From d7ae78179cf18bc79703ac2199e0ae03e556430f Mon Sep 17 00:00:00 2001
From: Leo Tenenbaum <pommicket@gmail.com>
Date: Thu, 31 Dec 2020 14:11:25 -0500
Subject: page up/down

---
 buffer.c  | 8 ++++++++
 command.c | 7 +++++++
 command.h | 9 +++++++--
 ted.cfg   | 7 +++++++
 4 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/buffer.c b/buffer.c
index e699548..c79a2df 100644
--- a/buffer.c
+++ b/buffer.c
@@ -695,6 +695,14 @@ void buffer_scroll(TextBuffer *buffer, double dx, double dy) {
 	buffer_correct_scroll(buffer);
 }
 
+void buffer_page_up(TextBuffer *buffer, i64 npages) {
+	buffer_scroll(buffer, 0, (double)(-npages * buffer_display_lines(buffer)));
+}
+
+void buffer_page_down(TextBuffer *buffer, i64 npages) {
+	buffer_scroll(buffer, 0, (double)(+npages * buffer_display_lines(buffer)));
+}
+
 // returns the position of the character at the given position in the buffer.
 v2 buffer_pos_to_pixels(TextBuffer *buffer, BufferPos pos) {
 	u32 line = pos.line, index = pos.index;
diff --git a/command.c b/command.c
index 4f1bb89..69ce9ee 100644
--- a/command.c
+++ b/command.c
@@ -100,6 +100,13 @@ void command_execute(Ted *ted, Command c, i64 argument) {
 	case CMD_DELETE_WORD:
 		buffer_delete_words_at_cursor(buffer, argument);
 		break;
+
+	case CMD_PAGE_DOWN:
+		buffer_page_down(buffer, argument);
+		break;
+	case CMD_PAGE_UP:
+		buffer_page_up(buffer, argument);
+		break;
 	
 	case CMD_SAVE:
 		buffer_save(buffer);
diff --git a/command.h b/command.h
index df6bf74..1057b4b 100644
--- a/command.h
+++ b/command.h
@@ -23,6 +23,10 @@ ENUM_U16 {
 	CMD_SELECT_START_OF_FILE,
 	CMD_SELECT_END_OF_FILE,
 
+	// scrolling
+	CMD_PAGE_UP,
+	CMD_PAGE_DOWN,
+
 	// deletion
 	CMD_BACKSPACE,
 	CMD_DELETE,
@@ -40,7 +44,6 @@ typedef struct {
 	char const *name;
 	Command cmd;
 } CommandName;
-
 static CommandName const command_names[CMD_COUNT] = {
 	{"unknown", CMD_UNKNOWN},
 	{"noop", CMD_NOOP},
@@ -64,12 +67,14 @@ static CommandName const command_names[CMD_COUNT] = {
 	{"end-of-file", CMD_END_OF_FILE},
 	{"select-start-of-file", CMD_SELECT_START_OF_FILE},
 	{"select-end-of-file", CMD_SELECT_END_OF_FILE},
+	{"page-up", CMD_PAGE_UP},
+	{"page-down", CMD_PAGE_DOWN},
 	{"backspace", CMD_BACKSPACE},
 	{"delete", CMD_DELETE},
 	{"backspace-word", CMD_BACKSPACE_WORD},
 	{"delete-word", CMD_DELETE_WORD},
 	{"save", CMD_SAVE},
 	{"undo", CMD_UNDO},
-	{"redo", CMD_REDO}
+	{"redo", CMD_REDO},
 };
 
diff --git a/ted.cfg b/ted.cfg
index ff97637..ba0ffb5 100644
--- a/ted.cfg
+++ b/ted.cfg
@@ -31,6 +31,13 @@ Ctrl+Delete = :delete-word
 Backspace = :backspace
 Ctrl+Backspace = :backspace-word
 
+# scrolling
+PageUp = :page-up
+PageDown = :page-down
+Ctrl+PageUp = 10 :page-up
+Ctrl+PageDown = 10 :page-down
+
 Ctrl+s = :save
 Ctrl+z = :undo
 Ctrl+Shift+z = :redo
+
-- 
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