scrolling and whatnot

ke/Makefile

@@ -20,7 +20,7 @@ clean:
 .PHONY: run
 run: $(BIN)
 	reset
-	./$(BIN) escapes.txt
+	./$(BIN) notes.txt
 
 %.o: %.c
 	$(CC) $(CFLAGS) -c $@ $<

ke/keys.txt

@@ -6,19 +6,19 @@ ESC: 1b
 Function keys: 1b followed by
 
 F1	F2	F3	F4	F5	F6	F7	F8
-4f O	4f O	4f O	4f O	5b	5b	5b	5b
+4f O	4F O	4F O	4F O	5B	5B	5B	5B
 50 P	51 Q	52 R	54 S	31 1	31 1	31 1	31 1
 				35 5	37 7	38 8	39 9
-				7e ~	7e ~	7e ~	7e ~
+				7E ~	7E ~	7E ~	7E ~
 
 F9	F10	F11	F12
-5b [	5b [	5b [	5b [
+5B [	5B [	5B [	5B [
 32 2	32 2	32 2	32 2
 30 0	31 1	33 3	34 4
-7e ~	7e ~	7e ~	7e ~
+7E ~	7E ~	7E ~	7E ~
 
-DEL	7f	- but it should be a 4-byte escape sequence?
-BKSP	7f
+DEL	7F	- BUT IT SHOULD BE A 4-BYTE ESCAPE SEQUENCE?
+BKSP	7F
 
 Arrow keys: 1b followed by
 UP	DN	LF	RT

ke/main.c

@@ -1,3 +1,9 @@
+/*
+ * kyle's editor
+ *
+ * first version is a run-through of the kilo editor walkthrough.
+ * https://viewsourcecode.org/snaptoken/kilo/
+ */
 #include <sys/ioctl.h>
 #include <ctype.h>
 #include <errno.h>
@@ -39,7 +45,10 @@ void	disable_termraw();
 
 typedef struct erow {
 	char	*line;
+	char	*render;
+
 	int	 size;
+	int	 rsize;
 } erow;
 
 struct {
@@ -48,6 +57,7 @@ struct {
 	int		 curx, cury;
 	int		 mode;
 	int		 nrows;
+	int		 rowoffs, coloffs;
 	erow		*row;
 } editor;
 
@@ -131,6 +141,10 @@ append_row(char *s, size_t len)
 	editor.row[at].line = malloc(len+1);
 	memcpy(editor.row[at].line, s, len);
 	editor.row[at].line[len] = '\0';
+
+	editor.row[at].rsize = 0;
+	editor.row[at].render = NULL;
+
 	editor.nrows++;
 }
 
@@ -241,65 +255,47 @@ get_keypress()
 }
 
 
-static inline void
-ymov(int dy)
-{
-	editor.cury += dy;
-	if (editor.cury < 0) {
-		editor.cury = 0;
-	} else if (editor.cury > editor.rows) {
-		/* 
-		 * NOTE(kyle): this should be restrited to buffer lines,
-		 * but we don't have a buffer yet.
-		 */
-		editor.cury = editor.rows;
-	}
-}
-
-
-static inline void
-xmov(int dx)
-{
-	editor.curx += dx;
-	if (editor.curx < 0) {
-		editor.curx = 0;
-		ymov(-1);
-	} else if (editor.curx > editor.cols) {
-		if (editor.cury == editor.rows) {
-			editor.curx = editor.cols;
-		} else {
-			editor.curx = 0;
-		}
-		ymov(1);
-	}
-}
-
-
 void
 move_cursor(int16_t c)
 {
+	erow	*row = (editor.cury >= editor.nrows) ?
+		       NULL : &editor.row[editor.cury];
 	int	 reps;
 
 	switch (c) {
 	case ARROW_UP:
 	case CTRL_KEY('p'):
-		ymov(-1);
+		if (editor.cury > 0) {
+			editor.cury--;
+		}
 		break;
 	case ARROW_DOWN:
 	case CTRL_KEY('n'):
-		ymov(1);
+		if (editor.cury < editor.nrows) {
+			editor.cury++;
+		}
 		break;
 	case ARROW_RIGHT:
 	case CTRL_KEY('f'):
-		xmov(1);
+		if (row && editor.curx < row->size) {
+			editor.curx++;
+		} else if (row && editor.curx == row->size) {
+			editor.cury++;
+			editor.curx = 0;
+		}
 		break;
 	case ARROW_LEFT:
 	case CTRL_KEY('b'):
-		xmov(-1);
+		if (editor.curx > 0) {
+			editor.curx--;
+		} else if (editor.cury > 0) {
+			editor.cury--;
+			editor.curx = editor.row[editor.cury].size;
+		}
 		break;
 	case PG_UP:
 	case PG_DN: {
-		reps = editor.rows;
+		reps = editor.rows+1;
 		while (--reps) {
 			move_cursor(c == PG_UP ? ARROW_UP : ARROW_DOWN);
 		}
@@ -314,6 +310,14 @@ move_cursor(int16_t c)
 	default:
 		break;
 	}
+
+
+	row = (editor.cury >= editor.nrows) ?
+	      NULL : &editor.row[editor.cury];
+	reps = row ? row->size : 0;
+	if (editor.curx > reps) {
+		editor.curx = reps;
+	}
 }
 
 
@@ -444,11 +448,12 @@ void
 draw_rows(struct abuf *ab)
 {
 	char	buf[editor.cols];
-	int	buflen, padding;
+	int	buflen, filerow, padding;
 	int	y;
 
 	for (y = 0; y < editor.rows; y++) {
-		if (y >= editor.nrows) {
+		filerow = y + editor.rowoffs;
+		if (filerow >= editor.nrows) {
 			if ((editor.nrows == 0) && (y == editor.rows / 3)) {
 				buflen = snprintf(buf, sizeof(buf),
 					"ke k%s", KE_VERSION);
@@ -465,11 +470,16 @@ draw_rows(struct abuf *ab)
 				ab_append(ab, "|", 1);
 			}
 		} else {
-			buflen = editor.row[y].size;
-			if (buflen > editor.rows) {
-				buflen = editor.rows;
+			buflen = editor.row[filerow].size - editor.coloffs;
+			if (buflen < 0) {
+				buflen = 0;
 			}
-			ab_append(ab, editor.row[y].line, buflen);
+
+			if (buflen > editor.cols) {
+				buflen = editor.cols;
+			}
+			ab_append(ab, editor.row[filerow].line+editor.coloffs,
+				  buflen);
 		}
 		ab_append(ab, ESCSEQ "K", 3);
 		if (y < (editor.rows - 1)) {
@@ -479,19 +489,43 @@ draw_rows(struct abuf *ab)
 }
 
 
+void
+scroll()
+{
+	if (editor.cury < editor.rowoffs) {
+		editor.rowoffs = editor.cury;
+	}
+
+	if (editor.cury >= editor.rowoffs + editor.rows) {
+		editor.rowoffs = editor.cury - editor.rows + 1;
+	}
+
+	if (editor.curx < editor.coloffs) {
+		editor.coloffs = editor.curx;
+	}
+
+	if (editor.curx >= editor.coloffs + editor.cols) {
+		editor.coloffs = editor.curx - editor.cols + 1;
+	}
+}
+
+
 void
 display_refresh()
 {
 	char		buf[32];
 	struct abuf	ab = ABUF_INIT;
 
+	scroll();
+
 	ab_append(&ab, ESCSEQ "?25l", 6);
 	display_clear(&ab);
 
 	draw_rows(&ab);
 	
-	snprintf(buf, sizeof(buf), ESCSEQ "%d;%dH", editor.cury+1,
-		 editor.curx+1);
+	snprintf(buf, sizeof(buf), ESCSEQ "%d;%dH",
+		 (editor.cury-editor.rowoffs)+1,
+		 (editor.curx-editor.coloffs)+1);
 	ab_append(&ab, buf, strnlen(buf, 32));
 	/* ab_append(&ab, ESCSEQ "1;2H", 7); */
 	ab_append(&ab, ESCSEQ "?25h", 6);
@@ -521,10 +555,10 @@ init_editor()
 		die("can't get window size");
 	}
 
-	editor.curx = 0;
-	editor.cury = 0;
+	editor.curx = editor.cury = 0;
 
 	editor.nrows = 0;
+	editor.rowoffs = editor.coloffs = 0;
 	editor.row = NULL;
 }
 

ke/notes.txt

@@ -85,3 +85,7 @@ enable_termraw()
 		die("tcsetattr while enabling raw mode");
 	}
 }
+
+So this is a really long line; it should overflow the buffer and it's helpful for doing things like testing horizontal scrolling. Furthermore, it's at least twice as long as the line is likely to be, so there's more opportunity to test whether scrolling works correctly.
+
+But this line is nominal.