Method: Magick::Pixel#alpha=

Defined in:
ext/RMagick/rmpixel.cpp

#alpha=(v) ⇒ Numeric

Set Pixel alpha value.

  • Pixel is Observable. Setters call #changed, #notify_observers

  • Setters return their argument values for backward compatibility to when Pixel was a Struct class.

Parameters:

  • v (Numeric) —

    the alpha value

Returns:

  • (Numeric) —

    the given alpha value



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# File 'ext/RMagick/rmpixel.cpp', line 195

VALUE
Pixel_alpha_eq(VALUE self, VALUE v)
{
    Pixel *pixel;

    rb_check_frozen(self);
    TypedData_Get_Struct(self, Pixel, &rm_pixel_data_type, pixel);
#if defined(IMAGEMAGICK_7)
    pixel->alpha = APP2QUANTUM(v);
    rb_funcall(self, rm_ID_changed, 0);
    rb_funcall(self, rm_ID_notify_observers, 1, self);
    return QUANTUM2NUM(pixel->alpha);
#else
    pixel->opacity = QuantumRange - APP2QUANTUM(v);
    rb_funcall(self, rm_ID_changed, 0);
    rb_funcall(self, rm_ID_notify_observers, 1, self);
    return QUANTUM2NUM(QuantumRange - pixel->opacity);
#endif
}