Clamp all color arguments to [0, 1] in cases where values outside that range don't make sense (fixed-point color values & sRGB colors). Closes issue #1315.

--HG--
branch : minor

src/modules/image/wrap_ImageData.cpp

@@ -88,22 +88,20 @@ int w_ImageData_getDimensions(lua_State *L)
 	return 2;
 }
 
-// TODO: rgba16f
-
 static void luax_checkpixel_rgba8(lua_State *L, int startidx, Pixel &p)
 {
 	for (int i = 0; i < 3; i++)
-		p.rgba8[i] = (uint8) (luaL_checknumber(L, startidx + i) * 255.0);
+		p.rgba8[i] = (uint8) (luax_checknumberclamped01(L, startidx + i) * 255.0);
 
-	p.rgba8[3] = (uint8) (luaL_optnumber(L, startidx + 3, 1.0) * 255.0);
+	p.rgba8[3] = (uint8) (luax_optnumberclamped01(L, startidx + 3, 1.0) * 255.0);
 }
 
 static void luax_checkpixel_rgba16(lua_State *L, int startidx, Pixel &p)
 {
 	for (int i = 0; i < 3; i++)
-		p.rgba16[i] = (uint16) (luaL_checknumber(L, startidx + i) * 65535.0);
+		p.rgba16[i] = (uint16) (luax_checknumberclamped01(L, startidx + i) * 65535.0);
 
-	p.rgba16[3] = (uint16) (luaL_optnumber(L, startidx + 3, 1.0) * 65535.0);
+	p.rgba16[3] = (uint16) (luax_optnumberclamped01(L, startidx + 3, 1.0) * 65535.0);
 }
 
 static void luax_checkpixel_rgba16f(lua_State *L, int startidx, Pixel &p)

src/modules/image/wrap_ImageData.lua

@@ -27,10 +27,15 @@ local ImageData = ImageData_mt.__index
 
 local tonumber, assert, error = tonumber, assert, error
 local type, pcall = type, pcall
-local floor = math.floor
+local floor = math.floor
+local min, max = math.min, math.max
 
 local function inside(x, y, w, h)
 	return x >= 0 and x < w and y >= 0 and y < h
+end
+
+local function clamp01(x)
+	return min(max(x, 0), 1)
 end
 
 -- Implement thread-safe ImageData:mapPixel regardless of whether the FFI is
@@ -111,10 +116,10 @@ local conversions = {
 			return tonumber(self.r) / 255, tonumber(self.g) / 255, tonumber(self.b) / 255, tonumber(self.a) / 255
 		end,
 		fromlua = function(self, r, g, b, a)
-			self.r = r * 255
-			self.g = g * 255
-			self.b = b * 255
-			self.a = a == nil and 255 or a * 255
+			self.r = clamp01(r) * 255
+			self.g = clamp01(g) * 255
+			self.b = clamp01(b) * 255
+			self.a = a == nil and 255 or clamp01(a) * 255
 		end,
 	},
 	rgba16 = {
@@ -123,10 +128,10 @@ local conversions = {
 			return tonumber(self.r) / 65535, tonumber(self.g) / 65535, tonumber(self.b) / 65535, tonumber(self.a) / 65535
 		end,
 		fromlua = function(self, r, g, b, a)
-			self.r = r * 65535
-			self.g = g * 65535
-			self.b = b * 65535
-			self.a = a == nil and 65535 or a * 65535
+			self.r = clamp01(r) * 65535
+			self.g = clamp01(g) * 65535
+			self.b = clamp01(b) * 65535
+			self.a = a == nil and 65535 or clamp01(a) * 65535
 		end,
 	},
 	rgba16f = {