add some ncurses snippets

Ncurses/scrollfile.c

@@ -0,0 +1,128 @@
+#include <ncurses.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#define MAXLEN 128
+
+typedef struct Line {
+    char contents[MAXLEN];
+    struct Line *prev, *next;
+} Line;
+
+#define MAXSTRL 120
+char inputstr[MAXSTRL+1] = {0};
+int currinp = 0;
+
+Line *head, *curr;
+
+int refreshmain = 1, refreshstr = 1;
+
+int nr_lines;
+int curr_line;
+WINDOW *mainwin, *onestring;
+
+int term_rows, term_cols;
+
+void load(const char *filename);
+void draw(Line *l);
+
+int main(int argc, char **argv)
+{
+    if (argc == 1)
+    {
+        fputs("less: No file to open\n", stderr);
+        return 1;
+    }
+
+    initscr();
+    noecho();
+    getmaxyx(stdscr, term_rows, term_cols);
+    term_rows -= 2;
+    mainwin = newwin(term_rows, term_cols, 0, 0);
+    onestring = newwin(1, term_cols, term_rows+1, 0);
+    keypad(onestring, TRUE);   // for KEY_UP, KEY_DOWN
+
+    waddstr(mainwin, "Reading text...\n");
+    wrefresh(mainwin);
+    sleep(1);
+    load(argv[1]);
+
+    curr = head;
+    curr_line = 0;
+
+    draw(curr);
+
+    int ch;
+    while ((ch = wgetch(onestring)) != EOF)
+    {
+        if (ch == KEY_UP && curr->prev != NULL)
+        {
+            curr_line--;
+            curr = curr->prev;
+            refreshmain = 1;
+        }
+        else if (ch == KEY_DOWN && curr->next != NULL
+            && curr_line + term_rows < nr_lines)
+        {
+            curr_line++;
+            curr = curr->next;
+            refreshmain = 1;
+        }
+        else if(ch == 10){
+            currinp = 0;
+            inputstr[0] = 0;
+            refreshstr = 1;
+        }else if(ch >= ' ' && ch < 256 && ch != 127){
+            if(currinp > MAXSTRL){
+                wclear(onestring);
+                waddstr(onestring, "Limit reached!");
+                wrefresh(onestring);
+            }else{
+                inputstr[currinp++] = ch;
+                inputstr[currinp] = 0;
+            }
+            refreshstr = 1;
+        }
+        draw(curr);
+    }
+
+    endwin();
+    return 0;
+}
+
+void load(const char *filename)
+{
+    FILE *fp = fopen(filename, "r");
+    Line *lp;
+
+    head = malloc(sizeof(Line));
+    head->prev = head->next = NULL;
+    curr = head;
+
+    while (fgets(curr->contents, MAXLEN, fp))
+    {
+        lp = malloc(sizeof(Line));
+        lp->prev = curr;
+        curr->next = lp;
+        curr = lp;
+        nr_lines++;
+    }
+    curr->next = NULL;
+}
+
+void draw(Line *l)
+{
+    if(refreshmain){
+        refreshmain = 0;
+        wclear(mainwin);
+        for(int i = 0; i < term_rows && l != NULL; i++, l = l->next)
+            waddstr(mainwin, l->contents);
+        wrefresh(mainwin);
+    }
+    if(refreshstr){
+        refreshstr = 0;
+        wclear(onestring);
+        wprintw(onestring, " > %s", inputstr);
+        wrefresh(onestring);
+    }
+}