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textinput: implement horizontal scrolling

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Scroll the textinput widget horizontally when it overflows either side.
This commit is contained in:
Tim Culverhouse 2024-03-18 08:26:53 -05:00
parent f18f6328bb
commit 15c64a0e66
1 changed files with 42 additions and 4 deletions
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46
src/widgets/TextInput.zig
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@ -14,11 +14,22 @@ const Event = union(enum) {
key_press: Key,
};
const ellipsis: Cell.Character = .{ .grapheme = "…", .width = 1 };
// Index of our cursor
cursor_idx: usize = 0,
grapheme_count: usize = 0,
buf: GapBuffer(u8),
/// the number of graphemes to skip when drawing. Used for horizontal scrolling
draw_offset: usize = 0,
/// the column we placed the cursor the last time we drew
prev_cursor_col: usize = 0,
/// the grapheme index of the cursor the last time we drew
prev_cursor_idx: usize = 0,
/// approximate distance from an edge before we scroll
scroll_offset: usize = 4,
pub fn init(alloc: std.mem.Allocator) TextInput {
return TextInput{
.buf = GapBuffer(u8).init(alloc),
@ -60,15 +71,31 @@ pub fn update(self: *TextInput, event: Event) !void {
}
pub fn draw(self: *TextInput, win: Window) void {
if (self.cursor_idx > self.prev_cursor_idx and
self.prev_cursor_col > (win.width -| self.scroll_offset))
self.draw_offset += 1;
if (self.cursor_idx < self.prev_cursor_idx and
self.prev_cursor_col < self.scroll_offset)
self.draw_offset -|= 1;
self.prev_cursor_idx = self.cursor_idx;
self.prev_cursor_col = 0;
// assumption!! the gap is never within a grapheme
// one way to _ensure_ this is to move the gap... but that's a cost we probably don't want to pay.
var first_iter = GraphemeIterator.init(self.buf.items);
var col: usize = 0;
var i: usize = 0;
var cursor_idx: usize = 0;
while (first_iter.next()) |grapheme| {
if (i < self.draw_offset) {
i += 1;
continue;
}
const g = grapheme.slice(self.buf.items);
const w = win.gwidth(g);
if (col + w >= win.width) {
win.writeCell(win.width - 1, 0, .{ .char = ellipsis });
break;
}
win.writeCell(col, 0, .{
.char = .{
.grapheme = g,
@ -77,13 +104,21 @@ pub fn draw(self: *TextInput, win: Window) void {
});
col += w;
i += 1;
if (i == self.cursor_idx) cursor_idx = col;
if (i == self.cursor_idx) self.prev_cursor_col = col;
}
const second_half = self.buf.secondHalf();
var second_iter = GraphemeIterator.init(second_half);
while (second_iter.next()) |grapheme| {
if (i < self.draw_offset) {
i += 1;
continue;
}
const g = grapheme.slice(second_half);
const w = win.gwidth(g);
if (col + w > win.width) {
win.writeCell(win.width - 1, 0, .{ .char = ellipsis });
break;
}
win.writeCell(col, 0, .{
.char = .{
.grapheme = g,
@ -92,9 +127,12 @@ pub fn draw(self: *TextInput, win: Window) void {
});
col += w;
i += 1;
if (i == self.cursor_idx) cursor_idx = col;
if (i == self.cursor_idx) self.prev_cursor_col = col;
}
win.showCursor(cursor_idx, 0);
if (self.draw_offset > 0) {
win.writeCell(0, 0, .{ .char = ellipsis });
}
win.showCursor(self.prev_cursor_col, 0);
}
pub fn clearAndFree(self: *TextInput) void {