Richard B's patch for resize behaviour. The scrollback now contains

a marker which defines everything before it as `permanent'
scrollback and everything after it as `temporary'; only temporary
scrollback lines are returned to the main screen when the window
height is increased. Screen clears mark the lines pushed into the
scrollback as permanent; so lines explicitly cleared off the screen
by ESC[2J are never returned to it by mistake. This patch also fixes
the incorrect state the primary screen is left in when the window is
resized while the alternate screen is active.

git-svn-id: svn://svn.tartarus.org/sgt/putty@2923 cda61777-01e9-0310-a592-d414129be87e

diff --git a/terminal.c b/terminal.c
index 4d0fdd0..2a9470b 100644 (file)
--- a/terminal.c
+++ b/terminal.c
@@ -355,6 +355,7 @@ void term_clrsb(Terminal *term)
     while ((line = delpos234(term->scrollback, 0)) != NULL) {
        sfree(line);
     }
+    term->tempsblines = 0;
     term->alt_sblines = 0;
     update_sbar(term);
 }
@@ -399,6 +400,7 @@ Terminal *term_init(Config *mycfg, struct unicode_data *ucsdata,
     term->curstype = 0;
 
     term->screen = term->alt_screen = term->scrollback = NULL;
+    term->tempsblines = 0;
     term->alt_sblines = 0;
     term->disptop = 0;
     term->disptext = term->dispcurs = NULL;
@@ -472,6 +474,7 @@ void term_size(Terminal *term, int newrows, int newcols, int newsavelines)
     if (term->rows == -1) {
        term->scrollback = newtree234(NULL);
        term->screen = newtree234(NULL);
+       term->tempsblines = 0;
        term->rows = 0;
     }
 
@@ -481,15 +484,14 @@ void term_size(Terminal *term, int newrows, int newcols, int newsavelines)
      * will take care of resizing each individual line if
      * necessary. So:
      * 
-     *  - If the new screen and the old screen differ in length, we
-     *    must shunt some lines in from the scrollback or out to
-     *    the scrollback.
-     * 
-     *  - If doing that fails to provide us with enough material to
-     *    fill the new screen (i.e. the number of rows needed in
-     *    the new screen exceeds the total number in the previous
-     *    screen+scrollback), we must invent some blank lines to
-     *    cover the gap.
+     *  - If the new screen is longer, we shunt lines in from temporary
+     *    scrollback if possible, otherwise we add new blank lines at
+     *    the bottom.
+     *
+     *  - If the new screen is shorter, we remove any blank lines at
+     *    the bottom if possible, otherwise shunt lines above the cursor
+     *    to scrollback if possible, otherwise delete lines below the
+     *    cursor.
      * 
      *  - Then, if the new scrollback length is less than the
      *    amount of scrollback we actually have, we must throw some
@@ -497,32 +499,58 @@ void term_size(Terminal *term, int newrows, int newcols, int newsavelines)
      */
     sblen = count234(term->scrollback);
     /* Do this loop to expand the screen if newrows > rows */
-    for (i = term->rows; i < newrows; i++) {
-       if (sblen > 0) {
+    assert(term->rows == count234(term->screen));
+    while (term->rows < newrows) {
+       if (term->tempsblines > 0) {
+           /* Insert a line from the scrollback at the top of the screen. */
+           assert(sblen >= term->tempsblines);
            line = delpos234(term->scrollback, --sblen);
+           term->tempsblines -= 1;
+           addpos234(term->screen, line, 0);
+           term->curs.y += 1;
+           term->savecurs.y += 1;
        } else {
+           /* Add a new blank line at the bottom of the screen. */
            line = smalloc(TSIZE * (newcols + 2));
            line[0] = newcols;
            for (j = 0; j < newcols; j++)
                line[j + 1] = ERASE_CHAR;
             line[newcols + 1] = LATTR_NORM;
+           addpos234(term->screen, line, count234(term->screen));
        }
-       addpos234(term->screen, line, 0);
+       term->rows += 1;
     }
     /* Do this loop to shrink the screen if newrows < rows */
-    for (i = newrows; i < term->rows; i++) {
-       line = delpos234(term->screen, 0);
-       addpos234(term->scrollback, line, sblen++);
+    while (term->rows > newrows) {
+       if (term->curs.y < term->rows - 1) {
+           /* delete bottom row, unless it contains the cursor */
+           sfree(delpos234(term->screen, term->rows - 1));
+       } else {
+           /* push top row to scrollback */
+           line = delpos234(term->screen, 0);
+           addpos234(term->scrollback, line, sblen++);
+           term->tempsblines += 1;
+           term->curs.y -= 1;
+           term->savecurs.y -= 1;
+       }
+       term->rows -= 1;
     }
+    assert(term->rows == newrows);
     assert(count234(term->screen) == newrows);
+
+    /* Delete any excess lines from the scrollback. */
     while (sblen > newsavelines) {
        line = delpos234(term->scrollback, 0);
        sfree(line);
        sblen--;
     }
+    if (sblen < term->tempsblines)
+       term->tempsblines = sblen;
     assert(count234(term->scrollback) <= newsavelines);
+    assert(count234(term->scrollback) >= term->tempsblines);
     term->disptop = 0;
 
+    /* Make a new displayed text buffer. */
     newdisp = smalloc(newrows * (newcols + 1) * TSIZE);
     for (i = 0; i < newrows * (newcols + 1); i++)
        newdisp[i] = ATTR_INVALID;
@@ -530,6 +558,7 @@ void term_size(Terminal *term, int newrows, int newcols, int newsavelines)
     term->disptext = newdisp;
     term->dispcurs = NULL;
 
+    /* Make a new alternate screen. */
     newalt = newtree234(NULL);
     for (i = 0; i < newrows; i++) {
        line = smalloc(TSIZE * (newcols + 2));
@@ -554,8 +583,11 @@ void term_size(Terminal *term, int newrows, int newcols, int newsavelines)
            term->tabs[i] = (i % 8 == 0 ? TRUE : FALSE);
     }
 
-    if (term->rows > 0)
-       term->curs.y += newrows - term->rows;
+    /* Check that the cursor positions are still valid. */
+    if (term->savecurs.y < 0)
+       term->savecurs.y = 0;
+    if (term->savecurs.y >= newrows)
+       term->savecurs.y = newrows - 1;
     if (term->curs.y < 0)
        term->curs.y = 0;
     if (term->curs.y >= newrows)
@@ -755,7 +787,7 @@ static void scroll(Terminal *term, int topline, int botline, int lines, int sb)
        while (lines > 0) {
            line = delpos234(term->screen, topline);
            if (sb && term->savelines > 0) {
-               int sblen = sblines(term);
+               int sblen = count234(term->scrollback);
                /*
                 * We must add this line to the scrollback. We'll
                 * remove a line from the top of the scrollback to
@@ -767,6 +799,7 @@ static void scroll(Terminal *term, int topline, int botline, int lines, int sb)
                } else {
                    line2 = smalloc(TSIZE * (term->cols + 2));
                    line2[0] = term->cols;
+                   term->tempsblines += 1;
                }
                addpos234(term->scrollback, line, sblen);
                line = line2;
@@ -1018,6 +1051,7 @@ static void erase_lots(Terminal *term,
 {
     pos start, end;
     int erase_lattr;
+    int erasing_lines_from_top = 0;
 
     if (line_only) {
        start.y = term->curs.y;
@@ -1047,8 +1081,12 @@ static void erase_lots(Terminal *term,
     if (start.y == 0 && start.x == 0 && end.y == term->rows)
        term_invalidate(term);
 
-    if (term->cfg.erase_to_scrollback &&
-       start.y == 0 && start.x == 0 && end.x == 0 && erase_lattr) {
+    /* Lines scrolled away shouldn't be brought back on if the terminal
+     * resizes. */
+    if (start.y == 0 && start.x == 0 && end.x == 0 && erase_lattr)
+       erasing_lines_from_top = 1;
+
+    if (term->cfg.erase_to_scrollback && erasing_lines_from_top) {
        /* If it's a whole number of lines, starting at the top, and
         * we're fully erasing them, erase by scrolling and keep the
         * lines in the scrollback. */
@@ -1075,6 +1113,12 @@ static void erase_lots(Terminal *term,
                ldata = lineptr(start.y);
        }
     }
+
+    /* After an erase of lines from the top of the screen, we shouldn't
+     * bring the lines back again if the terminal enlarges (since the user or
+     * application has explictly thrown them away). */
+    if (erasing_lines_from_top && !(term->alt_which))
+       term->tempsblines = 0;
 }
 
 /*

diff --git a/terminal.h b/terminal.h
index d969ecc..fe8263c 100644 (file)
--- a/terminal.h
+++ b/terminal.h
@@ -37,6 +37,8 @@ struct terminal_tag {
     tree234 *screen;                  /* lines on primary screen */
     tree234 *alt_screen;              /* lines on alternate screen */
     int disptop;                      /* distance scrolled back (0 or -ve) */
+    int tempsblines;                  /* number of lines in temporary
+                                         scrollback */
 
     unsigned long *cpos;              /* cursor position (convenience) */