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.

5 files changed, 47 insertions, 36 deletions

diff --git a/include/mupdf/fitz/output-pcl.h b/include/mupdf/fitz/output-pcl.h
index 309bfc23..338d7553 100644
--- a/include/mupdf/fitz/output-pcl.h
+++ b/include/mupdf/fitz/output-pcl.h
@@ -90,25 +90,13 @@ void fz_pcl_preset(fz_context *ctx, fz_pcl_options *opts, const char *preset);
 */
 void fz_pcl_option(fz_context *ctx, fz_pcl_options *opts, const char *option, int val);
 
-typedef struct fz_mono_pcl_output_context_s fz_mono_pcl_output_context;
-
-fz_mono_pcl_output_context *fz_write_mono_pcl_header(fz_context *ctx, fz_output *out, int w, int h, int xres, int yres, int pagenum, const fz_pcl_options *options);
-
-void fz_write_mono_pcl_band(fz_context *ctx, fz_output *out, fz_mono_pcl_output_context *poc, const fz_bitmap *bitmap);
-
-void fz_write_mono_pcl_trailer(fz_context *ctx, fz_output *out, fz_mono_pcl_output_context *pcoc);
+fz_band_writer *fz_new_mono_pcl_band_writer(fz_context *ctx, fz_output *out, const fz_pcl_options *options);
 
 void fz_write_bitmap_as_pcl(fz_context *ctx, fz_output *out, const fz_bitmap *bitmap, const fz_pcl_options *pcl);
 
 void fz_save_bitmap_as_pcl(fz_context *ctx, fz_bitmap *bitmap, char *filename, int append, const fz_pcl_options *pcl);
 
-typedef struct fz_color_pcl_output_context_s fz_color_pcl_output_context;
-
-fz_color_pcl_output_context *fz_write_color_pcl_header(fz_context *ctx, fz_output *out, int w, int h, int n, int xres, int yres, int pagenum, const fz_pcl_options *options);
-
-void fz_write_color_pcl_band(fz_context *ctx, fz_output *out, fz_color_pcl_output_context *poc, int w, int h, int n, int stride, int band_start, int bandheight, unsigned char *samples);
-
-void fz_write_color_pcl_trailer(fz_context *ctx, fz_output *out, fz_color_pcl_output_context *pcoc);
+fz_band_writer *fz_new_color_pcl_band_writer(fz_context *ctx, fz_output *out, const fz_pcl_options *options);
 
 void fz_write_pixmap_as_pcl(fz_context *ctx, fz_output *out, const fz_pixmap *pixmap, const fz_pcl_options *pcl);
 
diff --git a/include/mupdf/fitz/output-png.h b/include/mupdf/fitz/output-png.h
index d98d7c7f..60283c7c 100644
--- a/include/mupdf/fitz/output-png.h
+++ b/include/mupdf/fitz/output-png.h
@@ -20,11 +20,11 @@ void fz_save_pixmap_as_png(fz_context *ctx, fz_pixmap *pixmap, const char *filen
 */
 void fz_write_pixmap_as_png(fz_context *ctx, fz_output *out, const fz_pixmap *pixmap);
 
-typedef struct fz_png_output_context_s fz_png_output_context;
-
-fz_png_output_context *fz_write_png_header(fz_context *ctx, fz_output *out, int w, int h, int n, int alpha);
-void fz_write_png_band(fz_context *ctx, fz_output *out, fz_png_output_context *poc, int stride, int band_start, int bandheight, unsigned char *samples);
-void fz_write_png_trailer(fz_context *ctx, fz_output *out, fz_png_output_context *poc);
+/*
+	fz_new_png_band_writer: Obtain a fz_band_writer instance
+	for producing PNG output.
+*/
+fz_band_writer *fz_new_png_band_writer(fz_context *ctx, fz_output *out);
 
 /*
 	Create a new buffer containing the image/pixmap in PNG format.
diff --git a/include/mupdf/fitz/output-pnm.h b/include/mupdf/fitz/output-pnm.h
index 09cad4ef..66198325 100644
--- a/include/mupdf/fitz/output-pnm.h
+++ b/include/mupdf/fitz/output-pnm.h
@@ -13,8 +13,8 @@
 void fz_save_pixmap_as_pnm(fz_context *ctx, fz_pixmap *pixmap, char *filename);
 
 void fz_write_pixmap_as_pnm(fz_context *ctx, fz_output *out, fz_pixmap *pixmap);
-void fz_write_pnm_header(fz_context *ctx, fz_output *out, int w, int h, int n, int alpha);
-void fz_write_pnm_band(fz_context *ctx, fz_output *out, int w, int h, int n, int alpha, int stride, int band_start, int bandheight, unsigned char *p);
+
+fz_band_writer *fz_new_pnm_band_writer(fz_context *ctx, fz_output *out);
 
 /*
 	fz_save_pixmap_as_pam: Save a pixmap as a PAM image file.
@@ -22,8 +22,8 @@ void fz_write_pnm_band(fz_context *ctx, fz_output *out, int w, int h, int n, int
 void fz_save_pixmap_as_pam(fz_context *ctx, fz_pixmap *pixmap, char *filename);
 
 void fz_write_pixmap_as_pam(fz_context *ctx, fz_output *out, fz_pixmap *pixmap);
-void fz_write_pam_header(fz_context *ctx, fz_output *out, int w, int h, int n, int alpha);
-void fz_write_pam_band(fz_context *ctx, fz_output *out, int w, int h, int n, int alpha, int stride, int band_start, int bandheight, unsigned char *sp);
+
+fz_band_writer *fz_new_pam_band_writer(fz_context *ctx, fz_output *out);
 
 /*
 	fz_save_bitmap_as_pbm: Save a bitmap as a PBM image file.
@@ -32,9 +32,7 @@ void fz_save_bitmap_as_pbm(fz_context *ctx, fz_bitmap *bitmap, char *filename);
 
 void fz_write_bitmap_as_pbm(fz_context *ctx, fz_output *out, fz_bitmap *bitmap);
 
-void fz_write_pbm_header(fz_context *ctx, fz_output *out, int w, int h);
-
-void fz_write_pbm_band(fz_context *ctx, fz_output *out, fz_bitmap *bitmap);
+fz_band_writer *fz_new_pbm_band_writer(fz_context *ctx, fz_output *out);
 
 /*
 	fz_save_bitmap_as_pkm: Save a 4bpp cmyk bitmap as a PAM image file.
@@ -43,8 +41,6 @@ void fz_save_bitmap_as_pkm(fz_context *ctx, fz_bitmap *bitmap, char *filename);
 
 void fz_write_bitmap_as_pkm(fz_context *ctx, fz_output *out, fz_bitmap *bitmap);
 
-void fz_write_pkm_header(fz_context *ctx, fz_output *out, int w, int h);
-
-void fz_write_pkm_band(fz_context *ctx, fz_output *out, fz_bitmap *bitmap);
+fz_band_writer *fz_new_pkm_band_writer(fz_context *ctx, fz_output *out);
 
 #endif
diff --git a/include/mupdf/fitz/output-ps.h b/include/mupdf/fitz/output-ps.h
index 7caed53b..1f187663 100644
--- a/include/mupdf/fitz/output-ps.h
+++ b/include/mupdf/fitz/output-ps.h
@@ -6,8 +6,6 @@
 #include "mupdf/fitz/output.h"
 #include "mupdf/fitz/pixmap.h"
 
-typedef struct fz_ps_output_context_s fz_ps_output_context;
-
 /*
 	PS (image) output
 */
@@ -17,11 +15,7 @@ void fz_save_pixmap_as_ps(fz_context *ctx, fz_pixmap *pixmap, char *filename, in
 
 void fz_write_ps_file_header(fz_context *ctx, fz_output *out);
 
-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);
-
-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);
-
-void fz_write_ps_trailer(fz_context *ctx, fz_output *out, fz_ps_output_context *psoc);
+fz_band_writer *fz_new_ps_band_writer(fz_context *ctx, fz_output *out);
 
 void fz_write_ps_file_trailer(fz_context *ctx, fz_output *out, int pages);
 
diff --git a/include/mupdf/fitz/output.h b/include/mupdf/fitz/output.h
index d4abd712..ffa140f9 100644
--- a/include/mupdf/fitz/output.h
+++ b/include/mupdf/fitz/output.h
@@ -164,4 +164,37 @@ void fz_new_output_context(fz_context *ctx);
 void fz_drop_output_context(fz_context *ctx);
 fz_output_context *fz_keep_output_context(fz_context *ctx);
 
+/*
+	fz_band_writer
+*/
+typedef struct fz_band_writer_s fz_band_writer;
+
+typedef void (fz_write_header_fn)(fz_context *ctx, fz_band_writer *writer);
+typedef void (fz_write_band_fn)(fz_context *ctx, fz_band_writer *writer, int stride, int band_start, int bandheight, const unsigned char *samples);
+typedef void (fz_write_trailer_fn)(fz_context *ctx, fz_band_writer *writer);
+typedef void (fz_drop_band_writer_fn)(fz_context *ctx, fz_band_writer *writer);
+
+struct fz_band_writer_s
+{
+	fz_drop_band_writer_fn *drop;
+	fz_write_header_fn *header;
+	fz_write_band_fn *band;
+	fz_write_trailer_fn *trailer;
+	fz_output *out;
+	int w;
+	int h;
+	int n;
+	int alpha;
+	int xres;
+	int yres;
+	int pagenum;
+};
+
+fz_band_writer *fz_new_band_writer_of_size(fz_context *ctx, size_t size, fz_output *out);
+#define fz_new_band_writer(C,M,O) ((M *)Memento_label(fz_new_band_writer_of_size(ctx, sizeof(M), O), #M))
+void fz_write_header(fz_context *ctx, fz_band_writer *writer, int w, int h, int n, int alpha, int xres, int yres, int pagenum);
+void fz_write_band(fz_context *ctx, fz_band_writer *writer, int stride, int band_start, int bandheight, const unsigned char *samples);
+void fz_write_trailer(fz_context *ctx, fz_band_writer *writer);
+void fz_drop_band_writer(fz_context *ctx, fz_band_writer *writer);
+
 #endif