Route retained readbacks through GL backend

src/canvas_modes.cpp

@@ -36,6 +36,36 @@ void set_opengl_viewport(std::int32_t x, std::int32_t y, std::int32_t width, std
     glViewport(static_cast<GLint>(x), static_cast<GLint>(y), static_cast<GLsizei>(width), static_cast<GLsizei>(height));
 }
 
+void get_opengl_integer(std::uint32_t name, std::int32_t* values) noexcept
+{
+    static_assert(sizeof(GLint) == sizeof(std::int32_t));
+    glGetIntegerv(static_cast<GLenum>(name), reinterpret_cast<GLint*>(values));
+}
+
+void read_opengl_pixels(
+    std::int32_t x,
+    std::int32_t y,
+    std::int32_t width,
+    std::int32_t height,
+    std::uint32_t pixel_format,
+    std::uint32_t component_type,
+    void* pixels) noexcept
+{
+    glReadPixels(
+        static_cast<GLint>(x),
+        static_cast<GLint>(y),
+        static_cast<GLsizei>(width),
+        static_cast<GLsizei>(height),
+        static_cast<GLenum>(pixel_format),
+        static_cast<GLenum>(component_type),
+        pixels);
+}
+
+void bind_opengl_framebuffer(std::uint32_t target, std::uint32_t framebuffer) noexcept
+{
+    glBindFramebuffer(static_cast<GLenum>(target), static_cast<GLuint>(framebuffer));
+}
+
 void set_canvas_mode_active_texture_unit(std::uint32_t unit_index)
 {
     const auto status = pp::renderer::gl::activate_opengl_texture_unit(
@@ -76,6 +106,34 @@ void apply_canvas_mode_viewport(std::int32_t x, std::int32_t y, std::int32_t wid
         LOG("Canvas mode viewport dispatch failed because: %s", status.message);
 }
 
+std::uint32_t query_canvas_mode_read_framebuffer()
+{
+    std::int32_t read_framebuffer = 0;
+    get_opengl_integer(pp::renderer::gl::read_framebuffer_binding_query(), &read_framebuffer);
+    return static_cast<std::uint32_t>(read_framebuffer);
+}
+
+void read_canvas_mode_pixel(std::int32_t x, std::int32_t y, glm::u8vec4& pixel)
+{
+    const auto status = pp::renderer::gl::readback_opengl_framebuffer(
+        pp::renderer::gl::OpenGlFramebufferReadback {
+            .framebuffer = query_canvas_mode_read_framebuffer(),
+            .x = x,
+            .y = y,
+            .width = 1,
+            .height = 1,
+            .format = pp::renderer::gl::rgba8_readback_format(),
+            .pixels = &pixel,
+        },
+        pp::renderer::gl::OpenGlFramebufferReadbackDispatch {
+            .get_integer = get_opengl_integer,
+            .bind_framebuffer = bind_opengl_framebuffer,
+            .read_pixels = read_opengl_pixels,
+        });
+    if (!status.ok())
+        LOG("Canvas mode pixel readback dispatch failed because: %s", status.message);
+}
+
 }
 
 void CanvasModeBasicCamera::on_MouseEvent(MouseEvent* me, glm::vec2& loc)
@@ -343,19 +401,17 @@ void CanvasModePen::on_Draw(const glm::mat4& ortho, const glm::mat4& proj, const
             }
         }
         glm::u8vec4 pixel;
-        GLint fb_width = App::I->width;
-        GLint fb_height = App::I->height;
+        std::int32_t fb_width = static_cast<std::int32_t>(App::I->width);
+        std::int32_t fb_height = static_cast<std::int32_t>(App::I->height);
         if (node->m_density != 1.f)
         {
             fb_width = node->m_rtt.getWidth();
             fb_height = node->m_rtt.getHeight();
         }
-        glReadPixels((pos.x / App::I->width) * fb_width, 
-            ((App::I->height - pos.y - 1) / App::I->height) * fb_height,
-            1, 1,
-            pp::renderer::gl::rgba_pixel_format(),
-            pp::renderer::gl::unsigned_byte_component_type(),
-            &pixel);
+        read_canvas_mode_pixel(
+            static_cast<std::int32_t>((pos.x / App::I->width) * fb_width),
+            static_cast<std::int32_t>(((App::I->height - pos.y - 1) / App::I->height) * fb_height),
+            pixel);
         bool outline = glm::min(tip_scale.x, tip_scale.y) < 20 || m_resizing ? false : m_draw_outline;
         ShaderManager::u_int(kShaderUniform::DrawOutline, outline);
         ShaderManager::u_vec4(kShaderUniform::Col, outline ? glm::vec4(1.f - glm::vec3(pixel) / 255.f, 1.f) : tip_color);

src/node_panel_grid.cpp

@@ -231,19 +231,7 @@ void NodePanelGrid::init_controls()
         m_texture.create_mipmaps();
 #else
         // get the texture data and resize it
-        Image img;
-        img.create(m_texture.size().x, m_texture.size().y);
-        App::I->render_task([&]
-        {
-            m_texture.bind();
-            glGetTexImage(
-                pp::renderer::gl::texture_2d_target(),
-                0,
-                pp::renderer::gl::rgba_pixel_format(),
-                pp::renderer::gl::unsigned_byte_component_type(),
-                img.m_data.get());
-            m_texture.unbind();
-        });
+        Image img = m_texture.get_image();
         Image resized = img.resize(texres, texres);
         m_texture.create(resized);
         m_texture.create_mipmaps();