            Simp.prepare_text(my_font, suffix);
+            Simp.draw_prepared_text(my_font, start, top_of_line, White);
+        }
+
     }
 }
 
@@ -115,10 +138,9 @@ handle_window_resizes :: (window: Window_Type) {
 }
 
 handle_arrow :: (key_code: Input.Key_Code) {
-    num_lines_in_screen := window_height / line_height - 1;
-    viewable_lines := array_view(lines, first_line, num_lines_in_screen);
+    visible_lines := get_visible_lines();
 
-    max_chars := 30;
+    max_chars :: 100;
 
     if key_code == {
         case .ARROW_UP;    
@@ -126,39 +148,72 @@ handle_arrow :: (key_code: Input.Key_Code) {
             then 0
             else cursor_y - 1;
         case .ARROW_DOWN;
-            cursor_y = ifx cursor_y == viewable_lines.count 
-            then viewable_lines.count
+            cursor_y = ifx cursor_y == visible_lines.count - 1 
+            then visible_lines.count - 1
             else cursor_y + 1;
+
         case .ARROW_LEFT;  
             cursor_x = ifx cursor_x == 0
             then 0
             else cursor_x - 1;
         case .ARROW_RIGHT;
-            cursor_y = ifx cursor_x == max_chars
+            cursor_x = ifx cursor_x == max_chars
             then max_chars
             else cursor_x + 1;
     }
 }
 
-builder_to_line :: (using builder: *String_Builder) -> string {
-    result_builder: String_Builder;
-    result_builder.allocator = temporary_allocator;
+get_visible_lines :: () -> []String_Builder {
+    num_lines_in_screen := window_height / line_height - 1;
+    return array_view(lines, first_line, num_lines_in_screen);
+}
 
-    builder_str := builder_to_string(builder, do_reset = false,, temp);
+string_to_line :: (str: string, cursor_char_index := -1) -> string, string {
+    prefix_builder: String_Builder;
+    prefix_builder.allocator = temporary_allocator;
+
+    suffix_builder: String_Builder;
+    suffix_builder.allocator = temporary_allocator;
+
+    init_string_builder(*prefix_builder);
+    init_string_builder(*suffix_builder);
 
     start := 0;
-    for c: builder_str {
+    char_index := 0;
+    cursor_index := 0;
+
+    current_builder := *prefix_builder;
+
+    while char_index < str.count {
+        defer char_index += 1;
+        c := str.data[char_index];
+        
         if c == #char "\t" {
-            s := string.{data=builder_str.data + start, count=(it_index + 1) - start};
-            append(*result_builder, s);
-            start = it_index + 1;
+            // s := string.{data=str.data + start, count=(char_index + 1) - start};
+            // append(current_builder, s);
+            // append(current_builder, "    ");
+            // start = char_index + 1;
+            // cursor_index += 4;
+        } else {
+            cursor_index += 1;
+        }
+
+        if cursor_index == cursor_char_index {
+            s := string.{data=str.data + start, count=(char_index + 1) - start};
+            append(current_builder, s);
+            current_builder = *suffix_builder;
+            start = char_index + 1;
         } 
     }
     
-    s := string.{data=builder_str.data + start, count=builder_str.count - start};
-    append(*result_builder, s);
 
-    return builder_to_string(*result_builder,, temp);
+    s := string.{data=str.data + start, count=str.count - start};
+    append(current_builder, s);
+
+    prefix := builder_to_string(*prefix_builder,, temp);
+    suffix := builder_to_string(*suffix_builder,, temp);
+
+    return prefix, suffix;
 }
 
 get_time :: () -> s64 {