gdk: Add GdkTextureDownloader

It's the new object that allows more control about accessing texture
data.

1 files changed, 269 insertions, 0 deletions

diff --git a/gdk/gdktexturedownloader.c b/gdk/gdktexturedownloader.c
new file mode 100644
index 0000000000..f45a6aceb7
--- /dev/null
+++ b/gdk/gdktexturedownloader.c
@@ -0,0 +1,269 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2023 Benjamin Otte
+ *
+ * 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/>.
+ */
+
+/**
+ * GdkTextureDownloader:
+ *
+ * The `GdkTextureDownloader` is used to download the contents of a
+ * [class@Gdk.Texture].
+ *
+ * It is intended to be created as a short-term object for a single download,
+ * but can be used for multipe downloads of different textures or with different
+ * settings.
+ *
+ * `GdkTextureDownloader` can be used to convert data between different formats.
+ * Create a `GdkTexture` for the existing format and then download it in a
+ * different format.
+ *
+ * Since: 4.10
+ */
+
+#include "config.h"
+
+#include "gdktexturedownloaderprivate.h"
+
+#include "gdkmemoryformatprivate.h"
+#include "gdkmemorytextureprivate.h"
+#include "gdktextureprivate.h"
+
+G_DEFINE_BOXED_TYPE (GdkTextureDownloader, gdk_texture_downloader,
+                     gdk_texture_downloader_copy,
+                     gdk_texture_downloader_free)
+
+
+void
+gdk_texture_downloader_init (GdkTextureDownloader *self,
+                             GdkTexture           *texture)
+{
+  self->texture = g_object_ref (texture);
+  self->format = GDK_MEMORY_DEFAULT;
+}
+
+void
+gdk_texture_downloader_finish (GdkTextureDownloader *self)
+{
+  g_object_unref (self->texture);
+}
+
+/**
+ * gdk_texture_downloader_new:
+ * @texture: texture to download
+ *
+ * Creates a new texture downloader for @texture.
+ *
+ * Returns: A new texture downloader
+ *
+ * Since: 4.10
+ **/
+GdkTextureDownloader *
+gdk_texture_downloader_new (GdkTexture *texture)
+{
+  GdkTextureDownloader *self;
+
+  g_return_val_if_fail (GDK_IS_TEXTURE (texture), NULL);
+
+  self = g_slice_new (GdkTextureDownloader);
+  gdk_texture_downloader_init (self, texture);
+
+  return self;
+}
+
+/**
+ * gdk_texture_downloader_copy:
+ * @self: the downloader to copy
+ *
+ * Creates a copy of the downloader.
+ *
+ * This function is meant for language bindings.
+ *
+ * Returns: A copy of the downloader
+ *
+ * Since: 4.10
+ **/
+GdkTextureDownloader *
+gdk_texture_downloader_copy (const GdkTextureDownloader *self)
+{
+  GdkTextureDownloader *copy;
+
+  g_return_val_if_fail (self != NULL, NULL);
+
+  copy = gdk_texture_downloader_new (self->texture);
+  gdk_texture_downloader_set_format (copy, self->format);
+
+  return copy;
+}
+
+/**
+ * gdk_texture_downloader_free:
+ * @self: texture downloader to free
+ *
+ * Frees the given downloader and all its associated resources.
+ *
+ * Since: 4.10
+ **/
+void
+gdk_texture_downloader_free (GdkTextureDownloader *self)
+{
+  g_return_if_fail (self != NULL);
+
+  gdk_texture_downloader_finish (self);
+  g_slice_free (GdkTextureDownloader, self);
+}
+
+/**
+ * gdk_texture_downloader_set_texture:
+ * @self: a texture downloader
+ * @texture: the new texture to download
+ *
+ * Changes the texture the downloader will download.
+ *
+ * Since: 4.10
+ **/
+void
+gdk_texture_downloader_set_texture (GdkTextureDownloader *self,
+                                    GdkTexture           *texture)
+{
+  g_return_if_fail (self != NULL);
+  g_return_if_fail (GDK_IS_TEXTURE (texture));
+
+  g_set_object (&self->texture, texture);
+}
+
+/**
+ * gdk_texture_downloader_get_texture:
+ * @self: a texture downloader
+ *
+ * Gets the texture that the downloader will download.
+ *
+ * Returns: (transfer none): The texture to download
+ *
+ * Since: 4.10
+ **/
+GdkTexture *
+gdk_texture_downloader_get_texture (const GdkTextureDownloader *self)
+{
+  g_return_val_if_fail (self != NULL, NULL);
+
+  return self->texture;
+}
+
+/**
+ * gdk_texture_downloader_set_format:
+ * @self: a texture downloader
+ * @format: the format to use
+ *
+ * Sets the format the downloader will download.
+ *
+ * By default, GDK_MEMORY_DEFAULT is set.
+ *
+ * Since: 4.10
+ */
+void
+gdk_texture_downloader_set_format (GdkTextureDownloader *self,
+                                   GdkMemoryFormat       format)
+{
+  g_return_if_fail (self != NULL);
+
+  self->format = format;
+}
+
+/**
+ * gdk_texture_downloader_get_format:
+ * @self: a texture downloader
+ *
+ * Gets the format that the data will be downloaded in.
+ *
+ * Returns: The format of the download
+ *
+ * Since: 4.10
+ **/
+GdkMemoryFormat
+gdk_texture_downloader_get_format (const GdkTextureDownloader *self)
+{
+  g_return_val_if_fail (self != NULL, GDK_MEMORY_DEFAULT);
+
+  return self->format;
+}
+
+/**
+ * gdk_texture_downloader_download_into:
+ * @self: a texture downloader
+ * @data: (array): pointer to enough memory to be filled with the
+ *   downloaded data of the texture
+ * @stride: rowstride in bytes
+ *
+ * Downloads the @texture into local memory.
+ *
+ * Since: 4.10
+ **/
+void
+gdk_texture_downloader_download_into (const GdkTextureDownloader *self,
+                                      guchar                     *data,
+                                      gsize                       stride)
+{
+  g_return_if_fail (self != NULL);
+  g_return_if_fail (data != NULL);
+  g_return_if_fail (stride >= gdk_texture_get_width (self->texture) * gdk_memory_format_bytes_per_pixel (self->format));
+
+  gdk_texture_do_download (self->texture, self->format, data, stride);
+}
+
+/**
+ * gdk_texture_downloader_download_bytes:
+ * @self: the downloader
+ * @out_stride: (out): The stride of the resulting data in bytes.
+ *
+ * Downloads the given texture pixels into a `GBytes`. The rowstride will
+ * be stored in the stride value.
+ *
+ * This function will abort if it tries to download a large texture and
+ * fails to allocate memory. If you think that may happen, you should
+ * handle memory allocation yourself and use
+ * gdk_texture_downloader_download_into() once allocation succeeded.
+ *
+ * Returns: The downloaded pixels.
+ *
+ * Since: 4.10
+ **/
+GBytes *
+gdk_texture_downloader_download_bytes (const GdkTextureDownloader *self,
+                                       gsize                      *out_stride)
+{
+  guchar *data;
+  gsize stride;
+
+  g_return_val_if_fail (self != NULL, NULL);
+  g_return_val_if_fail (out_stride != NULL, NULL);
+
+  if (GDK_IS_MEMORY_TEXTURE (self->texture) &&
+      gdk_texture_get_format (self->texture) == self->format)
+    {
+      GdkMemoryTexture *memtex = GDK_MEMORY_TEXTURE (self->texture);
+
+      *out_stride = gdk_memory_texture_get_stride (memtex);
+      return g_bytes_ref (gdk_memory_texture_get_bytes (memtex));
+    }
+
+  stride = self->texture->width * gdk_memory_format_bytes_per_pixel (self->format);
+  data = g_malloc_n (stride, self->texture->height);
+
+  gdk_texture_do_download (self->texture, self->format, data, stride);
+
+  *out_stride = stride;
+  return g_bytes_new_take (data, stride * self->texture->height);
+}
+