src/ui/examples/frame-compression/base_view.h

// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef SRC_UI_EXAMPLES_FRAME_COMPRESSION_BASE_VIEW_H_
#define SRC_UI_EXAMPLES_FRAME_COMPRESSION_BASE_VIEW_H_

#include <lib/inspect/cpp/inspect.h>
#include <lib/inspect/cpp/vmo/types.h>
#include <lib/syslog/cpp/macros.h>
#include <lib/ui/scenic/cpp/resources.h>
#include <png.h>

#include "src/lib/fxl/macros.h"
#include "src/lib/ui/base_view/base_view.h"

namespace frame_compression {

// Base class for examples that generate compressed frames using the CPU,
// or by Vulkan compute.
class BaseView : public scenic::BaseView {
 public:
  BaseView(scenic::ViewContext context, const std::string& debug_name, uint32_t width,
           uint32_t height, inspect::Node inspect_node);
  ~BaseView() override = default;

  // Helper functions for PNG handling.
  static png_structp CreatePngReadStruct(FILE* png_fp, png_infop* info_ptr_ptr);
  static void DestroyPngReadStruct(png_structp png, png_infop info_ptr);

 protected:
  static constexpr uint32_t kTiledAfbcBodyAlignment = 4096u;
  static constexpr uint32_t kTiledAfbcWidthAlignment = 128u;
  static constexpr uint32_t kTiledAfbcHeightAlignment = 128u;
  static constexpr uint32_t kAfbcBytesPerBlockHeader = 16u;
  static constexpr uint32_t kAfbcTilePixelWidth = 16u;
  static constexpr uint32_t kAfbcTilePixelHeight = 16u;
  static constexpr uint32_t kAfbcHeaderTileWidth = 8u;
  static constexpr uint32_t kAfbcHeaderTileHeight = 8u;
  static constexpr uint32_t kAfbcHeaderTileBlocks = kAfbcHeaderTileWidth * kAfbcHeaderTileHeight;
  static constexpr uint32_t kAfbcSubtileSize = 4u;
  static constexpr uint32_t kTileBytesPerPixel = 4u;
  static constexpr uint32_t kTileNumPixels = kAfbcTilePixelWidth * kAfbcTilePixelHeight;
  static constexpr uint32_t kTileNumBytes = kTileNumPixels * kTileBytesPerPixel;
  static constexpr uint32_t kNumImages = 3u;

  const uint32_t width_;
  const uint32_t height_;
  scenic::Material material_;
  inspect::Node top_inspect_node_;

  uint32_t GetNextImageIndex();

  // Returns the color offset used for the producing contents for the next frame.
  // The color offset determines at what Y offset we should switch from first
  // to second color.
  uint32_t GetNextColorOffset();

  uint32_t GetNextFrameNumber();

  // Animate the translation for the shape node to swirl around the screen.
  void Animate(fuchsia::images::PresentationInfo presentation_info);

 private:
  // |scenic::SessionListener|
  void OnScenicError(std::string error) override { FX_LOGS(ERROR) << "Scenic Error " << error; }

  fpromise::promise<inspect::Inspector> PopulateStats() const;

  uint32_t next_color_offset_ = 0;
  uint32_t next_image_index_ = 0;
  uint32_t next_frame_number_ = 0;
  scenic::ShapeNode node_;
  inspect::LazyNode inspect_node_;

  FXL_DISALLOW_COPY_AND_ASSIGN(BaseView);
};

}  // namespace frame_compression

#endif  // SRC_UI_EXAMPLES_FRAME_COMPRESSION_BASE_VIEW_H_