Implemented ContourMask (mask for text fields)

git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@251 0fc631ac-6414-0410-93d0-97cfa31319b6

src/gfx/mask_image.cpp

@@ -49,3 +49,53 @@ bool AlphaMask::isTransparent(int x, int y) const {
 }
 
 // ----------------------------------------------------------------------------- : ContourMask
+
+ContourMask::ContourMask()
+	: width(0), height(0), lefts(nullptr), rights(nullptr)
+{}
+ContourMask::~ContourMask() {
+	unload();
+}
+
+void ContourMask::load(const Image& image) {
+	unload();
+	width  = image.GetWidth();
+	height = image.GetHeight();
+	lefts  = new int[height];
+	rights = new int[height];
+	// for each row: determine left and rightmost white pixel
+	Byte* data = image.GetData();
+	for (int y = 0 ; y < height ; ++y) {
+		lefts[y] = width; rights[y] = width;
+		for (int x = 0 ; x < width ; ++x) {
+			int v = data[0] + data[1] + data[2];
+			if (v > 50) { // white enough
+				rights[y] = x;
+				if (x < lefts[y]) lefts[y] = x;
+			}
+			data += 3;
+		}
+	}
+}
+
+void ContourMask::unload() {
+	delete lefts;
+	delete rights;
+	lefts = rights = nullptr;
+	width = height = 0;
+}
+
+double ContourMask::rowLeft (double y, RealSize size) const {
+	if (!ok() || y < 0 || y >= size.height) {
+		// no mask, or outside it
+		return 0;
+	}
+	return lefts[(int)(y * size.height / height)] * size.width / width;
+}
+double ContourMask::rowRight(double y, RealSize size) const {
+	if (!ok() || y < 0 || y >= size.height) {
+		// no mask, or outside it
+		return size.width;
+	}
+	return rights[(int)(y * size.height / height)] * size.width / width;
+}