AlphaMask implementation

src/gfx/mask_image.cpp

+//+----------------------------------------------------------------------------+
+//| Description:  Magic Set Editor - Program to make Magic (tm) cards          |
+//| Copyright:    (C) 2001 - 2006 Twan van Laarhoven                           |
+//| License:      GNU General Public License 2 or later (see file COPYING)     |
+//+----------------------------------------------------------------------------+
+
+// ----------------------------------------------------------------------------- : Includes
+
+#include <gfx/gfx.hpp>
+#include <util/error.hpp>
+
+// ----------------------------------------------------------------------------- : AlphaMask
+
+AlphaMask::AlphaMask(const Image& img)
+	: size(img.GetWidth(), img.GetHeight())
+{
+	// Copy red chanel to alpha
+	size_t n = size.GetWidth() * size.GetHeight();
+	alpha = new Byte[n];
+	Byte* from = img.GetData(), *to = alpha;
+	for (size_t i = 0 ; i < n ; ++i) {
+		*to = *from;
+		from += 3;
+		to   += 1;
+	}
+}
+
+AlphaMask::~AlphaMask() {
+	delete alpha;
+}
+
+void AlphaMask::setAlpha(Image& img) const {
+	if (img.GetWidth() != size.GetWidth() || img.GetHeight() != size.GetHeight()) {
+		throw InternalError(_("Image used with maks must have same size as mask"));
+	}
+	if (!img.HasAlpha()) img.InitAlpha();
+	memcpy(img.GetAlpha(), alpha, size.GetWidth() * size.GetHeight());
+}
+
+void AlphaMask::setAlpha(Bitmap& bmp) const {
+	Image img = bmp.ConvertToImage();
+	setAlpha(img);
+	bmp = Bitmap(img);
+}
+
+bool AlphaMask::isTransparent(int x, int y) const {
+	assert(x >= 0 && y >= 0 && x < size.GetWidth() && y < size.GetHeight());
+	return alpha[x + y * size.GetWidth()] < 20;
+}
+
+// ----------------------------------------------------------------------------- : ContourMask