Method: Vips.call

Defined in:

lib/vips8/call.rb

.call(name, *args) ⇒ Object

This is the public entry point for the vips8 binding. call will run any vips operation, for example:

out = Vips::call "black", 100, 100, :bands => 12

will call the C function

vips_black( &out, 100, 100, "bands", 12, NULL );

There are Vips::Image#method_missing hooks which will run call for you on Image for undefined instance or class methods. So you can also write:

out = Vips::Image.black 100, 100, :bands => 12

Or perhaps:

x = Vips::Image.black 100, 100
y = x.invert

to run the vips_invert() operator.

There are also a set of operator overloads and some convenience functions, see Image.

If the operator needs a vector constant, call will turn a scalar into a vector for you. So for x.linear(a, b), which calculates x * a + b where a and b are vector constants, you can write:

x = Vips::Image.black 100, 100, :bands => 3
y = x.linear(1, 2)
y = x.linear([1], 4)
y = x.linear([1, 2, 3], 4)

or any other combination. The operator overloads use this facility to support all the variations on:

x = Vips::Image.black 100, 100, :bands => 3
y = x * 2
y = x + [1,2,3]
y = x % [1]

Similarly, whereever an image is required, you can use a constant. The constant will be expanded to an image matching the first input image argument. For example, you can write:

x = Vips::Image.black 100, 100, :bands => 3
y = x.bandjoin(255)

to add an extra band to the image where each pixel in the new band has the constant value 255.

# File 'lib/vips8/call.rb', line 298

def self.call(name, *args)
    Vips::call_base name, nil, "", args
end