use crate::ActorMeta;
use glib::{object as gobject, object::IsA, translate::*};
use std::fmt;

glib_wrapper! {
    pub struct Effect(Object<ffi::ClutterEffect, ffi::ClutterEffectClass, EffectClass>) @extends ActorMeta, gobject::InitiallyUnowned;

    match fn {
        get_type => || ffi::clutter_effect_get_type(),
    }
}

pub const NONE_EFFECT: Option<&Effect> = None;

/// Trait containing all `Effect` methods.
///
/// # Implementors
///
/// [`Effect`](struct.Effect.html), [`OffscreenEffect`](struct.OffscreenEffect.html)
pub trait EffectExt: 'static {
    /// Queues a repaint of the effect. The effect can detect when the ‘paint’
    /// method is called as a result of this function because it will not
    /// have the `EffectPaintFlags::ActorDirty` flag set. In that case the
    /// effect is free to assume that the actor has not changed its
    /// appearance since the last time it was painted so it doesn't need to
    /// call `ActorExt::continue_paint` if it can draw a cached
    /// image. This is mostly intended for effects that are using a
    /// `cogl::Offscreen` to redirect the actor (such as
    /// `OffscreenEffect`). In that case the effect can save a bit of
    /// rendering time by painting the cached texture without causing the
    /// entire actor to be painted.
    ///
    /// This function can be used by effects that have their own animatable
    /// parameters. For example, an effect which adds a varying degree of a
    /// red tint to an actor by redirecting it through a CoglOffscreen
    /// might have a property to specify the level of tint. When this value
    /// changes, the underlying actor doesn't need to be redrawn so the
    /// effect can call `EffectExt::queue_repaint` to make sure the
    /// effect is repainted.
    ///
    /// Note however that modifying the position of the parent of an actor
    /// may change the appearance of the actor because its transformation
    /// matrix would change. In this case a redraw wouldn't be queued on
    /// the actor itself so the `EffectPaintFlags::ActorDirty` would still
    /// not be set. The effect can detect this case by keeping track of the
    /// last modelview matrix that was used to render the actor and
    /// veryifying that it remains the same in the next paint.
    ///
    /// Any other effects that are layered on top of the passed in effect
    /// will still be passed the `EffectPaintFlags::ActorDirty` flag. If
    /// anything queues a redraw on the actor without specifying an effect
    /// or with an effect that is lower in the chain of effects than this
    /// one then that will override this call. In that case this effect
    /// will instead be called with the `EffectPaintFlags::ActorDirty`
    /// flag set.
    fn queue_repaint(&self);
}

impl<O: IsA<Effect>> EffectExt for O {
    fn queue_repaint(&self) {
        unsafe {
            ffi::clutter_effect_queue_repaint(self.as_ref().to_glib_none().0);
        }
    }
}

impl fmt::Display for Effect {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "Effect")
    }
}
