Route canvas input policy through platform services

src/platform_windows/windows_platform_services.cpp

@@ -496,6 +496,23 @@ public:
     {
     }
 
+    [[nodiscard]] bool draws_canvas_tip_for_pointer(
+        bool is_mouse,
+        bool is_stylus,
+        bool is_left_button_release) override
+    {
+        (void)is_left_button_release;
+        return is_mouse || is_stylus;
+    }
+
+    [[nodiscard]] float adjust_canvas_input_pressure(float pressure) override
+    {
+        const auto curve = [](float x, float max) {
+            return x > max ? 1.f : glm::pow(1.f - glm::pow(x / max - 1.f, 2.f), 2.f);
+        };
+        return curve(pressure, 0.95f);
+    }
+
     [[nodiscard]] pp::platform::PreparedFileTarget prepare_writable_file(
         std::string_view type,
         std::string_view default_name,