FIX: Loaded/saved image data have reversed RGB colour order on macOS

resolves: Oldes/Rebol-issues#2495

Author: Oldes

src/os/osx/sys-codecs.m

@@ -80,7 +80,7 @@ int DecodeImageFromFile(const char *uri, unsigned int frame, REBCDI *codi)
 		pixels = (UInt32*)malloc(w * h * 4); // Rebol's library side must free it!
 		ASSERT_NOT_NULL(pixels, 4, "allocate pixels buffer");
 		space = CGColorSpaceCreateDeviceRGB();
-		ctx = CGBitmapContextCreate(pixels, w, h, bitsPerComponent, bytesPerPixel * w, space, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
+		ctx = CGBitmapContextCreate(pixels, w, h, bitsPerComponent, bytesPerPixel * w, space, kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Little);
 		ASSERT_NOT_NULL(ctx, 5, "create a bitmap context");
 		CGContextDrawImage(ctx, CGRectMake(0, 0, w, h), img);
 		CGColorSpaceRelease(space);
@@ -126,7 +126,7 @@ int EncodeImageToFile(const char *uri, REBCDI *codi)
 		data = CGDataProviderCreateWithData(NULL, codi->bits, codi->w * codi->h * 4, NULL);
 		ASSERT_NOT_NULL(data, 1, "prepare input data");
 		colorSpace = CGColorSpaceCreateDeviceRGB();
-		img = CGImageCreate(codi->w, codi->h, 8, 32, codi->w * 4, colorSpace, (kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big), data, NULL, TRUE, 0);
+		img = CGImageCreate(codi->w, codi->h, 8, 32, codi->w * 4, colorSpace, (kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Little), data, NULL, TRUE, 0);
 		CGDataProviderRelease(data);
 		CGColorSpaceRelease(colorSpace);
 		ASSERT_NOT_NULL(img, 2, "create an image");

src/tests/units/codecs-test.r3

@@ -447,6 +447,21 @@ if find codecs 'PNG [
 			3015 = size? %units/files/png-from-photoshop.png
 		]
 		try [delete %new.png]
+
+	--test-- "png rgb image"
+		;@@ https://github.com/Oldes/Rebol-issues/issues/2495
+		--assert all [
+			image? img: try [load %units/files/rbgw.png]
+			img/1 = 200.0.0.255
+			img/2 = 0.0.200.255
+			img/3 = 0.200.0.255
+			img/rgb = #{C800000000C800C800FFFFFF}
+		]
+		--assert all [
+			image? img: try [load save %new.png make image! [2x2 #{C800000000C800C800FFFFFF}]]
+			img/rgb = #{C800000000C800C800FFFFFF}
+		]
+		try [delete %new.png]
 	===end-group===
 ]
 
@@ -484,6 +499,21 @@ if find codecs 'GIF [
 	--test-- "gif/size?"
 		--assert 256x256 = codecs/gif/size? %units/files/flower.gif
 		--assert none?     codecs/gif/size? %units/files/test.aar
+
+	--test-- "gif rgb image"
+		;@@ https://github.com/Oldes/Rebol-issues/issues/2495
+		--assert all [
+			image? img: try [load %units/files/rbgw.gif]
+			img/1 = 200.0.0.255
+			img/2 = 0.0.200.255
+			img/3 = 0.200.0.255
+			img/rgb = #{C800000000C800C800FFFFFF}
+		]
+		--assert all [
+			image? img: try [load save %new.gif make image! [2x2 #{C800000000C800C800FFFFFF}]]
+			img/rgb = #{C800000000C800C800FFFFFF}
+		]
+		try [delete %new.gif]
 	===end-group===
 ]