Add new Lua function gui.line()

lua/gui-line.cpp

@@ -0,0 +1,95 @@
+#include "lua-int.hpp"
+#include "render.hpp"
+
+namespace
+{
+	struct render_object_line : public render_object
+	{
+		render_object_line(int32_t _x1, int32_t _x2, int32_t _y1, int32_t _y2, premultiplied_color _color)
+			throw()
+			: x1(_x1), y1(_y1), x2(_x2), y2(_y2), color(_color) {}
+		~render_object_line() throw() {}
+		void operator()(struct screen& scr) throw()
+		{
+			int32_t xdiff = x2 - x1;
+			int32_t ydiff = y2 - y1;
+			if(xdiff < 0)
+				xdiff = -xdiff;
+			if(ydiff < 0)
+				ydiff = -ydiff;
+			if(xdiff >= ydiff) {
+				//X-major line.
+				if(x2 < x1) {
+					//Swap points so that x1 < x2.
+					std::swap(x1, x2);
+					std::swap(y1, y2);
+				}
+				//The slope of the line is (y2 - y1) / (x2 - x1) = +-ydiff / xdiff
+				int32_t y = y1;
+				int32_t ysub = 0;
+				for(int32_t x = x1; x <= x2; x++) {
+					if(x < 0 || static_cast<uint32_t>(x) >= scr.width)
+						goto nodraw1;
+					if(y < 0 || static_cast<uint32_t>(y) >= scr.height)
+						goto nodraw1;
+					color.apply(scr.rowptr(y)[x]);
+nodraw1:
+					ysub += ydiff;
+					if(ysub >= xdiff) {
+						ysub -= xdiff;
+						if(y2 > y1)
+							y++;
+						else
+							y--;
+					}
+				}
+			} else {
+				//Y-major line.
+				if(x2 < x1) {
+					//Swap points so that y1 < y2.
+					std::swap(x1, x2);
+					std::swap(y1, y2);
+				}
+				//The slope of the line is (x2 - x1) / (y2 - y1) = +-xdiff / ydiff
+				int32_t x = x1;
+				int32_t xsub = 0;
+				for(int32_t y = y1; y <= y2; y++) {
+					if(x < 0 || static_cast<uint32_t>(x) >= scr.width)
+						goto nodraw2;
+					if(y < 0 || static_cast<uint32_t>(y) >= scr.height)
+						goto nodraw2;
+					color.apply(scr.rowptr(y)[x]);
+nodraw2:
+					xsub += xdiff;
+					if(xsub >= ydiff) {
+						xsub -= ydiff;
+						if(x2 > x1)
+							x++;
+						else
+							x--;
+					}
+				}
+			}
+		}
+	private:
+		int32_t x1;
+		int32_t y1;
+		int32_t x2;
+		int32_t y2;
+		premultiplied_color color;
+	};
+
+	function_ptr_luafun gui_pixel("gui.line", [](lua_State* LS, const std::string& fname) -> int {
+		if(!lua_render_ctx)
+			return 0;
+		int64_t color = 0xFFFFFFU;
+		int32_t x1 = get_numeric_argument<int32_t>(LS, 1, fname.c_str());
+		int32_t y1 = get_numeric_argument<int32_t>(LS, 2, fname.c_str());
+		int32_t x2 = get_numeric_argument<int32_t>(LS, 3, fname.c_str());
+		int32_t y2 = get_numeric_argument<int32_t>(LS, 4, fname.c_str());
+		get_numeric_argument<int64_t>(LS, 5, color, fname.c_str());
+		premultiplied_color pcolor(color);
+		lua_render_ctx->queue->add(*new render_object_line(x1, x2, y1, y2, pcolor));
+		return 0;
+	});
+}

manual.lyx

@@ -1808,10 +1808,12 @@ Most of these functions can only be called in on_paint and on_video callbacks.
 \end_layout
 
 \begin_layout Standard
-Colors are 15-bit.
+Colors are 32-bit.
- Each red, green and blue values are in range 0-31 and the final color value
+ Bits 0-7 are the blue component, bits 8-15 are the green component, bits
- is 1024*r+32*g+b.
+ 16-23 are the red component, bits 24-31 are alpha component (0 is fully
- Alpha range is 0 (fully transparent) to 32 (sic! fully opaque).
+ opaque, 255 is almost transparent).
+ -1 is the fully transparent color.
+ Alpha values greater than 127 do work.
 \end_layout
 
 \begin_layout Standard
@@ -1927,7 +1929,7 @@ color: Color of the pixel (default is 0xFFFFFF (white))
 \end_layout
 
 \begin_layout Subsubsection
-gui.crosshair(number x, number y[, number length[, number color]]
+gui.crosshair(number x, number y[, number length[, number color]])
 \end_layout
 
 \begin_layout Standard
@@ -1951,6 +1953,35 @@ length: Length of the crosshair lines (default 10).
 color: Color of the crosshair (default is 0xFFFFFF (white))
 \end_layout
 
+\begin_layout Subsubsection
+gui.line(number x1, number y1, number x2, number y2[, number color])
+\end_layout
+
+\begin_layout Standard
+Draw a thin line.
+ Parameters:
+\end_layout
+
+\begin_layout Itemize
+x1: X-coordinate of one end.
+\end_layout
+
+\begin_layout Itemize
+y1: Y-coordinate of one end.
+\end_layout
+
+\begin_layout Itemize
+x2: X-coordinate of the other end.
+\end_layout
+
+\begin_layout Itemize
+y2: Y-coordinate of the other end.
+\end_layout
+
+\begin_layout Itemize
+color: Color of the line (default is 0xFFFFFF (white)).
+\end_layout
+
 \begin_layout Subsubsection
 gui.repaint()
 \end_layout