Route canvas clear state through GL backend

src/canvas_layer.cpp

@@ -6,6 +6,8 @@
 #include "rtt.h"
 #include "util.h"
 
+#include <array>
+
 uint32_t Layer::s_count = 0;
 
 namespace {
@@ -40,6 +42,11 @@ void clear_opengl_buffer(std::uint32_t mask) noexcept
     glClear(static_cast<GLbitfield>(mask));
 }
 
+void get_opengl_float(std::uint32_t name, float* values) noexcept
+{
+    glGetFloatv(static_cast<GLenum>(name), values);
+}
+
 void copy_opengl_tex_sub_image_2d(
     std::uint32_t target,
     std::int32_t level,
@@ -142,9 +149,27 @@ void clear_layer_color_buffer(const glm::vec4& color)
         LOG("Layer clear dispatch failed because: %s", status.message);
 }
 
-void restore_layer_clear_color(const GLfloat* color)
+std::array<float, 4> query_layer_clear_color()
 {
-    set_opengl_clear_color(color[0], color[1], color[2], color[3]);
+    const auto result = pp::renderer::gl::query_opengl_clear_color(
+        pp::renderer::gl::OpenGlClearColorQueryDispatch {
+            .get_float = get_opengl_float,
+        });
+    if (!result.ok()) {
+        LOG("Layer clear-color query dispatch failed because: %s", result.status().message);
+    }
+    return result.value();
+}
+
+void restore_layer_clear_color(std::array<float, 4> color)
+{
+    const auto status = pp::renderer::gl::apply_opengl_clear_color(
+        color,
+        pp::renderer::gl::OpenGlClearColorDispatch {
+            .clear_color = set_opengl_clear_color,
+        });
+    if (!status.ok())
+        LOG("Layer clear-color dispatch failed because: %s", status.message);
 }
 
 }
@@ -601,8 +626,7 @@ void LayerFrame::clear(const glm::vec4& c)
     App::I->render_task([&]
     {
         // push clear color state
-        GLfloat cc[4];
-        glGetFloatv(pp::renderer::gl::color_clear_value_query(), cc);
+        const auto cc = query_layer_clear_color();
 
         bool erase = (c.a == 0.f);