Regularize band writer interface.

We have various functions that, for different image formats,
write a header, then a band, then (sometimes) a trailer.

Push them all through a single interface.

This change also fixes potential problems caused by the trailer
writing being an implicit destructor, which can cause problems
in cleanup code if the trailer writing throws an error.

1 files changed, 87 insertions, 48 deletions

diff --git a/source/fitz/output-ps.c b/source/fitz/output-ps.c
index d183adf6..6e63110c 100644
--- a/source/fitz/output-ps.c
+++ b/source/fitz/output-ps.c
@@ -2,14 +2,15 @@
 
 #include <zlib.h>
 
-struct fz_ps_output_context_s
+typedef struct ps_band_writer_s
 {
+	fz_band_writer super;
 	z_stream stream;
 	int input_size;
 	unsigned char *input;
 	int output_size;
 	unsigned char *output;
-};
+} ps_band_writer;
 
 void
 fz_write_ps_file_header(fz_context *ctx, fz_output *out)
@@ -39,20 +40,35 @@ void fz_write_ps_file_trailer(fz_context *ctx, fz_output *out, int pages)
 	fz_printf(ctx, out, "%%%%Trailer\n%%%%Pages: %d\n%%%%EOF\n", pages);
 }
 
-fz_ps_output_context *fz_write_ps_header(fz_context *ctx, fz_output *out, int w, int h, int n, int xres, int yres, int pagenum)
+static void
+ps_write_header(fz_context *ctx, fz_band_writer *writer_)
 {
+	ps_band_writer *writer = (ps_band_writer *)writer_;
+	fz_output *out = writer->super.out;
+	int w = writer->super.w;
+	int h = writer->super.h;
+	int n = writer->super.n;
+	int alpha = writer->super.alpha;
+	int xres = writer->super.xres;
+	int yres = writer->super.yres;
+	int pagenum = writer->super.pagenum;
 	int w_points = (w * 72 + (xres>>1)) / xres;
 	int h_points = (h * 72 + (yres>>1)) / yres;
 	float sx = w/(float)w_points;
 	float sy = h/(float)h_points;
-	fz_ps_output_context *psoc;
 	int err;
 
-	psoc = fz_malloc_struct(ctx, fz_ps_output_context);
-	err = deflateInit(&psoc->stream, Z_DEFAULT_COMPRESSION);
+	if (alpha != 0)
+		fz_throw(ctx, FZ_ERROR_GENERIC, "Postscript output cannot have alpha");
+
+	writer->super.w = w;
+	writer->super.h = h;
+	writer->super.n = n;
+
+	err = deflateInit(&writer->stream, Z_DEFAULT_COMPRESSION);
 	if (err != Z_OK)
 	{
-		fz_free(ctx, psoc);
+		fz_free(ctx, writer);
 		fz_throw(ctx, FZ_ERROR_GENERIC, "compression error %d", err);
 	}
 
@@ -90,49 +106,54 @@ fz_ps_output_context *fz_write_ps_header(fz_context *ctx, fz_output *out, int w,
 		">>\n"
 		"image\n"
 		, w, h, sx, sy, h);
-
-	return psoc;
 }
 
-void fz_write_ps_trailer(fz_context *ctx, fz_output *out, fz_ps_output_context *psoc)
+static void
+ps_write_trailer(fz_context *ctx, fz_band_writer *writer_)
 {
-	if (psoc)
-	{
-		int err;
+	ps_band_writer *writer = (ps_band_writer *)writer_;
+	fz_output *out = writer->super.out;
+	int err;
 
-		psoc->stream.next_in = NULL;
-		psoc->stream.avail_in = 0;
-		psoc->stream.next_out = (Bytef*)psoc->output;
-		psoc->stream.avail_out = (uInt)psoc->output_size;
+	writer->stream.next_in = NULL;
+	writer->stream.avail_in = 0;
+	writer->stream.next_out = (Bytef*)writer->output;
+	writer->stream.avail_out = (uInt)writer->output_size;
 
-		err = deflate(&psoc->stream, Z_FINISH);
-		if (err != Z_STREAM_END)
-			fz_throw(ctx, FZ_ERROR_GENERIC, "compression error %d", err);
+	err = deflate(&writer->stream, Z_FINISH);
+	if (err != Z_STREAM_END)
+		fz_throw(ctx, FZ_ERROR_GENERIC, "compression error %d", err);
 
-		fz_write(ctx, out, psoc->output, psoc->output_size - psoc->stream.avail_out);
-		fz_free(ctx, psoc->input);
-		fz_free(ctx, psoc->output);
-		fz_free(ctx, psoc);
-	}
+	fz_write(ctx, out, writer->output, writer->output_size - writer->stream.avail_out);
 	fz_printf(ctx, out, "\nshowpage\n%%%%PageTrailer\n%%%%EndPageTrailer\n\n");
+}
 
+static void
+ps_drop_band_writer(fz_context *ctx, fz_band_writer *writer_)
+{
+	ps_band_writer *writer = (ps_band_writer *)writer_;
+
+	fz_free(ctx, writer->input);
+	fz_free(ctx, writer->output);
 }
 
 void fz_write_pixmap_as_ps(fz_context *ctx, fz_output *out, const fz_pixmap *pixmap)
 {
-	fz_ps_output_context *psoc;
+	fz_band_writer *writer;
 
 	fz_write_ps_file_header(ctx, out);
 
-	psoc = fz_write_ps_header(ctx, out, pixmap->w, pixmap->h, pixmap->n, pixmap->xres, pixmap->yres, 1);
+	writer = fz_new_ps_band_writer(ctx, out);
 
 	fz_try(ctx)
 	{
-		fz_write_ps_band(ctx, out, psoc, pixmap->w, pixmap->h, pixmap->n, pixmap->stride, 0, 0, pixmap->samples);
+		fz_write_header(ctx, writer, pixmap->w, pixmap->h, pixmap->n, pixmap->alpha, pixmap->xres, pixmap->yres, 1);
+		fz_write_band(ctx, writer, pixmap->stride, 0, pixmap->h, pixmap->samples);
+		fz_write_trailer(ctx, writer);
 	}
 	fz_always(ctx)
 	{
-		fz_write_ps_trailer(ctx, out, psoc);
+		fz_drop_band_writer(ctx, writer);
 	}
 	fz_catch(ctx)
 	{
@@ -153,8 +174,14 @@ void fz_save_pixmap_as_ps(fz_context *ctx, fz_pixmap *pixmap, char *filename, in
 		fz_rethrow(ctx);
 }
 
-void fz_write_ps_band(fz_context *ctx, fz_output *out, fz_ps_output_context *psoc, int w, int h, int n, int stride, int band_start, int bandheight, unsigned char *samples)
+static void
+ps_write_band(fz_context *ctx, fz_band_writer *writer_, int stride, int band_start, int bandheight, const unsigned char *samples)
 {
+	ps_band_writer *writer = (ps_band_writer *)writer_;
+	fz_output *out = writer->super.out;
+	int w = writer->super.w;
+	int h = writer->super.h;
+	int n = writer->super.n;
 	int x, y, i, err;
 	int required_input;
 	int required_output;
@@ -164,25 +191,25 @@ void fz_write_ps_band(fz_context *ctx, fz_output *out, fz_ps_output_context *pso
 		bandheight = h - band_start;
 
 	required_input = w*(n-1)*bandheight;
-	required_output = (int)deflateBound(&psoc->stream, required_input);
+	required_output = (int)deflateBound(&writer->stream, required_input);
 
-	if (psoc->input == NULL || psoc->input_size < required_input)
+	if (writer->input == NULL || writer->input_size < required_input)
 	{
-		fz_free(ctx, psoc->input);
-		psoc->input = NULL;
-		psoc->input = fz_malloc(ctx, required_input);
-		psoc->input_size = required_input;
+		fz_free(ctx, writer->input);
+		writer->input = NULL;
+		writer->input = fz_malloc(ctx, required_input);
+		writer->input_size = required_input;
 	}
 
-	if (psoc->output == NULL || psoc->output_size < required_output)
+	if (writer->output == NULL || writer->output_size < required_output)
 	{
-		fz_free(ctx, psoc->output);
-		psoc->output = NULL;
-		psoc->output = fz_malloc(ctx, required_output);
-		psoc->output_size = required_output;
+		fz_free(ctx, writer->output);
+		writer->output = NULL;
+		writer->output = fz_malloc(ctx, required_output);
+		writer->output_size = required_output;
 	}
 
-	o = psoc->input;
+	o = writer->input;
 	for (y = 0; y < bandheight; y++)
 	{
 		for (x = 0; x < w; x++)
@@ -194,14 +221,26 @@ void fz_write_ps_band(fz_context *ctx, fz_output *out, fz_ps_output_context *pso
 		samples += stride - w*n;
 	}
 
-	psoc->stream.next_in = (Bytef*)psoc->input;
-	psoc->stream.avail_in = required_input;
-	psoc->stream.next_out = (Bytef*)psoc->output;
-	psoc->stream.avail_out = (uInt)psoc->output_size;
+	writer->stream.next_in = (Bytef*)writer->input;
+	writer->stream.avail_in = required_input;
+	writer->stream.next_out = (Bytef*)writer->output;
+	writer->stream.avail_out = (uInt)writer->output_size;
 
-	err = deflate(&psoc->stream, Z_NO_FLUSH);
+	err = deflate(&writer->stream, Z_NO_FLUSH);
 	if (err != Z_OK)
 		fz_throw(ctx, FZ_ERROR_GENERIC, "compression error %d", err);
 
-	fz_write(ctx, out, psoc->output, psoc->output_size - psoc->stream.avail_out);
+	fz_write(ctx, out, writer->output, writer->output_size - writer->stream.avail_out);
+}
+
+fz_band_writer *fz_new_ps_band_writer(fz_context *ctx, fz_output *out)
+{
+	fz_band_writer *writer = fz_new_band_writer(ctx, fz_band_writer, out);
+
+	writer->header = ps_write_header;
+	writer->band = ps_write_band;
+	writer->trailer = ps_write_trailer;
+	writer->drop = ps_drop_band_writer;
+
+	return writer;
 }