Add `ALT`+`UP`/`DOWN`/`mouse wheel` scroll support

Before the change, the only way to scroll was usage of page up/down,
it allowed to scroll only by skipping pages, which was not smooth.

docs/profanity.1

@@ -71,6 +71,14 @@ Page the occupants or roster panel up.
 .BI ALT+PAGEDOWN
 Page the occupants or roster panel down.
 .TP
+.BI ALT+UP " or " ALT+WHEEL UP
+Scroll up. Note: limited support for scrolling with mouse wheel,
+please, get in touch with devs if you know how to add support 
+for other terminals.
+.TP
+.BI ALT+DOWN " or " ALT+WHEEL DOWN
+Scroll down. See note above.
+.TP
 .BI ALT+a
 Jump to the next unread window.
 .TP

src/command/cmd_funcs.c

@@ -81,6 +81,7 @@
 #include "tools/bookmark_ignore.h"
 #include "tools/editor.h"
 #include "plugins/plugins.h"
+#include "ui/inputwin.h"
 #include "ui/ui.h"
 #include "ui/window_list.h"
 #include "xmpp/avatar.h"

src/ui/inputwin.c

@@ -136,6 +136,7 @@ static int _inp_rl_subwin_pageup_handler(int count, int key);
 static int _inp_rl_subwin_pagedown_handler(int count, int key);
 static int _inp_rl_startup_hook(void);
 static int _inp_rl_down_arrow_handler(int count, int key);
+static int _inp_rl_scroll_handler(int count, int key);
 static int _inp_rl_send_to_editor(int count, int key);
 static int _inp_rl_print_newline_symbol(int count, int key);
 
@@ -554,6 +555,8 @@ _inp_rl_startup_hook(void)
     rl_bind_key('\t', _inp_rl_tab_handler);
     rl_bind_keyseq("\\e[Z", _inp_rl_shift_tab_handler);
 
+    rl_bind_keyseq("\\e[1;3A", _inp_rl_scroll_handler);     // alt + scroll/arrow up
+    rl_bind_keyseq("\\e[1;3B", _inp_rl_scroll_handler);     // alt + scroll/arrow down
     rl_bind_keyseq("\\e[1;5B", _inp_rl_down_arrow_handler); // ctrl+arrow down
     rl_bind_keyseq("\\eOb", _inp_rl_down_arrow_handler);
 
@@ -906,7 +909,7 @@ static int
 _inp_rl_win_pageup_handler(int count, int key)
 {
     ProfWin* current = wins_get_current();
-    win_page_up(current);
+    win_page_up(current, 0);
     return 0;
 }
 
@@ -914,7 +917,7 @@ static int
 _inp_rl_win_pagedown_handler(int count, int key)
 {
     ProfWin* current = wins_get_current();
-    win_page_down(current);
+    win_page_down(current, 0);
     return 0;
 }
 
@@ -934,6 +937,21 @@ _inp_rl_subwin_pagedown_handler(int count, int key)
     return 0;
 }
 
+static int
+_inp_rl_scroll_handler(int count, int key)
+{
+    ProfWin* window = wins_get_current();
+
+    if (key == 'B') {
+        // mouse wheel down
+        win_page_down(window, 4);
+    } else if (key == 'A') {
+        // mouse wheel up
+        win_page_up(window, 4);
+    }
+    return 0;
+}
+
 static int
 _inp_rl_down_arrow_handler(int count, int key)
 {

src/ui/window.c

@@ -623,17 +623,20 @@ win_free(ProfWin* window)
 }
 
 void
-win_page_up(ProfWin* window)
+win_page_up(ProfWin* window, int scroll_size)
 {
     _reached_bottom_of_database = FALSE;
     int rows = getmaxy(stdscr);
-    int y = getcury(window->layout->win);
+    int total_rows = getcury(window->layout->win);
     int page_space = rows - 4;
     int* page_start = &(window->layout->y_pos);
+    int page_start_initial = *page_start;
+    if (scroll_size == 0)
+        scroll_size = page_space;
 
-    *page_start -= page_space;
+    *page_start -= scroll_size;
 
-    if (*page_start == -page_space && window->type == WIN_CHAT) {
+    if (*page_start == -scroll_size && window->type == WIN_CHAT) {
         ProfChatWin* chatwin = (ProfChatWin*)window;
         ProfBuffEntry* first_entry = buffer_size(window->layout->buffer) != 0 ? buffer_get_entry(window->layout->buffer, 0) : NULL;
 
@@ -655,27 +658,33 @@ win_page_up(ProfWin* window)
         *page_start = 0;
 
     window->layout->paged = 1;
-    win_update_virtual(window);
+    // update only if position has changed
+    if (page_start_initial != *page_start) {
+        win_update_virtual(window);
+    }
 
     // switch off page if last line and space line visible
-    if ((y) - *page_start == page_space) {
+    if ((total_rows) - *page_start == page_space) {
         window->layout->paged = 0;
     }
 }
 
 void
-win_page_down(ProfWin* window)
+win_page_down(ProfWin* window, int scroll_size)
 {
     _reached_top_of_database = FALSE;
     int rows = getmaxy(stdscr);
-    int y = getcury(window->layout->win);
-    int page_space = rows - 4;
     int* page_start = &(window->layout->y_pos);
+    int total_rows = getcury(window->layout->win);
+    int page_space = rows - 4;
+    int page_start_initial = *page_start;
+    if (scroll_size == 0)
+        scroll_size = page_space;
 
-    *page_start += page_space;
+    *page_start += scroll_size;
 
     // Scrolled down after reaching the bottom of the page
-    if ((*page_start == y || (*page_start == page_space && *page_start >= y)) && window->type == WIN_CHAT) {
+    if ((*page_start == total_rows || (*page_start == page_space && *page_start >= total_rows)) && window->type == WIN_CHAT) {
         int bf_size = buffer_size(window->layout->buffer);
         if (bf_size > 0) {
             auto_gchar gchar* start = g_date_time_format_iso8601(buffer_get_entry(window->layout->buffer, bf_size - 1)->time);
@@ -691,18 +700,21 @@ win_page_down(ProfWin* window)
     }
 
     // only got half a screen, show full screen
-    if ((y - (*page_start)) < page_space)
-        *page_start = y - page_space;
+    if ((total_rows - (*page_start)) < page_space)
+        *page_start = total_rows - page_space;
 
     // went past end, show full screen
-    else if (*page_start >= y)
-        *page_start = y - page_space - 1;
+    else if (*page_start >= total_rows)
+        *page_start = total_rows - page_space - 1;
 
     window->layout->paged = 1;
-    win_update_virtual(window);
+    // update only if position has changed
+    if (page_start_initial != *page_start) {
+        win_update_virtual(window);
+    }
 
     // switch off page if last line and space line visible
-    if ((y) - *page_start == page_space) {
+    if ((total_rows) - *page_start == page_space) {
         window->layout->paged = 0;
     }
 }

src/ui/window.h

@@ -88,8 +88,8 @@ void win_update_entry_message(ProfWin* window, const char* const id, const char*
 
 gboolean win_has_active_subwin(ProfWin* window);
 
-void win_page_up(ProfWin* window);
-void win_page_down(ProfWin* window);
+void win_page_up(ProfWin* window, int scroll_size);
+void win_page_down(ProfWin* window, int scroll_size);
 void win_sub_page_down(ProfWin* window);
 void win_sub_page_up(ProfWin* window);