blitting functions

1 files changed, 41 insertions, 0 deletions

diff --git a/js/blit.js b/js/blit.js
new file mode 100644
index 0000000..09f39b2
--- /dev/null
+++ b/js/blit.js
@@ -0,0 +1,41 @@
+var blit = (function(){
+	var blit = {}
+	blit.and = blit.atop = function(A, B, x, y){
+		x = x || 0 ; y = y || 0
+		B.forEach(function(lex, u, v){
+			var cell = A.getCell(u+x, v+y)
+			if (cell && lex.opacity > 0) {
+				cell.clone(lex)
+			}
+		})
+	}
+	blit.or = blit.under = function(A, B, x, y){
+		x = x || 0 ; y = y || 0
+		B.forEach(function(lex, u, v){
+			var cell = A.getCell(u+x, v+y)
+			if (cell && cell.opacity == 0) {
+				cell.clone(lex)
+			}
+		})
+	}
+	blit.set = blit.replace = function(A, B, x, y){
+		x = x || 0 ; y = y || 0
+		B.forEach(function(lex, u, v){
+			var cell = A.getCell(u+x, v+y)
+			if (cell) {
+				cell.clone(lex)
+			}
+		})
+	}
+	blit.invert = function(A, B, x, y){
+		x = x || 0 ; y = y || 0
+		B.forEach(function(lex, u, v){
+			var cell = A.getCell(u+x, v+y)
+			if (cell && lex.opacity > 0) {
+				cell.fg = get_inverse(cell.fg)
+				cell.bg = get_inverse(cell.bg)
+			}
+		})
+	}
+	return blit
+})()