From 3145f6abee72ae31dd3721be1f02483c4c211b7a Mon Sep 17 00:00:00 2001
From: Troy Gilbert <troy.gilbert@gmail.com>
Date: Wed, 18 Dec 2013 15:56:29 -0600
Subject: [PATCH] Added support for foreground coloring to tile.js

---
 src/display/tile.js | 41 +++++++++++++++++++++++++++++++++++------
 1 file changed, 35 insertions(+), 6 deletions(-)

diff --git a/src/display/tile.js b/src/display/tile.js
index f5cbd76b..a123237f 100644
--- a/src/display/tile.js
+++ b/src/display/tile.js
@@ -6,6 +6,7 @@ ROT.Display.Tile = function(context) {
 	ROT.Display.Rect.call(this, context);
 	
 	this._options = {};
+	this._tileCache = {};
 }
 ROT.Display.Tile.extend(ROT.Display.Rect);
 
@@ -33,16 +34,44 @@ ROT.Display.Tile.prototype.draw = function(data, clearBefore) {
 
 	if (!ch) { return; }
 
+	var fgColor = fg ? ROT.Color.fromString(fg) : false;
+
 	var chars = [].concat(ch);
 	for (var i=0;i<chars.length;i++) {
 		var tile = this._options.tileMap[chars[i]];
 		if (!tile) { throw new Error("Char '" + chars[i] + "' not found in tileMap"); }
-		
-		this._context.drawImage(
-			this._options.tileSet,
-			tile[0], tile[1], tileWidth, tileHeight,
-			x*tileWidth, y*tileHeight, tileWidth, tileHeight
-		);
+
+		if (fgColor) {
+			var cacheKey = tile.concat(fgColor).join(",");
+			if (!(cacheKey in this._tileCache)) {
+				// create an offscreen canvas to cache our tile
+				var canvas = document.createElement("canvas");
+				canvas.width = tileWidth;
+				canvas.height = tileHeight;
+				var context = canvas.getContext("2d");
+
+				// draw the tile into the context
+				context.drawImage(this._options.tileSet, tile[0], tile[1], tileWidth, tileHeight, 0, 0, tileWidth, tileHeight);
+
+				// multiply the foreground color times the image data
+				var imageData = context.getImageData(0, 0, tileWidth, tileHeight);
+				for (i = 0; i < imageData.data.length; i += 4) { // 4 bytes (RGBA) per pixel
+					imageData.data[i+0] *= fgColor[0] / 255;
+					imageData.data[i+1] *= fgColor[1] / 255;
+					imageData.data[i+2] *= fgColor[2] / 255;
+				}
+				context.putImageData(imageData, 0, 0);
+
+				// update cache
+				this._tileCache[cacheKey] = canvas;
+				cachedTile = canvas;
+
+			} else {
+				cachedTile = this._tileCache[cacheKey];
+			}
+
+			this._context.drawImage(cachedTile, x*tileWidth, y*tileHeight);
+		}
 	}
 }