From c06f141189c51450be3bfd896b9df7a9d423e79d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Mon, 5 Aug 2019 20:16:17 +0200
Subject: [PATCH] term: cancel selection when scrolling wraps

If we scroll enough, we'll eventually end up wrapping around the
entire scrollback buffer. At this point, a selection is no longer
valid, so cancel it.

Note: this was very obvious when scrolling in the alt screen, since
its scrollback buffer is what you see on the screen (i.e. it has no
scrollback).
---
 selection.c | 14 ++++++++++++++
 selection.h |  1 +
 terminal.c  | 10 ++++++++--
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/selection.c b/selection.c
index fe4f4297..f69338a4 100644
--- a/selection.c
+++ b/selection.c
@@ -24,6 +24,20 @@ selection_enabled(const struct terminal *term)
             term->mouse_tracking != MOUSE_MOTION);
 }
 
+bool
+selection_on_row_in_view(const struct terminal *term, int row_no)
+{
+    if (term->selection.start.row == -1 || term->selection.end.row == -1)
+        return false;
+
+    const struct coord *start = &term->selection.start;
+    const struct coord *end = &term->selection.end;
+    assert(start->row <= end->row);
+
+    row_no += term->grid->view;
+    return row_no >= start->row && row_no <= end->row;
+}
+
 static char *
 extract_selection(const struct terminal *term)
 {
diff --git a/selection.h b/selection.h
index 9d712da1..2e574b0b 100644
--- a/selection.h
+++ b/selection.h
@@ -18,6 +18,7 @@ void selection_mark_word(struct terminal *term, int col, int row,
 void selection_to_clipboard(struct terminal *term, uint32_t serial);
 void selection_from_clipboard(struct terminal *term, uint32_t serial);
 void selection_from_primary(struct terminal *term);
+bool selection_on_row_in_view(const struct terminal *term, int row_no);
 
 bool text_to_clipboard(struct terminal *term, char *text, uint32_t serial);
 void text_from_clipboard(
diff --git a/terminal.c b/terminal.c
index e8811ce5..622cd47a 100644
--- a/terminal.c
+++ b/terminal.c
@@ -282,8 +282,11 @@ term_scroll_partial(struct terminal *term, struct scroll_region region, int rows
         grid_swap_row(term->grid, i - rows, i);
 
     /* Erase scrolled in lines */
-    for (int r = max(region.end - rows, 0); r < region.end; r++)
+    for (int r = max(region.end - rows, 0); r < region.end; r++) {
         erase_line(term, grid_row(term->grid, r));
+        if (selection_on_row_in_view(term, r))
+            selection_cancel(term);
+    }
 
     term_damage_scroll(term, DAMAGE_SCROLL, region, rows);
     term->grid->cur_row = grid_row(term->grid, term->cursor.row);
@@ -325,8 +328,11 @@ term_scroll_reverse_partial(struct terminal *term,
         grid_swap_row(term->grid, i, i - rows);
 
     /* Erase scrolled in lines */
-    for (int r = region.start; r < min(region.start + rows, region.end); r++)
+    for (int r = region.start; r < min(region.start + rows, region.end); r++) {
         erase_line(term, grid_row(term->grid, r));
+        if (selection_on_row_in_view(term, r))
+            selection_cancel(term);
+    }
 
     term_damage_scroll(term, DAMAGE_SCROLL_REVERSE, region, rows);
     term->grid->cur_row = grid_row(term->grid, term->cursor.row);