[gtk/image-loading: 5/7] Add code to load jpegs

[Matthias Clasen <matthiasc src gnome org>]

commit 59b0b40a7661b10758ff62574eef2e22c0ebe490
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Sep 9 23:52:39 2021 -0400

    Add code to load jpegs
    
    This lets us avoid gdk-pixbuf for loading
    textures from the common image formats.
    
    As a consequence, we are now linking against libjpeg.

 gdk/gdkjpeg.c        | 241 +++++++++++++++++++++++++++++++++++++++++++++++++++
 gdk/gdkjpegprivate.h |  35 ++++++++
 gdk/meson.build      |   3 +-
 meson.build          |  14 +++
 4 files changed, 292 insertions(+), 1 deletion(-)
---
diff --git a/gdk/gdkjpeg.c b/gdk/gdkjpeg.c
new file mode 100644
index 0000000000..63afc484be
--- /dev/null
+++ b/gdk/gdkjpeg.c
@@ -0,0 +1,241 @@
+/* GDK - The GIMP Drawing Kit
+ * Copyright (C) 2021 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include "gdkjpegprivate.h"
+
+#include "gdktexture.h"
+#include "gdkmemorytextureprivate.h"
+#include <jpeglib.h>
+#include <jerror.h>
+#include <setjmp.h>
+
+/* {{{ IO handling */
+
+#define BUF_SIZE 65536
+
+typedef struct {
+  struct jpeg_source_mgr pub;
+  JOCTET buffer[BUF_SIZE];
+  long skip_next;
+  GInputStream *stream;
+} my_source_mgr;
+
+static void
+init_source (j_decompress_ptr info)
+{
+  my_source_mgr *src = (my_source_mgr *) info->src;
+  src->skip_next = 0;
+}
+
+static void
+term_source (j_decompress_ptr info)
+{
+}
+
+static boolean
+fill_input_buffer (j_decompress_ptr info)
+{
+  my_source_mgr *src = (my_source_mgr *) info->src;
+  size_t nbytes;
+
+  nbytes = g_input_stream_read (src->stream, src->buffer, BUF_SIZE, NULL, NULL);
+
+  if (nbytes <= 0)
+    {
+      /* Insert a fake EOI marker */
+      src->buffer[0] = (JOCTET) 0xFF;
+      src->buffer[1] = (JOCTET) JPEG_EOI;
+      nbytes = 2;
+    }
+
+  src->pub.next_input_byte = src->buffer;
+  src->pub.bytes_in_buffer = nbytes;
+
+  return TRUE;
+}
+
+static void
+skip_input_data (j_decompress_ptr info,
+                 long             num_bytes)
+{
+  my_source_mgr *src = (my_source_mgr *) info->src;
+
+  if (num_bytes > 0)
+    {
+      while (num_bytes > src->pub.bytes_in_buffer)
+        {
+          num_bytes -= src->pub.bytes_in_buffer;
+          fill_input_buffer (info);
+        }
+
+      src->pub.next_input_byte += num_bytes;
+      src->pub.bytes_in_buffer -= num_bytes;
+    }
+}
+
+/* }}} */
+/* {{{ Error handling */
+
+/* No sigsetjmp on Windows */
+#ifndef HAVE_SIGSETJMP
+#define sigjmp_buf jmp_buf
+#define sigsetjmp(jb, x) setjmp(jb)
+#define siglongjmp longjmp
+#endif
+
+struct error_handler_data {
+        struct jpeg_error_mgr pub;
+        sigjmp_buf setjmp_buffer;
+        GError **error;
+};
+
+static void
+fatal_error_handler (j_common_ptr cinfo)
+{
+  struct error_handler_data *errmgr;
+
+  errmgr = (struct error_handler_data *) cinfo->err;
+
+  siglongjmp (errmgr->setjmp_buffer, 1);
+
+  g_assert_not_reached ();
+}
+
+static void
+output_message_handler (j_common_ptr cinfo)
+{
+  /* do nothing */
+}
+
+/* }}} */
+ /* {{{ Public API */
+
+GdkTexture *
+gdk_load_jpeg (GInputStream  *stream,
+               GError       **error)
+{
+  struct jpeg_decompress_struct info;
+  struct error_handler_data jerr;
+  struct jpeg_error_mgr err;
+  my_source_mgr src;
+  int width, height;
+  int size;
+  unsigned char *data;
+  unsigned char *row[1];
+  GBytes *bytes;
+  GdkTexture *texture;
+
+  info.err = jpeg_std_error (&jerr.pub);
+  jerr.pub.error_exit = fatal_error_handler;
+  jerr.pub.output_message = output_message_handler;
+  jerr.error = error;
+
+  if (sigsetjmp (jerr.setjmp_buffer, 1))
+    {
+      jpeg_destroy_decompress (&info);
+      return NULL;
+    }
+
+  info.err = jpeg_std_error (&err);
+  jpeg_create_decompress (&info);
+
+  src.pub.init_source = init_source;
+  src.pub.fill_input_buffer = fill_input_buffer;
+  src.pub.skip_input_data = skip_input_data;
+  src.pub.resync_to_restart = jpeg_resync_to_restart;
+  src.pub.term_source = term_source;
+  src.pub.bytes_in_buffer = 0;
+  src.pub.next_input_byte = NULL;
+  src.stream = stream;
+
+  info.src = (struct jpeg_source_mgr *)&src;
+
+  jpeg_read_header (&info, TRUE);
+  jpeg_start_decompress (&info);
+
+  width = info.output_width;
+  height = info.output_height;
+
+  size = width * height * 3;
+  data = g_malloc (size);
+
+  while (info.output_scanline < info.output_height)
+    {
+       row[0] = (unsigned char *)(&data[3 *info.output_width * info.output_scanline]);
+       jpeg_read_scanlines (&info, row, 1);
+    }
+
+  jpeg_finish_decompress (&info);
+  jpeg_destroy_decompress (&info);
+
+  bytes = g_bytes_new_take (data, size);
+
+  texture = gdk_memory_texture_new (width, height,
+                                    GDK_MEMORY_R8G8B8,
+                                    bytes, width * 3);
+
+  g_bytes_unref (bytes);
+
+  return texture;
+}
+
+/* }}} */
+/* {{{ Async code */
+
+static void
+load_jpeg_in_thread (GTask        *task,
+                     gpointer      source_object,
+                     gpointer      task_data,
+                     GCancellable *cancellable)
+{
+  GInputStream *stream = source_object;
+  GdkTexture *texture;
+  GError *error = NULL;
+
+  texture = gdk_load_jpeg (stream, &error);
+
+  if (texture)
+    g_task_return_pointer (task, texture, g_object_unref);
+  else
+    g_task_return_error (task, error);
+}
+
+void
+gdk_load_jpeg_async (GInputStream         *stream,
+                     GCancellable         *cancellable,
+                     GAsyncReadyCallback   callback,
+                     gpointer              user_data)
+{
+  GTask *task;
+
+  task = g_task_new (stream, cancellable, callback, user_data);
+  g_task_run_in_thread (task, load_jpeg_in_thread);
+  g_object_unref (task);
+}
+
+GdkTexture *
+gdk_load_jpeg_finish (GAsyncResult  *result,
+                      GError       **error)
+{
+  return g_task_propagate_pointer (G_TASK (result), error);
+}
+
+/* }}} */
+
+/* vim:set foldmethod=marker expandtab: */
diff --git a/gdk/gdkjpegprivate.h b/gdk/gdkjpegprivate.h
new file mode 100644
index 0000000000..7820ed7406
--- /dev/null
+++ b/gdk/gdkjpegprivate.h
@@ -0,0 +1,35 @@
+/* GDK - The GIMP Drawing Kit
+ * Copyright (C) 2021 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GDK_JPEG_PRIVATE_H__
+#define __GDK_JPEG_PRIVATE_H__
+
+#include "gdkmemorytexture.h"
+#include <gio/gio.h>
+
+GdkTexture *gdk_load_jpeg         (GInputStream     *stream,
+                                   GError          **error);
+
+void        gdk_load_jpeg_async   (GInputStream           *stream,
+                                   GCancellable           *cancellable,
+                                   GAsyncReadyCallback     callback,
+                                   gpointer                user_data);
+
+GdkTexture *gdk_load_jpeg_finish  (GAsyncResult           *result,
+                                   GError                **error);
+
+#endif
diff --git a/gdk/meson.build b/gdk/meson.build
index dad0c82286..c3eea5657c 100644
--- a/gdk/meson.build
+++ b/gdk/meson.build
@@ -53,6 +53,7 @@ gdk_public_sources = files([
   'gdkdragsurface.c',
   'gdkpng.c',
   'gdktiff.c',
+  'gdkjpeg.c',
 ])
 
 gdk_public_headers = files([
@@ -258,7 +259,7 @@ endif
 
 libgdk = static_library('gdk',
   sources: [gdk_sources, gdk_backends_gen_headers, gdkconfig],
-  dependencies: gdk_deps + [libgtk_css_dep, png_dep, tiff_dep],
+  dependencies: gdk_deps + [libgtk_css_dep, png_dep, tiff_dep, jpeg_dep],
   link_with: [libgtk_css],
   include_directories: [confinc, gdkx11_inc, wlinc],
   c_args: libgdk_c_args + common_cflags,
diff --git a/meson.build b/meson.build
index 0aaeb5936a..1f0f6a4283 100644
--- a/meson.build
+++ b/meson.build
@@ -208,6 +208,17 @@ foreach func : check_functions
   endif
 endforeach
 
+# We use links() because sigsetjmp() is often a macro hidden behind other macros
+cdata.set('HAVE_SIGSETJMP',
+  cc.links('''#define _POSIX_SOURCE
+              #include <setjmp.h>
+              int main (void) {
+                sigjmp_buf env;
+                sigsetjmp (env, 0);
+                return 0;
+              }''', name: 'sigsetjmp'),
+)
+
 # Check for __uint128_t (gcc) by checking for 128-bit division
 uint128_t_src = '''int main() {
 static __uint128_t v1 = 100;
@@ -396,6 +407,9 @@ png_dep        = dependency('libpng',
 tiff_dep       = dependency('libtiff-4',
                             fallback: ['libtiff', 'libtiff4_dep'],
                             required: true)
+jpeg_dep       = dependency('libjpeg',
+                            fallback: ['libjpeg-turbo', 'jpeg_dep'],
+                            required: true)
 
 epoxy_dep      = dependency('epoxy', version: epoxy_req,
                             fallback: ['libepoxy', 'libepoxy_dep'])