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gsk: Add skew transforms

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Add gsk_transform_skew() to make our transform
api more complete wrt to what you would expect
for a graphics api.
This commit is contained in:
Matthias Clasen
2021-09-17 22:01:55 -04:00
parent 9e6adaa913
commit 1289e68931
2 changed files with 179 additions and 20 deletions
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195
gsk/gsktransform.c
View File

@@ -1005,7 +1005,178 @@ gsk_transform_rotate_3d (GskTransform *next,
}
/* }}} */
/* {{{ SCALE */
/* {{{ SKEW */
typedef struct _GskSkewTransform GskSkewTransform;
struct _GskSkewTransform
{
GskTransform parent;
float skew_x;
float skew_y;
};
static void
gsk_skew_transform_finalize (GskTransform *self)
{
}
static void
gsk_skew_transform_to_matrix (GskTransform *transform,
graphene_matrix_t *out_matrix)
{
GskSkewTransform *self = (GskSkewTransform *) transform;
graphene_matrix_init_skew (out_matrix,
self->skew_x / 180.0 * G_PI,
self->skew_y / 180.0 * G_PI);
}
static void
gsk_skew_transform_apply_2d (GskTransform *transform,
float *out_xx,
float *out_yx,
float *out_xy,
float *out_yy,
float *out_dx,
float *out_dy)
{
graphene_matrix_t sm, mat;
gsk_skew_transform_to_matrix (transform, &sm);
graphene_matrix_init_from_2d (&mat, *out_xx, *out_yx,
*out_xy, *out_yy,
*out_dx, *out_dy);
graphene_matrix_multiply (&sm, &mat, &mat);
*out_xx = graphene_matrix_get_value (&mat, 0, 0);
*out_yx = graphene_matrix_get_value (&mat, 0, 1);
*out_xy = graphene_matrix_get_value (&mat, 1, 0);
*out_yy = graphene_matrix_get_value (&mat, 1, 1);
*out_dx = graphene_matrix_get_value (&mat, 3, 0);
*out_dy = graphene_matrix_get_value (&mat, 3, 1);
}
static GskTransform *
gsk_skew_transform_apply (GskTransform *transform,
GskTransform *apply_to)
{
GskSkewTransform *self = (GskSkewTransform *) transform;
return gsk_transform_skew (apply_to, self->skew_x, self->skew_y);
}
static void
gsk_skew_transform_print (GskTransform *transform,
GString *string)
{
GskSkewTransform *self = (GskSkewTransform *) transform;
if (self->skew_y == 0)
{
g_string_append (string, "skewX(");
string_append_double (string, self->skew_x);
g_string_append (string, ")");
}
else if (self->skew_x == 0)
{
g_string_append (string, "skewY(");
string_append_double (string, self->skew_y);
g_string_append (string, ")");
}
else
{
g_string_append (string, "skew(");
string_append_double (string, self->skew_x);
g_string_append (string, ", ");
string_append_double (string, self->skew_y);
g_string_append (string, ")");
}
}
static GskTransform *
gsk_skew_transform_invert (GskTransform *transform,
GskTransform *next)
{
GskSkewTransform *self = (GskSkewTransform *) transform;
float tx, ty;
graphene_matrix_t matrix;
tx = tanf (self->skew_x / 180.0 * G_PI);
ty = tanf (self->skew_y / 180.0 * G_PI);
graphene_matrix_init_from_2d (&matrix,
1 / (1 - tx * ty),
- ty / (1 - tx * ty),
- tx / (1 - tx * ty),
1 / (1 - tx * ty),
0, 0);
return gsk_transform_matrix_with_category (next,
&matrix,
GSK_TRANSFORM_CATEGORY_2D);
}
static gboolean
gsk_skew_transform_equal (GskTransform *first_transform,
GskTransform *second_transform)
{
GskSkewTransform *first = (GskSkewTransform *) first_transform;
GskSkewTransform *second = (GskSkewTransform *) second_transform;
return G_APPROX_VALUE (first->skew_x, second->skew_x, FLT_EPSILON) &&
G_APPROX_VALUE (first->skew_y, second->skew_y, FLT_EPSILON);
}
static const GskTransformClass GSK_SKEW_TRANSFORM_CLASS =
{
sizeof (GskSkewTransform),
"GskSkewTransform",
gsk_skew_transform_finalize,
gsk_skew_transform_to_matrix,
gsk_skew_transform_apply_2d,
NULL,
NULL,
gsk_skew_transform_print,
gsk_skew_transform_apply,
gsk_skew_transform_invert,
gsk_skew_transform_equal,
};
/**
* gsk_transform_skew:
* @next: (nullable) (transfer full): the next transform
* @skew_x: skew factor, in degrees, on the X axis
* @skew_y: skew factor, in degrees, on the Y axis
*
* Applies a skew transform.
*
* Returns: The new transform
*
* Since: 4.6
*/
GskTransform *
gsk_transform_skew (GskTransform *next,
float skew_x,
float skew_y)
{
GskSkewTransform *result;
if (skew_x == 0 && skew_y == 0)
return next;
result = gsk_transform_alloc (&GSK_SKEW_TRANSFORM_CLASS,
GSK_TRANSFORM_CATEGORY_2D,
next);
result->skew_x = skew_x;
result->skew_y = skew_y;
return &result->parent;
}
/* }}} */
/* {{{ SCALE */
typedef struct _GskScaleTransform GskScaleTransform;
@@ -2057,40 +2228,24 @@ gsk_transform_parser_parse (GtkCssParser *parser,
}
else if (gtk_css_token_is_function (token, "skew"))
{
graphene_matrix_t matrix;
if (!gtk_css_parser_consume_function (parser, 2, 2, gsk_transform_parse_float, f))
goto fail;
f[0] = f[0] / 180.0 * G_PI;
f[1] = f[1] / 180.0 * G_PI;
graphene_matrix_init_skew (&matrix, f[0], f[1]);
transform = gsk_transform_matrix (transform, &matrix);
transform = gsk_transform_skew (transform, f[0], f[1]);
}
else if (gtk_css_token_is_function (token, "skewX"))
{
graphene_matrix_t matrix;
if (!gtk_css_parser_consume_function (parser, 1, 1, gsk_transform_parse_float, f))
goto fail;
f[0] = f[0] / 180.0 * G_PI;
graphene_matrix_init_skew (&matrix, f[0], 0);
transform = gsk_transform_matrix (transform, &matrix);
transform = gsk_transform_skew (transform, f[0], 0);
}
else if (gtk_css_token_is_function (token, "skewY"))
{
graphene_matrix_t matrix;
if (!gtk_css_parser_consume_function (parser, 1, 1, gsk_transform_parse_float, f))
goto fail;
f[0] = f[0] / 180.0 * G_PI;
graphene_matrix_init_skew (&matrix, 0, f[0]);
transform = gsk_transform_matrix (transform, &matrix);
transform = gsk_transform_skew (transform, 0, f[0]);
}
else
{

4
gsk/gsktransform.h
View File

@@ -92,6 +92,10 @@ GskTransform * gsk_transform_translate (GskTransform
GDK_AVAILABLE_IN_ALL
GskTransform * gsk_transform_translate_3d (GskTransform *next,
const graphene_point3d_t *point) G_GNUC_WARN_UNUSED_RESULT;
GDK_AVAILABLE_IN_4_6
GskTransform * gsk_transform_skew (GskTransform *next,
float skew_x,
float skew_y) G_GNUC_WARN_UNUSED_RESULT;
GDK_AVAILABLE_IN_ALL
GskTransform * gsk_transform_rotate (GskTransform *next,
float angle) G_GNUC_WARN_UNUSED_RESULT;