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// Copyright 2020 The xi-editor Authors. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. //! The context types that are passed into various widget methods. use std::{ any::{Any, TypeId}, ops::{Deref, DerefMut}, time::Duration, }; use crate::core::{CommandQueue, FocusChange, WidgetState}; use crate::piet::Piet; use crate::piet::RenderContext; use crate::{ commands, Affine, Command, ContextMenu, Cursor, Insets, MenuDesc, Point, Rect, SingleUse, Size, Target, Text, TimerToken, Vec2, WidgetId, WindowDesc, WindowHandle, WindowId, }; /// A macro for implementing methods on multiple contexts. /// /// There are a lot of methods defined on multiple contexts; this lets us only /// have to write them out once. macro_rules! impl_context_method { ($ty:ty, { $($method:item)+ } ) => { impl $ty { $($method)+ } }; ( $ty:ty, $($more:ty),+, { $($method:item)+ } ) => { impl_context_method!($ty, { $($method)+ }); impl_context_method!($($more),+, { $($method)+ }); }; } /// Static state that is shared between most contexts. pub(crate) struct ContextState<'a> { pub(crate) command_queue: &'a mut CommandQueue, pub(crate) window_id: WindowId, pub(crate) window: &'a WindowHandle, /// The id of the widget that currently has focus. pub(crate) focus_widget: Option<WidgetId>, pub(crate) root_app_data_type: TypeId, } /// A mutable context provided to event handling methods of widgets. /// /// Widgets should call [`request_paint`] whenever an event causes a change /// in the widget's appearance, to schedule a repaint. /// /// [`request_paint`]: #method.request_paint pub struct EventCtx<'a, 'b> { pub(crate) state: &'a mut ContextState<'b>, pub(crate) widget_state: &'a mut WidgetState, pub(crate) cursor: &'a mut Option<Cursor>, pub(crate) is_handled: bool, pub(crate) is_root: bool, } /// A mutable context provided to the [`lifecycle`] method on widgets. /// /// Certain methods on this context are only meaningful during the handling of /// specific lifecycle events; for instance [`register_child`] /// should only be called while handling [`LifeCycle::WidgetAdded`]. /// /// [`lifecycle`]: trait.Widget.html#tymethod.lifecycle /// [`register_child`]: #method.register_child /// [`LifeCycle::WidgetAdded`]: enum.LifeCycle.html#variant.WidgetAdded pub struct LifeCycleCtx<'a, 'b> { pub(crate) widget_state: &'a mut WidgetState, pub(crate) state: &'a mut ContextState<'b>, } /// A mutable context provided to data update methods of widgets. /// /// Widgets should call [`request_paint`] whenever a data change causes a change /// in the widget's appearance, to schedule a repaint. /// /// [`request_paint`]: #method.request_paint pub struct UpdateCtx<'a, 'b> { pub(crate) state: &'a mut ContextState<'b>, pub(crate) widget_state: &'a mut WidgetState, } /// A context provided to layout handling methods of widgets. /// /// As of now, the main service provided is access to a factory for /// creating text layout objects, which are likely to be useful /// during widget layout. pub struct LayoutCtx<'a, 'b> { pub(crate) state: &'a mut ContextState<'b>, pub(crate) widget_state: &'a mut WidgetState, pub(crate) mouse_pos: Option<Point>, } /// Z-order paint operations with transformations. pub(crate) struct ZOrderPaintOp { pub z_index: u32, pub paint_func: Box<dyn FnOnce(&mut PaintCtx) + 'static>, pub transform: Affine, } /// A context passed to paint methods of widgets. /// /// Widgets paint their appearance by calling methods on the /// `render_ctx`, which PaintCtx derefs to for convenience. /// This struct is expected to grow, for example to include the /// "damage region" indicating that only a subset of the entire /// widget hierarchy needs repainting. pub struct PaintCtx<'a, 'b, 'c> { pub(crate) state: &'a mut ContextState<'b>, pub(crate) widget_state: &'a WidgetState, /// The render context for actually painting. pub render_ctx: &'a mut Piet<'c>, /// The z-order paint operations. pub(crate) z_ops: Vec<ZOrderPaintOp>, /// The currently visible region. pub(crate) region: Region, /// The approximate depth in the tree at the time of painting. pub(crate) depth: u32, } /// A region of a widget, generally used to describe what needs to be drawn. /// /// This is currently just a single `Rect`, but may become more complicated in the future. Although /// this is just a wrapper around `Rect`, it has some different conventions. Mainly, "signed" /// invalidation regions don't make sense. Therefore, a rectangle with non-positive width or height /// is considered "empty", and all empty rectangles are treated the same. #[derive(Debug, Clone)] pub struct Region(Rect); // methods on everyone impl_context_method!( EventCtx<'_, '_>, UpdateCtx<'_, '_>, LifeCycleCtx<'_, '_>, PaintCtx<'_, '_, '_>, LayoutCtx<'_, '_>, { /// get the `WidgetId` of the current widget. pub fn widget_id(&self) -> WidgetId { self.widget_state.id } /// Returns a reference to the current `WindowHandle`. pub fn window(&self) -> &WindowHandle { &self.state.window } /// Get the `WindowId` of the current window. pub fn window_id(&self) -> WindowId { self.state.window_id } /// Get an object which can create text layouts. pub fn text(&self) -> Text { self.state.window.text() } } ); // methods on everyone but layoutctx impl_context_method!( EventCtx<'_, '_>, UpdateCtx<'_, '_>, LifeCycleCtx<'_, '_>, PaintCtx<'_, '_, '_>, { /// The layout size. /// /// This is the layout size as ultimately determined by the parent /// container, on the previous layout pass. /// /// Generally it will be the same as the size returned by the child widget's /// [`layout`] method. /// /// [`layout`]: trait.Widget.html#tymethod.layout pub fn size(&self) -> Size { self.widget_state.size() } /// The "hot" (aka hover) status of a widget. /// /// A widget is "hot" when the mouse is hovered over it. Widgets will /// often change their appearance as a visual indication that they /// will respond to mouse interaction. /// /// The hot status is computed from the widget's layout rect. In a /// container hierarchy, all widgets with layout rects containing the /// mouse position have hot status. /// /// Discussion: there is currently some confusion about whether a /// widget can be considered hot when some other widget is active (for /// example, when clicking to one widget and dragging to the next). /// The documentation should clearly state the resolution. pub fn is_hot(&self) -> bool { self.widget_state.is_hot } /// The active status of a widget. /// /// Active status generally corresponds to a mouse button down. Widgets /// with behavior similar to a button will call [`set_active`] on mouse /// down and then up. /// /// When a widget is active, it gets mouse events even when the mouse /// is dragged away. /// /// [`set_active`]: struct.EventCtx.html#method.set_active pub fn is_active(&self) -> bool { self.widget_state.is_active } /// The focus status of a widget. /// /// Returns `true` if this specific widget is focused. /// To check if any descendants are focused use [`has_focus`]. /// /// Focus means that the widget receives keyboard events. /// /// A widget can request focus using the [`request_focus`] method. /// It's also possible to register for automatic focus via [`register_for_focus`]. /// /// If a widget gains or loses focus it will get a [`LifeCycle::FocusChanged`] event. /// /// Only one widget at a time is focused. However due to the way events are routed, /// all ancestors of that widget will also receive keyboard events. /// /// [`request_focus`]: struct.EventCtx.html#method.request_focus /// [`register_for_focus`]: struct.LifeCycleCtx.html#method.register_for_focus /// [`LifeCycle::FocusChanged`]: enum.LifeCycle.html#variant.FocusChanged /// [`has_focus`]: #method.has_focus pub fn is_focused(&self) -> bool { self.state.focus_widget == Some(self.widget_id()) } /// The (tree) focus status of a widget. /// /// Returns `true` if either this specific widget or any one of its descendants is focused. /// To check if only this specific widget is focused use [`is_focused`], /// /// [`is_focused`]: #method.is_focused pub fn has_focus(&self) -> bool { self.widget_state.has_focus } } ); // methods on event, update, and lifecycle impl_context_method!(EventCtx<'_, '_>, UpdateCtx<'_, '_>, LifeCycleCtx<'_, '_>, { #[deprecated(since = "0.5.0", note = "use request_paint instead")] pub fn invalidate(&mut self) { self.request_paint(); } /// Request a [`paint`] pass. This is equivalent to calling /// [`request_paint_rect`] for the widget's [`paint_rect`]. /// /// [`paint`]: trait.Widget.html#tymethod.paint /// [`request_paint_rect`]: #method.request_paint_rect /// [`paint_rect`]: struct.WidgetPod.html#method.paint_rect pub fn request_paint(&mut self) { self.request_paint_rect( self.widget_state.paint_rect() - self.widget_state.layout_rect().origin().to_vec2(), ); } /// Request a [`paint`] pass for redrawing a rectangle, which is given /// relative to our layout rectangle. /// /// [`paint`]: trait.Widget.html#tymethod.paint pub fn request_paint_rect(&mut self, rect: Rect) { self.widget_state.invalid.add_rect(rect); } /// Request a layout pass. /// /// A Widget's [`layout`] method is always called when the widget tree /// changes, or the window is resized. /// /// If your widget would like to have layout called at any other time, /// (such as if it would like to change the layout of children in /// response to some event) it must call this method. /// /// [`layout`]: trait.Widget.html#tymethod.layout pub fn request_layout(&mut self) { self.widget_state.needs_layout = true; } /// Request an animation frame. pub fn request_anim_frame(&mut self) { self.widget_state.request_anim = true; self.request_paint(); } /// Request a timer event. /// /// The return value is a token, which can be used to associate the /// request with the event. pub fn request_timer(&mut self, deadline: Duration) -> TimerToken { self.state.request_timer(&mut self.widget_state, deadline) } /// Indicate that your children have changed. /// /// Widgets must call this method after adding a new child. pub fn children_changed(&mut self) { self.widget_state.children_changed = true; self.request_layout(); } /// Submit a [`Command`] to be run after this event is handled. /// /// Commands are run in the order they are submitted; all commands /// submitted during the handling of an event are executed before /// the [`update`] method is called; events submitted during [`update`] /// are handled after painting. /// /// [`Command`]: struct.Command.html /// [`update`]: trait.Widget.html#tymethod.update pub fn submit_command(&mut self, cmd: impl Into<Command>, target: impl Into<Option<Target>>) { self.state.submit_command(cmd.into(), target.into()) } /// Set the menu of the window containing the current widget. /// `T` must be the application's root `Data` type (the type provided to [`AppLauncher::launch`]). /// /// [`AppLauncher::launch`]: struct.AppLauncher.html#method.launch pub fn set_menu<T: Any>(&mut self, menu: MenuDesc<T>) { self.state.set_menu(menu); } }); impl EventCtx<'_, '_> { /// Set the cursor icon. /// /// Call this when handling a mouse move event, to set the cursor for the /// widget. A container widget can safely call this method, then recurse /// to its children, as a sequence of calls within an event propagation /// only has the effect of the last one (ie no need to worry about /// flashing). /// /// This method is expected to be called mostly from the [`MouseMove`] /// event handler, but can also be called in response to other events, /// for example pressing a key to change the behavior of a widget. /// /// [`MouseMove`]: enum.Event.html#variant.MouseMove pub fn set_cursor(&mut self, cursor: &Cursor) { *self.cursor = Some(cursor.clone()); } /// Set the "active" state of the widget. /// /// See [`EventCtx::is_active`](struct.EventCtx.html#method.is_active). pub fn set_active(&mut self, active: bool) { self.widget_state.is_active = active; // TODO: plumb mouse grab through to platform (through druid-shell) } /// Create a new window. /// `T` must be the application's root `Data` type (the type provided to [`AppLauncher::launch`]). /// /// [`AppLauncher::launch`]: struct.AppLauncher.html#method.launch pub fn new_window<T: Any>(&mut self, desc: WindowDesc<T>) { if self.state.root_app_data_type == TypeId::of::<T>() { self.submit_command( Command::new(commands::NEW_WINDOW, SingleUse::new(Box::new(desc))), Target::Global, ); } else { const MSG: &str = "WindowDesc<T> - T must match the application data type."; if cfg!(debug_assertions) { panic!(MSG); } else { log::error!("EventCtx::new_window: {}", MSG) } } } /// Show the context menu in the window containing the current widget. /// `T` must be the application's root `Data` type (the type provided to [`AppLauncher::launch`]). /// /// [`AppLauncher::launch`]: struct.AppLauncher.html#method.launch pub fn show_context_menu<T: Any>(&mut self, menu: ContextMenu<T>) { if self.state.root_app_data_type == TypeId::of::<T>() { self.submit_command( Command::new(commands::SHOW_CONTEXT_MENU, Box::new(menu)), Target::Window(self.state.window_id), ); } else { const MSG: &str = "ContextMenu<T> - T must match the application data type."; if cfg!(debug_assertions) { panic!(MSG); } else { log::error!("EventCtx::show_context_menu: {}", MSG) } } } /// Set the event as "handled", which stops its propagation to other /// widgets. pub fn set_handled(&mut self) { self.is_handled = true; } /// Determine whether the event has been handled by some other widget. pub fn is_handled(&self) -> bool { self.is_handled } /// Request keyboard focus. /// /// Because only one widget can be focused at a time, multiple focus requests /// from different widgets during a single event cycle means that the last /// widget that requests focus will override the previous requests. /// /// See [`is_focused`] for more information about focus. /// /// [`is_focused`]: struct.EventCtx.html#method.is_focused pub fn request_focus(&mut self) { // We need to send the request even if we're currently focused, // because we may have a sibling widget that already requested focus // and we have no way of knowing that yet. We need to override that // to deliver on the "last focus request wins" promise. let id = self.widget_id(); self.widget_state.request_focus = Some(FocusChange::Focus(id)); } /// Transfer focus to the next focusable widget. /// /// This should only be called by a widget that currently has focus. /// /// See [`is_focused`] for more information about focus. /// /// [`is_focused`]: struct.EventCtx.html#method.is_focused pub fn focus_next(&mut self) { if self.is_focused() { self.widget_state.request_focus = Some(FocusChange::Next); } else { log::warn!("focus_next can only be called by the currently focused widget"); } } /// Transfer focus to the previous focusable widget. /// /// This should only be called by a widget that currently has focus. /// /// See [`is_focused`] for more information about focus. /// /// [`is_focused`]: struct.EventCtx.html#method.is_focused pub fn focus_prev(&mut self) { if self.is_focused() { self.widget_state.request_focus = Some(FocusChange::Previous); } else { log::warn!("focus_prev can only be called by the currently focused widget"); } } /// Give up focus. /// /// This should only be called by a widget that currently has focus. /// /// See [`is_focused`] for more information about focus. /// /// [`is_focused`]: struct.EventCtx.html#method.is_focused pub fn resign_focus(&mut self) { if self.is_focused() { self.widget_state.request_focus = Some(FocusChange::Resign); } else { log::warn!( "resign_focus can only be called by the currently focused widget ({:?})", self.widget_id() ); } } } impl LifeCycleCtx<'_, '_> { /// Registers a child widget. /// /// This should only be called in response to a `LifeCycle::WidgetAdded` event. /// /// In general, you should not need to call this method; it is handled by /// the `WidgetPod`. pub fn register_child(&mut self, child_id: WidgetId) { self.widget_state.children.add(&child_id); } /// Register this widget to be eligile to accept focus automatically. /// /// This should only be called in response to a [`LifeCycle::WidgetAdded`] event. /// /// See [`EventCtx::is_focused`] for more information about focus. /// /// [`LifeCycle::WidgetAdded`]: enum.Lifecycle.html#variant.WidgetAdded /// [`EventCtx::is_focused`]: struct.EventCtx.html#method.is_focused pub fn register_for_focus(&mut self) { self.widget_state.focus_chain.push(self.widget_id()); } } impl LayoutCtx<'_, '_> { /// Set explicit paint [`Insets`] for this widget. /// /// You are not required to set explicit paint bounds unless you need /// to paint outside of your layout bounds. In this case, the argument /// should be an [`Insets`] struct that indicates where your widget /// needs to overpaint, relative to its bounds. /// /// For more information, see [`WidgetPod::paint_insets`]. /// /// [`Insets`]: struct.Insets.html /// [`WidgetPod::paint_insets`]: struct.WidgetPod.html#method.paint_insets pub fn set_paint_insets(&mut self, insets: impl Into<Insets>) { self.widget_state.paint_insets = insets.into().nonnegative(); } } impl PaintCtx<'_, '_, '_> { /// The depth in the tree of the currently painting widget. /// /// This may be used in combination with [`paint_with_z_index`] in order /// to correctly order painting operations. /// /// The `depth` here may not be exact; it is only guaranteed that a child will /// have a greater depth than its parent. /// /// [`paint_with_z_index`]: #method.paint_with_z_index #[inline] pub fn depth(&self) -> u32 { self.depth } /// Returns the currently visible [`Region`]. /// /// [`Region`]: struct.Region.html #[inline] pub fn region(&self) -> &Region { &self.region } /// Creates a temporary `PaintCtx` with a new visible region, and calls /// the provided function with that `PaintCtx`. /// /// This is used by containers to ensure that their children have the correct /// visible region given their layout. pub fn with_child_ctx(&mut self, region: impl Into<Region>, f: impl FnOnce(&mut PaintCtx)) { let mut child_ctx = PaintCtx { render_ctx: self.render_ctx, state: self.state, widget_state: self.widget_state, z_ops: Vec::new(), region: region.into(), depth: self.depth + 1, }; f(&mut child_ctx); self.z_ops.append(&mut child_ctx.z_ops); } /// Saves the current context, executes the closures, and restores the context. /// /// This is useful if you would like to transform or clip or otherwise /// modify the drawing context but do not want that modification to /// effect other widgets. /// /// # Examples /// /// ``` /// # use druid::{Env, PaintCtx, RenderContext, theme}; /// # struct T; /// # impl T { /// fn paint(&mut self, ctx: &mut PaintCtx, _data: &T, env: &Env) { /// let clip_rect = ctx.size().to_rect().inset(5.0); /// ctx.with_save(|ctx| { /// ctx.clip(clip_rect); /// ctx.stroke(clip_rect, &env.get(theme::PRIMARY_DARK), 5.0); /// }); /// } /// # } /// ``` pub fn with_save(&mut self, f: impl FnOnce(&mut PaintCtx)) { if let Err(e) = self.render_ctx.save() { log::error!("Failed to save RenderContext: '{}'", e); return; } f(self); if let Err(e) = self.render_ctx.restore() { log::error!("Failed to restore RenderContext: '{}'", e); } } /// Allows to specify order for paint operations. /// /// Larger `z_index` indicate that an operation will be executed later. pub fn paint_with_z_index( &mut self, z_index: u32, paint_func: impl FnOnce(&mut PaintCtx) + 'static, ) { let current_transform = self.render_ctx.current_transform(); self.z_ops.push(ZOrderPaintOp { z_index, paint_func: Box::new(paint_func), transform: current_transform, }) } } impl<'a> ContextState<'a> { pub(crate) fn new<T: 'static>( command_queue: &'a mut CommandQueue, window: &'a WindowHandle, window_id: WindowId, focus_widget: Option<WidgetId>, ) -> Self { ContextState { command_queue, window, window_id, focus_widget, root_app_data_type: TypeId::of::<T>(), } } fn submit_command(&mut self, command: Command, target: Option<Target>) { let target = target.unwrap_or_else(|| self.window_id.into()); self.command_queue.push_back((target, command)) } fn set_menu<T: Any>(&mut self, menu: MenuDesc<T>) { if self.root_app_data_type == TypeId::of::<T>() { self.submit_command( Command::new(commands::SET_MENU, Box::new(menu)), Some(Target::Window(self.window_id)), ); } else { const MSG: &str = "MenuDesc<T> - T must match the application data type."; if cfg!(debug_assertions) { panic!(MSG); } else { log::error!("EventCtx::set_menu: {}", MSG) } } } fn request_timer(&self, widget_state: &mut WidgetState, deadline: Duration) -> TimerToken { let timer_token = self.window.request_timer(deadline); widget_state.add_timer(timer_token); timer_token } } impl Region { /// An empty region. pub const EMPTY: Region = Region(Rect::ZERO); /// Returns the smallest `Rect` that encloses the entire region. pub fn to_rect(&self) -> Rect { self.0 } /// Returns `true` if `self` intersects with `other`. #[inline] pub fn intersects(&self, other: Rect) -> bool { self.0.intersect(other).area() > 0. } /// Returns `true` if this region is empty. pub fn is_empty(&self) -> bool { self.0.width() <= 0.0 || self.0.height() <= 0.0 } /// Adds a new `Rect` to this region. /// /// This differs from `Rect::union` in its treatment of empty rectangles: an empty rectangle has /// no effect on the union. pub(crate) fn add_rect(&mut self, rect: Rect) { if self.is_empty() { self.0 = rect; } else if rect.width() > 0.0 && rect.height() > 0.0 { self.0 = self.0.union(rect); } } /// Modifies this region by including everything in the other region. pub(crate) fn merge_with(&mut self, other: Region) { self.add_rect(other.0); } /// Modifies this region by intersecting it with the given rectangle. pub(crate) fn intersect_with(&mut self, rect: Rect) { self.0 = self.0.intersect(rect); } } impl std::ops::AddAssign<Vec2> for Region { fn add_assign(&mut self, offset: Vec2) { self.0 = self.0 + offset; } } impl std::ops::SubAssign<Vec2> for Region { fn sub_assign(&mut self, offset: Vec2) { self.0 = self.0 - offset; } } impl From<Rect> for Region { fn from(src: Rect) -> Region { // We maintain the invariant that the width/height of the rect are non-negative. Region(src.abs()) } } impl<'c> Deref for PaintCtx<'_, '_, 'c> { type Target = Piet<'c>; fn deref(&self) -> &Self::Target { self.render_ctx } } impl<'c> DerefMut for PaintCtx<'_, '_, 'c> { fn deref_mut(&mut self) -> &mut Self::Target { self.render_ctx } }