QRCode Encoder SDK Dynamic Library — API overview and examples
Overview
- Purpose: native dynamic library (DLL/.so/.dylib) exposing an API to encode data into QR Codes for embedding in desktop, server, or embedded apps.
- Typical features: encode text/URLs, set error-correction level, choose version/size, output raster (PNG/JPEG/bitmap) or vector (SVG), set margin/scale/colors, embed logo, return raw module matrix, stream output, and thread-safe encoder contexts.
Key API components (assumed/common)
- Initialization / lifetime
- create_encoder(config) → encoder_handle
- destroy_encoder(encoder_handle)
- Encoding functions
- encode_text(encoder_handle, const chardata, options, output_buffer) → status
- encode_segments(encoder_handle, segments[], options, output_buffer*)
- Output formats
- output_as_png(encoder_handle, quality, stream_cb, user_ctx)
- output_as_svg(encoder_handle, scale, bool include_margin, char** out_svg)
- output_raw_matrix(encoder_handle, uint8_t** matrix, int* size)
- Options / parameters (options struct)
- error_correction: L/M/Q/H
- version: 0 (auto) or 1..40
- mask: -1 (auto) or 0..7
- scale / module_pixel_size
- margin (quiet zone) in modules
- foreground_color / background_color (RGB / hex)
- image_format: PNG/JPEG/SVG/RAW
- center_logo (image data + scale/opacity)
- boost_ecc (bool)
- Streaming & callbacks
- encoder supports stream callback to write output in chunks (useful for large images / limited memory)
- Error handling
- status codes: OK, INVALID_INPUT, BUFFER_TOO_SMALL, ENCODING_FAILED, IO_ERROR
- get_last_error(encoder_handle) → const char
- Threading
- encoderhandle is thread-safe for concurrent read-only ops; create separate handles for parallel encodes if library docs recommend.
Minimal usage example (C API)
c
// create EncoderConfig cfg = { .error_correction = ECC_MEDIUM, .version = 0, .scale = 4, .margin = 4 }; EncoderHandle h = create_encoder(&cfg); // encode to PNG in-memory OutputBuffer out = {0}; Status s = encode_text(h, “https://example.com”, NULL, &out); if (s == OK) { // out.data (uint8_t) and out.size contain PNG bytes write_file(“qrcode.png”, out.data, out.size); } free_output(&out); destroyencoder(h);
Example: get raw module matrix ©
c
EncoderHandle h = create_encoder(NULL); uint8_t* matrix = NULL; int size = 0; if (encode_text_raw_matrix(h, “12345”, &matrix, &size) == OK) { // matrix is size*size bytes; 1 = dark module, 0 = light // render or inspect modules free(matrix); } destroy_encoder(h);
Example: usage from C# (P/Invoke) — calling PNG stream callback
- P/Invoke signatures for create_encoder, encode_text_stream(encoder, data, callback, ctx), destroy_encoder.
- Provide a managed callback that receives byte chunks and writes to FileStream.
Example: Java / JNI
- Load native lib, expose native methods encodeToPNG(byte[] input, Options) returning byte[]; call from Java and write to file or ImageIO.
Best-practice recommendations
- Use auto-version (0) unless strict size control is needed.
- Let library auto-select mask for best readability unless you need deterministic output.
- Use at least M or Q ECC for production; H if embedding logos.
- Stream large outputs to avoid large in-memory buffers.
- Validate input length vs chosen version/ecc; library may return BUFFER_TOO_SMALL or VERSION_TOO_SMALL.
- Cache encoder instances when reusing identical config to reduce init overhead.
If you want, I can produce: (1) a concrete C header + minimal implementation stub for this API, (2) P/Invoke C# signatures, or (3) a full example for embedding a logo and producing PNG — tell me which.
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