From 521263a2c67d2b5df507858dcd240a9e42790780 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marc=20Andr=C3=A9=20Tanner?= <mat@brain-dump.org>
Date: Sat, 27 Sep 2014 19:51:29 +0200
Subject: Implement 'zt', 'zz', 'zb'

In particular 'zb' might not work if there are wrapped lines involved.
---
 config.def.h |  3 +++
 vis.c        |  8 +++++++-
 window.c     | 42 ++++++++++++++++++++++++++++++++++++++++++
 window.h     |  4 ++++
 4 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/config.def.h b/config.def.h
index ebc9057..484b152 100644
--- a/config.def.h
+++ b/config.def.h
@@ -402,6 +402,9 @@ static KeyBinding vis_mode_normal[] = {
 	{ { NONE(':')               }, prompt,         { .s = ":"                  } },
 	{ { NONE('Z'), NONE('Z')    }, cmd,            { .s = "wq"                 } },
 	{ { NONE('Z'), NONE('Q')    }, cmd,            { .s = "q!"                 } },
+	{ { NONE('z'), NONE('t')    }, window,         { .w = window_redraw_top    } },
+	{ { NONE('z'), NONE('z')    }, window,         { .w = window_redraw_center } },
+	{ { NONE('z'), NONE('b')    }, window,         { .w = window_redraw_bottom } },
 	{ /* empty last element, array terminator */                                 },
 };
 
diff --git a/vis.c b/vis.c
index f2da978..9127c9e 100644
--- a/vis.c
+++ b/vis.c
@@ -48,7 +48,7 @@ typedef union {
 	bool b;
 	int i;
 	const char *s;
-	size_t (*m)(Win*);  /* cursor movement based on window content */
+	void (*w)(Win*);    /* generic window commands */
 	void (*f)(Editor*); /* generic editor commands */
 } Arg;
 
@@ -449,6 +449,8 @@ static void wscroll(const Arg *arg);
 static void wslide(const Arg *arg);
 /* call editor function as indicated by arg->f */
 static void call(const Arg *arg);
+/* call window function as indicated by arg->w */
+static void window(const Arg *arg);
 /* quit editor, discard all changes */
 static void quit(const Arg *arg);
 
@@ -981,6 +983,10 @@ static void call(const Arg *arg) {
 	arg->f(vis);
 }
 
+static void window(const Arg *arg) {
+	arg->w(vis->win->win);
+}
+
 static void insert(const Arg *arg) {
 	editor_insert_key(vis, arg->s, arg->s ? strlen(arg->s) : 0);
 }
diff --git a/window.c b/window.c
index cb22f56..43bae70 100644
--- a/window.c
+++ b/window.c
@@ -639,6 +639,48 @@ static bool window_viewport_up(Win *win, int n) {
 	return true;
 }
 
+void window_redraw_top(Win *win) {
+	Line *line = win->cursor.line;
+	for (Line *cur = win->topline; cur && cur != line; cur = cur->next)
+		win->start += cur->len;
+	window_draw(win);
+	window_cursor_to(win, win->cursor.pos);
+}
+
+void window_redraw_center(Win *win) {
+	int center = win->height / 2;
+	size_t pos = win->cursor.pos;
+	for (int i = 0; i < 2; i++) {
+		int linenr = 0;
+		Line *line = win->cursor.line;
+		for (Line *cur = win->topline; cur && cur != line; cur = cur->next)
+			linenr++;
+		if (linenr < center) {
+			window_slide_down(win, center - linenr);
+			continue;
+		}
+		for (Line *cur = win->topline; cur && cur != line && linenr > center; cur = cur->next) {
+			win->start += cur->len;
+			linenr--;
+		}
+		break;
+	}
+	window_draw(win);
+	window_cursor_to(win, pos);
+}
+
+void window_redraw_bottom(Win *win) {
+	Line *line = win->cursor.line;
+	if (line == win->lastline)
+		return;
+	int linenr = 0;
+	size_t pos = win->cursor.pos;
+	for (Line *cur = win->topline; cur && cur != line; cur = cur->next)
+		linenr++;
+	window_slide_down(win, win->height - linenr - 1);
+	window_cursor_to(win, pos);
+}
+
 size_t window_slide_up(Win *win, int lines) {
 	Cursor *cursor = &win->cursor;
 	if (window_viewport_down(win, lines)) {
diff --git a/window.h b/window.h
index 6c4b72f..4d00b48 100644
--- a/window.h
+++ b/window.h
@@ -58,6 +58,10 @@ void window_scroll_to(Win*, size_t pos);
  * position is visible. if the position is in the middle of a line, try to
  * adjust the viewport in such a way that the whole line is displayed */
 void window_cursor_to(Win*, size_t pos);
+/* redraw current cursor line at top/center/bottom of window */
+void window_redraw_top(Win*);
+void window_redraw_center(Win*);
+void window_redraw_bottom(Win*);
 /* start selected area at current cursor position. further cursor movements will
  * affect the selected region. */
 void window_selection_start(Win*);
-- 
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