Initial work on progressive loading

We are testing this using a new -p flag to mupdf that sets a bitrate at
which data will appear to arrive progressively as time goes on. For
example:

  mupdf -p 102400 pdf_reference17.pdf

Details of the scheme used here are presented in docs/progressive.txt

1 files changed, 7 insertions, 0 deletions

diff --git a/source/fitz/error.c b/source/fitz/error.c
index fb0dc77e..0da7d29e 100644
--- a/source/fitz/error.c
+++ b/source/fitz/error.c
@@ -180,3 +180,10 @@ void fz_rethrow_message(fz_context *ctx, const char *fmt, ...)
 
 	throw(ctx->error);
 }
+
+void fz_rethrow_if(fz_context *ctx, int err)
+{
+	assert(ctx && ctx->error && ctx->error->errcode >= FZ_ERROR_NONE);
+	if (ctx->error->errcode == err)
+		fz_rethrow(ctx);
+}