First commit.

react/src/Rect.tsx

@@ -0,0 +1,70 @@
+const LARGE_NUMBER = 0x1FFFFFFF;
+const EMPTY_WIDTH = -LARGE_NUMBER * 2;
+
+class Rect {
+    x: number;
+    y: number;
+    width: number;
+    height: number;
+
+    constructor(x: number = LARGE_NUMBER, y: number = LARGE_NUMBER, width: number = EMPTY_WIDTH, height: number = EMPTY_WIDTH)
+    {
+        this.x = x; this.y = y; this.width = width; this.height = height;
+    }
+
+    toString() { return '{' + this.x + "," + this.y + " " + this.width + "," + this.height +"}"; }
+    copy(): Rect {
+        let result = new Rect();
+        result.x = this.x;
+        result.y = this.y;
+        result.width = this.width;
+        result.height = this.height;
+        return result;
+
+    }
+    contains(x: number, y: number)
+    {
+        return (x >= this.x)
+        && x < this.x+this.width
+        && y >= this.y 
+        && y < this.y + this.height;
+    }
+    get right(): number {
+        return this.x + this.width;
+    }
+    get bottom(): number {
+        return this.y + this.height;
+    }
+    isEmpty(): boolean {
+        return this.width === 0 || this.height === 0;
+    }
+    clear(): void {
+        this.x = LARGE_NUMBER;
+        this.y = LARGE_NUMBER;
+        this.width = EMPTY_WIDTH;
+        this.height = EMPTY_WIDTH;
+
+    }
+    accumulate(rect: Rect): void {
+        let right = Math.max(rect.x + rect.width, this.x + this.width);
+        let bottom = Math.max(rect.y + rect.height, this.y + this.height);
+        this.x = Math.min(rect.x, this.x);
+        this.y = Math.min(rect.y, this.y);
+        this.width = right - this.x;
+        this.height = bottom - this.y;
+    }
+    union(rect: Rect): Rect {
+        let result = new Rect();
+        result.x = Math.min(this.x, rect.x);
+        result.y = Math.min(this.y, rect.y);
+        result.width = Math.max(this.x + this.width, rect.x + rect.width) - result.x;
+        result.height = Math.max(this.y + this.height, rect.x + rect.height) - result.y;
+        return result;
+    }
+    offset(xOffset: number, yOffset: number) {
+        this.x += xOffset;
+        this.y += yOffset;
+    }
+}
+
+export default Rect;