added support for alternate screen.

1 files changed, 56 insertions, 14 deletions

diff --git a/st.c b/st.c
index 73121ef..d928f0d 100644
--- a/st.c
+++ b/st.c
@@ -50,7 +50,7 @@ enum { CURSOR_UP, CURSOR_DOWN, CURSOR_LEFT, CURSOR_RIGHT,
        CURSOR_SAVE, CURSOR_LOAD };
 enum { CURSOR_DEFAULT = 0, CURSOR_HIDE = 1, CURSOR_WRAPNEXT = 2 };
 enum { GLYPH_SET=1, GLYPH_DIRTY=2 };
-enum { MODE_WRAP=1, MODE_INSERT=2, MODE_APPKEYPAD=4 };
+enum { MODE_WRAP=1, MODE_INSERT=2, MODE_APPKEYPAD=4, MODE_ALTSCREEN=8 };
 enum { ESC_START=1, ESC_CSI=2, ESC_OSC=4, ESC_TITLE=8, ESC_ALTCHARSET=16 };
 enum { SCREEN_UPDATE, SCREEN_REDRAW };
 
@@ -86,7 +86,8 @@ typedef struct {
 typedef struct {
         int row;        /* nb row */  
         int col;        /* nb col */
-        Line* line; /* screen */
+        Line* line;     /* screen */
+        Line* alt;      /* alternate screen */
         TCursor c;      /* cursor */
         int top;        /* top    scroll limit */
         int bot;        /* bottom scroll limit */
@@ -156,6 +157,7 @@ static void tscrolldown(int);
 static void tsetattr(int*, int);
 static void tsetchar(char);
 static void tsetscroll(int, int);
+static void tswapscreen(void);
 
 static void ttynew(void);
 static void ttyread(void);
@@ -337,13 +339,24 @@ tnew(int col, int row) {
         /* set screen size */
         term.row = row, term.col = col;
         term.line = malloc(term.row * sizeof(Line));
-        for(row = 0 ; row < term.row; row++)
+        term.alt  = malloc(term.row * sizeof(Line));
+        for(row = 0 ; row < term.row; row++) {
                 term.line[row] = malloc(term.col * sizeof(Glyph));
+                term.alt [row] = malloc(term.col * sizeof(Glyph));
+        }
         /* setup screen */
         treset();
 }
 
 void
+tswapscreen(void) {
+        Line* tmp = term.line;
+        term.line = term.alt;
+        term.alt = tmp;
+        term.mode ^= MODE_ALTSCREEN;
+}
+
+void
 tscrolldown (int n) {
         int i;
         Line temp;
@@ -712,10 +725,21 @@ csihandle(void) {
                         case 25:
                                 term.c.state |= CURSOR_HIDE;
                                 break;
-                        case 1048: /* XXX: no alt. screen to erase/save */
+                        case 1047:
+                                if(IS_SET(MODE_ALTSCREEN)) {
+                                        tclearregion(0, 0, term.col-1, term.row-1);
+                                        tswapscreen();
+                                }
+                                break;
+                        case 1048:
+                                tcursor(CURSOR_LOAD);
+                                break;
                         case 1049:
                                 tcursor(CURSOR_LOAD);
-                                tclearregion(0, 0, term.col-1, term.row-1);
+                                if(IS_SET(MODE_ALTSCREEN)) {
+                                        tclearregion(0, 0, term.col-1, term.row-1);
+                                        tswapscreen();
+                                }
                                 break;
                         default:
                                 goto unknown;
@@ -761,10 +785,21 @@ csihandle(void) {
                         case 25:
                                 term.c.state &= ~CURSOR_HIDE;
                                 break;
-                        case 1048: 
-                        case 1049: /* XXX: no alt. screen to erase/save */
+                        case 1047:
+                                if(IS_SET(MODE_ALTSCREEN))
+                                        tclearregion(0, 0, term.col-1, term.row-1);
+                                else
+                                        tswapscreen();
+                                break;                          
+                        case 1048:
+                                tcursor(CURSOR_SAVE);
+                                break;
+                        case 1049:
                                 tcursor(CURSOR_SAVE);
-                                tclearregion(0, 0, term.col-1, term.row-1);
+                                if(IS_SET(MODE_ALTSCREEN))
+                                        tclearregion(0, 0, term.col-1, term.row-1);
+                                else
+                                        tswapscreen();
                                 break;
                         default: goto unknown;
                         }
@@ -889,19 +924,19 @@ tputc(char c) {
                                 treset();
                                 term.esc = 0;
                                 break;
-                        case '=': /* DECPAM */
+                        case '=': /* DECPAM -- Application keypad */
                                 term.mode |= MODE_APPKEYPAD;
                                 term.esc = 0;
                                 break;
-                        case '>': /* DECPNM */
+                        case '>': /* DECPNM -- Normal keypad */
                                 term.mode &= ~MODE_APPKEYPAD;
                                 term.esc = 0;
                                 break;
-                        case '7':
+                        case '7': /* DECSC -- Save Cursor*/
                                 tcursor(CURSOR_SAVE);
                                 term.esc = 0;
                                 break;
-                        case '8':
+                        case '8': /* DECRC -- Restore Cursor */
                                 tcursor(CURSOR_LOAD);
                                 term.esc = 0;
                                 break;
@@ -961,21 +996,28 @@ tresize(int col, int row) {
                 return;
 
         /* free uneeded rows */
-        for(i = row; i < term.row; i++)
+        for(i = row; i < term.row; i++) {
                 free(term.line[i]);
+                free(term.alt[i]);
+        }
 
         /* resize to new height */
         term.line = realloc(term.line, row * sizeof(Line));
+        term.line = realloc(term.alt,  row * sizeof(Line));
 
         /* resize each row to new width, zero-pad if needed */
         for(i = 0; i < minrow; i++) {
                 term.line[i] = realloc(term.line[i], col * sizeof(Glyph));
+                term.alt[i]  = realloc(term.alt[i],  col * sizeof(Glyph));
                 memset(term.line[i] + mincol, 0, (col - mincol) * sizeof(Glyph));
+                memset(term.alt[i]  + mincol, 0, (col - mincol) * sizeof(Glyph));
         }
 
         /* allocate any new rows */
-        for(/* i == minrow */; i < row; i++)
+        for(/* i == minrow */; i < row; i++) {
                 term.line[i] = calloc(col, sizeof(Glyph));
+                term.alt [i] = calloc(col, sizeof(Glyph));
+        }
         
         /* update terminal size */
         term.col = col, term.row = row;