LibWeb: Add a basic SVGContext object, add to PaintContext

This will be used to transmit any svg-relevant data between svg nodes.
This is prep for moving a lot of the SVG logic into Layout nodes.

Libraries/LibWeb/SVG/SVGContext.h

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2020, Matthew Olsson <matthewcolsson@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+namespace Web {
+
+class SVGContext {
+public:
+    SVGContext()
+    {
+        push_state();
+    }
+
+    const Gfx::Color& fill_color() const { return state().fill_color; }
+    const Gfx::Color& stroke_color() const { return state().stroke_color; }
+    float stroke_width() const { return state().stroke_width; }
+
+    void set_fill_color(Gfx::Color color) { state().fill_color = color; }
+    void set_stroke_color(Gfx::Color color) { state().stroke_color = color; }
+    void set_stroke_width(float width) { state().stroke_width = width; }
+
+    void push_state() { m_states.append(State()); }
+
+    void pop_state() { m_states.take_last(); }
+
+private:
+    struct State {
+        Gfx::Color fill_color { Gfx::Color::Black };
+        Gfx::Color stroke_color { Gfx::Color::Transparent };
+        float stroke_width { 1.0 };
+    };
+
+    const State& state() const { return m_states.last(); }
+    State& state() { return m_states.last(); }
+
+    Vector<State> m_states;
+};
+
+}