Yalantis/uCrop · error · CImgIOException

load_jxl(): Failed to load image data '%s'.

Error message

load_jxl(): Failed to load image data '%s'.

What it means

After configuring the decoder, load_jxl() feeds the raw file bytes with JxlDecoderSetInput(buffer, size). A return value other than JXL_DEC_SUCCESS means libjxl rejected the input buffer setup, so CImg destroys the decoder and throws. Note the message text is reused later for basic-info failure; this specific throw corresponds to the SetInput step.

Source

Thrown at ucrop/src/main/jni/CImg.h:57167

      cimg::fread(buffer._data,buffer._width,nfile);
      cimg::fclose(nfile);

      bool hasAlpha = false, isGray = false;
      uint32_t nChannels = 0;
      JxlBasicInfo jxlInfo;
      JxlPixelFormat format = { 1,JXL_TYPE_UINT8,cimg::endianness()?JXL_BIG_ENDIAN:JXL_LITTLE_ENDIAN,0 };
      CImg<ucharT> imgData;
      JxlDecoder *decoder = JxlDecoderCreate(NULL);
      if (JXL_DEC_SUCCESS!=JxlDecoderSubscribeEvents(decoder,JXL_DEC_BASIC_INFO | JXL_DEC_FULL_IMAGE)) {
        JxlDecoderDestroy(decoder);
        throw CImgIOException(_cimg_instance
                              "load_jxl(): Failed to configure decoder '%s'.",
                              cimg_instance,
                              nfilename);
      }
      if (JXL_DEC_SUCCESS!=JxlDecoderSetInput(decoder,buffer._data,buffer._width)) {
        JxlDecoderDestroy(decoder);
        throw CImgIOException(_cimg_instance
                              "load_jxl(): Failed to load image data '%s'.",
                              cimg_instance,
                              nfilename);
      }
      JxlDecoderCloseInput(decoder);

      while (true) {
        JxlDecoderStatus status = JxlDecoderProcessInput(decoder);
        if (status==JXL_DEC_SUCCESS || status==JXL_DEC_FULL_IMAGE) break;
        else if (status==JXL_DEC_ERROR || status==JXL_DEC_NEED_MORE_INPUT) {
          JxlDecoderDestroy(decoder);
          throw CImgIOException(_cimg_instance
                                "load_jxl(): Failed to decode image '%s'.",
                                cimg_instance,
                                nfilename);
        } else if (status==JXL_DEC_BASIC_INFO) {
          if (JXL_DEC_SUCCESS!=JxlDecoderGetBasicInfo(decoder,&jxlInfo)) {
            JxlDecoderDestroy(decoder);

View on GitHub (pinned to f788b534b4)

Solutions

  1. Check that the file was fully read: verify fread() returned dataSize bytes before calling load_jxl.
  2. Re-check the file's integrity/size; re-copy the .jxl file if it was truncated during transfer.
  3. If constructing buffers manually, ensure data is non-null and size equals the actual byte count.

Example fix

// before
CImg<unsigned char> buf(dataSize);
cimg::fread(buf._data, buf._width, file); // return ignored
img.load_jxl(...); // may throw at SetInput
// after
const size_t got = cimg::fread(buf._data, buf._width, file);
if (got != dataSize) { /* handle short read */ }
Defensive patterns

Strategy: validation

Validate before calling

bool readFileFully(const char* path, CImg<unsigned char>& buf) {
  std::FILE* f = std::fopen(path, "rb");
  if (!f) return false;
  long sz = cimg::fsize(f);
  if (sz <= 0) { std::fclose(f); return false; }
  buf.assign(sz);
  size_t got = cimg::fread(buf._data, buf._width, f);
  std::fclose(f);
  return got == (size_t)sz;
}

Try / catch

try { img.load_jxl(path); } catch (CImgIOException& e) { retryWithReCopiedFile(path); }

Prevention

When it happens

Trigger: JxlDecoderSetInput(decoder, buffer._data, buffer._width) returns != JXL_DEC_SUCCESS, i.e. the input pointer/size pair was rejected (null data with non-zero size or invalid state).

Common situations: The file was read into an empty buffer (fread failure, truncated file between fsize and read), or memory pressure made the CImg buffer allocation degenerate.

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

AI-assisted analysis of Yalantis/uCrop@f788b534b4 (2026-09-08). Data as JSON: /api/errors/950d8cab9b7a990f. Report an issue: GitHub.