Add progress monitoring C api

The C API is missing the ability to monitor the progress of the
recognition. This patch adds C wrappers to the progress monitor
that allow monitoring the progress and canceling the recognition
process early.

src/api/capi.cpp

@@ -807,3 +807,43 @@ TESS_API float TESS_CALL TessChoiceIteratorConfidence(const TessChoiceIterator*
 {
     return handle->Confidence();
 }
+
+TESS_API ETEXT_DESC* TESS_CALL TessMonitorCreate()
+{
+    return new ETEXT_DESC();
+}
+
+TESS_API void TESS_CALL TessMonitorcDelete( ETEXT_DESC* monitor )
+{
+    delete monitor;
+}
+
+TESS_API void TESS_CALL TessMonitorSetCancelFunc( ETEXT_DESC* monitor, TessCancelFunc cancelFunc )
+{
+    monitor->cancel = cancelFunc;
+}
+
+TESS_API void TESS_CALL TessMonitorSetCancelThis( ETEXT_DESC* monitor, void* cancelThis )
+{
+    monitor->cancel_this = cancelThis;
+}
+
+TESS_API void* TESS_CALL TessMonitorGetCancelThis( ETEXT_DESC* monitor )
+{
+    return monitor->cancel_this;
+}
+
+TESS_API void TESS_CALL TessMonitorSetProgressFunc( ETEXT_DESC* monitor, TessProgressFunc2 progressFunc )
+{
+    monitor->progress_callback2 = progressFunc;
+}
+
+TESS_API int TESS_CALL TessMonitorGetProgress( ETEXT_DESC* monitor )
+{
+    return monitor->progress;
+}
+
+TESS_API void TESS_CALL TessMonitorSetDeadlineMSecs( ETEXT_DESC* monitor, int deadline )
+{
+    monitor->set_deadline_msecs( deadline );
+}

src/api/capi.h

@@ -24,6 +24,7 @@
 
 #ifdef TESS_CAPI_INCLUDE_BASEAPI
 #   include "baseapi.h"
+#   include "ocrclass.h"
 #   include "pageiterator.h"
 #   include "resultiterator.h"
 #   include "renderer.h"
@@ -104,6 +105,10 @@ typedef enum TessTextlineOrder     { TEXTLINE_ORDER_LEFT_TO_RIGHT, TEXTLINE_ORDE
 typedef struct ETEXT_DESC ETEXT_DESC;
 #endif
 
+typedef bool (*TessCancelFunc)(void* cancel_this, int words);
+typedef bool (*TessProgressFunc)(ETEXT_DESC* ths, int left, int right, int top,
+                                 int bottom);
+
 struct Pix;
 struct Boxa;
 struct Pixa;
@@ -392,6 +397,17 @@ TESS_API BOOL  TESS_CALL TessChoiceIteratorNext(TessChoiceIterator* handle);
 TESS_API const char* TESS_CALL TessChoiceIteratorGetUTF8Text(const TessChoiceIterator* handle);
 TESS_API float TESS_CALL TessChoiceIteratorConfidence(const TessChoiceIterator* handle);
 
+/* Progress monitor */
+
+TESS_API ETEXT_DESC* TESS_CALL TessMonitorCreate();
+TESS_API void TESS_CALL TessMonitorcDelete( ETEXT_DESC* monitor );
+TESS_API void TESS_CALL TessMonitorSetCancelFunc( ETEXT_DESC* monitor, TessCancelFunc cancelFunc );
+TESS_API void TESS_CALL TessMonitorSetCancelThis( ETEXT_DESC* monitor, void* cancelThis );
+TESS_API void* TESS_CALL TessMonitorGetCancelThis( ETEXT_DESC* monitor );
+TESS_API void TESS_CALL TessMonitorSetProgressFunc( ETEXT_DESC* monitor, TessProgressFunc progressFunc );
+TESS_API int TESS_CALL TessMonitorGetProgress( ETEXT_DESC* monitor );
+TESS_API void TESS_CALL TessMonitorSetDeadlineMSecs( ETEXT_DESC* monitor, int deadline );
+
 #ifdef __cplusplus
 }
 #endif