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

4 files changed, 99 insertions, 6 deletions

diff --git a/platform/win32/libmupdf.vcproj b/platform/win32/libmupdf.vcproj
index ac9e3707..0fdfd672 100644
--- a/platform/win32/libmupdf.vcproj
+++ b/platform/win32/libmupdf.vcproj
@@ -626,6 +626,10 @@
 				>
 			</File>
 			<File
+				RelativePath="..\..\source\fitz\stream-prog.c"
+				>
+			</File>
+			<File
 				RelativePath="..\..\source\fitz\stream-read.c"
 				>
 			</File>
diff --git a/platform/x11/pdfapp.c b/platform/x11/pdfapp.c
index 71561f14..c891558f 100644
--- a/platform/x11/pdfapp.c
+++ b/platform/x11/pdfapp.c
@@ -157,6 +157,11 @@ static void event_cb(pdf_doc_event *event, void *data)
 
 void pdfapp_open(pdfapp_t *app, char *filename, int reload)
 {
+	pdfapp_open_progressive(app, filename, reload, 0);
+}
+
+void pdfapp_open_progressive(pdfapp_t *app, char *filename, int reload, int bps)
+{
 	fz_context *ctx = app->ctx;
 	char *password = "";
 
@@ -164,7 +169,32 @@ void pdfapp_open(pdfapp_t *app, char *filename, int reload)
 	{
 		pdf_document *idoc;
 
-		app->doc = fz_open_document(ctx, filename);
+		if (bps == 0)
+		{
+			app->doc = fz_open_document(ctx, filename);
+		}
+		else
+		{
+			fz_stream *stream = fz_open_file_progressive(ctx, filename, bps);
+			while (1)
+			{
+				fz_try(ctx)
+				{
+					fz_seek(stream, 0, SEEK_SET);
+					app->doc = fz_open_document_with_stream(ctx, filename, stream);
+				}
+				fz_catch(ctx)
+				{
+					if (fz_caught(ctx) == FZ_ERROR_TRYLATER)
+					{
+						pdfapp_warn(app, "not enough data to open yet");
+						continue;
+					}
+					fz_rethrow(ctx);
+				}
+				break;
+			}
+		}
 
 		idoc = pdf_specifics(app->doc);
 
@@ -193,8 +223,41 @@ void pdfapp_open(pdfapp_t *app, char *filename, int reload)
 			app->doctitle = strrchr(app->doctitle, '/') + 1;
 		app->doctitle = fz_strdup(ctx, app->doctitle);
 
-		app->pagecount = fz_count_pages(app->doc);
-		app->outline = fz_load_outline(app->doc);
+		while (1)
+		{
+			fz_try(ctx)
+			{
+				app->pagecount = fz_count_pages(app->doc);
+			}
+			fz_catch(ctx)
+			{
+				if (fz_caught(ctx) == FZ_ERROR_TRYLATER)
+				{
+					pdfapp_warn(app, "not enough data to count pages yet");
+					continue;
+				}
+				fz_rethrow(ctx);
+			}
+			break;
+		}
+		while (1)
+		{
+			fz_try(ctx)
+			{
+				app->outline = fz_load_outline(app->doc);
+			}
+			fz_catch(ctx)
+			{
+				if (fz_caught(ctx) == FZ_ERROR_TRYLATER)
+				{
+					pdfapp_warn(app, "not enough data to load outline yet - ignoring");
+					/* FIXME: Set 'outline_deferred' and retry at end? */
+				}
+				else
+					fz_rethrow(ctx);
+			}
+			break;
+		}
 	}
 	fz_catch(ctx)
 	{
@@ -441,6 +504,7 @@ static void pdfapp_loadpage(pdfapp_t *app)
 		/* Create display lists */
 		app->page_list = fz_new_display_list(app->ctx);
 		mdev = fz_new_list_device(app->ctx, app->page_list);
+		cookie.incomplete_ok = 1;
 		fz_run_page_contents(app->doc, app->page, mdev, &fz_identity, &cookie);
 		fz_free_device(mdev);
 		mdev = NULL;
@@ -453,6 +517,10 @@ static void pdfapp_loadpage(pdfapp_t *app)
 			pdfapp_warn(app, "Errors found on page");
 			errored = 1;
 		}
+		if (cookie.incomplete)
+		{
+			pdfapp_warn(app, "Incomplete page rendering");
+		}
 	}
 	fz_always(app->ctx)
 	{
diff --git a/platform/x11/pdfapp.h b/platform/x11/pdfapp.h
index 0b89923e..eabb6ca5 100644
--- a/platform/x11/pdfapp.h
+++ b/platform/x11/pdfapp.h
@@ -130,6 +130,7 @@ struct pdfapp_s
 
 void pdfapp_init(fz_context *ctx, pdfapp_t *app);
 void pdfapp_open(pdfapp_t *app, char *filename, int reload);
+void pdfapp_open_progressive(pdfapp_t *app, char *filename, int reload, int bps);
 void pdfapp_close(pdfapp_t *app);
 int pdfapp_preclose(pdfapp_t *app);
 
diff --git a/platform/x11/win_main.c b/platform/x11/win_main.c
index a22e7fc0..51dada02 100644
--- a/platform/x11/win_main.c
+++ b/platform/x11/win_main.c
@@ -1143,6 +1143,8 @@ WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShow
 	MSG msg;
 	int code;
 	fz_context *ctx;
+	int arg;
+	int bps = 0;
 
 	ctx = fz_new_context(NULL, NULL, FZ_STORE_DEFAULT);
 	if (!ctx)
@@ -1157,9 +1159,24 @@ WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShow
 
 	winopen();
 
-	if (argc == 2)
+	arg = 1;
+	while (arg < argc)
 	{
-		wcscpy(wbuf, argv[1]);
+		if (!wcscmp(argv[arg], L"-p"))
+		{
+			if (arg+1 < argc)
+				bps = _wtoi(argv[++arg]);
+			else
+				bps = 4096;
+		}
+		else
+			break;
+		arg++;
+	}
+
+	if (arg < argc)
+	{
+		wcscpy(wbuf, argv[arg]);
 	}
 	else
 	{
@@ -1171,7 +1188,10 @@ WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShow
 	if (code == 0)
 		winerror(&gapp, "cannot convert filename to utf-8");
 
-	pdfapp_open(&gapp, filename, 0);
+	if (bps)
+		pdfapp_open_progressive(&gapp, filename, 0, bps);
+	else
+		pdfapp_open(&gapp, filename, 0);
 
 	while (GetMessage(&msg, NULL, 0, 0))
 	{