From: Benjamin Otte Date: Sat, 14 Aug 2010 02:40:52 +0000 (+0200) Subject: API: Add gdk_cairo_region_create_from_surface() X-Git-Url: http://pileus.org/git/?a=commitdiff_plain;h=96b387599d8fb2d27717256ed098fde0dee83e29;p=~andy%2Fgtk API: Add gdk_cairo_region_create_from_surface() The function converts the given surface into an alpha bitmap mask. This is mostly useful for setting shape regions. Also adds a new internal function _gdk_cairo_surface_extents() that computes a surface's extents. --- diff --git a/docs/reference/gdk/gdk3-sections.txt b/docs/reference/gdk/gdk3-sections.txt index 554d5c805..0f4534ed2 100644 --- a/docs/reference/gdk/gdk3-sections.txt +++ b/docs/reference/gdk/gdk3-sections.txt @@ -656,6 +656,7 @@ gdk_cairo_set_source_pixmap gdk_cairo_rectangle gdk_cairo_region gdk_cairo_reset_clip +gdk_cairo_region_create_from_surface
diff --git a/gdk/gdk.symbols b/gdk/gdk.symbols index a040f427d..9d048fe15 100644 --- a/gdk/gdk.symbols +++ b/gdk/gdk.symbols @@ -293,6 +293,7 @@ gdk_cairo_set_source_pixbuf gdk_cairo_set_source_pixmap gdk_cairo_rectangle gdk_cairo_region +gdk_cairo_region_create_from_surface #endif #endif diff --git a/gdk/gdkcairo.c b/gdk/gdkcairo.c index c5ead4ef6..c5a55c5c1 100644 --- a/gdk/gdkcairo.c +++ b/gdk/gdkcairo.c @@ -18,6 +18,9 @@ */ #include "gdkcairo.h" + +#include + #include "gdkdrawable.h" #include "gdkinternals.h" @@ -287,3 +290,141 @@ gdk_cairo_set_source_pixmap (cairo_t *cr, cairo_set_source_surface (cr, surface, pixmap_x, pixmap_y); cairo_surface_destroy (surface); } + +/** + * _gdk_cairo_surface_extents: + * @surface: surface to measure + * @extents: (out): rectangle to put the extents + * + * Measures the area covered by @surface and puts it into @extents. + * Note that this function respects device offsets set on @surface. + * if @surface is unbounded, the resulting extents will be empty and + * not be a maximal sized rectangle. This is to avoid careless coding. + * You must explicitly check the return value of you want to handle + * that case. + * + * Returns: %TRUE if the extents fit in a #GdkRectangle, %FALSE if not. + **/ +gboolean +_gdk_cairo_surface_extents (cairo_surface_t *surface, + GdkRectangle *extents) +{ + double x1, x2, y1, y2; + cairo_t *cr; + + g_return_val_if_fail (surface != NULL, FALSE); + g_return_val_if_fail (extents != NULL, FALSE); + + cr = cairo_create (surface); + cairo_clip_extents (cr, &x1, &y1, &x2, &y2); + + x1 = floor (x1); + y1 = floor (y1); + x2 = ceil (x2); + y2 = ceil (y2); + x2 -= x1; + y2 -= y1; + + if (x1 < G_MININT || x1 > G_MAXINT || + y1 < G_MININT || y1 > G_MAXINT || + x2 > G_MAXINT || y2 > G_MAXINT) + { + extents->x = extents->y = extents->width = extents->height = 0; + return FALSE; + } + + extents->x = x1; + extents->y = y1; + extents->width = x2; + extents->height = y2; + + return TRUE; +} + +/* This function originally from Jean-Edouard Lachand-Robert, and + * available at www.codeguru.com. Simplified for our needs, not sure + * how much of the original code left any longer. Now handles just + * one-bit deep bitmaps (in Window parlance, ie those that GDK calls + * bitmaps (and not pixmaps), with zero pixels being transparent. + */ +/** + * gdk_cairo_region_create_from_surface: + * @surface: A surface + * + * Creates region that describes covers the area where the given @surface + * is more than 50% opaque. This function takes into account device + * offsets that might be set with cairo_surface_set_device_offset(). + * + * Returns: A new region + **/ +cairo_region_t * +gdk_cairo_region_create_from_surface (cairo_surface_t *surface) +{ + cairo_region_t *region; + GdkRectangle extents, rect; + cairo_surface_t *image; + cairo_t *cr; + gint x, y, stride; + guchar *data; + + _gdk_cairo_surface_extents (surface, &extents); + + if (cairo_surface_get_content (surface) == CAIRO_CONTENT_COLOR) + return cairo_region_create_rectangle (&extents); + + if (cairo_surface_get_type (surface) != CAIRO_SURFACE_TYPE_IMAGE || + cairo_image_surface_get_format (surface) != CAIRO_FORMAT_A1) + { + /* coerce to an A1 image */ + image = cairo_image_surface_create (CAIRO_FORMAT_A1, + extents.width, extents.height); + cr = cairo_create (image); + cairo_set_source_surface (cr, surface, extents.x, extents.y); + cairo_paint (cr); + cairo_destroy (cr); + } + else + image = cairo_surface_reference (surface); + + data = cairo_image_surface_get_data (image); + stride = cairo_image_surface_get_stride (image); + + region = cairo_region_create (); + + for (y = 0; y < extents.height; y++) + { + for (x = 0; x < extents.width; x++) + { + /* Search for a continuous range of "non transparent pixels"*/ + gint x0 = x; + while (x < extents.width) + { + if (((data[x / 8] >> (x%8)) & 1) == 0) + /* This pixel is "transparent"*/ + break; + x++; + } + + if (x > x0) + { + /* Add the pixels (x0, y) to (x, y+1) as a new rectangle + * in the region + */ + rect.x = x0; + rect.width = x - x0; + rect.y = y; + rect.height = 1; + + cairo_region_union_rectangle (region, &rect); + } + } + data += stride; + } + + cairo_surface_destroy (image); + + cairo_region_translate (region, extents.x, extents.y); + + return region; +} + diff --git a/gdk/gdkcairo.h b/gdk/gdkcairo.h index 4ecb037a8..c2a71e8a9 100644 --- a/gdk/gdkcairo.h +++ b/gdk/gdkcairo.h @@ -50,6 +50,10 @@ void gdk_cairo_rectangle (cairo_t *cr, void gdk_cairo_region (cairo_t *cr, const cairo_region_t *region); +cairo_region_t * + gdk_cairo_region_create_from_surface + (cairo_surface_t *surface); + G_END_DECLS #endif /* __GDK_CAIRO_H__ */ diff --git a/gdk/gdkinternals.h b/gdk/gdkinternals.h index 7740bce66..eda1e55b5 100644 --- a/gdk/gdkinternals.h +++ b/gdk/gdkinternals.h @@ -313,6 +313,8 @@ void gdk_synthesize_window_state (GdkWindow *window, GdkDeviceManager * _gdk_device_manager_new (GdkDisplay *display); +gboolean _gdk_cairo_surface_extents (cairo_surface_t *surface, + GdkRectangle *extents); cairo_surface_t *_gdk_drawable_ref_cairo_surface (GdkDrawable *drawable);