draw_jpg with buffer support

overload.hpp

struct JpegDecodeBuffer
{
  std::uint8_t body[4096];
};

bool draw_jpg(DataWrapper* data, int16_t x, int16_t y, int16_t maxWidth, int16_t maxHeight, int16_t offX, int16_t offY, jpeg_div_t scale, JpegDecodeBuffer& decodeBuffer)
{
  //...
  auto jres = jd_prepare(&jpegdec, jpg_read_data, decodeBuffer.body, sz_pool, &jpeg);
  //...
}

// User can select where the buffer is allocated from.
// The buffer is allocated from the stack by default.
bool drawJpgFile( fs::FS &fs, const char *path, int16_t x=0, int16_t y=0, int16_t maxWidth=0, int16_t maxHeight=0, int16_t offX=0, int16_t offY=0, jpeg_div_t scale=JPEG_DIV_NONE) {
  JpegDecodeBuffer decodeBuffer;
  return drawJpgFile(fs, path, x, y, maxWidth, maxHeight, offX, offY, scale, decodeBuffer);
}
bool drawJpgFile( fs::FS &fs, const char *path, int16_t x=0, int16_t y=0, int16_t maxWidth=0, int16_t maxHeight=0, int16_t offX=0, int16_t offY=0, jpeg_div_t scale=JPEG_DIV_NONE, JpegDecodeBuffer& decodeBuffer) {
  bool res;
  FileWrapper file;
  file.setFS(fs);
//      drawJpgFile(&file, path, x, y, maxWidth, maxHeight, offX, offY, scale);

  file.need_transaction &= this->_has_transaction;
  if (file.need_transaction) this->endTransaction();
  if (file.open(path, "rb")) {
    DecodeBufferType decodeBuffer;  // Allocate a decode buffer.
    res = draw_jpg(&file, x, y, maxWidth, maxHeight, offX, offY, scale, decodeBuffer);
    file.close();
  }
  if (file.need_transaction && this->_transaction_count) { this->beginTransaction(); }
  return res;
}

drawJpgFile(...); // Allocate decode buffer from the stack.

auto decodeBuffer = new JpegDecodeBuffer() // Allocate decode buffer from the heap.
drawJpgFile(..., *decodeBuffer); 

template.hpp

struct StaticJpegDecodeBuffer
{
  std::uint8_t body[4096];
  std::uint8_t* get() const { return this->body; }
};
class DynamicJpegDecodeBuffer
{
public:
  DynamicJpegDecodeBuffer() : buffer(nullptr) {
    this->buffer = new StaticJpegDecodeBuffer();
  }
  ~DynamicJpegDecodeBuffer() {
    if(this->buffer != nullptr) {
      delete this->buffer;
      this->buffer = nullptr; 
    }
  }
  std::uint8_t* get() const { return this->buffer->get(); }
private:
  StaticJpegDecodeBuffer* buffer;
};

template<typename DecodeBufferType>
bool draw_jpg(DataWrapper* data, int16_t x, int16_t y, int16_t maxWidth, int16_t maxHeight, int16_t offX, int16_t offY, jpeg_div_t scale, DecodeBufferType& decodeBuffer)
{
  //...
  auto jres = jd_prepare(&jpegdec, jpg_read_data, decodeBuffer.get(), sz_pool, &jpeg);
  //...
}

// User can select where the buffer is allocated from.
// The buffer is allocated from the stack by default.
template<typename DecodeBufferType = StaticJpegDecodeBuffer>
bool drawJpgFile( fs::FS &fs, const char *path, int16_t x=0, int16_t y=0, int16_t maxWidth=0, int16_t maxHeight=0, int16_t offX=0, int16_t offY=0, jpeg_div_t scale=JPEG_DIV_NONE) {
  bool res;
  FileWrapper file;
  file.setFS(fs);
//      drawJpgFile(&file, path, x, y, maxWidth, maxHeight, offX, offY, scale);

  file.need_transaction &= this->_has_transaction;
  if (file.need_transaction) this->endTransaction();
  if (file.open(path, "rb")) {
    DecodeBufferType decodeBuffer;  // Allocate a decode buffer.
    res = draw_jpg(&file, x, y, maxWidth, maxHeight, offX, offY, scale, decodeBuffer);
    file.close();
  }
  if (file.need_transaction && this->_transaction_count) { this->beginTransaction(); }
  return res;
}

drawJpgFile(...); // Allocate decode buffer from the stack.
drawJpgFile<DynamicDecodeBuffer>(...); // Allocate decode buffer from the heap.