Struct View 

pub struct View {
    draft: Option<Draft>,
    hovered: bool,
    primary_drag_pans: bool,
    touch_pans: bool,
    camera: Camera,
    images: Rc<RefCell<ImageRegistry>>,
}

The canvas as egui shows it: the rect it is laid out in, the pointer and the gestures over it, and the in-place editor drawn into it. Where the diagram is shown from is the session’s; this reads what would move it and reports the move.

Fields

draft: Option<Draft>

The in-place editor shown last frame and what has been typed into it, so a freshly-shown editor (different id, or none previously) opens on the request’s text and grabs keyboard focus exactly once.

hovered: bool

Whether the pointer was over the canvas response (not a floating overlay) as of the last Self::begin. Lets the app suppress the tool cursor when the pointer sits over the nav bar, toolbar, or selection overlay.

primary_drag_pans: bool

Whether the primary-button drag in progress is panning the canvas (it began with the pan key held). Latched at drag start so releasing the key mid-drag can’t hand a half-finished pan to a tool.

touch_pans: bool

Whether a two-finger gesture is in progress. MultiTouchInfo vanishes the instant a finger lifts, but the finger still down keeps arriving as an ordinary drag — so the latch holds the canvas until the last one leaves, rather than handing a half-finished pan to a tool.

camera: Camera

What the last Self::begin made of the frame’s camera input, kept for the chrome drawn after the canvas pass.

images: Rc<RefCell<ImageRegistry>>

The artwork the display list may name, registered through Self::register_image as each asset’s bytes are handed off.

Implementations

impl View

pub fn register_image(&self, ctx: &Context, hash: AssetHash, asset: &Asset)

Hand an asset’s bytes to the loader under the hash the display list names it by. Idempotent, so a re-sent asset costs nothing.

pub fn canvas_hovered(&self) -> bool

Whether the pointer was over the canvas (not a floating overlay) as of the last Self::begin. The app gates the tool cursor on this so it never leaks over the nav bar, toolbar, or selection overlay.

pub fn camera(&self) -> Camera

Whether the camera is being worked, as of the last Self::begin. The selection overlay is drawn after the canvas pass and reads it there.

pub fn focused_edit_id(&self) -> Option<Id>

Id of the in-place editor rendered last frame. A fallback for surrendering editor focus when Memory::focused can’t be trusted to name it.

pub fn begin(&mut self, ui: &mut Ui) -> Canvas

Open the canvas frame: allocate the viewport and read this frame’s pan/zoom — everything that would move the camera, and nothing that paints under it. The Canvas it answers with is a value, so the frame can carry it across whatever runs between reading the pointer and painting.

pub fn show( &mut self, ui: &Ui, canvas: &Canvas, diagram: Diagram<'_>, ) -> Option<Cursor>

Paint the frame: the ground and the grid under diagram’s camera, then its display list replayed over them, clipped to the canvas — into the slot Self::begin reserved, so it lies under whatever the frame placed over the canvas in between. Answers the cursor the pointer is left with: the diagram’s own, unless the camera is being worked — an armed or in-progress pan owns the pointer.

fn handle_pan_zoom( &mut self, ui: &Ui, response: &Response, rect: Rect, moves: &mut Vec<Move>, ) -> Camera

Wheel zoom (centered on the cursor), two-finger pan/pinch, and drag pan — right/middle button, or the primary button with the pan key held — each reported as a [Move] for the session to apply.

fn handle_touch_gesture( &mut self, ui: &Ui, response: &Response, moves: &mut Vec<Move>, ) -> Option<Camera>

Two fingers pan and pinch the canvas together, about the gesture’s own center. Some means the gesture owns the frame — the primary finger also arrives as an ordinary drag, which a tool would otherwise read as a marquee or a wire.

This is the only pan a touch screen has: it has no wheel, no middle button, and no space bar to hold.

fn grid(vantage: Vantage, rect: Rect, chrome: CanvasChrome) -> Vec<Shape>

The canvas background and the grid over it, in the chrome colors the caller already resolved rather than through the palette-based recording.

pub fn capture( &mut self, ui: &mut Ui, field: Option<&EditField>, vantage: Vantage, ) -> Option<TextEvent>

The editor the last call asked for, run as egui’s own text field over the diagram: it keeps the draft, the caret and the selection, and says only how the edit ended. angle is not honoured — egui cannot rotate a TextEdit — so a vertical label is edited upright.

Trait Implementations

impl Default for View

fn default() -> Self

Returns the “default value” for a type.