X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/03f60a6278574d259d07e54b3c32a78050a21cfd..875e0b16f64f7b97171d58fe34ebcd57314eb739:/terminal.c

diff --git a/terminal.c b/terminal.c
index 5ab7e1bf..2a9470ba 100644
--- a/terminal.c
+++ b/terminal.c
@@ -110,6 +110,19 @@ static unsigned long *resizeline(unsigned long *line, int cols)
 }
 
 /*
+ * Get the number of lines in the scrollback.
+ */
+static int sblines(Terminal *term)
+{
+    int sblines = count234(term->scrollback);
+    if (term->cfg.erase_to_scrollback &&
+	term->alt_which && term->alt_screen) {
+	    sblines += term->alt_sblines;
+    }
+    return sblines;
+}
+
+/*
  * Retrieve a line of the screen or of the scrollback, according to
  * whether the y coordinate is non-negative or negative
  * (respectively).
@@ -124,8 +137,19 @@ static unsigned long *lineptr(Terminal *term, int y, int lineno)
 	whichtree = term->screen;
 	treeindex = y;
     } else {
-	whichtree = term->scrollback;
-	treeindex = y + count234(term->scrollback);
+	int altlines = 0;
+	if (term->cfg.erase_to_scrollback &&
+	    term->alt_which && term->alt_screen) {
+	    altlines = term->alt_sblines;
+	}
+	if (y < -altlines) {
+	    whichtree = term->scrollback;
+	    treeindex = y + altlines + count234(term->scrollback);
+	} else {
+	    whichtree = term->alt_screen;
+	    treeindex = y + term->alt_sblines;
+	    /* treeindex = y + count234(term->alt_screen); */
+	}
     }
     line = index234(whichtree, treeindex);
 
@@ -331,6 +355,8 @@ void term_clrsb(Terminal *term)
     while ((line = delpos234(term->scrollback, 0)) != NULL) {
 	sfree(line);
     }
+    term->tempsblines = 0;
+    term->alt_sblines = 0;
     update_sbar(term);
 }
 
@@ -374,6 +400,8 @@ 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;
     term->tabs = NULL;
@@ -446,6 +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;
     }
 
@@ -455,15 +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
@@ -471,32 +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;
@@ -504,6 +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));
@@ -519,6 +574,7 @@ void term_size(Terminal *term, int newrows, int newcols, int newsavelines)
 	freetree234(term->alt_screen);
     }
     term->alt_screen = newalt;
+    term->alt_sblines = 0;
 
     term->tabs = srealloc(term->tabs, newcols * sizeof(*term->tabs));
     {
@@ -527,8 +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)
@@ -565,6 +624,25 @@ void term_provide_resize_fn(Terminal *term,
 	resize_fn(resize_ctx, term->cols, term->rows);
 }
 
+/* Find the bottom line on the screen that has any content.
+ * If only the top line has content, returns 0.
+ * If no lines have content, return -1.
+ */ 
+static int find_last_nonempty_line(Terminal * term, tree234 * screen)
+{
+    int i;
+    for (i = count234(screen) - 1; i >= 0; i--) {
+	unsigned long *line = index234(screen, i);
+	int j;
+	int cols = line[0];
+	for (j = 0; j < cols; j++) {
+	    if (line[j + 1] != term->erase_char) break;
+	}
+	if (j != cols) break;
+    }
+    return i;
+}
+
 /*
  * Swap screens. If `reset' is TRUE and we have been asked to
  * switch to the alternate screen, we must bring most of its
@@ -586,6 +664,7 @@ static void swap_screen(Terminal *term, int which, int reset, int keep_cur_pos)
 	ttr = term->alt_screen;
 	term->alt_screen = term->screen;
 	term->screen = ttr;
+	term->alt_sblines = find_last_nonempty_line(term, term->alt_screen) + 1;
 	t = term->curs.x;
 	if (!reset && !keep_cur_pos)
 	    term->curs.x = term->alt_x;
@@ -643,10 +722,7 @@ static void swap_screen(Terminal *term, int which, int reset, int keep_cur_pos)
  */
 static void update_sbar(Terminal *term)
 {
-    int nscroll;
-
-    nscroll = count234(term->scrollback);
-
+    int nscroll = sblines(term);
     set_sbar(term->frontend, nscroll + term->rows,
 	     nscroll + term->disptop, term->rows);
 }
@@ -723,6 +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;
@@ -974,7 +1051,7 @@ static void erase_lots(Terminal *term,
 {
     pos start, end;
     int erase_lattr;
-    unsigned long *ldata;
+    int erasing_lines_from_top = 0;
 
     if (line_only) {
 	start.y = term->curs.y;
@@ -1004,19 +1081,44 @@ static void erase_lots(Terminal *term,
     if (start.y == 0 && start.x == 0 && end.y == term->rows)
 	term_invalidate(term);
 
-    ldata = lineptr(start.y);
-    while (poslt(start, end)) {
-	if (start.x == term->cols) {
-            if (!erase_lattr)
-                ldata[start.x] &= ~(LATTR_WRAPPED | LATTR_WRAPPED2);
-            else
-                ldata[start.x] = LATTR_NORM;
-        } else {
-	    ldata[start.x] = term->erase_char;
-        }
-	if (incpos(start) && start.y < term->rows)
-	    ldata = lineptr(start.y);
+    /* 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. */
+	int scrolllines = end.y;
+	if (end.y == term->rows) {
+	    /* Shrink until we find a non-empty row.*/
+	    scrolllines = find_last_nonempty_line(term, term->screen) + 1;
+	}
+	if (scrolllines > 0)
+	    scroll(term, 0, scrolllines - 1, scrolllines, TRUE);
+	fix_cpos;
+    } else {
+	unsigned long *ldata = lineptr(start.y);
+	while (poslt(start, end)) {
+	    if (start.x == term->cols) {
+		if (!erase_lattr)
+		    ldata[start.x] &= ~(LATTR_WRAPPED | LATTR_WRAPPED2);
+		else
+		    ldata[start.x] = LATTR_NORM;
+	    } else {
+		ldata[start.x] = term->erase_char;
+	    }
+	    if (incpos(start) && start.y < term->rows)
+		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;
 }
 
 /*
@@ -3428,7 +3530,7 @@ void term_paint(Terminal *term, Context ctx,
  */
 void term_scroll(Terminal *term, int rel, int where)
 {
-    int sbtop = -count234(term->scrollback);
+    int sbtop = -sblines(term);
 #ifdef OPTIMISE_SCROLL
     int olddisptop = term->disptop;
     int shift;
@@ -3605,7 +3707,7 @@ static void clipme(Terminal *term, pos top, pos bottom, int rect)
 void term_copyall(Terminal *term)
 {
     pos top;
-    top.y = -count234(term->scrollback);
+    top.y = -sblines(term);
     top.x = 0;
     clipme(term, top, term->curs, 0);
 }
@@ -3732,7 +3834,7 @@ static pos sel_spread_half(Terminal *term, pos p, int dir)
 {
     unsigned long *ldata;
     short wvalue;
-    int topy = -count234(term->scrollback);
+    int topy = -sblines(term);
 
     ldata = lineptr(p.y);
 
@@ -4602,7 +4704,7 @@ int term_ldisc(Terminal *term, int option)
 /*
  * from_backend(), to get data from the backend for the terminal.
  */
-int from_backend(void *vterm, int is_stderr, char *data, int len)
+int from_backend(void *vterm, int is_stderr, const char *data, int len)
 {
     Terminal *term = (Terminal *)vterm;