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fix: make TextArea word wrap ANSI-aware #44

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fix: make TextArea word wrap ANSI-aware #44

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123 changes: 123 additions & 0 deletions src/components/text_area.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -692,9 +692,19 @@ pub const TextArea = struct {

if (width_limit == 0) return;

const preserve_ansi = std.mem.indexOfScalar(u8, line, 0x1b) != null;
var rendered_width: usize = 0;
var byte_idx = start;
while (byte_idx < end and rendered_width < width_limit) {
if (line[byte_idx] == 0x1b) {
const seq_end = ansiSequenceEnd(line, byte_idx);
if (seq_end > byte_idx) {
try writer.writeAll(line[byte_idx..seq_end]);
byte_idx = seq_end;
continue;
}
}

const is_cursor = is_cursor_line and self.focused and byte_idx == self.cursor_col;

const byte_len = std.unicode.utf8ByteSequenceLength(line[byte_idx]) catch 1;
Expand All @@ -713,6 +723,8 @@ pub const TextArea = struct {
const styled = try self.cursor_style.render(allocator, char_slice);
defer allocator.free(styled);
try writer.writeAll(styled);
} else if (preserve_ansi) {
try writer.writeAll(char_slice);
} else {
const styled = try self.text_style.render(allocator, char_slice);
defer allocator.free(styled);
Expand All @@ -739,13 +751,21 @@ pub const TextArea = struct {

fn renderLine(self: *const TextArea, writer: anytype, allocator: std.mem.Allocator, line: []const u8, line_idx: usize, max_width: u16) !void {
const is_cursor_line = line_idx == self.cursor_row;
const preserve_ansi = std.mem.indexOfScalar(u8, line, 0x1b) != null;

// Apply horizontal scroll
var col: usize = 0;
var byte_idx: usize = 0;

// Skip to viewport_col (using display columns)
while (col < self.viewport_col and byte_idx < line.len) {
if (line[byte_idx] == 0x1b) {
const seq_end = ansiSequenceEnd(line, byte_idx);
if (seq_end > byte_idx) {
byte_idx = seq_end;
continue;
}
}
const byte_len = std.unicode.utf8ByteSequenceLength(line[byte_idx]) catch 1;
if (byte_idx + byte_len <= line.len) {
const cp = std.unicode.utf8Decode(line[byte_idx..][0..byte_len]) catch {
Expand All @@ -761,6 +781,15 @@ pub const TextArea = struct {
// Render visible portion
var rendered_width: usize = 0;
while (byte_idx < line.len and rendered_width < max_width) {
if (line[byte_idx] == 0x1b) {
const seq_end = ansiSequenceEnd(line, byte_idx);
if (seq_end > byte_idx) {
try writer.writeAll(line[byte_idx..seq_end]);
byte_idx = seq_end;
continue;
}
}

const is_cursor = is_cursor_line and self.focused and byte_idx == self.cursor_col;

const byte_len = std.unicode.utf8ByteSequenceLength(line[byte_idx]) catch 1;
Expand All @@ -781,6 +810,8 @@ pub const TextArea = struct {
const styled = try self.cursor_style.render(allocator, char_slice);
defer allocator.free(styled);
try writer.writeAll(styled);
} else if (preserve_ansi) {
try writer.writeAll(char_slice);
} else {
const styled = try self.text_style.render(allocator, char_slice);
defer allocator.free(styled);
Expand Down Expand Up @@ -813,6 +844,13 @@ pub const TextArea = struct {
var display_col: usize = 0;
var byte_idx: usize = 0;
while (byte_idx < self.cursor_col and byte_idx < line.items.len) {
if (line.items[byte_idx] == 0x1b) {
const seq_end = ansiSequenceEnd(line.items, byte_idx);
if (seq_end > byte_idx) {
byte_idx = seq_end;
continue;
}
}
const byte_len = std.unicode.utf8ByteSequenceLength(line.items[byte_idx]) catch 1;
if (byte_idx + byte_len <= line.items.len) {
const cp = std.unicode.utf8Decode(line.items[byte_idx..][0..byte_len]) catch {
Expand Down Expand Up @@ -964,6 +1002,13 @@ pub const TextArea = struct {
var segment_width: usize = 0;

while (i < line.len) {
if (line[i] == 0x1b) {
const seq_end = ansiSequenceEnd(line, i);
if (seq_end > i) {
i = seq_end;
continue;
}
}
const byte_len = std.unicode.utf8ByteSequenceLength(line[i]) catch 1;
if (i + byte_len > line.len) break;

Expand Down Expand Up @@ -994,6 +1039,13 @@ pub const TextArea = struct {
var width: usize = 0;
var i = @min(start, clamped_end);
while (i < clamped_end) {
if (line[i] == 0x1b) {
const seq_end = ansiSequenceEnd(line, i);
if (seq_end > i) {
i = @min(seq_end, clamped_end);
continue;
}
}
const byte_len = std.unicode.utf8ByteSequenceLength(line[i]) catch 1;
if (i + byte_len > line.len) break;
const cp = std.unicode.utf8Decode(line[i..][0..byte_len]) catch {
Expand All @@ -1017,6 +1069,14 @@ pub const TextArea = struct {
while (i < clamped_end) {
if (col >= target_col) return i;

if (line[i] == 0x1b) {
const seq_end = ansiSequenceEnd(line, i);
if (seq_end > i) {
i = @min(seq_end, clamped_end);
continue;
}
}

const byte_len = std.unicode.utf8ByteSequenceLength(line[i]) catch 1;
if (i + byte_len > line.len) break;
const cp = std.unicode.utf8Decode(line[i..][0..byte_len]) catch {
Expand All @@ -1041,6 +1101,39 @@ pub const TextArea = struct {
return @min(char_width, max_width);
}

// ANSI escape parsing reference:
// https://zh.wikipedia.org/wiki/ANSI%E8%BD%AC%E4%B9%89%E5%BA%8F%E5%88%97
// For CSI, the final byte follows the standard 0x40..0x7E range.
fn ansiSequenceEnd(line: []const u8, start: usize) usize {
if (start >= line.len or line[start] != 0x1b or start + 1 >= line.len) return start;

switch (line[start + 1]) {
// CSI
'[' => {
var i = start + 2;
while (i < line.len) : (i += 1) {
const c = line[i];
if (c >= 0x40 and c <= 0x7E) return i + 1;
if (c < 0x20 or c == 0x7F) return start;
}
return start;
},
// OSC
']' => {
var i = start + 2;
while (i < line.len) : (i += 1) {
if (line[i] == 0x07) return i + 1;
if (line[i] == 0x1b) {
const next = i + 1;
if (next < line.len and line[next] == '\\') return next + 1;
}
}
return start;
},
else => return @min(start + 2, line.len),
}
}

fn clampCursorToLineBoundary(self: *TextArea) void {
const line = self.currentLine();
self.cursor_col = clampToUtf8Boundary(line.items, self.cursor_col);
Expand All @@ -1054,3 +1147,33 @@ pub const TextArea = struct {
return clamped;
}
};

test "word wrap preserves ansi styled content" {
const allocator = std.testing.allocator;

const dim = (style_mod.Style{}).dim(true).fg(Color.gray(8));
const bad = (style_mod.Style{}).bg(Color.red()).fg(Color.white()).bold(true);

const dimmed = try dim.render(allocator, "abc");
defer allocator.free(dimmed);
const highlighted = try bad.render(allocator, "de");
defer allocator.free(highlighted);
const styled_text = try std.fmt.allocPrint(allocator, "{s}{s}{s}", .{ dimmed, highlighted, "fg" });
defer allocator.free(styled_text);

var area = TextArea.init(allocator);
defer area.deinit();
area.word_wrap = true;
area.focused = false;
area.setSize(4, 3);
try area.setValue(styled_text);

const rendered = try area.view(allocator);
defer allocator.free(rendered);

try std.testing.expect(std.mem.indexOf(u8, rendered, "\x1b[2m") != null);
try std.testing.expect(std.mem.indexOf(u8, rendered, "\x1b[41m") != null);
try std.testing.expect(std.mem.indexOf(u8, rendered, "abc") != null);
try std.testing.expect(std.mem.indexOf(u8, rendered, "fg") != null);
try std.testing.expect(std.mem.indexOf(u8, rendered, "[0m[") == null);
}
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