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// Copyright © SixtyFPS GmbH <info@sixtyfps.io>
// SPDX-License-Identifier: (GPL-3.0-only OR LicenseRef-SixtyFPS-commercial)
#![warn(missing_docs)]
//! module for rendering the tree of items
use super::graphics::RenderingCache;
use super::items::*;
use crate::component::ComponentRc;
use crate::graphics::Rect;
use crate::item_tree::ItemVisitorResult;
use core::cell::{Cell, RefCell};
use core::pin::Pin;
/// This structure must be present in items that are Rendered and contains information.
/// Used by the backend.
#[derive(Default, Debug)]
#[repr(C)]
pub struct CachedRenderingData {
/// Used and modified by the backend, should be initialized to 0 by the user code
pub(crate) cache_index: Cell<usize>,
/// Used and modified by the backend, should be initialized to 0 by the user code.
/// The backend compares this generation against the one of the cache to verify
/// the validity of the cache_index field.
pub(crate) cache_generation: Cell<usize>,
}
impl CachedRenderingData {
/// This function allows retrieving the backend specific per-item data cache, updating
/// it if depending properties have changed. The supplied update_fn will be called when
/// properties have changed or the cache is initialized the first time.
pub fn get_or_update<T: Clone>(
&self,
cache: &RefCell<RenderingCache<T>>,
update_fn: impl FnOnce() -> T,
) -> T {
if self.cache_generation.get() == cache.borrow().generation()
&& cache.borrow().contains(self.cache_index.get())
{
let index = self.cache_index.get();
let tracker = cache.borrow_mut().get_mut(index).unwrap().dependency_tracker.take();
let maybe_new_data =
tracker.as_ref().and_then(|tracker| tracker.as_ref().evaluate_if_dirty(update_fn));
let mut cache = cache.borrow_mut();
let cache_entry = cache.get_mut(index).unwrap();
cache_entry.dependency_tracker = tracker;
if let Some(new_data) = maybe_new_data {
cache_entry.data = new_data
}
return cache_entry.data.clone();
}
let cache_entry = crate::graphics::CachedGraphicsData::new(update_fn);
self.cache_index.set(cache.borrow_mut().insert(cache_entry));
self.cache_generation.set(cache.borrow().generation());
cache.borrow().get(self.cache_index.get()).unwrap().data.clone()
}
/// This function can be used to remove an entry from the rendering cache for a given item, if it
/// exists, i.e. if any data was ever cached. This is typically called by the graphics backend's
/// implementation of the release_item_graphics_cache function.
pub fn release<T>(&self, cache: &mut RenderingCache<T>) -> Option<T> {
if self.cache_generation.get() == cache.generation() {
let index = self.cache_index.get();
self.cache_generation.set(0);
Some(cache.remove(index).data)
} else {
None
}
}
}
/// Return true if the item might be a clipping item
pub(crate) fn is_clipping_item(item: Pin<ItemRef>) -> bool {
//(FIXME: there should be some flag in the vtable instead of downcasting)
ItemRef::downcast_pin::<Flickable>(item).is_some()
|| ItemRef::downcast_pin::<Clip>(item).is_some()
}
/// Renders the tree of items that component holds, using the specified renderer. Rendering is done
/// relative to the specified origin.
pub fn render_component_items(
component: &ComponentRc,
renderer: &mut dyn ItemRenderer,
origin: crate::graphics::Point,
) {
renderer.save_state();
renderer.translate(origin.x, origin.y);
let renderer = RefCell::new(renderer);
crate::item_tree::visit_items_with_post_visit(
component,
crate::item_tree::TraversalOrder::BackToFront,
|_, item, _, _| {
renderer.borrow_mut().save_state();
let item_geometry = item.as_ref().geometry();
let item_origin = item_geometry.origin;
// Don't render items that are clipped, with the exception of the Clip or Flickable since
// they themselves clip their content.
if !renderer.borrow().get_current_clip().intersects(&item_geometry)
&& !is_clipping_item(item)
// HACK, the geometry of the box shadow does not include the shadow, because when the shadow is the root for repeated elements it would translate the children
&& ItemRef::downcast_pin::<BoxShadow>(item).is_none()
{
renderer.borrow_mut().translate(item_origin.x, item_origin.y);
return (ItemVisitorResult::Continue(()), ());
}
renderer.borrow_mut().translate(item_origin.x, item_origin.y);
item.as_ref().render(&mut (*renderer.borrow_mut() as &mut dyn ItemRenderer));
(ItemVisitorResult::Continue(()), ())
},
|_, _, _, r| {
renderer.borrow_mut().restore_state();
r
},
(),
);
let renderer = renderer.into_inner();
renderer.restore_state();
}
/// Trait used to render each items.
///
/// The item needs to be rendered relative to its (x,y) position. For example,
/// draw_rectangle should draw a rectangle in `(pos.x + rect.x, pos.y + rect.y)`
#[allow(missing_docs)]
pub trait ItemRenderer {
fn draw_rectangle(&mut self, rect: Pin<&Rectangle>);
fn draw_border_rectangle(&mut self, rect: Pin<&BorderRectangle>);
fn draw_image(&mut self, image: Pin<&ImageItem>);
fn draw_clipped_image(&mut self, image: Pin<&ClippedImage>);
fn draw_text(&mut self, text: Pin<&Text>);
fn draw_text_input(&mut self, text_input: Pin<&TextInput>);
#[cfg(feature = "std")]
fn draw_path(&mut self, path: Pin<&Path>);
fn draw_box_shadow(&mut self, box_shadow: Pin<&BoxShadow>);
/// Clip the further call until restore_state.
/// radius/border_width can be used for border rectangle clip.
/// (FIXME: consider removing radius/border_width and have another function that take a path instead)
fn combine_clip(&mut self, rect: Rect, radius: f32, border_width: f32);
/// Get the current clip bounding box in the current transformed coordinate.
fn get_current_clip(&self) -> Rect;
fn translate(&mut self, x: f32, y: f32);
fn rotate(&mut self, angle_in_degrees: f32);
/// Apply the opacity (between 0 and 1) for all following items until the next call to restore_state.
fn apply_opacity(&mut self, opacity: f32);
fn save_state(&mut self);
fn restore_state(&mut self);
/// Returns the scale factor
fn scale_factor(&self) -> f32;
/// Draw a pixmap in position indicated by the `pos`.
/// The pixmap will be taken from cache if the cache is valid, otherwise, update_fn will be called
/// with a callback that need to be called once with `fn (width, height, data)` where data are the
/// RGBA premultiplied pixel values
fn draw_cached_pixmap(
&mut self,
item_cache: &CachedRenderingData,
update_fn: &dyn Fn(&mut dyn FnMut(u32, u32, &[u8])),
);
// Draw the given string with the specified color at current (0, 0) with the default font. Mainly
// used by the performance counter overlay.
fn draw_string(&mut self, string: &str, color: crate::Color);
fn window(&self) -> crate::window::WindowRc;
/// Return the internal renderer
fn as_any(&mut self) -> &mut dyn core::any::Any;
}