image_decoder.h

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#pragma once
#include "esphome/core/color.h"
#include "image_format.h"
 
namespace esphome::runtime_image {
 
enum DecodeError : int {
  DECODE_ERROR_INVALID_TYPE = -1,
  DECODE_ERROR_UNSUPPORTED_FORMAT = -2,
  DECODE_ERROR_OUT_OF_MEMORY = -3,
  DECODE_ERROR_INTERNAL_DECODER_ERROR = -4,
};
 
constexpr const char *decode_error_to_string(int error) {
  switch (error) {
    case DECODE_ERROR_INVALID_TYPE:
      return "Invalid type";
    case DECODE_ERROR_UNSUPPORTED_FORMAT:
      return "Unsupported format";
    case DECODE_ERROR_OUT_OF_MEMORY:
      return "Out of memory";
    case DECODE_ERROR_INTERNAL_DECODER_ERROR:
      return "Internal decoder error";
    default:
      return "Unknown error";
  }
}
 
class RuntimeImage;
 
class ImageDecoder {
 public:
  ImageDecoder(RuntimeImage *image, ImageFormat format) : image_(image), format_(format) {}
  virtual ~ImageDecoder() = default;
 
  ImageFormat get_format() const { return this->format_; }
 
  bool is_active() const { return this->active_; }
 
  virtual void reset() {
    this->active_ = false;
    this->expected_size_ = 0;
    this->decoded_bytes_ = 0;
    this->size_valid_ = true;
    this->x_scale_ = 1.0;
    this->y_scale_ = 1.0;
  }
 
  virtual int prepare(size_t expected_size) {
    this->reset();
    this->expected_size_ = expected_size;
    this->active_ = true;
    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);
 
  virtual bool is_finished() const {
    if (this->expected_size_ > 0) {
      return this->decoded_bytes_ >= this->expected_size_;
    }
    // If size is unknown, derived classes should override this
    return false;
  }
 
 protected:
  double x_scale_ = 1.0;
  double y_scale_ = 1.0;
  RuntimeImage *image_;
  size_t expected_size_ = 0;  // Expected data size (0 if unknown)
  size_t decoded_bytes_ = 0;  // Bytes processed so far
  const ImageFormat format_;
  bool active_ = false;     // A decoding session is in progress
  bool size_valid_ = true;  // Last set_size() result; draw() no-ops while false
};
 
}  // namespace esphome::runtime_image