factored out procedure for rendering selected lines

src/main.odin

@@ -32,17 +32,17 @@ Viewport :: struct {
 	end:   int,
 }
 
-Cursor :: struct {
+Position :: struct {
 	line: int,
 	char: int,
 }
 
+Cursor :: distinct Position
+
 Selection :: struct {
-	active:     bool,
-	start_line: int,
-	end_line:   int,
-	start_char: int,
-	end_char:   int,
+	active: bool,
+	start:  Position,
+	end:    Position,
 }
 
 window_width := 800
@@ -168,48 +168,15 @@ main :: proc() {
 			}
 			raw_data(line)[len(line)] = 0
 
-
 			if selection.active &&
-			   line_index == selection.start_line &&
-			   line_index == selection.end_line {
-				selection_begin := min(selection.start_char, selection.end_char)
-				selection_end := max(selection.start_char, selection.end_char)
-				prefix := line[:selection_begin]
-				suffix := line[selection_end + 1:] if selection_end + 1 < len(line) else []u8{}
-				// need to copy these into separate buffers for zero value
-				x: f32 = 0.0
-				if len(prefix) != 0 {
-					cstr := strings.clone_to_cstring(string(prefix), context.temp_allocator)
-					measurements := r.MeasureTextEx(font, cstr, font_size, 0)
-					pos := r.Vector2{x, font_size * f32(line_index)}
-					r.DrawTextEx(font, cstr, pos, font_size, 0, r.WHITE)
-					x += measurements.x
-				}
-
-				selected_str := string(line[selection_begin:selection_end + 1])
-				cstr :=
-					strings.clone_to_cstring(selected_str, context.temp_allocator) if len(suffix) != 0 else strings.unsafe_string_to_cstring(selected_str)
-				measurements := r.MeasureTextEx(font, cstr, font_size, 0)
-				pos := r.Vector2{x, font_size * f32(line_index)}
-				r.DrawRectangle(
-					i32(pos.x),
-					i32(pos.y),
-					i32(measurements.x),
-					i32(measurements.y),
-					r.WHITE,
-				)
-				r.DrawTextEx(font, cstr, pos, font_size, 0, r.BLACK)
-				x += measurements.x
-
-				if len(suffix) != 0 {
-					cstr := strings.unsafe_string_to_cstring(string(suffix))
-					// cstr := strings.clone_to_cstring(string(suffix), context.temp_allocator)
-					pos := r.Vector2{x, font_size * f32(line_index)}
-					r.DrawTextEx(font, cstr, pos, font_size, 0, r.WHITE)
-				}
-			} else if selection.active && line_index == selection.start_line {
-			} else if selection.active && line_index == selection.end_line {
-			} else if selection.active && selection.start_line < line_index && line_index < selection.end_line {
+			   line_index == selection.start.line &&
+			   line_index == selection.end.line {
+				render_line_with_selection(line[:], line_index, font)
+			} else if selection.active && line_index == selection.start.line {
+			} else if selection.active && line_index == selection.end.line {
+			} else if selection.active &&
+			   selection.start.line < line_index &&
+			   line_index < selection.end.line {
 			} else {
 				// No selection active
 				cstr := strings.unsafe_string_to_cstring(string(line[:]))
@@ -281,14 +248,83 @@ handle_selection_start :: proc() {
 		return
 	}
 	if selection.active && was_active do return
-	selection.start_line = cursor.line
-	selection.start_char = cursor.char
+	selection.start.line = cursor.line
+	selection.start.char = cursor.char
 }
 
 handle_selection_end :: proc() {
 	if !selection.active do return
-	selection.end_char = cursor.char
-	selection.end_line = cursor.line
+	selection.end.char = cursor.char
+	selection.end.line = cursor.line
+}
+
+render_line_with_selection :: proc(line: []u8, line_index: int, font: r.Font) {
+	earliest: Position
+	latest: Position
+	if selection.start.line < selection.end.line {
+		// Started highlighting on a previous line, selecting downwards
+		earliest = selection.start
+		latest = selection.end
+	} else if selection.start.line > selection.end.line {
+		// Started highlighting on a later line, selecting upwards
+		earliest = selection.end
+		latest = selection.start
+	} else if selection.start.char < selection.end.char {
+		// Selection on one line, selecting rightwards
+		earliest = selection.start
+		latest = selection.end
+	} else {
+		// Selection on one line, selecting leftwards
+		earliest = selection.end
+		latest = selection.start
+	}
+
+	selection_begin: int
+	selection_end: int
+	if line_index == earliest.line && line_index == latest.line {
+		selection_begin = min(selection.start.char, selection.end.char)
+		selection_end = max(selection.start.char, selection.end.char)
+	} else if line_index == earliest.line {
+
+	} else if line_index == latest.line {
+
+	} else if earliest.line < line_index && line_index < latest.line {
+
+	} else {
+
+	}
+
+	prefix := line[:selection_begin]
+	suffix := line[selection_end:] if selection_end < len(line) else []u8{}
+	// need to copy these into separate buffers for zero value
+	x: f32 = 0.0
+	if len(prefix) != 0 {
+		cstr := strings.clone_to_cstring(string(prefix), context.temp_allocator)
+		measurements := r.MeasureTextEx(font, cstr, font_size, 0)
+		pos := r.Vector2{x, font_size * f32(line_index)}
+		r.DrawTextEx(font, cstr, pos, font_size, 0, r.WHITE)
+		x += measurements.x
+	}
+
+	selected_str: string
+	if selection_end < len(line) {
+		selected_str = string(line[selection_begin:selection_end])
+	} else {
+		selected_str = string(line[selection_begin:])
+	}
+	cstr :=
+		strings.clone_to_cstring(selected_str, context.temp_allocator) if len(suffix) != 0 else strings.unsafe_string_to_cstring(selected_str)
+	measurements := r.MeasureTextEx(font, cstr, font_size, 0)
+	pos := r.Vector2{x, font_size * f32(line_index)}
+	r.DrawRectangle(i32(pos.x), i32(pos.y), i32(measurements.x), i32(measurements.y), r.WHITE)
+	r.DrawTextEx(font, cstr, pos, font_size, 0, r.BLACK)
+	x += measurements.x
+
+	if len(suffix) != 0 {
+		cstr := strings.unsafe_string_to_cstring(string(suffix))
+		pos := r.Vector2{x, font_size * f32(line_index)}
+		r.DrawTextEx(font, cstr, pos, font_size, 0, r.WHITE)
+	}
 }
 
 move_cursor :: proc() {
@@ -297,7 +333,7 @@ move_cursor :: proc() {
 		defer handle_selection_end()
 		preferred_position := cursor.char + 1
 		if cursor.char == len(current_line()) && cursor.line != len(lines) - 1 {
-			cursor.char = 0
+			preferred_position = 0
 			cursor.line += 1
 		}
 		if r.IsKeyDown(r.KeyboardKey.LEFT_ALT) && cursor.char + 1 < len(current_line()) {
@@ -324,7 +360,7 @@ move_cursor :: proc() {
 		preferred_position := cursor.char - 1
 		if cursor.char == 0 && cursor.line != 0 {
 			cursor.line -= 1
-			cursor.char = len(current_line())
+			preferred_position = len(current_line())
 		}
 		if r.IsKeyDown(r.KeyboardKey.LEFT_ALT) && 0 < cursor.char {
 			found := false