DarkRoom/ui/dr-ui/ui/spots.slint

import { Theme } from "theme.slint";
import { Button, PanelHeading, Caption, Value } from "widgets.slint";
import { Segmented, SliderRow } from "controls.slint";

// TRACES: FR-DEV-8
// Spot removal on the canvas: what is drawn over the photograph, and what a
// finger can take hold of.
//
// A repair is two circles and the line between them — the disc being covered,
// and the patch it is copied from. Both are drawn at the size they actually
// are, not as abstract handles, because the size *is* the edit: a photographer
// judging whether a disc covers a mark is judging a circle against a speck, and
// a fixed-size dot standing in for it would tell them nothing.
//
// Positions arrive already mapped through the framing, as fractions of the
// shown image, exactly as `GradientHandle` does — see `spots_ui.rs`. Nothing
// here knows what a crop is.

/// Which half of a repair a handle is.
export enum SpotRole {
    /// The disc over the mark. Dragging it moves the whole repair, source and
    /// all, which is what a photographer means by nudging a spot.
    destination,
    /// Where the patch is read from. Dragging it moves the source alone.
    source,
}

/// One circle of one repair, in fractions of the shown image.
export struct SpotHandle {
    id: string,
    role: SpotRole,
    /// Centre, in fractions of the shown image's width and height.
    x: float,
    y: float,
    /// The disc's radius as a fraction of the shown image's **height**.
    ///
    /// One axis rather than two, because a repair is a circle: normalising x
    /// by the width and y by the height would draw it as an ellipse on every
    /// frame that is not square. The caller resolves the aspect on the way in.
    radius: float,
    /// Whether this repair is the one the panel is describing.
    selected: bool,
    /// Whether the repair draws at all — a spot switched off is still shown,
    /// faintly, because it is still an edit somebody made.
    enabled: bool,
}

/// TRACES: FR-DEV-8
/// The column while the repair tool is up.
///
/// One repair at a time, because that is how repairs are made: a photographer
/// covers a mark, looks at it, and moves on. There is no stack here for the
/// same reason there is one for masks — a mask is a thing you come back to and
/// re-shape, and a repair is either right or deleted.
///
/// **The controls describe the selected repair, and when none is selected they
/// describe nothing.** An earlier shape had them set the defaults for the
/// *next* repair, which reads identically on screen and does something
/// completely different: a photographer dragging Size with nothing selected
/// would see no change on the photograph and conclude the slider was broken.
export component SpotPanel inherits Rectangle {
    in property <bool> enabled: true;
    /// Whether a repair is selected — everything below is about it.
    in property <bool> has-selection: false;
    /// How many repairs are on this photograph.
    in property <int> count: 0;

    /// In frame units, which is what the model stores. The slider shows them
    /// as a percentage of the frame's height, since "0.012" means nothing to
    /// anybody and "1.2%" at least says how much of the picture is covered.
    in property <float> radius: 0.012;
    in property <float> feather: 0.35;
    // `spot-opacity` and not `opacity`, which every element already has as a
    // built-in: overriding it is refused by the compiler, and had it been
    // allowed it would have faded the panel instead of describing the repair.
    in property <float> spot-opacity: 1.0;
    /// 0 heal, 1 clone — the order the chips are listed in below.
    in property <int> mode: 0;

    callback radius-changed(float);
    callback feather-changed(float);
    callback opacity-changed(float);
    callback mode-picked(int);
    callback removed();

    background: Theme.surface;

    /// TRACES: FR-UI-2
    /// How wide this panel has to be before it starts clipping itself. The
    /// develop column is the largest of these and nothing else; publishing it
    /// as `min-width` too is what makes the enclosing layout aggregate them
    /// without this panel having to be referenced by name.
    out property <length> content-width: layout.preferred-width;
    min-width: root.content-width;

    // Flat rather than nested, for the reason `MaskPanel` gives: a nested
    // conditional layout under-reported its height and drew rows on top of one
    // another.
    layout := VerticalLayout {
        padding: Theme.gap;
        spacing: Theme.gap-sm;
        alignment: start;

        HorizontalLayout {
            PanelHeading { text: "REPAIR"; }
            Rectangle { horizontal-stretch: 1; }
            if root.count > 0: Value {
                text: root.count + (root.count == 1 ? " spot" : " spots");
            }
        }

        if !root.enabled: Caption { text: "No image"; }

        // The instruction, which is the whole interface until the first click.
        // A tool whose canvas gesture is its only way in has to say so, or it
        // is a mode that appears to do nothing.
        if root.enabled && !root.has-selection: Caption {
            text: root.count == 0
                ? "Click a mark on the photograph to cover it."
                : "Click a mark to cover it, or a circle to adjust it.";
            wrap: word-wrap;
        }

        if root.enabled && root.has-selection: SliderRow {
            label: "Size";
            hint: "% of frame";
            value: root.radius * 100;
            default-value: 1.2;
            minimum: 0.1;
            maximum: 25;
            precision: 1;
            changed(v) => { root.radius-changed(v / 100); }
            reset => { root.radius-changed(0.012); }
        }

        if root.enabled && root.has-selection: SliderRow {
            label: "Feather";
            hint: "% of size";
            value: root.feather * 100;
            default-value: 35;
            minimum: 0;
            maximum: 100;
            precision: 0;
            changed(v) => { root.feather-changed(v / 100); }
            reset => { root.feather-changed(0.35); }
        }

        if root.enabled && root.has-selection: SliderRow {
            label: "Opacity";
            value: root.spot-opacity * 100;
            default-value: 100;
            minimum: 0;
            maximum: 100;
            precision: 0;
            changed(v) => { root.opacity-changed(v / 100); }
            reset => { root.opacity-changed(1.0); }
        }

        // Heal first, because it is the default and the right answer for dust.
        // Clone is the escape for a repair that straddles an edge, where
        // interpolating the boundary smears the edge across the disc.
        if root.enabled && root.has-selection: Segmented {
            label: "Blend";
            options: ["Heal", "Clone"];
            selected: root.mode;
            picked(i) => { root.mode-picked(i); }
        }

        if root.enabled && root.has-selection: Rectangle {
            height: Theme.gap-sm;
        }

        if root.enabled && root.has-selection: Button {
            text: "Delete Repair";
            clicked => { root.removed(); }
        }
    }
}

/// TRACES: FR-DEV-8
/// The repairs, drawn on the photograph.
///
/// **Drawn at the size they are.** A gradient's handles are dots because a
/// gradient has no edge to show; a repair is a disc, and whether that disc
/// covers a speck of dust is the entire judgement a photographer is making. A
/// fixed-size dot standing in for it would say nothing about the edit.
///
/// The source circle appears for the **selected** repair only. Every repair
/// showing both would double the circles on a dusty sky and leave no way to
/// tell which source belongs to which disc; Rust decides, and simply does not
/// send the others.
///
/// Sized by the develop view to the fitted image rect, so every position in
/// here is a plain fraction of `root.width` and `root.height`. The fractions
/// themselves arrive already mapped through the framing, so a repair follows a
/// crop, a zoom and a rotation rather than sitting where it used to be.
export component SpotHandles inherits Rectangle {
    in property <[SpotHandle]> handles;

    /// Touching a repair chooses it.
    callback selected(string);
    /// id, role, from-x, from-y, to-x, to-y — fractions of this rect.
    callback dragged(string, SpotRole, float, float, float, float);
    callback released();

    background: transparent;

    for spot in root.handles: Rectangle {
        property <length> disc: max(2 * spot.radius * root.height, 8px);
        property <bool> is-source: spot.role == SpotRole.source;

        x: spot.x * root.width - self.width / 2;
        y: spot.y * root.height - self.height / 2;
        // Never smaller than a finger, whatever the repair's own size: a spot
        // on a dust speck is a few pixels across at fit-to-window, and a
        // target that small cannot be picked up again on a phone (FR-UI-3).
        // The *drawn* circle keeps its true size; only the reach is padded.
        width: max(self.disc, Theme.touch-target);
        height: self.width;

        Rectangle {
            width: parent.disc;
            height: self.width;
            x: (parent.width - self.width) / 2;
            y: (parent.height - self.height) / 2;
            border-radius: self.width / 2;
            border-width: spot.selected ? 2px : 1px;
            // White on a dark ring, so a repair is visible on a blown sky and
            // on a black frame alike — the same treatment the gradient handles
            // use, and no theme token, because this is drawn over the
            // photograph rather than over the interface.
            border-color: spot.enabled ? #ffffffcc : #ffffff55;
            background: parent.is-source
                ? #ffffff14
                : (spot.selected ? #ffffff22 : transparent);
        }

        // A second, darker ring just outside the first. One white circle
        // vanishes against a white sky however it is drawn; two rings of
        // opposite tone cannot both vanish against anything.
        Rectangle {
            width: parent.disc + 2px;
            height: self.width;
            x: (parent.width - self.width) / 2;
            y: (parent.height - self.height) / 2;
            border-radius: self.width / 2;
            border-width: 1px;
            border-color: #00000066;
        }

        grab := TouchArea {
            width: 100%;
            height: 100%;
            mouse-cursor: MouseCursor.move;

            // Where the press landed, in the fractions the callback reports
            // in — captured on the way down so the gesture is measured from
            // one origin.
            property <float> from-x;
            property <float> from-y;

            function fraction-x(local-x: length) -> float {
                return (parent.x + local-x) / max(root.width, 1px);
            }
            function fraction-y(local-y: length) -> float {
                return (parent.y + local-y) / max(root.height, 1px);
            }

            pointer-event(ev) => {
                if (ev.kind == PointerEventKind.down) {
                    self.from-x = self.fraction-x(self.pressed-x);
                    self.from-y = self.fraction-y(self.pressed-y);
                    // Touching a repair is choosing it. On the way *down*, so
                    // the column has re-scoped by the time the drag begins and
                    // the controls describe what is moving.
                    root.selected(spot.id);
                }
                if (ev.kind == PointerEventKind.up) {
                    root.released();
                }
            }

            moved => {
                if (self.pressed) {
                    root.dragged(
                        spot.id,
                        spot.role,
                        self.from-x,
                        self.from-y,
                        self.fraction-x(self.mouse-x),
                        self.fraction-y(self.mouse-y),
                    );
                }
            }
        }
    }
}