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cssimage: Add a few convenience functions

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This commit is contained in:
Benjamin Otte 2011-12-21 17:40:16 +01:00
parent cdd4ed6600
commit 2bb899b5c0
2 changed files with 165 additions and 0 deletions
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153
gtk/gtkcssimage.c
View File

@ -160,6 +160,159 @@ _gtk_css_image_print (GtkCssImage *image,
klass->print (image, string);
}
/* Applies the algorithm outlined in
* http://dev.w3.org/csswg/css3-images/#default-sizing
*/
void
_gtk_css_image_get_concrete_size (GtkCssImage *image,
double specified_width,
double specified_height,
double default_width,
double default_height,
double *concrete_width,
double *concrete_height)
{
double image_width, image_height, image_aspect;
g_return_if_fail (GTK_IS_CSS_IMAGE (image));
g_return_if_fail (specified_width >= 0);
g_return_if_fail (specified_height >= 0);
g_return_if_fail (default_width > 0);
g_return_if_fail (default_height > 0);
g_return_if_fail (concrete_width != NULL);
g_return_if_fail (concrete_height != NULL);
/* If the specified size is a definite width and height,
* the concrete object size is given that width and height.
*/
if (specified_width && specified_height)
{
*concrete_width = specified_width;
*concrete_height = specified_height;
return;
}
image_width = _gtk_css_image_get_width (image);
image_height = _gtk_css_image_get_height (image);
image_aspect = _gtk_css_image_get_aspect_ratio (image);
/* If the specified size has neither a definite width nor height,
* and has no additional contraints, the dimensions of the concrete
* object size are calculated as follows:
*/
if (specified_width == 0.0 && specified_height == 0.0)
{
/* If the object has only an intrinsic aspect ratio,
* the concrete object size must have that aspect ratio,
* and additionally be as large as possible without either
* its height or width exceeding the height or width of the
* default object size.
*/
if (image_aspect > 0 && image_width == 0 && image_height == 0)
{
if (image_aspect * default_height > default_width)
{
*concrete_width = default_height * image_aspect;
*concrete_height = default_height;
}
else
{
*concrete_width = default_width;
*concrete_height = default_width / image_aspect;
}
}
/* Otherwise, the width and height of the concrete object
* size is the same as the object's intrinsic width and
* intrinsic height, if they exist.
* If the concrete object size is still missing a width or
* height, and the object has an intrinsic aspect ratio,
* the missing dimension is calculated from the present
* dimension and the intrinsic aspect ratio.
* Otherwise, the missing dimension is taken from the default
* object size.
*/
if (image_width)
*concrete_width = image_width;
else if (image_aspect)
*concrete_width = image_height * image_aspect;
else
*concrete_width = default_width;
if (image_height)
*concrete_height = image_height;
else if (image_aspect)
*concrete_height = image_width / image_aspect;
else
*concrete_height = default_height;
return;
}
/* If the specified size has only a width or height, but not both,
* then the concrete object size is given that specified width or height.
* The other dimension is calculated as follows:
* If the object has an intrinsic aspect ratio, the missing dimension of
* the concrete object size is calculated using the intrinsic aspect-ratio
* and the present dimension.
* Otherwise, if the missing dimension is present in the object's intrinsic
* dimensions, the missing dimension is taken from the object's intrinsic
* dimensions.
* Otherwise, the missing dimension of the concrete object size is taken
* from the default object size.
*/
if (specified_width)
{
*concrete_width = specified_width;
if (image_aspect)
*concrete_height = specified_width / image_aspect;
else if (image_height)
*concrete_height = image_height;
else
*concrete_height = default_height;
}
else
{
*concrete_height = specified_height;
if (image_aspect)
*concrete_width = specified_height * image_aspect;
else if (image_width)
*concrete_width = image_width;
else
*concrete_width = default_width;
}
}
cairo_surface_t *
_gtk_css_image_get_surface (GtkCssImage *image,
cairo_surface_t *target,
int surface_width,
int surface_height)
{
cairo_surface_t *result;
cairo_t *cr;
g_return_val_if_fail (GTK_IS_CSS_IMAGE (image), NULL);
g_return_val_if_fail (surface_width > 0, NULL);
g_return_val_if_fail (surface_height > 0, NULL);
if (target)
result = cairo_surface_create_similar (target,
CAIRO_CONTENT_COLOR_ALPHA,
surface_width,
surface_height);
else
result = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
surface_width,
surface_height);
cr = cairo_create (result);
_gtk_css_image_draw (image, cr, surface_width, surface_height);
cairo_destroy (cr);
return result;
}
GtkCssImage *
_gtk_css_image_new_parse (GtkCssParser *parser,
GFile *base)

12
gtk/gtkcssimageprivate.h
View File

@ -92,6 +92,18 @@ void _gtk_css_image_draw (GtkCssImage *image,
void _gtk_css_image_print (GtkCssImage *image,
GString *string);
void _gtk_css_image_get_concrete_size (GtkCssImage *image,
double specified_width,
double specified_height,
double default_width,
double default_height,
double *concrete_width,
double *concrete_height);
cairo_surface_t *
_gtk_css_image_get_surface (GtkCssImage *image,
cairo_surface_t *target,
int surface_width,
int surface_height);
G_END_DECLS