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jdenticon-js/src/renderer/transform.js

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+/**
+ * Jdenticon
+ * https://github.com/dmester/jdenticon
+ * Copyright © Daniel Mester Pirttijärvi
+ */
+
+import { Point } from "./point";
+
+/**
+ * Translates and rotates a point before being passed on to the canvas context. This was previously done by the canvas context itself, 
+ * but this caused a rendering issue in Chrome on sizes > 256 where the rotation transformation of inverted paths was not done properly.
+ */
+export class Transform {
+    /**
+     * @param {number} x The x-coordinate of the upper left corner of the transformed rectangle.
+     * @param {number} y The y-coordinate of the upper left corner of the transformed rectangle.
+     * @param {number} size The size of the transformed rectangle.
+     * @param {number} rotation Rotation specified as 0 = 0 rad, 1 = 0.5π rad, 2 = π rad, 3 = 1.5π rad
+     */
+    constructor(x, y, size, rotation) {
+        this._x = x;
+        this._y = y;
+        this._size = size;
+        this._rotation = rotation;
+    }
+
+    /**
+     * Transforms the specified point based on the translation and rotation specification for this Transform.
+     * @param {number} x x-coordinate
+     * @param {number} y y-coordinate
+     * @param {number=} w The width of the transformed rectangle. If greater than 0, this will ensure the returned point is of the upper left corner of the transformed rectangle.
+     * @param {number=} h The height of the transformed rectangle. If greater than 0, this will ensure the returned point is of the upper left corner of the transformed rectangle.
+     */
+    transformIconPoint(x, y, w, h) {
+        const right = this._x + this._size,
+              bottom = this._y + this._size,
+              rotation = this._rotation;
+        return rotation === 1 ? new Point(right - y - (h || 0), this._y + x) :
+               rotation === 2 ? new Point(right - x - (w || 0), bottom - y - (h || 0)) :
+               rotation === 3 ? new Point(this._x + y, bottom - x - (w || 0)) :
+               new Point(this._x + x, this._y + y);
+    }
+}
+
+export const NO_TRANSFORM = new Transform(0, 0, 0, 0);