LibWeb: Implement CanvasRenderingContext2D.transform

Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.cpp

@@ -691,6 +691,20 @@ NonnullRefPtr<CanvasGradient> CanvasRenderingContext2D::create_conic_gradient(do
     return CanvasGradient::create_conic(start_angle, x, y);
 }
 
+// https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-transform
+void CanvasRenderingContext2D::transform(double a, double b, double c, double d, double e, double f)
+{
+    // 1. If any of the arguments are infinite or NaN, then return.
+    if (!isfinite(a) || !isfinite(b) || !isfinite(c) || !isfinite(d) || !isfinite(e) || !isfinite(f))
+        return;
+
+    // 2. Replace the current transformation matrix with the result of multiplying the current transformation matrix with the matrix described by:
+    //    a c e
+    //    b d f
+    //    0 0 1
+    m_drawing_state.transform.multiply({ static_cast<float>(a), static_cast<float>(b), static_cast<float>(c), static_cast<float>(d), static_cast<float>(e), static_cast<float>(f) });
+}
+
 // https://html.spec.whatwg.org/multipage/canvas.html#check-the-usability-of-the-image-argument
 DOM::ExceptionOr<CanvasImageSourceUsability> check_usability_of_image(CanvasImageSource const& image)
 {

Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.h

@@ -98,6 +98,8 @@ public:
     NonnullRefPtr<CanvasGradient> create_linear_gradient(double x0, double y0, double x1, double y1);
     NonnullRefPtr<CanvasGradient> create_conic_gradient(double start_angle, double x, double y);
 
+    void transform(double a, double b, double c, double d, double e, double f);
+
 private:
     explicit CanvasRenderingContext2D(HTMLCanvasElement&);
 

Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.idl

@@ -55,4 +55,7 @@ interface CanvasRenderingContext2D {
     CanvasGradient createLinearGradient(double x0, double y0, double x1, double y1);
     CanvasGradient createConicGradient(double startAngle, double x, double y);
 
+    // FIXME: All these `double`s should be `unrestricted double`
+    undefined transform(double a, double b, double c, double d, double e, double f);
+
 };