From 5c4279a654a4b75dd9f8f3dbca3fb799506174fc Mon Sep 17 00:00:00 2001
From: Thomas Goyne <plorkyeran@aegisub.org>
Date: Thu, 6 Jun 2013 18:57:14 -0700
Subject: [PATCH] Add command "edit/line/duplicate/shift_back"

---
 aegisub/src/command/edit.cpp | 42 ++++++++++++++++++++++++++----------
 1 file changed, 31 insertions(+), 11 deletions(-)

diff --git a/aegisub/src/command/edit.cpp b/aegisub/src/command/edit.cpp
index 41d28e713..74037372e 100644
--- a/aegisub/src/command/edit.cpp
+++ b/aegisub/src/command/edit.cpp
@@ -571,7 +571,8 @@ struct in_selection : public std::unary_function<AssEntry, bool> {
 	}
 };
 
-static void duplicate_lines(agi::Context *c, bool shift) {
+template<typename Func>
+static void duplicate_lines(agi::Context *c, Func&& shift) {
 	in_selection sel(c->selectionController->GetSelectedSet());
 	SubtitleSelectionController::Selection new_sel;
 	AssDialogue *new_active = 0;
@@ -596,12 +597,7 @@ static void duplicate_lines(agi::Context *c, bool shift) {
 			new_sel.insert(new_diag);
 			if (!new_active)
 				new_active = new_diag;
-
-			if (shift) {
-				int pos = c->videoController->FrameAtTime(new_diag->End, agi::vfr::END) + 1;
-				new_diag->Start = c->videoController->TimeAtFrame(pos, agi::vfr::START);
-				new_diag->End = c->videoController->TimeAtFrame(pos, agi::vfr::END);
-			}
+			shift(new_diag);
 		} while (start++ != last);
 
 		// Skip over the lines we just made
@@ -623,17 +619,16 @@ struct edit_line_duplicate : public validate_sel_nonempty {
 	STR_HELP("Duplicate the selected lines")
 
 	void operator()(agi::Context *c) {
-		duplicate_lines(c, false);
+		duplicate_lines(c, [](AssDialogue *){});
 	}
 };
 
-
 /// Duplicate lines and shift by one frame.
 struct edit_line_duplicate_shift : public Command {
 	CMD_NAME("edit/line/duplicate/shift")
 	STR_MENU("D&uplicate and Shift by 1 Frame")
 	STR_DISP("Duplicate and Shift by 1 Frame")
-	STR_HELP("Duplicate lines and shift by one frame")
+	STR_HELP("Duplicate lines and shift them to the frame after the original end frame")
 	CMD_TYPE(COMMAND_VALIDATE)
 
 	bool Validate(const agi::Context *c) {
@@ -641,7 +636,31 @@ struct edit_line_duplicate_shift : public Command {
 	}
 
 	void operator()(agi::Context *c) {
-		duplicate_lines(c, true);
+		duplicate_lines(c, [=](AssDialogue *new_diag) {
+			int pos = c->videoController->FrameAtTime(new_diag->End, agi::vfr::END) + 1;
+			new_diag->Start = c->videoController->TimeAtFrame(pos, agi::vfr::START);
+			new_diag->End = c->videoController->TimeAtFrame(pos, agi::vfr::END);
+		});
+	}
+};
+
+struct edit_line_duplicate_shift_back : public Command {
+	CMD_NAME("edit/line/duplicate/shift_back")
+	STR_MENU("Du&plicate and Shift by 1 Frame Backwards")
+	STR_DISP("Duplicate and Shift by 1 Frame Backwards")
+	STR_HELP("Duplicate selected lines and shift them to the frame before the original start frame")
+	CMD_TYPE(COMMAND_VALIDATE)
+
+	bool Validate(const agi::Context *c) {
+		return !c->selectionController->GetSelectedSet().empty() && c->videoController->IsLoaded();
+	}
+
+	void operator()(agi::Context *c) {
+		duplicate_lines(c, [=](AssDialogue *new_diag) {
+			int pos = c->videoController->FrameAtTime(new_diag->Start, agi::vfr::START) - 1;
+			new_diag->Start = c->videoController->TimeAtFrame(pos, agi::vfr::START);
+			new_diag->End = c->videoController->TimeAtFrame(pos, agi::vfr::END);
+		});
 	}
 };
 
@@ -1000,6 +1019,7 @@ namespace cmd {
 		reg(new edit_line_delete);
 		reg(new edit_line_duplicate);
 		reg(new edit_line_duplicate_shift);
+		reg(new edit_line_duplicate_shift_back);
 		reg(new edit_line_join_as_karaoke);
 		reg(new edit_line_join_concatenate);
 		reg(new edit_line_join_keep_first);