From 981104e3080fcc4b71923c21cec5347c2346ce1e Mon Sep 17 00:00:00 2001
From: Jonathan G Rennison <j.g.rennison@gmail.com>
Date: Thu, 19 May 2022 00:12:17 +0100
Subject: [PATCH] Add a functor fill mode to GfxFillPolygon

---
 src/gfx.cpp    | 7 ++++++-
 src/gfx_func.h | 2 +-
 src/gfx_type.h | 3 +++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/gfx.cpp b/src/gfx.cpp
index ea56408cea..3c26803a4b 100644
--- a/src/gfx.cpp
+++ b/src/gfx.cpp
@@ -226,8 +226,9 @@ static std::vector<LineSegment> MakePolygonSegments(const std::vector<Point> &sh
  *         FILLRECT_OPAQUE:   Fill the polygon with the specified colour.
  *         FILLRECT_CHECKER:  Fill every other pixel with the specified colour, in a checkerboard pattern.
  *         FILLRECT_RECOLOUR: Apply a recolour sprite to every pixel in the polygon.
+ *         FILLRECT_FUNCTOR:  Apply a functor to a line of pixels.
  */
-void GfxFillPolygon(const std::vector<Point> &shape, int colour, FillRectMode mode)
+void GfxFillPolygon(const std::vector<Point> &shape, int colour, FillRectMode mode, GfxFillRectModeFunctor *fill_functor)
 {
 	Blitter *blitter = BlitterFactory::GetCurrentBlitter();
 	const DrawPixelInfo *dpi = _cur_dpi;
@@ -308,6 +309,10 @@ void GfxFillPolygon(const std::vector<Point> &shape, int colour, FillRectMode mo
 						blitter->SetPixel(dst, x, 0, (uint8)colour);
 					}
 					break;
+				case FILLRECT_FUNCTOR:
+					/* Call the provided fill functor. */
+					fill_functor(dst, x2 - x1);
+					break;
 			}
 		}
 
diff --git a/src/gfx_func.h b/src/gfx_func.h
index ead2ff8e1c..6c37a97f04 100644
--- a/src/gfx_func.h
+++ b/src/gfx_func.h
@@ -104,7 +104,7 @@ int DrawStringMultiLine(int left, int right, int top, int bottom, StringID str,
 void DrawCharCentered(WChar c, const Rect &r, TextColour colour);
 
 void GfxFillRect(int left, int top, int right, int bottom, int colour, FillRectMode mode = FILLRECT_OPAQUE);
-void GfxFillPolygon(const std::vector<Point> &shape, int colour, FillRectMode mode = FILLRECT_OPAQUE);
+void GfxFillPolygon(const std::vector<Point> &shape, int colour, FillRectMode mode = FILLRECT_OPAQUE, GfxFillRectModeFunctor *fill_functor = nullptr);
 void GfxDrawLine(int left, int top, int right, int bottom, int colour, int width = 1, int dash = 0);
 void DrawBox(int x, int y, int dx1, int dy1, int dx2, int dy2, int dx3, int dy3);
 
diff --git a/src/gfx_type.h b/src/gfx_type.h
index 377278f466..30fcbc67b8 100644
--- a/src/gfx_type.h
+++ b/src/gfx_type.h
@@ -288,8 +288,11 @@ enum FillRectMode {
 	FILLRECT_OPAQUE,  ///< Fill rectangle with a single colour
 	FILLRECT_CHECKER, ///< Draw only every second pixel, used for greying-out
 	FILLRECT_RECOLOUR, ///< Apply a recolour sprite to the screen content
+	FILLRECT_FUNCTOR, ///<  Apply a functor to a line of pixels
 };
 
+typedef void GfxFillRectModeFunctor(void *pixel, int count);
+
 /** Palettes OpenTTD supports. */
 enum PaletteType {
 	PAL_DOS,        ///< Use the DOS palette.