From 3de48ab3baa671d8d140df1ef24605d18a026917 Mon Sep 17 00:00:00 2001
From: nmlgc <nmlgc@nmlgc.net>
Date: Sat, 23 Dec 2023 17:39:30 +0100
Subject: [PATCH] [Effects] [Bug] Music title: Consistently right-align based
 on rendered width

Unfortunately has a significant effect on the animation, especially for
shorter titles, but maintains consistency with the obviously
whitespace-trimmed title tags in the upcoming BGM mod packs. Let's fix
that animation later, in #55.

Completes P0272, funded by Ember2528.
---
 GIAN07/EFFECT.CPP  | 10 +++++-----
 GIAN07/FONTUTY.CPP |  7 +++++--
 GIAN07/FONTUTY.H   |  2 +-
 game/bgm.cpp       | 34 +++++++++++++++++++++++++++++++++-
 4 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/GIAN07/EFFECT.CPP b/GIAN07/EFFECT.CPP
index b3dd7b1..f7f1a40 100644
--- a/GIAN07/EFFECT.CPP
+++ b/GIAN07/EFFECT.CPP
@@ -239,17 +239,17 @@ void SetMusicTitle(int y, Narrow::string_view s)
 	}
 	if(n==SEFFECT_MAX) return;
 
+	const auto extent = DrawGrdFont(MTitleRect, s);
+
 	// 曲のタイトルが長すぎる場合、どうしましょう？ //
-	auto x = (640 - 128 - 16 - (9 * min(s.length(), (23 + 1))));
+	auto x = (640 - 128 - 32 - min(extent.w, 216));
 
 	SEffect[n].cmd  = SEFC_MTITLE1;
 	SEffect[n].x    = (x<<6);// + (64*2)*16;
 	SEffect[n].y    = y<<6;
 	SEffect[n].time = 64*2;
-	SEffect[n].vx   = (s.length() * 16);
-	SEffect[n].vy   = 16;
-
-	DrawGrdFont(MTitleRect, s);
+	SEffect[n].vx   = extent.w;
+	SEffect[n].vy   = extent.h;
 }
 
 // エフェクトを動かす(仕様変更の可能性があります) //
diff --git a/GIAN07/FONTUTY.CPP b/GIAN07/FONTUTY.CPP
index 9fe76d4..0399661 100644
--- a/GIAN07/FONTUTY.CPP
+++ b/GIAN07/FONTUTY.CPP
@@ -254,9 +254,10 @@ TEXTRENDER_GDI<GRAPHICS_DDRAW, SURFACE_DDRAW, GIAN_FONT_ID> TextObj = {
 	DxObj, GrText, GDIFonts.fonts
 };
 
-void DrawGrdFont(TEXTRENDER_RECT_ID rect_id, Narrow::string_view str)
+PIXEL_SIZE DrawGrdFont(TEXTRENDER_RECT_ID rect_id, Narrow::string_view str)
 {
-	TextObj.Prerender(rect_id, [&str](GIAN_TEXTRENDER_SESSION auto& s) {
+	PIXEL_SIZE extent = { 0, 0 };
+	TextObj.Prerender(rect_id, [&](GIAN_TEXTRENDER_SESSION auto& s) {
 		// The MIDI sequence titles passed to this function tend to come with
 		// lots of trailing whitespace. Adding 1 also turns `npos` to 0.
 		str = str.substr(0, (str.find_last_not_of(" ") + 1));
@@ -272,6 +273,7 @@ void DrawGrdFont(TEXTRENDER_RECT_ID rect_id, Narrow::string_view str)
 		s.Put({ 1, 2 }, str, RGBA{   0,   0, 128 });
 		s.Put({ 1, 1 }, str, RGBA{ 255, 255, 255 });
 		s.Put({ 0, 1 }, str, RGBA{ 255, 255, 255 });
+		extent += s.Extent(str);
 
 		constexpr auto FSIZE = 8;
 		const PIXEL_COORD w = (str.size() * 16);
@@ -286,4 +288,5 @@ void DrawGrdFont(TEXTRENDER_RECT_ID rect_id, Narrow::string_view str)
 			}
 		}
 	});
+	return extent;
 }
diff --git a/GIAN07/FONTUTY.H b/GIAN07/FONTUTY.H
index 993415c..ca5bd99 100644
--- a/GIAN07/FONTUTY.H
+++ b/GIAN07/FONTUTY.H
@@ -51,7 +51,7 @@ extern void GrpPutScore(int x, int y, char *s);	// 得点アイテムのスコ
 extern void GrpPutMidNum(int x, int y, int n);	// MIDI 用フォントを描画する
 
 // グラデーション付きフォントを描画する
-void DrawGrdFont(TEXTRENDER_RECT_ID rect_id, Narrow::string_view str);
+PIXEL_SIZE DrawGrdFont(TEXTRENDER_RECT_ID rect_id, Narrow::string_view str);
 
 
 #endif
diff --git a/game/bgm.cpp b/game/bgm.cpp
index f5ec673..f1ad5ea 100644
--- a/game/bgm.cpp
+++ b/game/bgm.cpp
@@ -45,7 +45,39 @@ std::chrono::duration<int32_t, std::milli> BGM_PlayTime(void)
 
 Narrow::string_view BGM_Title(void)
 {
-	return Mid_GetTitle();
+	auto ret = Mid_GetTitle();
+
+	// pbg bug: Four of the original track titles start with leading fullwidth
+	// spaces:
+	//
+	// 	#04: "　　　幻想帝都"
+	// 	#07: "　　天空アーミー"
+	// 	#11: "　魔法少女十字軍"
+	// 	#16: "　　シルクロードアリス"
+	//
+	// This looks like it was done on purpose to center the titles within the
+	// 216 maximum pixels that the original code designated for the in-game
+	// animation. However:
+	//
+	// • None of those actually has the correct amount of spaces that would
+	//   have been required for exact centering.
+	// • If pbg intended to center all the tracks, there should have been
+	//   leading whitespace in 14 of the track titles, and not just in 4.
+	//
+	// Since the in-game animation code does clearly intend these titles to be
+	// right-aligned, it makes more sense to just remove all leading
+	// whitespace. Doing this here will also benefit the Music Room.
+	const auto trim_leading = [](auto& str, Narrow::string_view prefix) {
+		const auto ret = str.starts_with(prefix);
+		if(ret) {
+			str.remove_prefix(prefix.size());
+		}
+		return ret;
+	};
+	while(trim_leading(ret, " ") || trim_leading(ret, "\x81\x40")) {
+	};
+
+	return ret;
 }
 
 bool BGM_ChangeMIDIDevice(int8_t direction)