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macos: align image surface rowstride to 16-bytes

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When creating a cairo_image_surface_t we want both the framebuffer pointer
and each row to be aligned to 16-bytes so that Core Graphics will use more
optimal paths.

However, cairo_image_surface_create() will not guarantee that the rowstride
is aligned to 16-bytes so we must do that ourselves.
This commit is contained in:
Christian Hergert 2022-02-03 18:21:43 -08:00
parent 58159552ba
commit 4373743d4c
1 changed files with 30 additions and 10 deletions
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40
gdk/macos/gdkmacoscairocontext.c
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@ -47,26 +47,46 @@ G_DEFINE_TYPE (GdkMacosCairoContext, _gdk_macos_cairo_context, GDK_TYPE_CAIRO_CO
static cairo_surface_t *
create_cairo_surface_for_surface (GdkSurface *surface)
{
static const cairo_user_data_key_t buffer_key;
cairo_surface_t *cairo_surface;
guint8 *data;
cairo_format_t format;
size_t size;
size_t rowstride;
size_t width;
size_t height;
int scale;
int width;
int height;
g_assert (GDK_IS_MACOS_SURFACE (surface));
/* We use a cairo image surface here instead of a quartz surface because
* we get strange artifacts with the quartz surface such as empty
* cross-fades when hovering buttons. For performance, we want to be using
* GL rendering so there isn't much point here as correctness is better.
*
* Additionally, so we can take avantage of faster paths in Core
* Graphics, we want our data pointer to be 16-byte aligned and our rows
* to be 16-byte aligned or we risk errors below us. Normally, cairo
* image surface does not guarantee the later, which means we could end
* up doing some costly copies along the way to compositing.
*/
if ([GDK_MACOS_SURFACE (surface)->window isOpaque])
format = CAIRO_FORMAT_RGB24;
else
format = CAIRO_FORMAT_ARGB32;
scale = gdk_surface_get_scale_factor (surface);
width = scale * gdk_surface_get_width (surface);
height = scale * gdk_surface_get_height (surface);
rowstride = (cairo_format_stride_for_width (format, width) + 0xF) & ~0xF;
size = rowstride * height;
data = g_malloc0 (size);
cairo_surface = cairo_image_surface_create_for_data (data, format, width, height, rowstride);
cairo_surface_set_user_data (cairo_surface, &buffer_key, data, g_free);
cairo_surface_set_device_scale (cairo_surface, scale, scale);
/* We use a cairo image surface here instead of a quartz surface because we
* get strange artifacts with the quartz surface such as empty cross-fades
* when hovering buttons. For performance, we want to be using GL rendering
* so there isn't much point here as correctness is better.
*/
cairo_surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, width, height);
if (cairo_surface != NULL)
cairo_surface_set_device_scale (cairo_surface, scale, scale);
return cairo_surface;
}