(WIP) Attempt at adding metadata to PNG output

cairo_png.c

@@ -0,0 +1,138 @@
+#include <assert.h>
+#include <cairo.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <png.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "cairo_png.h"
+
+cairo_status_t cairo_surface_write_to_png_mem(cairo_surface_t *sfc,
+                                              unsigned char **data,
+                                              unsigned long *len) {
+  int png_color_type;
+  int bpc;
+#ifdef PNG_pHYs_SUPPORTED
+  double dpix, dpiy;
+#endif
+
+  int height = cairo_image_surface_get_height(sfc);
+  int width = cairo_image_surface_get_width(sfc);
+  cairo_format_t cformat = cairo_image_surface_get_format(sfc);
+
+  /* PNG complains about "Image width or height is zero in IHDR" */
+  if (width == 0 || height == 0) {
+    return CAIRO_STATUS_WRITE_ERROR;
+  }
+
+  png_structp png =
+    png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+  if (png == NULL) {
+    return CAIRO_STATUS_NO_MEMORY;
+  }
+
+  png_infop info = png_create_info_struct(png);
+  if (info == NULL) {
+    png_destroy_write_struct(&png, &info);
+    return CAIRO_STATUS_NO_MEMORY;
+  }
+
+#ifdef PNG_SETJMP_SUPPORTED
+  if (setjmp(png_jmpbuf(png))) {
+    png_destroy_write_struct(&png, &info);
+    return 2;
+  }
+#endif
+
+  //png_set_write_fn(png, &state, my_png_write_data, png_simple_output_flush_fn);
+
+  FILE *f = fopen("/tmp/meow.png", "wb");
+  if (f == NULL) {
+    fprintf(stderr, "failed to open output file\n");
+    exit(EXIT_FAILURE);
+  }
+  png_init_io(png, f);
+
+  switch (cformat) {
+  case CAIRO_FORMAT_ARGB32:
+    bpc = 8;
+    png_color_type = PNG_COLOR_TYPE_RGB_ALPHA;
+    break;
+  case CAIRO_FORMAT_INVALID:
+  default:
+    png_destroy_write_struct(&png, &info);
+    return CAIRO_STATUS_INVALID_FORMAT;
+  }
+
+  png_set_IHDR(png, info, width, height, bpc, png_color_type,
+               PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
+               PNG_FILTER_TYPE_DEFAULT);
+
+#ifdef PNG_pHYs_SUPPORTED
+  cairo_surface_get_fallback_resolution(sfc, &dpix, &dpiy);
+  png_set_pHYs(png, info, dpix * 1000 / 25.4, dpiy * 1000 / 25.4,
+               PNG_RESOLUTION_METER);
+#endif
+
+  png_write_info(png, info);
+
+  for (size_t i = 0; i < (size_t)height; ++i) {
+    png_bytep row = (png_byte *)cairo_image_surface_get_data(sfc) + i * cairo_image_surface_get_stride(sfc);
+    png_write_row(png, row);
+  }
+
+  png_write_end(png, info);
+
+  return CAIRO_STATUS_SUCCESS;
+}
+
+static cairo_status_t cj_write(void *closure, const unsigned char *data,
+                               unsigned int length) {
+  if (write((long)closure, data, length) < (ssize_t)length) {
+    return CAIRO_STATUS_WRITE_ERROR;
+  } else {
+    return CAIRO_STATUS_SUCCESS;
+  }
+}
+
+cairo_status_t cairo_surface_write_to_png_stream(cairo_surface_t *sfc,
+                                                 cairo_write_func_t write_func,
+                                                 void *closure) {
+  cairo_status_t e;
+  unsigned char *data = NULL;
+  unsigned long len = 0;
+
+  e = cairo_surface_write_to_png_mem(sfc, &data, &len);
+  if (e == CAIRO_STATUS_SUCCESS) {
+    assert(sizeof(unsigned long) <= sizeof(size_t) ||
+           !(len >> (sizeof(size_t) * CHAR_BIT)));
+    e = write_func(closure, data, len);
+    free(data);
+  }
+
+  return e;
+}
+
+cairo_status_t cairo_surface_write_to_png(cairo_surface_t *sfc,
+                                          const char *filename) {
+  cairo_status_t e;
+  int outfile;
+
+  outfile =
+      open(filename, O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+
+  if (outfile == -1) {
+    return CAIRO_STATUS_DEVICE_ERROR;
+  }
+
+  e = cairo_surface_write_to_png_stream(sfc, cj_write, (void *)(long)outfile);
+
+  close(outfile);
+  return e;
+}

include/cairo_png.h

@@ -0,0 +1,10 @@
+#ifndef _CAIRO_PNG_H
+#define _CAIRO_PNG_H
+
+#include <cairo.h>
+
+cairo_status_t cairo_surface_write_to_png_mem(cairo_surface_t *sfc, unsigned char **data, unsigned long *len);
+cairo_status_t cairo_surface_write_to_png_stream(cairo_surface_t *sfc, cairo_write_func_t write_func, void *closure);
+cairo_status_t cairo_surface_write_to_png(cairo_surface_t *sfc, const char *filename);
+
+#endif

main.c

@@ -117,6 +117,9 @@ static void output_handle_geometry(void *data, struct wl_output *wl_output,
 
 	output->geometry.x = x;
 	output->geometry.y = y;
+	output->geometry.physical_width = physical_width;
+	output->geometry.physical_height = physical_height;
+        printf("debug phys: %dmm x %dmm\n", physical_width, physical_height);
 	output->transform = transform;
 }
 
@@ -305,6 +308,7 @@ int main(int argc, char *argv[]) {
 
 			free(geometry);
 			geometry = calloc(1, sizeof(struct grim_box));
+
 			if (!parse_box(geometry, geometry_str)) {
 				fprintf(stderr, "invalid geometry\n");
 				return EXIT_FAILURE;
@@ -478,6 +482,12 @@ int main(int argc, char *argv[]) {
 		get_output_layout_extents(&state, geometry);
 	}
 
+        printf("debug output_layout_extents: %dpx x %dpx\n", geometry->width, geometry->height);
+	//TODO
+	//int px_per_mm_x = geometry->width/(output_layout_extents_physical);
+	//int px_per_mm_y = geometry->height/(output_layout_extents_physical);
+	//printf("px/mm values: %d x %d\n", pxmm_x, pxmm_y);
+
 	cairo_surface_t *surface = render(&state, geometry, scale);
 	if (surface == NULL) {
 		return EXIT_FAILURE;
@@ -519,6 +529,7 @@ int main(int argc, char *argv[]) {
 #endif
 		}
 	}
+	printf("Status was: %d, success is %d", status, CAIRO_STATUS_SUCCESS);
 	if (status != CAIRO_STATUS_SUCCESS) {
 		fprintf(stderr, "%s\n", cairo_status_to_string(status));
 		if (status == CAIRO_STATUS_WRITE_ERROR && strlen(output_filepath) > NAME_MAX) {

meson.build

@@ -20,6 +20,7 @@ cc = meson.get_compiler('c')
 cairo = dependency('cairo')
 jpeg = dependency('libjpeg', required: get_option('jpeg'))
 math = cc.find_library('m')
+png = dependency('libpng')
 realtime = cc.find_library('rt')
 wayland_client = dependency('wayland-client')
 wayland_protos = dependency('wayland-protocols', version: '>=1.14')
@@ -37,12 +38,14 @@ grim_files = [
 	'output-layout.c',
 	'render.c',
 	'cairo_ppm.c',
+	'cairo_png.c',
 ]
 
 grim_deps = [
 	cairo,
 	client_protos,
 	math,
+	png,
 	realtime,
 	wayland_client,
 ]