TIFFWarning =========== Synopsis -------- .. highlight:: c :: #include #include .. c:function:: void TIFFWarning(const char* module, const char* fmt, ...) .. c:function:: void TIFFWarningExt(thandle_t fd, const char* module, const char* fmt, ...) .. c:function:: void TIFFWarningExtR(TIFF *tif, const char* module, const char* fmt, ...) .. c:type:: void (*TIFFWarningHandler)(const char * module, const char* fmt, va_list ap) .. c:type:: void (*TIFFWarningHandlerExt)(thandle_t fd, const char* module, const char* fmt, va_list ap) .. c:type:: int (*TIFFWarningHandlerExtR)(TIFF* tif, void* user_data, const char* module, const char* fmt, va_list ap) .. c:function:: TIFFWarningHandler TIFFSetWarningHandler(TIFFWarningHandler handler) .. c:function:: TIFFWarningHandlerExt TIFFSetWarningHandlerExt(TIFFWarningHandlerExt handler) Description ----------- :c:func:`TIFFWarning` invokes the library-wide warning handler function to (normally) write a warning message to the ``stderr``. The *fmt* parameter is a :c:func:`printf` format string, and any number arguments can be supplied. The *module* parameter is interpreted as a string that, if non-zero, should be printed before the message; it typically is used to identify the software module in which a warning is detected. Applications that desire to capture control in the event of a warning should use :c:func:`TIFFSetWarningHandler` to override the default warning handler. A :c:macro:`NULL` (0) warning handler function may be installed to suppress warning messages. Two more application-specific warning handler callbacks are available, each with different call parameters and passing parameters to the handler. Each handler is also linked with a warning message function, i.e. :c:func:`TIFFWarningExt` and :c:func:`TIFFWarningExtR` if the application intends to call the handler with those extended parameters. :c:func:`TIFFWarningExt` provides a file handle as parameter. Within ``libtiff`` :c:func:`TIFFWarningExt` is called passing ``tif->tif_clientdata`` as *fd*, which represents the TIFF file handle (file descriptor). The application-specific and library-wide handler for :c:func:`TIFFWarningExt` is setup with :c:func:`TIFFSetWarningHandlerExt`. :c:func:`TIFFWarningExtR` (introduced with libtiff 4.5) is called with its TIFF handle and thus provides access to a per-TIFF handle (re-entrant) warning handler. That means for different TIFF handles, different warning handlers can be setup. This application-specific handler can be setup when a TIFF file is opened with one of the following functions: :c:func:`TIFFOpenExt`, :c:func:`TIFFOpenWExt`, :c:func:`TIFFFdOpenExt` or :c:func:`TIFFClientOpenExt`. Furthermore, a **custom defined data structure** *user_data* for the warning handler can be given along. Note ---- Both functions :c:func:`TIFFWarning` and :c:func:`TIFFWarningExt` each attempt to call both handler functions if they are defined. First :c:func:`TIFFWarningHandler` is called and then :c:func:`TIFFWarningHandlerExt`. However, :c:func:`TIFFWarning` passes a "0" as a file handle to :c:func:`TIFFWarningHandlerExt`. :c:func:`TIFFWarningExtR` tries first to call the per-TIFF handle defined warning handler. If :c:func:`TIFFWarningHandlerExtR` is not defined or returns 0, :c:func:`TIFFWarningHandler` and then :c:func:`TIFFWarningHandlerExt` are called. From libtiff 4.5 onwards :c:func:`TIFFWarningExtR` is used within the ``libtiff`` library. Return values ------------- :c:func:`TIFFSetWarningHandler` and :c:func:`TIFFSetWarningHandlerExt` returns a reference to the previous warning handler function. :c:func:`TIFFWarningHandlerExtR` returns an integer as "stop" to control the call of furhter warning handler functions within :c:func:`TIFFWarningExtR`: - 0: both functions :c:func:`TIFFWarningHandler` and :c:func:`TIFFWarningHandlerExt` are called. - non-zero: no further warning message function is called. See also -------- :doc:`TIFFError` (3tiff), :doc:`TIFFOpen` (3tiff), :doc:`libtiff` (3tiff), printf (3)