image_decoder.h

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#pragma once
#include "esphome/core/color.h"

namespace esphome {
namespace online_image {

enum DecodeError : int {
  DECODE_ERROR_INVALID_TYPE = -1,
  DECODE_ERROR_UNSUPPORTED_FORMAT = -2,
  DECODE_ERROR_OUT_OF_MEMORY = -3,
};

class OnlineImage;

class ImageDecoder {
 public:
  ImageDecoder(OnlineImage *image) : image_(image) {}
  virtual ~ImageDecoder() = default;

  virtual int prepare(size_t download_size) {
    this->download_size_ = download_size;
    return 0;
  }

  virtual int decode(uint8_t *buffer, size_t size) = 0;

  bool set_size(int width, int height);

  void draw(int x, int y, int w, int h, const Color &color);

  bool is_finished() const { return this->decoded_bytes_ == this->download_size_; }

 protected:
  OnlineImage *image_;
  // Initializing to 1, to ensure it is distinguishable from initial "decoded_bytes_".
  // Will be overwritten anyway once the download size is known.
  size_t download_size_ = 1;
  size_t decoded_bytes_ = 0;
  double x_scale_ = 1.0;
  double y_scale_ = 1.0;
};

class DownloadBuffer {
 public:
  DownloadBuffer(size_t size);

  virtual ~DownloadBuffer() { this->allocator_.deallocate(this->buffer_, this->size_); }

  uint8_t *data(size_t offset = 0);

  uint8_t *append() { return this->data(this->unread_); }

  size_t unread() const { return this->unread_; }
  size_t size() const { return this->size_; }
  size_t free_capacity() const { return this->size_ - this->unread_; }

  size_t read(size_t len);
  size_t write(size_t len) {
    this->unread_ += len;
    return this->unread_;
  }

  void reset() { this->unread_ = 0; }

  size_t resize(size_t size);

 protected:
  RAMAllocator<uint8_t> allocator_{};
  uint8_t *buffer_;
  size_t size_;
  size_t unread_;
};

}  // namespace online_image
}  // namespace esphome