Fix: Poor contrast in cargo dest flow legend window cargo labels.

Select foreground colour depending on the brightness of the background.

Previously all cargo labels were rendered using black text, even
the background cargo colour was dark/black.
As an example: FIRS coal was black text on a black background.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/linkgraph/linkgraph_gui.cpp b/src/linkgraph/linkgraph_gui.cpp
index 015dc52ff..7cb9e5091 100644
--- a/src/linkgraph/linkgraph_gui.cpp
+++ b/src/linkgraph/linkgraph_gui.cpp
@@ -496,7 +496,7 @@ void LinkGraphLegendWindow::DrawWidget(const Rect &r, int widget) const
 		if (this->IsWidgetDisabled(widget)) return;
 		CargoSpec *cargo = CargoSpec::Get(widget - WID_LGL_CARGO_FIRST);
 		GfxFillRect(r.left + 2, r.top + 2, r.right - 2, r.bottom - 2, cargo->legend_colour);
-		DrawString(r.left, r.right, (r.top + r.bottom + 1 - FONT_HEIGHT_SMALL) / 2, cargo->abbrev, TC_BLACK, SA_HOR_CENTER);
+		DrawString(r.left, r.right, (r.top + r.bottom + 1 - FONT_HEIGHT_SMALL) / 2, cargo->abbrev, GetContrastColour(cargo->legend_colour, 73), SA_HOR_CENTER);
 	}
 }