bmp_decoder.cpp

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#include "bmp_decoder.h"
 
#ifdef USE_RUNTIME_IMAGE_BMP
 
#include "esphome/components/display/display.h"
#include "esphome/core/helpers.h"
#include "esphome/core/log.h"
 
namespace esphome::runtime_image {
 
static const char *const TAG = "image_decoder.bmp";
 
int HOT BmpDecoder::decode(uint8_t *buffer, size_t size) {
  size_t index = 0;
  if (this->current_index_ == 0 && index == 0 && size > 14) {
    // Check if the file is a BMP image
    if (buffer[0] != 'B' || buffer[1] != 'M') {
      ESP_LOGE(TAG, "Not a BMP file");
      return DECODE_ERROR_INVALID_TYPE;
    }
 
    // BMP file contains its own size in the header
    size_t file_size = encode_uint32(buffer[5], buffer[4], buffer[3], buffer[2]);
    if (this->expected_size_ == 0) {
      this->expected_size_ = file_size;  // Use file header size if not provided
    }
    this->data_offset_ = encode_uint32(buffer[13], buffer[12], buffer[11], buffer[10]);
 
    this->current_index_ = 14;
    index = 14;
  }
  if (this->current_index_ == 14 && index == 14 && size > this->data_offset_) {
    this->width_ = encode_uint32(buffer[21], buffer[20], buffer[19], buffer[18]);
    this->height_ = encode_uint32(buffer[25], buffer[24], buffer[23], buffer[22]);
    this->bits_per_pixel_ = encode_uint16(buffer[29], buffer[28]);
    this->compression_method_ = encode_uint32(buffer[33], buffer[32], buffer[31], buffer[30]);
    this->image_data_size_ = encode_uint32(buffer[37], buffer[36], buffer[35], buffer[34]);
    this->color_table_entries_ = encode_uint32(buffer[49], buffer[48], buffer[47], buffer[46]);
 
    switch (this->bits_per_pixel_) {
      case 1:
        this->width_bytes_ = (this->width_ % 8 == 0) ? (this->width_ / 8) : (this->width_ / 8 + 1);
        break;
      case 24:
        this->width_bytes_ = this->width_ * 3;
        if (this->width_bytes_ % 4 != 0) {
          this->padding_bytes_ = 4 - (this->width_bytes_ % 4);
          this->width_bytes_ += this->padding_bytes_;
        }
        break;
      default:
        ESP_LOGE(TAG, "Unsupported bits per pixel: %d", this->bits_per_pixel_);
        return DECODE_ERROR_UNSUPPORTED_FORMAT;
    }
 
    if (this->compression_method_ != 0) {
      ESP_LOGE(TAG, "Unsupported compression method: %d", this->compression_method_);
      return DECODE_ERROR_UNSUPPORTED_FORMAT;
    }
 
    if (!this->set_size(this->width_, this->height_)) {
      return DECODE_ERROR_OUT_OF_MEMORY;
    }
    this->current_index_ = this->data_offset_;
    index = this->data_offset_;
  }
  switch (this->bits_per_pixel_) {
    case 1: {
      while (index < size) {
        uint8_t current_byte = buffer[index];
        for (uint8_t i = 0; i < 8; i++) {
          size_t x = (this->paint_index_ % static_cast<size_t>(this->width_)) + i;
          size_t y = static_cast<size_t>(this->height_ - 1) - (this->paint_index_ / static_cast<size_t>(this->width_));
          Color c = (current_byte & (1 << (7 - i))) ? display::COLOR_ON : display::COLOR_OFF;
          this->draw(x, y, 1, 1, c);
        }
        this->paint_index_ += 8;
        this->current_index_++;
        index++;
      }
      break;
    }
    case 24: {
      while (index < size) {
        if (index + 2 >= size) {
          this->decoded_bytes_ += index;
          return index;
        }
        uint8_t b = buffer[index];
        uint8_t g = buffer[index + 1];
        uint8_t r = buffer[index + 2];
        size_t x = this->paint_index_ % static_cast<size_t>(this->width_);
        size_t y = static_cast<size_t>(this->height_ - 1) - (this->paint_index_ / static_cast<size_t>(this->width_));
        Color c = Color(r, g, b);
        this->draw(x, y, 1, 1, c);
        this->paint_index_++;
        this->current_index_ += 3;
        index += 3;
        size_t last_col = static_cast<size_t>(this->width_) - 1;
        if (x == last_col && this->padding_bytes_ > 0) {
          index += this->padding_bytes_;
          this->current_index_ += this->padding_bytes_;
        }
      }
      break;
    }
    default:
      ESP_LOGE(TAG, "Unsupported bits per pixel: %d", this->bits_per_pixel_);
      return DECODE_ERROR_UNSUPPORTED_FORMAT;
  }
  this->decoded_bytes_ += size;
  return size;
};
 
}  // namespace esphome::runtime_image
 
#endif  // USE_RUNTIME_IMAGE_BMP