Add PHP API for registering custom gradient presents #17774
Description
As originally discussed in #17169 (comment) and with work continue #17603 .
In #17169 gradient presents were added to buttons. This function similar to the present colors already found in gutenberg. The present colours allow for register of list of colours in PHP using theme supports. Example.
add_theme_support( 'editor-color-palette',
array(
array(
'name' => __( 'Primary', 'twentynineteen' ),
'slug' => 'primary',
'color' => twentynineteen_hsl_hex( 'default' === get_theme_mod( 'primary_color' ) ? 199 : get_theme_mod( 'primary_color_hue', 199 ), 100, 33 ),
),
array(
'name' => __( 'Secondary', 'twentynineteen' ),
'slug' => 'secondary',
'color' => twentynineteen_hsl_hex( 'default' === get_theme_mod( 'primary_color' ) ? 199 : get_theme_mod( 'primary_color_hue', 199 ), 100, 23 ),
),
array(
'name' => __( 'Dark Gray', 'twentynineteen' ),
'slug' => 'dark-gray',
'color' => '#111',
),
array(
'name' => __( 'Light Gray', 'twentynineteen' ),
'slug' => 'light-gray',
'color' => '#767676',
),
array(
'name' => __( 'White', 'twentynineteen' ),
'slug' => 'white',
'color' => '#FFF',
),
)
);
A similar api should be added for gradient presents. I would recommend the name editor-gradient-presets.