[vte] emulation: Migrating from terminfo: scrolling operations

[Egmont Koblinger <egmontkob src gnome org>]

commit a2f3bc6664cc3c4e3844151f8cf2faeebc11e996
Author: Egmont Koblinger <egmont gmail com>
Date:   Mon May 19 14:56:15 2014 +0200

    emulation: Migrating from terminfo: scrolling operations
    
    Hardwire the behavior of scrolling operations, rather than relying on
    terminfo.
    
    Make the parameter parsing of scroll regions more compatible with xterm.
    
    Drop support for "cS", there's no corresponding xterm terminfo entry.

 src/vteseq-2.gperf |    4 +-
 src/vteseq.c       |   88 +++++++++++++--------------------------------------
 2 files changed, 25 insertions(+), 67 deletions(-)
---
diff --git a/src/vteseq-2.gperf b/src/vteseq-2.gperf
index 739b5bf..8aff9f5 100644
--- a/src/vteseq-2.gperf
+++ b/src/vteseq-2.gperf
@@ -158,7 +158,7 @@ struct vteseq_2_struct {
 #"bc", VTE_SEQUENCE_HANDLER(vte_sequence_handler_le)
 #"bl", VTE_SEQUENCE_HANDLER(vte_sequence_handler_bl)
 #"bt", VTE_SEQUENCE_HANDLER(vte_sequence_handler_bt)
-"cS", VTE_SEQUENCE_HANDLER(vte_sequence_handler_cS)
+#"cS", VTE_SEQUENCE_HANDLER(vte_sequence_handler_cS)
 #"cb", VTE_SEQUENCE_HANDLER(vte_sequence_handler_cb)
 "cc", VTE_SEQUENCE_HANDLER(vte_sequence_handler_noop)
 #"cd", VTE_SEQUENCE_HANDLER(vte_sequence_handler_cd)
@@ -167,7 +167,7 @@ struct vteseq_2_struct {
 #"cl", VTE_SEQUENCE_HANDLER(vte_sequence_handler_cl)
 #"cm", VTE_SEQUENCE_HANDLER(vte_sequence_handler_cm)
 #"cr", VTE_SEQUENCE_HANDLER(vte_sequence_handler_cr)
-"cs", VTE_SEQUENCE_HANDLER(vte_sequence_handler_cs)
+#"cs", VTE_SEQUENCE_HANDLER(vte_sequence_handler_cs)
 #"ct", VTE_SEQUENCE_HANDLER(vte_sequence_handler_ct)
 #"cv", VTE_SEQUENCE_HANDLER(vte_sequence_handler_cv)
 #"dc", VTE_SEQUENCE_HANDLER(vte_sequence_handler_dc)
diff --git a/src/vteseq.c b/src/vteseq.c
index ec54ba7..549788a 100644
--- a/src/vteseq.c
+++ b/src/vteseq.c
@@ -1164,84 +1164,52 @@ vte_sequence_handler_carriage_return (VteTerminal *terminal, GValueArray *params
 
 /* Restrict scrolling and updates to a subset of the visible lines. */
 static void
-vte_sequence_handler_cs (VteTerminal *terminal, GValueArray *params)
+vte_sequence_handler_set_scrolling_region (VteTerminal *terminal, GValueArray *params)
 {
        long start=-1, end=-1, rows;
        GValue *value;
        VteScreen *screen;
 
-       _vte_terminal_home_cursor (terminal);
-
        /* We require two parameters.  Anything less is a reset. */
        screen = terminal->pvt->screen;
        if ((params == NULL) || (params->n_values < 2)) {
+                _vte_terminal_home_cursor (terminal);
                screen->scrolling_restricted = FALSE;
                return;
        }
        /* Extract the two values. */
        value = g_value_array_get_nth(params, 0);
        if (G_VALUE_HOLDS_LONG(value)) {
-               start = g_value_get_long(value);
+                start = g_value_get_long(value) - 1;
        }
        value = g_value_array_get_nth(params, 1);
        if (G_VALUE_HOLDS_LONG(value)) {
-               end = g_value_get_long(value);
+                end = g_value_get_long(value) - 1;
        }
-       /* Catch garbage. */
        rows = terminal->pvt->row_count;
-       if (start <= 0 || start >= rows) {
+        /* A (1-based) value of 0 means default. */
+        if (start == -1) {
                start = 0;
        }
-       if (end <= 0 || end >= rows) {
+        if (end == -1) {
+                end = rows - 1;
+        }
+        /* Bail out on garbage, require at least 2 rows, as per xterm. */
+        if (start < 0 || start >= rows - 1 || end < start + 1) {
+                return;
+        }
+        if (end >= rows) {
                end = rows - 1;
        }
-       /* Set the right values. */
-       screen->scrolling_region.start = start;
-       screen->scrolling_region.end = end;
-       screen->scrolling_restricted = TRUE;
-       if (screen->scrolling_region.start == 0 &&
-           screen->scrolling_region.end == rows - 1) {
-               /* Special case -- run wild, run free. */
-               screen->scrolling_restricted = FALSE;
-       } else {
-               /* Maybe extend the ring -- bug 710483 */
-               while (_vte_ring_next(screen->row_data) < screen->insert_delta + rows)
-                       _vte_ring_insert(screen->row_data, _vte_ring_next(screen->row_data));
-       }
-}
 
-/* Restrict scrolling and updates to a subset of the visible lines, because
- * GNU Emacs is special. */
-static void
-vte_sequence_handler_cS (VteTerminal *terminal, GValueArray *params)
-{
-       long start=0, end=terminal->pvt->row_count-1, rows;
-       GValue *value;
-       VteScreen *screen;
+        _vte_terminal_home_cursor (terminal);
 
-       /* We require four parameters. */
-       screen = terminal->pvt->screen;
-       if ((params == NULL) || (params->n_values < 2)) {
-               screen->scrolling_restricted = FALSE;
-               return;
-       }
-       /* Extract the two parameters we care about, encoded as the number
-        * of lines above and below the scrolling region, respectively. */
-       value = g_value_array_get_nth(params, 1);
-       if (G_VALUE_HOLDS_LONG(value)) {
-               start = g_value_get_long(value);
-       }
-       value = g_value_array_get_nth(params, 2);
-       if (G_VALUE_HOLDS_LONG(value)) {
-               end -= g_value_get_long(value);
-       }
        /* Set the right values. */
        screen->scrolling_region.start = start;
        screen->scrolling_region.end = end;
        screen->scrolling_restricted = TRUE;
-       rows = terminal->pvt->row_count;
-       if ((screen->scrolling_region.start == 0) &&
-           (screen->scrolling_region.end == rows - 1)) {
+       if (screen->scrolling_region.start == 0 &&
+           screen->scrolling_region.end == rows - 1) {
                /* Special case -- run wild, run free. */
                screen->scrolling_restricted = FALSE;
        } else {
@@ -1249,10 +1217,6 @@ vte_sequence_handler_cS (VteTerminal *terminal, GValueArray *params)
                while (_vte_ring_next(screen->row_data) < screen->insert_delta + rows)
                        _vte_ring_insert(screen->row_data, _vte_ring_next(screen->row_data));
        }
-       /* Clamp the cursor to the scrolling region. */
-       screen->cursor_current.row = CLAMP(screen->cursor_current.row,
-                                          screen->insert_delta + start,
-                                          screen->insert_delta + end);
 }
 
 /* Move the cursor to the beginning of the Nth next line, no scrolling. */
@@ -1645,7 +1609,7 @@ vte_sequence_handler_sc (VteTerminal *terminal, GValueArray *params)
                                         0, terminal->pvt->row_count - 1);
 }
 
-/* Scroll the text down, but don't move the cursor. */
+/* Scroll the text down N lines, but don't move the cursor. */
 static void
 vte_sequence_handler_scroll_down (VteTerminal *terminal, GValueArray *params)
 {
@@ -1759,7 +1723,7 @@ vte_sequence_handler_reset_color (VteTerminal *terminal, GValueArray *params)
        }
 }
 
-/* Scroll the text up, but don't move the cursor. */
+/* Scroll the text up N lines, but don't move the cursor. */
 static void
 vte_sequence_handler_scroll_up (VteTerminal *terminal, GValueArray *params)
 {
@@ -2485,22 +2449,16 @@ vte_sequence_handler_set_current_file_uri (VteTerminal *terminal, GValueArray *p
 
 /* Restrict the scrolling region. */
 static void
-vte_sequence_handler_set_scrolling_region (VteTerminal *terminal, GValueArray *params)
-{
-       vte_sequence_handler_offset(terminal, params, -1, vte_sequence_handler_cs);
-}
-
-static void
 vte_sequence_handler_set_scrolling_region_from_start (VteTerminal *terminal, GValueArray *params)
 {
        GValue value = {0};
 
        g_value_init (&value, G_TYPE_LONG);
-       g_value_set_long (&value, 0); /* Out of range means start/end */
+        g_value_set_long (&value, 0);  /* A missing value is treated as 0 */
 
        g_value_array_insert (params, 0, &value);
 
-       vte_sequence_handler_offset(terminal, params, -1, vte_sequence_handler_cs);
+        vte_sequence_handler_set_scrolling_region (terminal, params);
 }
 
 static void
@@ -2509,11 +2467,11 @@ vte_sequence_handler_set_scrolling_region_to_end (VteTerminal *terminal, GValueA
        GValue value = {0};
 
        g_value_init (&value, G_TYPE_LONG);
-       g_value_set_long (&value, 0); /* Out of range means start/end */
+        g_value_set_long (&value, 0);  /* A missing value is treated as 0 */
 
        g_value_array_insert (params, 1, &value);
 
-       vte_sequence_handler_offset(terminal, params, -1, vte_sequence_handler_cs);
+        vte_sequence_handler_set_scrolling_region (terminal, params);
 }
 
 /* Set the application or normal keypad. */