edo

commit 1d9b68f7e0d73a9206b1841f134708d7ad17113e
parent d1e14aafe3edd19e4350a0378a5ac1ac87da8ec5
Author: Claudio Alessi <smoppy@gmail.com>
Date:   Mon, 24 Nov 2025 12:21:21 +0100

Implement fine clipping when scrolling horizontally.

Toy implementation, just to sort things out in my mind.

Diffstat:
M
edo.c
 | 
56
+++++++++++++++++++++++++-------------------------------
M
tui.c
 | 
60
++++++++++++++++++++++++++++++++++++++++++++++++++++--------
M
ui.h
 | 
3
++-

3 files changed, 79 insertions(+), 40 deletions(-)
diff --git a/edo.c b/edo.c
@@ -61,7 +61,8 @@ void view_cursor_left(View *v);
 void view_cursor_right(View *v);
 void view_cursor_up(View *v);
 void view_cursor_down(View *v);
-int view_col2x(View *v, Line *line, int col);
+int view_idx2col(View *v, Line *line, int idx);
+int view_col2idx(View *v, Line *line, int col);
 void view_scroll_fix(View *v);
 void draw_view(View *v);
 
@@ -277,7 +278,6 @@ view_cursor_left(View *v) {
 
 void
 view_cursor_right(View *v) {
-	//if(!v->buf->lines_tot) return;
 	Line *l = v->buf->lines[v->line_num];
 
 	if(v->col_num < l->len)
@@ -294,7 +294,6 @@ view_cursor_up(View *v) {
 
 void
 view_cursor_down(View *v) {
-	//if(!v->buf->lines_tot) return;
 	if(v->line_num < v->buf->lines_tot - 1) {
 		++v->line_num;
 		view_cursor_hfix(v);
@@ -302,9 +301,15 @@ view_cursor_down(View *v) {
 }
 
 int
-view_col2x(View *v, Line *line, int col) {
+view_idx2col(View *v, Line *line, int idx) {
 	(void)v;
-	return ui->text_width(line->buf, col);
+	return ui->text_width(line->buf, idx);
+}
+
+int
+view_col2idx(View *v, Line *line, int col) {
+	(void)v;
+	return ui->text_index_at(line->buf, col);
 }
 
 void
@@ -326,51 +331,40 @@ void
 draw_view(View *v) {
 	Line *l;
 	int row, len, y;
+	int idx, sx, shift;
 
 	ui->frame_start();
 	view_scroll_fix(v);
 
 	for(y = 0; y < v->screen_rows; y++) {
 		row = v->row_offset + y;
+
 		if(row >= v->buf->lines_tot) {
 			ui->draw_symbol(0, y, SYM_EMPTYLINE);
 			continue;
 		}
 
 		l = buffer_get_line(v->buf, row);
-		assert(l);
-
-		len = l->len - v->col_offset;
+		idx = view_col2idx(v, l, v->col_offset);
+		len = l->len - idx;
 
-		/* lines may be hidden when scrolling horizontally */
-		if(len < 0) continue;
+		/* fine clipping */
+		sx = view_idx2col(v, l, idx);
+		shift = sx - v->col_offset;
 
-		if(len > v->screen_cols) len = v->screen_cols;
-		ui->draw_text(0, y, l->buf + v->col_offset, len);
+		ui->draw_line(shift, y, l->buf + idx, len);
 	}
 
-	Line *curline = buffer_get_line(v->buf, v->line_num);
-	int cx, cy;
-	if(curline) {
-		cx = view_col2x(v, curline, v->col_num);     /* absolute */
-		cx -= view_col2x(v, curline, v->col_offset); /* offset */
-		cy = v->line_num - v->row_offset;
+	l = buffer_get_line(v->buf, v->line_num);
+	if(l) {
+		row = view_idx2col(v, l, v->col_num);
+		row -= v->col_offset;
+		y = v->line_num - v->row_offset;
 	} else {
-		cx = cy = 0;
+		row = y = 0;
 	}
 
-#if 0
-	char *t = ecalloc(1, 128);
-	int tl;
-	tl = snprintf(t, 128, "\"%s\" %ld lines [%dx%d] (%d/%d)",
-		v->buf->file_name ? v->buf->file_name : "[none]", v->buf->lines_tot,
-		v->screen_cols, v->screen_rows, v->col_num, v->buf->lines[0]->len
-	);
-	ui->draw_text(0, v->screen_rows, t, tl);
-	free(t);
-#endif
-
-	ui->move_cursor(cx, cy);
+	ui->move_cursor(row, y);
 	ui->frame_flush();
 }
 
diff --git a/tui.c b/tui.c
@@ -13,7 +13,6 @@
 #define CURPOS          "\33[%d;%dH"
 //#define CLEARLEFT       "\33[1K"
 #define CLEARRIGHT      "\33[0K"
-#define CLEARLINE       "\33[2K"
 #define CURHIDE         "\33[?25l"
 #define CURSHOW         "\33[?25h"
 
@@ -42,7 +41,7 @@ int tui_text_width(char *s, int len);
 void tui_get_window_size(int *rows, int *cols);
 void tui_exit(void);
 void tui_move_cursor(int x, int y);
-void tui_draw_text(int c, int r, char *txt, int len);
+void tui_draw_line(int c, int r, char *txt, int len);
 void tui_draw_symbol(int r, int c, Symbol sym);
 void tui_init(void);
 
@@ -116,8 +115,8 @@ tui_frame_flush(void) {
 
 int
 tui_text_width(char *s, int len) {
-	int w = 0, i;
 	int tabstop = 8;
+	int w = 0, i;
 
 	for(i = 0; i < len; i++) {
 		if(s[i] == '\t')
@@ -128,6 +127,21 @@ tui_text_width(char *s, int len) {
 	return w;
 }
 
+int
+tui_text_index_at(char *str, int target_x) {
+	int tabstop = 8;
+	int x = 0, i = 0, w;
+
+	while(str[i]) {
+		w = (str[i] == '\t') ? tabstop : 1;
+		if (x + w > target_x)
+			return i;
+		x += w;
+		i++;
+	}
+	return i;
+}
+
 void
 tui_get_window_size(int *rows, int *cols) {
 	*rows = ws.ws_row;
@@ -146,9 +160,38 @@ tui_move_cursor(int c, int r) {
 }
 
 void
-tui_draw_text(int c, int r, char *txt, int len) {
-	tui_move_cursor(c, r);
-	ab_printf(&frame, CLEARLINE "%.*s", len, txt);
+tui_draw_line(int c, int r, char *txt, int len) {
+	if(c >= ws.ws_col || r >= ws.ws_row) return;
+
+	int x = c;
+	int tabstop = 8;
+	int i = 0;
+	int cw, clen;
+
+	tui_move_cursor(x < 0 ? 0 : x, r);
+	while(i < len) {
+		cw = (txt[i] == '\t' ? tabstop : 1);
+
+		if(x + cw <= 0)
+			continue;
+
+		if(txt[i] == '\t') {
+			int spaces = tabstop;
+			clen = 1;
+
+			if(x < 0) spaces += x;
+			if(x + cw > ws.ws_col) spaces -= (x + cw - ws.ws_col);
+			while(spaces--) ab_write(&frame, " ", 1);
+		} else {
+			if(x + cw > ws.ws_col) break;
+			clen = 1;
+			ab_write(&frame, txt + i, clen);
+		}
+
+		x += cw;
+		i += clen;
+	}
+	ab_write(&frame, CLEARRIGHT, strlen(CLEARRIGHT));
 }
 
 void
@@ -161,7 +204,7 @@ tui_draw_symbol(int c, int r, Symbol sym) {
 	}
 
 	tui_move_cursor(c, r);
-	ab_printf(&frame, CLEARRIGHT "%c", symch);
+	ab_printf(&frame, "%c" CLEARRIGHT, symch);
 }
 
 void
@@ -210,8 +253,9 @@ UI ui_tui = {
 	.frame_start = tui_frame_start,
 	.frame_flush = tui_frame_flush,
 	.text_width = tui_text_width,
+	.text_index_at = tui_text_index_at,
 	.move_cursor = tui_move_cursor,
-	.draw_text = tui_draw_text,
+	.draw_line = tui_draw_line,
 	.draw_symbol = tui_draw_symbol,
 	.get_window_size = tui_get_window_size,
 	.next_event = tui_next_event
diff --git a/ui.h b/ui.h
@@ -24,8 +24,9 @@ typedef struct {
 	void (*frame_start)(void);
 	void (*frame_flush)(void);
 	int (*text_width)(char *s, int len);
+	int (*text_index_at)(char *s, int idx);
 	void (*move_cursor)(int x, int y);
-	void (*draw_text)(int r, int c, char *txt, int len);
+	void (*draw_line)(int r, int c, char *txt, int len);
 	void (*draw_symbol)(int r, int c, Symbol sym);
 	void (*get_window_size)(int *rows, int *cols);
 	Event (*next_event)(void);