implement loading screen

src/js/net/minecraft/client/gui/Gui.js

@@ -1,10 +1,23 @@
 window.Gui = class {
 
     drawRect(stack, left, top, right, bottom, color, alpha = 1) {
+        stack.save();
         stack.fillStyle = color;
         stack.globalAlpha = alpha;
         stack.fillRect(left, top, right - left, bottom - top);
-        stack.globalAlpha = alpha;
+        stack.restore();
+    }
+
+    drawString(stack, string, x, y, color) {
+        this._drawString(stack, string, x, y, color, 0, false);
+    }
+
+    _drawString(stack, string, x, y, color, alignment, bold) {
+        let size = 24;
+        stack.font = (bold ? "bold" : "normal") + " " + size + "px Minecraftia";
+        stack.fillStyle = color;
+        stack.textAlign = alignment === 0 ? "center" : alignment < 0 ? "left" : "right";
+        stack.fillText(string, x, y);
     }
 
     drawTexture(stack, texture, x, y, width, height, alpha = 1.0) {
@@ -12,9 +25,21 @@ window.Gui = class {
     }
 
     drawSprite(stack, texture, spriteX, spriteY, spriteWidth, spriteHeight, x, y, width, height, alpha = 1.0) {
+        stack.save();
         stack.globalAlpha = alpha;
         stack.drawImage(texture, spriteX, spriteY, spriteWidth, spriteHeight, x, y, width, height);
-        stack.globalAlpha = 1.0;
+        stack.restore();
+    }
+
+    drawBackground(stack, texture, width, height, scale = 8) {
+        let pattern = stack.createPattern(texture, "repeat");
+        stack.save();
+        stack.filter = "brightness(50%)";
+        stack.scale(scale, scale);
+        stack.rect(0, 0, width / scale, height / scale);
+        stack.fillStyle = pattern;
+        stack.fill();
+        stack.restore();
     }
 
     loadTexture(path) {