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app, libgimp*, plug-ins: fix previous commit and add gimp_cairo_surface_get_buffer().

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The previous commit was not taking into account usages of
gimp_cairo_surface_create_buffer(), other than the text layer rendering
usage, as it was focused on fixing #14970.

In particular, in other pieces of code, we were using a temporary
GeglBuffer as a way to edit the original Cairo surface but the syncing
back was not happening anymore. So previous commit was breaking all
thumbnails of layers or images, as well as PDF export for all raster
layers.

After some thought, I decided to implement a new function
gimp_cairo_surface_get_buffer() which would do what
gimp_cairo_surface_create_buffer() was doing, but adding a boolean flag
to declare whether or not we were expecting to sync back into the Cairo
surface's data. After all, when we don't need to sync back, better avoid
the useless work of copying possibly huge data.

I also added back the possibility of returning a linear-memory backed
buffer, after some discussion with pippin. Because for very small
surfaces, and if we are indeed looking to sync back into the source
Cairo surface, the advantages of using a linear buffer may still be
worth it, even though it's not true for the general case (where tiled
buffers will be much more efficient). I used 4096 (64^2 because our
current tile dimensions are 64 right now in GIMP), though this number is
kinda random and doesn't matter too much (it doesn't have to be the
square of the tile's width or height). I don't put any info about this
in the new function's documentation because developers should not have
any expectations on the type of buffer they get (only whether or not it
will sync back to the source).

As a consequence of all this, gimp_cairo_surface_create_buffer() has
been deprecated as of GIMP 3.2, though it will still work the same. The
new function will be recommended as a replacement.
This commit is contained in:
Jehan 2025-11-08 18:16:36 +01:00
parent ade0bdc487
commit 926d5c6daa
8 changed files with 140 additions and 14 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
app/text/gimptextlayer.c
View file

@ -1114,7 +1114,7 @@ gimp_text_layer_render_layout (GimpTextLayer *layer,
#else
format = babl_format_with_space ("cairo-ARGB32", gimp_text_layout_get_space (layout));
#endif
buffer = gimp_cairo_surface_create_buffer (surface, format);
buffer = gimp_cairo_surface_get_buffer (surface, format, FALSE);
gimp_gegl_buffer_copy (buffer, NULL, GEGL_ABYSS_NONE,
gimp_drawable_get_buffer (drawable), NULL);

4
app/widgets/gimpviewrenderer.c
View file

@ -1300,13 +1300,14 @@ gimp_view_render_temp_buf_to_surface (GimpViewRenderer *renderer,
width, height);
src_buffer = gimp_temp_buf_create_buffer (temp_buf);
dest_buffer = gimp_cairo_surface_create_buffer (tmp_surface, NULL);
dest_buffer = gimp_cairo_surface_get_buffer (tmp_surface, NULL, TRUE);
transform =
gimp_view_renderer_get_color_transform (renderer, widget,
gegl_buffer_get_format (src_buffer),
gegl_buffer_get_format (dest_buffer));
gegl_buffer_freeze_changed (dest_buffer);
if (transform)
{
gimp_color_transform_process_buffer (transform,
@ -1327,6 +1328,7 @@ gimp_view_render_temp_buf_to_surface (GimpViewRenderer *renderer,
dest_buffer,
GEGL_RECTANGLE (0, 0, 0, 0));
}
gegl_buffer_thaw_changed (dest_buffer);
g_object_unref (src_buffer);
g_object_unref (dest_buffer);

2
libgimp/gimplayer.c
View file

@ -219,7 +219,7 @@ gimp_layer_new_from_surface (GimpImage *image,
if (layer == NULL)
return NULL;
src_buffer = gimp_cairo_surface_create_buffer (surface, NULL);
src_buffer = gimp_cairo_surface_get_buffer (surface, NULL, FALSE);
dest_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (layer));
gegl_buffer_copy (src_buffer, NULL, GEGL_ABYSS_NONE,

135
libgimpcolor/gimpcairo.c
View file

@ -31,6 +31,7 @@
#include "gimpcolortypes.h"
#include "gimpcairo.h"
#include "gimpcolor-private.h"
/**
@ -43,6 +44,11 @@
**/
static void gimp_cairo_surface_buffer_changed (GeglBuffer *buffer,
const GeglRectangle *rect,
cairo_surface_t *surface);
/**
* gimp_cairo_checkerboard_create:
* @cr: Cairo context
@ -171,29 +177,138 @@ gimp_cairo_surface_get_format (cairo_surface_t *surface)
* Returns: (transfer full): a #GeglBuffer
*
* Since: 2.10
*
* Deprecated: 3.2: Use gimp_cairo_surface_get_buffer().
**/
GeglBuffer *
gimp_cairo_surface_create_buffer (cairo_surface_t *surface,
const Babl *format)
{
GeglBuffer *buffer;
GeglRectangle extent = {0};
return gimp_cairo_surface_get_buffer (surface, format, TRUE);
}
/**
* gimp_cairo_surface_get_buffer:
* @surface: a Cairo surface
* @format: a Babl format.
* @sync_back: whether changes on the returned buffer should be synced
* back to @surface.
*
* This function returns a [class@Gegl.Buffer] containing @surface's
* pixels. It must only be called on image surfaces, calling it on other
* surface types is an error.
*
* If @format is set, the returned buffer will use it. It has to map
* with @surface Cairo format. If unset, the buffer format will be
* determined from @surface. The main difference is that automatically
* determined format has sRGB space and TRC by default.
*
* If you want the changes to the returned buffer to be synced back to
* @surface data, set @sync_back to %TRUE. If you don't need this and
* only want a copy of @surface at a given time, %FALSE will be less
* costly.
*
* When @sync_back is %TRUE, [method@Gegl.Buffer.freeze_changed] and
* [method@Gegl.Buffer.thaw_changed] may be useful to block intermediate
* syncing.
*
* Returns: (transfer full): a #GeglBuffer
*
* Since: 3.2
**/
GeglBuffer *
gimp_cairo_surface_get_buffer (cairo_surface_t *surface,
const Babl *format,
gboolean sync_back)
{
const Babl *surface_format;
GeglBuffer *buffer;
GeglRectangle extent = {0};
gint rowstride;
gint bpp;
g_return_val_if_fail (surface != NULL, NULL);
g_return_val_if_fail (cairo_surface_get_type (surface) ==
CAIRO_SURFACE_TYPE_IMAGE, NULL);
g_return_val_if_fail (format == NULL ||
babl_format_get_bytes_per_pixel (format) == babl_format_get_bytes_per_pixel (gimp_cairo_surface_get_format (surface)),
NULL);
g_return_val_if_fail (cairo_surface_get_type (surface) == CAIRO_SURFACE_TYPE_IMAGE, NULL);
surface_format = gimp_cairo_surface_get_format (surface);
rowstride = cairo_image_surface_get_stride (surface);
bpp = babl_format_get_bytes_per_pixel (surface_format);
g_return_val_if_fail (format == NULL || babl_format_get_bytes_per_pixel (format) == bpp, NULL);
if (format == NULL)
format = gimp_cairo_surface_get_format (surface);
format = surface_format;
extent.width = cairo_image_surface_get_width (surface);
extent.height = cairo_image_surface_get_height (surface);
buffer = gegl_buffer_new (&extent, format);
if ( ! sync_back || rowstride % bpp != 0 ||
extent.width * extent.height > GIMP_LINEAR_BUFFER_MAX_SIZE)
buffer = gegl_buffer_new (&extent, format);
else
return gegl_buffer_linear_new_from_data (cairo_image_surface_get_data (surface),
format, &extent, rowstride,
(GDestroyNotify) cairo_surface_destroy,
cairo_surface_reference (surface));
gegl_buffer_set (buffer, &extent, 0, format, cairo_image_surface_get_data (surface), cairo_image_surface_get_stride (surface));
gegl_buffer_set (buffer, &extent, 0, format,
cairo_image_surface_get_data (surface),
rowstride);
if (sync_back)
{
/* Making sure we don't work on a destroyed surface. */
g_object_set_data_full (G_OBJECT (buffer),
"gimp-cairo-surface-get-buffer-surface",
cairo_surface_reference (surface),
(GDestroyNotify) cairo_surface_destroy);
gegl_buffer_signal_connect (buffer, "changed",
G_CALLBACK (gimp_cairo_surface_buffer_changed),
surface);
}
return buffer;
}
/* Private functions */
static void
gimp_cairo_surface_buffer_changed (GeglBuffer *buffer,
const GeglRectangle *rect,
cairo_surface_t *surface)
{
unsigned char *data;
gint stride;
gint bpp;
data = cairo_image_surface_get_data (surface);
stride = cairo_image_surface_get_stride (surface);
bpp = babl_format_get_bytes_per_pixel (gegl_buffer_get_format (buffer));
data += stride * rect->y + rect->x * bpp;
if ((rect->x == 0 && rect->width == gegl_buffer_get_width (buffer)) || rect->height == 1)
{
gegl_buffer_get (buffer, rect, 1.0, NULL,
data, stride, GEGL_ABYSS_NONE);
}
else
{
GeglRectangle extent;
extent.x = rect->x;
extent.width = rect->width;
extent.height = 1;
for (gint y = rect->y; y < rect->y + rect->height; y++)
{
extent.y = y;
gegl_buffer_get (buffer, &extent, 1.0, NULL,
data, stride, GEGL_ABYSS_NONE);
data += stride;
}
}
cairo_surface_mark_dirty (surface);
}

4
libgimpcolor/gimpcairo.h
View file

@ -30,8 +30,12 @@ cairo_pattern_t * gimp_cairo_checkerboard_create (cairo_t *cr,
const GeglColor *dark);
const Babl * gimp_cairo_surface_get_format (cairo_surface_t *surface);
GIMP_DEPRECATED_FOR(gimp_cairo_surface_get_buffer)
GeglBuffer * gimp_cairo_surface_create_buffer (cairo_surface_t *surface,
const Babl *format);
GeglBuffer * gimp_cairo_surface_get_buffer (cairo_surface_t *surface,
const Babl *format,
gboolean sync_back);
/* some useful macros for writing directly to a Cairo surface */

2
libgimpcolor/gimpcolor-private.h
View file

@ -19,6 +19,8 @@
#ifndef __GIMP_COLOR_PRIVATE_H__
#define __GIMP_COLOR_PRIVATE_H__
#define GIMP_LINEAR_BUFFER_MAX_SIZE 4096
/* Legacy definition to calculate luminance from sRGB.
*
* These values and macro are specific to a "RGB float" to "Y float"

1
libgimpcolor/gimpcolor.def
View file

@ -8,6 +8,7 @@ EXPORTS
gimp_bilinear_rgb
gimp_cairo_checkerboard_create
gimp_cairo_surface_create_buffer
gimp_cairo_surface_get_buffer
gimp_cairo_surface_get_format
gimp_color_is_out_of_gamut
gimp_color_is_out_of_self_gamut

4
plug-ins/common/file-pdf-export.c
View file

@ -1430,7 +1430,7 @@ get_cairo_surface (GimpDrawable *drawable,
return NULL;
}
dest_buffer = gimp_cairo_surface_create_buffer (surface, NULL);
dest_buffer = gimp_cairo_surface_get_buffer (surface, NULL, TRUE);
if (as_mask)
{
/* src_buffer represents a mask in "Y u8", "Y u16", etc. formats.
@ -1442,7 +1442,9 @@ get_cairo_surface (GimpDrawable *drawable,
gegl_buffer_set_format (dest_buffer, babl_format ("Y u8"));
}
gegl_buffer_freeze_changed (dest_buffer);
gegl_buffer_copy (src_buffer, NULL, GEGL_ABYSS_NONE, dest_buffer, NULL);
gegl_buffer_thaw_changed (dest_buffer);
cairo_surface_mark_dirty (surface);