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paintable: Add gdk_paintable_compute_concrete_size()

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Do the CSS size computation routine. This will be used elsewhere soon.
This commit is contained in:
Benjamin Otte 2018-02-26 20:51:38 +01:00
parent bcf1aa7cb2
commit 536714a147
3 changed files with 157 additions and 0 deletions
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1
docs/reference/gdk/gdk4-sections.txt
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@ -724,6 +724,7 @@ gdk_paintable_get_flags
gdk_paintable_get_intrinsic_width
gdk_paintable_get_intrinsic_height
gdk_paintable_get_intrinsic_aspect_ratio
gdk_paintable_compute_concrete_size
gdk_paintable_invalidate_contents
gdk_paintable_invalidate_size
<SECTION>

148
gdk/gdkpaintable.c
View File

@ -394,3 +394,151 @@ gdk_paintable_invalidate_size (GdkPaintable *paintable)
g_signal_emit (paintable, signals[INVALIDATE_SIZE], 0);
}
/**
* gdk_paintable_compute_concrete_size:
* @paintable: a #GdkPaintable
* @specified_width: the width @paintable could be drawn into or
* 0.0 if unknown
* @specified_height: the height @paintable could be drawn into or
* 0.0 if unknown
* @default_width: the width @paintable would be drawn into if
* no other constraints were given
* @default_height: the height @paintable would be drawn into if
* no other constraints were given
* @concrete_width: (out): will be set to the concrete width
* computed.
* @concrete_height: (out): will be set to the concrete height
* computed.
*
* Applies the sizing algorithm outlined in
* https://drafts.csswg.org/css-images-3/#default-sizing
* to the given @paintable. See that link for more details.
*
* It is not necessary to call this function when both @specified_width
* and @specified_height are known, but it is useful to call this
* function in GtkWidget:measure implementations to compute the
* other dimension when only one dimension is given.
*/
void
gdk_paintable_compute_concrete_size (GdkPaintable *paintable,
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 (GDK_IS_PAINTABLE (paintable));
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 = gdk_paintable_get_intrinsic_width (paintable);
image_height = gdk_paintable_get_intrinsic_height (paintable);
image_aspect = gdk_paintable_get_intrinsic_aspect_ratio (paintable);
/* 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_width;
*concrete_height = default_width / image_aspect;
}
else
{
*concrete_width = default_height * image_aspect;
*concrete_height = default_height;
}
}
else
{
/* 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;
}
}

8
gdk/gdkpaintable.h
View File

@ -126,6 +126,14 @@ int gdk_paintable_get_intrinsic_height (GdkPaintable
GDK_AVAILABLE_IN_ALL
double gdk_paintable_get_intrinsic_aspect_ratio(GdkPaintable *paintable);
GDK_AVAILABLE_IN_ALL
void gdk_paintable_compute_concrete_size (GdkPaintable *paintable,
double specified_width,
double specified_height,
double default_width,
double default_height,
double *concrete_width,
double *concrete_height);
/* for implementations only */
GDK_AVAILABLE_IN_ALL
void gdk_paintable_invalidate_contents (GdkPaintable *paintable);