ledit

commit 4f2001a6c39e051d22db3d88377e5de414aac97d
parent 1619b579fa72a45217ceeab062cd5dc6c9961a37
Author: lumidify <nobody@lumidify.org>
Date:   Sat, 30 Oct 2021 09:11:58 +0200

Sort of fix cursor movement when scrolling whole screens

Diffstat:
M
buffer.h
 | 
3
+--
M
keys_basic.c
 | 
21
+++++++++++++++------

2 files changed, 16 insertions(+), 8 deletions(-)
diff --git a/buffer.h b/buffer.h
@@ -33,8 +33,7 @@ struct ledit_buffer {
 	int trailing_bytes; /* same thing, but with bytes instead of utf8 characters */
 	int end_of_soft_line; /* used to handle special behavior at end end of soft line */
 	long total_height; /* total pixel height of all lines */
-	double display_offset; /* current pixel offset of viewport - this
-	                        * is a double to make scrolling smoother */
+	long display_offset; /* current pixel offset of viewport */
 	int selecting;
 	ledit_range sel; /* current selection; all entries -1 if no selection */
 	ledit_cache *cache;
diff --git a/keys_basic.c b/keys_basic.c
@@ -345,8 +345,8 @@ delete_selection(ledit_buffer *buffer) {
 
 /* get the number of times a command should be repeated, or -1 if anything
    invalid was on the stack - this is for commands that just take a repeat
-   count and nothin else (cursor movement keys are different because they
-   can use other elements on the key stack to, for instance, call a callback
+   count and nothing else (cursor movement keys are different because they
+   can use other elements on the key stack too, for instance call a callback
    as is done for deletion */
 static int
 get_key_repeat(void) {
@@ -368,13 +368,23 @@ get_key_repeat(void) {
 	return num;
 }
 
-/* movement is multiplied to the window height and added to the display offset
-   the cursor is moved to the top if movement is upwards, to the bottom otherwise */
+/* movement is multiplied with the window height and the result is added to the display offset
+   the cursor is moved to the bottom if movement is upwards, to the top otherwise
+   (unless the screen is already at the very top or bottom - then it is the other way around) */
 static void
 move_screen(ledit_buffer *buffer, int movement) {
 	int w, h;
 	ledit_window_get_textview_size(buffer->window, &w, &h);
+	/* FIXME: overflow */
 	long total = movement * (long)h;
+	/* new pixel position of cursor */
+	/* FIXME: in certain cases, just using h as the y position could make it
+	   move slightly further down than a screen once ensure_cursor_shown is called */
+	int y = movement > 0 ? 0 : h;
+	if (buffer->display_offset + total < 0)
+		y = 0;
+	else if (buffer->display_offset + total + h > buffer->total_height)
+		y = h;
 	ledit_buffer_scroll(buffer, buffer->display_offset + total);
 	ledit_buffer_wipe_line_cursor_attrs(buffer, buffer->cur_line);
 	/* try to keep current x position of cursor */
@@ -382,9 +392,8 @@ move_screen(ledit_buffer *buffer, int movement) {
 	int x, softline;
 	/* FIXME: properly document what uses PANGO_SCALE and what not */
 	ledit_pos_to_x_softline(ll, buffer->cur_index, &x, &softline);
-	/* if movement is up, move cursor to top, else to bottom of current screen */
 	ledit_xy_to_line_byte(
-	    buffer, x / PANGO_SCALE, movement < 0 ? 0 : h, 0,
+	    buffer, x / PANGO_SCALE, y, 0,
 	    &buffer->cur_line, &buffer->cur_index
 	);
 	ledit_buffer_set_line_cursor_attrs(buffer, buffer->cur_line, buffer->cur_index);