Share CanvasMode GL dispatch adapters

src/legacy_ui_gl_dispatch.h

@@ -53,6 +53,37 @@ inline void bind_opengl_texture(std::uint32_t target, std::uint32_t texture) noe
     glBindTexture(static_cast<GLenum>(target), static_cast<GLuint>(texture));
 }
 
+inline void bind_opengl_framebuffer(std::uint32_t target, std::uint32_t framebuffer) noexcept
+{
+    glBindFramebuffer(static_cast<GLenum>(target), static_cast<GLuint>(framebuffer));
+}
+
+inline 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);
+}
+
+inline void get_opengl_integer_scalar(std::uint32_t name, std::int32_t* value) noexcept
+{
+    GLint raw_value = 0;
+    glGetIntegerv(static_cast<GLenum>(name), &raw_value);
+    *value = static_cast<std::int32_t>(raw_value);
+}
+
 inline void get_opengl_integer(std::uint32_t name, std::int32_t* values) noexcept
 {
     GLint raw_values[4] {};
@@ -109,6 +140,14 @@ inline bool query_capability(std::uint32_t state, const char* context)
     return result.value();
 }
 
+inline std::uint32_t query_read_framebuffer(const char* context)
+{
+    std::int32_t read_framebuffer = 0;
+    get_opengl_integer_scalar(pp::renderer::gl::read_framebuffer_binding_query(), &read_framebuffer);
+    (void)context;
+    return static_cast<std::uint32_t>(read_framebuffer);
+}
+
 inline void set_capability(std::uint32_t state, bool enabled, const char* context)
 {
     const auto status = pp::renderer::gl::apply_opengl_capability(
@@ -183,6 +222,32 @@ inline void apply_scissor_rect(
         LOG("%s scissor dispatch failed because: %s", context, status.message);
 }
 
+inline void read_framebuffer_rgba8_pixel(
+    std::uint32_t framebuffer,
+    std::int32_t x,
+    std::int32_t y,
+    void* pixel,
+    const char* context)
+{
+    const auto status = pp::renderer::gl::readback_opengl_framebuffer(
+        pp::renderer::gl::OpenGlFramebufferReadback {
+            .framebuffer = 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_scalar,
+            .bind_framebuffer = bind_opengl_framebuffer,
+            .read_pixels = read_opengl_pixels,
+        });
+    if (!status.ok())
+        LOG("%s pixel readback dispatch failed because: %s", context, status.message);
+}
+
 inline void clear_color_buffer(std::array<float, 4> color, const char* context)
 {
     const auto status = pp::renderer::gl::clear_opengl_render_target(