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+// This file is part of www.nand2tetris.org
+// and the book "The Elements of Computing Systems"
+// by Nisan and Schocken, MIT Press.
+// File name: projects/11/Pong/Bat.jack
+
+/**
+ * A graphical Pong bat. 
+ * Displayed as a filled horizontal rectangle that has 
+ * a screen location, a width and a height.
+ * Has methods for drawing, erasing, moving left and right, 
+ * and changing its width (to make the hitting action more challenging).
+ * This class should have been called "paddle", following the 
+ * standard Pong terminology. But, unaware of this terminology,
+ * we called it "bat", and then decided to stick to it. 
+ */
+class Bat {
+
+    field int x, y;           // the bat's screen location
+    field int width, height;  // the bat's width and height
+    field int direction;      // direction of the bat's movement (1 = left, 2 = right)
+
+    /** Constructs a new bat with the given location and width. */
+    constructor Bat new(int Ax, int Ay, int Awidth, int Aheight) {
+        let x = Ax;
+        let y = Ay;
+        let width = Awidth;
+        let height = Aheight;
+        let direction = 2;
+        do show();
+        return this;
+    }
+
+    /** Deallocates the object's memory. */
+    method void dispose() {
+        do Memory.deAlloc(this);
+        return;
+    }
+
+    /** Shows the bat. */
+    method void show() {
+        do Screen.setColor(true);
+        do draw();
+        return;
+    }
+
+    /** Hides the bat. */
+    method void hide() {
+        do Screen.setColor(false);
+        do draw();
+        return;
+    }
+
+    /** Draws the bat. */
+    method void draw() {
+        do Screen.drawRectangle(x, y, x + width, y + height);
+        return;
+    }
+
+    /** Sets the bat's direction (0=stop, 1=left, 2=right). */
+    method void setDirection(int Adirection) {
+        let direction = Adirection;
+        return;
+    }
+
+    /** Returns the bat's left edge. */
+    method int getLeft() {
+        return x;
+    }
+
+    /** Returns the bat's right edge. */
+    method int getRight() {
+        return x + width;
+    }
+
+    /** Sets the bat's width. */
+    method void setWidth(int Awidth) {
+        do hide();
+        let width = Awidth;
+        do show();
+        return;
+    }
+
+    /** Moves the bat one step in the bat's direction. */
+    method void move() {
+	    if (direction = 1) {
+            let x = x - 4;
+            if (x < 0) { let x = 0; }
+            do Screen.setColor(false);
+            do Screen.drawRectangle((x + width) + 1, y, (x + width) + 4, y + height);
+            do Screen.setColor(true);
+            do Screen.drawRectangle(x, y, x + 3, y + height);
+        }
+        else {
+            let x = x + 4;
+            if ((x + width) > 511) { let x = 511 - width; }
+            do Screen.setColor(false);
+            do Screen.drawRectangle(x - 4, y, x - 1, y + height);
+            do Screen.setColor(true);
+            do Screen.drawRectangle((x + width) - 3, y, x + width, y + height);
+        }
+        return;
+    }
+}