Nomad changes

crates/kreuzberg-tesseract/patches/README.md

@@ -0,0 +1,74 @@
+# Tesseract WASM Patches
+
+This directory contains patches needed to compile Tesseract for WebAssembly (WASM) targets using WASI SDK.
+
+These patches are vendored from the [tesseract-wasm](https://github.com/naptha/tesseract.js) project and have been proven to work with WASM compilation.
+
+## Patches
+
+### tesseract.diff
+
+A comprehensive patch that makes Tesseract compatible with WASM compilation. The patch includes the following changes:
+
+#### 1. CMakeLists.txt Modifications
+
+- **New CMake option**: `BUILD_TESSERACT_BINARY` (default: ON)
+  - Allows disabling the Tesseract CLI binary build, which is not needed for WASM
+  - Wraps all executable and installation targets for the tesseract binary
+
+- **Disabled components for WASM**:
+  - Removes OpenCL support (`src/opencl/*.cpp`) - not applicable to WASM
+  - Removes viewer support (`src/viewer/*.cpp`) - UI components not needed for WASM
+  - Removes C API bindings (`src/api/capi.cpp`) - only hocrrenderer is kept
+  - Removes PDF and rendering support files:
+    - `src/api/renderer.cpp`
+    - `src/api/altorenderer.cpp`
+    - `src/api/lstmboxrenderer.cpp`
+    - `src/api/pdfrenderer.cpp`
+    - `src/api/wordstrboxrenderer.cpp`
+
+#### 2. SIMD Detection Fixes (src/arch/simddetect.cpp)
+
+- Guards CPUID detection with `#if !defined(__wasm__)`
+- Prevents attempts to use CPU feature detection that don't exist in WASM
+- The HAS_CPUID macro is only defined for non-WASM builds
+- This allows the code to gracefully handle WASM's SIMD limitations
+
+#### 3. Pointer Type Fixes (src/ccmain/pageiterator.cpp, src/ccmain/pagesegmain.cpp, src/ccmain/tesseractclass.cpp)
+
+**Changed from stack allocation to heap allocation** in `tesseractclass.h`:
+
+- `pixa_debug_` changed from `DebugPixa` to `std::unique_ptr<DebugPixa>`
+- This prevents large allocations on the stack, which is limited in WASM
+
+**Updated all references** throughout the codebase:
+
+- `.get()` calls added where raw pointers are needed
+- Arrow operator `->` replaces dot operator `.` for member access
+- Null checks added before dereferencing to prevent crashes
+
+**Affected functions**:
+
+- `PageIterator::Orientation()` - added null vector check
+- `Tesseract::AutoPageSeg()` - updated pointer passing
+- `Tesseract::SetupPageSegAndDetectOrientation()` - multiple pointer updates
+- `Tesseract::Clear()` - added null check before WritePDF
+- `Tesseract::PrepareForPageseg()` - updated Split() calls
+- `Tesseract::PrepareForTessOCR()` - updated Split() calls
+
+#### 4. Additional Fixes
+
+- **Orientation detection**: Changed comparison from `> 0.0F` to `>= 0.0F` in `pageiterator.cpp` to handle null vectors gracefully when orientation info is not available
+
+## How to Apply
+
+These patches are applied during the WASM build process. They modify the Tesseract source code to:
+
+1. Disable WASM-incompatible features (OpenCL, viewers, renderers)
+2. Prevent CPUID detection in WASM environment
+3. Use heap allocation instead of stack allocation for large objects
+4. Handle missing pointer initialization gracefully
+
+## Source
+
+These patches are based on the proven WASM compilation approach used by the tesseract.js project, which successfully compiles Tesseract to WebAssembly and deploys it in production environments.