moving on screen

Makefile

@@ -10,7 +10,7 @@ BUILD_DIR=build
 
 BUILD_FLAGS=-Wall -Wextra -pedantic
 
-build: main.c main.h
+build: main.c
 	if [ ! -d beluga-output ]; then mkdir beluga-output; fi
 	if [ ! -d beluga-output/build ]; then mkdir beluga-output/build; fi
 	$(CC) main.c -o $(BELUGA_OUTPUT)/$(BUILD_DIR)/beluga $(BUILD_FLAGS)
@@ -20,7 +20,7 @@ DEBUG_DIR=debug
 
 DEBUG_FLAGS=-Wall -Wextra -pedantic -Werror -fsanitize=address,undefined -g
 
-debug:  main.c main.h
+debug:  main.c
 	if [ ! -d beluga-output ]; then mkdir beluga-output; fi
 	if [ ! -d beluga-output/debug ]; then mkdir beluga-output/debug; fi
 	$(CC) main.c -o $(BELUGA_OUTPUT)/$(DEBUG_DIR)/beluga $(DEBUG_FLAGS)

main.c

@@ -5,19 +5,36 @@
  * interactions. \version 0.1 \date 21 septembre 2024
  */
 
-#include "main.h"
 #include <asm-generic/ioctls.h>
-#include <ctype.h>
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <sys/ioctl.h>
 #include <termios.h>
+#include <time.h>
 #include <unistd.h>
 
 /* defines */
+#define BELUGA_VERSION "0.1"
+
 #define CTRL_KEY(k) ((k) & 0x1f)
+
 #define CURSOR_TOP_LEFT "\x1b[H"
+#define HIDE_CURSOR "\x1b[?25l"
+#define SHOW_CURSOR "\x1b[?25h"
+#define ERASE_END_LINE "\x1b[K"
+
+#define ABUF_INIT {NULL, 0}
+
+enum editorKey {
+  CURSOR_UP = 1000,
+  CURSOR_DOWN,
+  CURSOR_LEFT,
+  CURSOR_RIGHT,
+  PAGE_UP,
+  PAGE_DOWN
+};
 
 /* data */
 /**
@@ -25,11 +42,17 @@
  * \brief Containing our editor state.
  */
 struct editorConfig {
+  int cursor_x, cursor_y;
   int screenrows;
   int screencols;
   struct termios orig_termios;
 };
 
+struct abuf {
+  char *b;
+  int len;
+};
+
 struct editorConfig E;
 
 /* terminal */
@@ -40,7 +63,8 @@ struct editorConfig E;
  * \param *s Error string
  * */
 void die(const char *s) {
-  wipeScreen();
+  write(STDOUT_FILENO, "\x1b[2J", 4);
+  write(STDOUT_FILENO, CURSOR_TOP_LEFT, 3);
   perror(s);
   exit(1);
 }
@@ -70,16 +94,53 @@ void enableRawMode() {
   }
 }
 
-char editorReadKey() {
+int editorReadKey() {
   int nread;
   char c;
+  char seq[3];
   while ((nread = read(STDIN_FILENO, &c, 1)) != 1) {
     if (nread == -1 && errno != EAGAIN) {
       die("read");
     }
   }
+
+  if (c == '\x1b') {
+    if (read(STDIN_FILENO, &seq[0], 1) != 1 ||
+        read(STDIN_FILENO, &seq[1], 1) != 1) {
+      return '\x1b';
+    }
+    if (seq[0] == '[') {
+      if (seq[1] >= '0' && seq[1] <= '9') {
+        if (read(STDIN_FILENO, &seq[2], 1) != 1) {
+          return '\x1b';
+        }
+        if (seq[2] == '~') {
+          switch (seq[1]) {
+          case '5':
+            return PAGE_UP;
+          case '6':
+            return PAGE_DOWN;
+          }
+        }
+      } else {
+
+        switch (seq[1]) {
+        case 'A':
+          return CURSOR_UP;
+        case 'B':
+          return CURSOR_DOWN;
+        case 'C':
+          return CURSOR_LEFT;
+        case 'D':
+          return CURSOR_RIGHT;
+        }
+      }
+    }
+    return '\x1b';
+  } else {
     return c;
   }
+}
 
 int getCursorPosition(int *rows, int *cols) {
   char buf[32];
@@ -125,34 +186,74 @@ int getWindowSize(int *rows, int *cols) {
   }
 }
 
-/* output */
+/* append buffer */
+void abAppend(struct abuf *ab, const char *s, int len) {
+  char *new = realloc(ab->b, ab->len + len);
 
-/** \fn void wipeScreen()
+  if (new == NULL) {
- * \brief Wipe the terminal screen and put the cursor on the top left corner.
+    return;
- * */
+  }
-void wipeScreen() {
+  memcpy(&new[ab->len], s, len);
-  /* Clear the screen */
+  ab->b = new;
-  write(STDOUT_FILENO, "\x1b[2J", 4);
+  ab->len += len;
-  /* Put the cursor at the top left corner */
-  write(STDOUT_FILENO, CURSOR_TOP_LEFT, 3);
 }
 
+void abFree(struct abuf *ab) { free(ab->b); }
+
+/* output */
+
 /**
- * \fn void editorDrawRows()
+ * \fn void editorDrawRows(struct abuf *ab)
  * \brief Draws left rows of the editor.
  */
-void editorDrawRows() {
+void editorDrawRows(struct abuf *ab) {
   int y;
+  char welcome[80];
+  int welcome_len;
+  int padding;
   for (y = 0; y < E.screenrows; ++y) {
-    write(STDOUT_FILENO, "~\r\n", 3);
+    if (y == E.screenrows / 3) {
+      welcome_len =
+          snprintf(welcome, sizeof(welcome), "Beluga text editor -- version %s",
+                   BELUGA_VERSION);
+      if (welcome_len > E.screencols) {
+        welcome_len = E.screencols;
+      }
+      padding = (E.screencols - welcome_len) / 2;
+      if (padding) {
+        abAppend(ab, "~", 1);
+        --padding;
+      }
+      while (padding--) {
+        abAppend(ab, " ", 1);
+      }
+      abAppend(ab, welcome, welcome_len);
+    } else {
+      abAppend(ab, "~", 1);
+    }
+    abAppend(ab, ERASE_END_LINE, 3);
+    if (y < E.screenrows - 1) {
+      abAppend(ab, "\r\n", 2);
+    }
   }
 }
 
 void editorRefreshScreen() {
-  wipeScreen();
+  struct abuf ab = ABUF_INIT;
-  editorDrawRows();
+  char buf[32];
 
-  write(STDOUT_FILENO, CURSOR_TOP_LEFT, 3);
+  abAppend(&ab, HIDE_CURSOR, 6);
+  abAppend(&ab, CURSOR_TOP_LEFT, 3);
+
+  editorDrawRows(&ab);
+
+  snprintf(buf, sizeof(buf), "\x1b[%d;%dH", E.cursor_y + 1, E.cursor_x + 1);
+  abAppend(&ab, buf, strlen(buf));
+
+  abAppend(&ab, SHOW_CURSOR, 6);
+
+  write(STDOUT_FILENO, ab.b, ab.len);
+  abFree(&ab);
 }
 
 /* input */
@@ -161,14 +262,57 @@ void editorRefreshScreen() {
  * \fn void editorProcessKeypress()
  * \brief Get the last key input and do the proper action.
  */
+
+void editorMoveCursor(int key) {
+  switch (key) {
+  case CURSOR_LEFT:
+    if (E.cursor_x != 0) {
+      --E.cursor_x;
+    }
+    break;
+  case CURSOR_DOWN:
+    if (E.cursor_x != E.screencols - 1) {
+      ++E.cursor_y;
+    }
+    break;
+  case CURSOR_UP:
+    if (E.cursor_y != 0) {
+      --E.cursor_y;
+    }
+    break;
+  case CURSOR_RIGHT:
+    if (E.cursor_y != E.screenrows - 1) {
+      ++E.cursor_x;
+    }
+    break;
+  }
+}
+
 void editorProcessKeypress() {
-  char c = editorReadKey();
+  int c = editorReadKey();
+  int times;
 
   switch (c) {
   case CTRL_KEY('q'):
-    wipeScreen();
+    write(STDOUT_FILENO, "\x1b[2J", 4);
+    write(STDOUT_FILENO, CURSOR_TOP_LEFT, 3);
     exit(0);
     break;
+
+  case PAGE_UP:
+  case PAGE_DOWN: {
+    times = E.screenrows;
+    while (--times) {
+      editorMoveCursor(c == PAGE_UP ? CURSOR_UP : CURSOR_DOWN);
+    }
+  } break;
+
+  case CURSOR_UP:
+  case CURSOR_DOWN:
+  case CURSOR_LEFT:
+  case CURSOR_RIGHT:
+    editorMoveCursor(c);
+    break;
   }
 }
 
@@ -179,6 +323,8 @@ void editorProcessKeypress() {
  * \brief Job's function is to initialize all the fields of editorConfig.
  * */
 void initEditor() {
+  E.cursor_x = 0;
+  E.cursor_y = 0;
   if (getWindowSize(&E.screenrows, &E.screencols) == -1) {
     die("getWindowSize");
   }

main.h

@@ -1,17 +0,0 @@
-#ifndef MAIN_H
-#define MAIN_H
-/* terminal */
-
-void die(const char *s);
-void disableRawMode();
-void enableRawMode();
-char editorReadKey();
-
-/* output */
-void wipeScreen();
-void editorDrawRows();
-void editorRefreshScreen();
-
-/* input */
-void editorProcessKeypress();
-#endif