handle moving and scrolling separately

only lf/ri should be scrolling, and only if they start on the border of
the scroll region and try to move off of it. also, all absolute movement
should be absolute in the context of the full terminal, but relative
vertical movement should be clamped to the scroll regions.

1 files changed, 31 insertions, 27 deletions

diff --git a/src/screen.c b/src/screen.c
index 1dc8f75..afae515 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -170,7 +170,7 @@ void vt100_screen_show_string_ascii(VT100Screen *vt, char *buf, size_t len)
 
         if (col >= vt->grid->max.col) {
             vt100_screen_row_at(vt, vt->grid->cur.row)->wrapped = 1;
-            vt100_screen_move_to(vt, vt->grid->cur.row + 1, 0, 1);
+            vt100_screen_move_down_or_scroll(vt);
             col = 0;
         }
         cell = vt100_screen_cell_at(vt, vt->grid->cur.row, col++);
@@ -180,7 +180,7 @@ void vt100_screen_show_string_ascii(VT100Screen *vt, char *buf, size_t len)
         cell->attrs = vt->attrs;
         cell->is_wide = 0;
     }
-    vt100_screen_move_to(vt, vt->grid->cur.row, col, 0);
+    vt100_screen_move_to(vt, vt->grid->cur.row, col);
 }
 
 void vt100_screen_show_string_utf8(VT100Screen *vt, char *buf, size_t len)
@@ -245,7 +245,7 @@ void vt100_screen_show_string_utf8(VT100Screen *vt, char *buf, size_t len)
         else {
             if (col + (is_wide ? 2 : 1) > vt->grid->max.col) {
                 vt100_screen_row_at(vt, vt->grid->cur.row)->wrapped = 1;
-                vt100_screen_move_to(vt, vt->grid->cur.row + 1, 0, 1);
+                vt100_screen_move_down_or_scroll(vt);
                 col = 0;
             }
             cell = vt100_screen_cell_at(vt, vt->grid->cur.row, col);
@@ -263,33 +263,17 @@ void vt100_screen_show_string_utf8(VT100Screen *vt, char *buf, size_t len)
             break;
         }
     }
-    vt100_screen_move_to(vt, vt->grid->cur.row, col, 0);
+    vt100_screen_move_to(vt, vt->grid->cur.row, col);
 }
 
-void vt100_screen_move_to(VT100Screen *vt, int row, int col, int scroll)
+void vt100_screen_move_to(VT100Screen *vt, int row, int col)
 {
-    int top = vt->grid->scroll_top, bottom = vt->grid->scroll_bottom;
-
-    if (row > bottom) {
-        if (scroll) {
-            vt100_screen_scroll_up(vt, row - bottom);
-        }
-        row = bottom;
-    }
-    else if (row < top) {
-        if (scroll) {
-            vt100_screen_scroll_down(vt, top - row);
-        }
-        row = top;
-    }
-
-    if (col < 0) {
-        col = 0;
-    }
-
-    if (col >= vt->grid->max.col) {
-        col = vt->grid->max.col - 1;
-    }
+    row = row < 0                  ? 0
+        : row >= vt->grid->max.row ? vt->grid->max.row - 1
+        : row;
+    col = col < 0                  ? 0
+        : col >= vt->grid->max.col ? vt->grid->max.col - 1
+        : col;
 
     vt->grid->cur.row = row;
     vt->grid->cur.col = col;
@@ -611,6 +595,26 @@ void vt100_screen_scroll_up(VT100Screen *vt, int count)
     vt->dirty = 1;
 }
 
+void vt100_screen_move_down_or_scroll(VT100Screen *vt)
+{
+    if (vt->grid->cur.row == vt->grid->scroll_bottom) {
+        vt100_screen_scroll_up(vt, 1);
+    }
+    else {
+        vt100_screen_move_to(vt, vt->grid->cur.row + 1, vt->grid->cur.col);
+    }
+}
+
+void vt100_screen_move_up_or_scroll(VT100Screen *vt)
+{
+    if (vt->grid->cur.row == vt->grid->scroll_top) {
+        vt100_screen_scroll_down(vt, 1);
+    }
+    else {
+        vt100_screen_move_to(vt, vt->grid->cur.row - 1, vt->grid->cur.col);
+    }
+}
+
 void vt100_screen_set_scroll_region(
     VT100Screen *vt, int top, int bottom, int left, int right)
 {