Enum extendr_api::graphics::device_driver::ClippingStrategy

pub enum ClippingStrategy {
    Device,
    DeviceAndEngine,
    Engine,
}

The underlying C structure DevDesc has two fields related to clipping:

• canClip
• deviceClip (available on R >= 4.1)

canClip indicates whether the device has clipping functionality at all. If not, the graphic engine kindly clips before sending the drawing operations to the device. But, this isn’t very ideal in some points. Especially, it’s bad that the engine will omit “any text that does not appear to be wholly inside the clipping region,” according to the R Internals. So, the device should implement clip() and set canClip to true if possible.

Even when canClip is true, the engine does clip to protect the device from large values by default. But, for efficiency, the device can take all the responsibility of clipping. That is deviceClip, which was introduced in R 4.1. If this is set to true, the engine will perform no clipping at all. For more details, please refer to [the offical announcement blog post].

So, in short, a graphic device can choose either of the following:

• clipping without the help of the graphic engine (Device)
• clipping with the help of the graphic engine (DeviceAndEngine)
• no clipping at all (Engine)

Variants

Device

DeviceAndEngine

Engine