Implementation of drawBitmap with background overload.

Adafruit_GFX.cpp

@@ -345,6 +345,23 @@ void Adafruit_GFX::drawBitmap(int16_t x, int16_t y,
   }
 }
 
+void Adafruit_GFX::drawBitmap(int16_t x, int16_t y,
+			      const uint8_t *bitmap, int16_t w, int16_t h,
+			      uint16_t color, uint16_t bg) {
+
+  int16_t i, j, byteWidth = (w + 7) / 8;
+  
+  for(j=0; j<h; j++) {
+    for(i=0; i<w; i++ ) {
+      if(pgm_read_byte(bitmap + j * byteWidth + i / 8) & (128 >> (i & 7))) {
+        drawPixel(x+i, y+j, color);
+      }
+      else {
+      	drawPixel(x+i, y+j, bg);
+      }
+    }
+  }
+}
 
 #if ARDUINO >= 100
 size_t Adafruit_GFX::write(uint8_t c) {