Plan stroke preview composite sequence

src/legacy_canvas_stroke_preview_services.h

@@ -0,0 +1,55 @@
+#pragma once
+
+namespace pp::panopainter {
+
+struct LegacyStrokePreviewCopySize {
+    int width = 0;
+    int height = 0;
+};
+
+template <
+    typename SetupCheckerboard,
+    typename DrawPlane,
+    typename BindBackgroundTexture,
+    typename CopyFramebufferToTexture>
+void execute_legacy_stroke_preview_background_capture(
+    SetupCheckerboard&& setup_checkerboard,
+    DrawPlane&& draw_plane,
+    BindBackgroundTexture&& bind_background_texture,
+    CopyFramebufferToTexture&& copy_framebuffer_to_texture,
+    LegacyStrokePreviewCopySize copy_size)
+{
+    setup_checkerboard();
+    draw_plane();
+    bind_background_texture();
+    copy_framebuffer_to_texture(0, 0, 0, 0, copy_size.width, copy_size.height);
+}
+
+template <
+    typename SetupCompositeShader,
+    typename BindCompositeSamplers,
+    typename BindCompositeInputs,
+    typename DrawPlane>
+void execute_legacy_stroke_preview_final_composite(
+    SetupCompositeShader&& setup_composite_shader,
+    BindCompositeSamplers&& bind_composite_samplers,
+    BindCompositeInputs&& bind_composite_inputs,
+    DrawPlane&& draw_plane)
+{
+    setup_composite_shader();
+    bind_composite_samplers();
+    bind_composite_inputs();
+    draw_plane();
+}
+
+template <typename BindPreviewTexture, typename CopyFramebufferToTexture>
+void copy_legacy_stroke_preview_texture(
+    BindPreviewTexture&& bind_preview_texture,
+    CopyFramebufferToTexture&& copy_framebuffer_to_texture,
+    LegacyStrokePreviewCopySize copy_size)
+{
+    bind_preview_texture();
+    copy_framebuffer_to_texture(0, 0, 0, 0, copy_size.width, copy_size.height);
+}
+
+} // namespace pp::panopainter