From 69e64e6ac4215c9cdbf19ce706fbaf2fd8d32a72 Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Fri, 19 Mar 2021 10:34:08 -0400
Subject: help: Add event loop

---
diff --git a/src/help.c b/src/help.c
index 60bcdb7..39db3cb 100644
--- a/src/help.c
+++ b/src/help.c
@@ -56,6 +56,8 @@ const char *_db_help_text =
 	"they bounce off walls in the opposite direction.  To stop, move "
 	"against a wall.";
 
+static int _db_help_quit;
+
 static void
 _db_help_triangle(SDL_Renderer *renderer, Uint8 r, Uint8 g, Uint8 b, Uint8 a,
 		int x_min, int y_min, int dir)
@@ -92,6 +94,7 @@ db_help(void)
 	SDL_Texture  *texture;
 	SDL_Rect      text_src_rect;
 	SDL_Rect      text_dst_rect;
+	SDL_Event     event;
 
 	font_path = db_strcat(db_get_fonts_dir(), "/UbuntuTitling-Bold.ttf");
 
@@ -132,10 +135,66 @@ db_help(void)
 	text_dst_rect.w = 592;
 	text_dst_rect.h = 448;
 
-	SDL_RenderClear(renderer);
-	SDL_RenderCopy(renderer, texture, &text_src_rect, &text_dst_rect);
-	_db_help_triangle(renderer, 0x3F, 0x3F, 0x7F, 0xFF, 608,  16, -1);
-	_db_help_triangle(renderer, 0x00, 0x00, 0xFF, 0xFF, 608, 456,  1);
-	SDL_RenderPresent(renderer);
-	SDL_Delay(1000);
+	_db_help_quit = 0;
+	while (SDL_WaitEvent(&event)) {
+		switch (event.type) {
+			case SDL_QUIT:
+				_db_help_quit = 1;
+				break;
+			case SDL_KEYDOWN:
+				switch (event.key.keysym.sym) {
+					case SDLK_UP:
+						text_src_rect.y -= 16;
+						if (text_src_rect.y < 0) {
+							text_src_rect.y = 0;
+						}
+						break;
+					case SDLK_DOWN:
+						text_src_rect.y += 16;
+						if (text_src_rect.y > surface->h
+								-
+								text_src_rect.h)
+						{
+							text_src_rect.y =
+								surface->h -
+								text_src_rect.h;
+						}
+						break;
+					case SDLK_HOME:
+						text_src_rect.y = 0;
+						break;
+					case SDLK_END:
+						text_src_rect.y = surface->h -
+							text_src_rect.h;
+						break;
+					default:
+						break;
+				}
+				break;
+			default:
+				break;
+		}
+		if (_db_help_quit == 1) {
+			break;
+		}
+		SDL_SetRenderDrawColor(renderer, 0x7F, 0x7F, 0x7F, 0xFF);
+		SDL_RenderClear(renderer);
+		SDL_RenderCopy(renderer, texture,
+				&text_src_rect, &text_dst_rect);
+		if (text_src_rect.y > 0) {
+			_db_help_triangle(renderer,
+					0x00, 0x00, 0xFF, 0xFF, 608,  16, -1);
+		} else {
+			_db_help_triangle(renderer,
+					0x3F, 0x3F, 0x7F, 0xFF, 608,  16, -1);
+		}
+		if (text_src_rect.y < surface->h - text_src_rect.h) {
+			_db_help_triangle(renderer,
+					0x00, 0x00, 0xFF, 0xFF, 608, 456,  1);
+		} else {
+			_db_help_triangle(renderer,
+					0x3F, 0x3F, 0x7F, 0xFF, 608, 456,  1);
+		}
+		SDL_RenderPresent(renderer);
+	}
 }
--
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