DarkRoom/ui/dr-ui/ui/peaking.slint

// TRACES: FR-CULL-3
// The focus-peaking switch, and the two choices it exposes.
//
// **An instrument, not an operation**, exactly as the histogram above it is:
// it has no parameters in the edit graph, changes nothing about the
// photograph, and answers a question rather than asking one. So it is written
// by hand rather than generated from a descriptor, and FR-DEV-3a is untroubled
// by it — nothing here names an operation or reads a parameter out of one.
//
// **Both choices are words, not swatches.** The colour picker is the obvious
// place to draw four coloured squares, and NFR-A11Y-3 is the reason not to:
// a control for choosing between hues, presented only as hues, is unusable by
// the person most likely to need to change it. The chips say "Red" and "Cyan".
//
// **Why the two chip rows only exist while peaking is on.** They are settings
// for something that is not happening, and the develop column is the
// photographer's instrument panel — every row it holds is a slider pushed
// below the fold. The panel's own height is bound to its content, so the
// column reflows rather than leaving a gap.

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

// TRACES: FR-CULL-3
// The marks themselves, composited over the canvas.
//
// **A layer over the photograph and not a tint in it**, which is the same rule
// `app.slint` states on the region map: a diagnostic "must not reach the
// histogram, an export, or the texture the develop pass hands the compositor".
// `HistogramPass` counts whatever the develop pass last rendered, so marks
// painted into that frame would arrive in the histogram as a spike and in the
// clipping figure as blown highlights. The layer is transparent everywhere
// except where something is in focus.
//
// **No `source-clip` and no rotation**, unlike the region map. That is a
// source-space picture being windowed down to the visible part; this was
// measured on the rendered frame itself, so it is already cropped, zoomed and
// turned exactly as the canvas is. One fewer thing that can drift out of
// registration.
//
// The caller places it on `canvas-area`'s fitted rect, which is the shared
// contract for anything that lands on the picture.
export component FocusMarks inherits Image {
    /// The overlay `DevelopSession::focus_overlay` produced for this frame.
    in property <image> marks;

    source: root.marks;
    image-fit: fill;
    // Nearest-neighbour: a mark is one pixel wide, and smoothing spreads it
    // into a grey haze that reads as softness — the opposite of what it is
    // reporting.
    image-rendering: ImageRendering.pixelated;
}

// TRACES: FR-CULL-3
export component FocusPanel inherits Rectangle {
    /// Whether this device could build the overlay at all.
    ///
    /// A compute pass can fail to compile on a driver nobody here has, and the
    /// honest response is to say so rather than to offer a switch that does
    /// nothing when pressed. The develop view keeps working without it; only
    /// this panel changes.
    in property <bool> available: true;
    /// Whether the overlay is currently being drawn.
    ///
    /// `showing` rather than the obvious `on`: Slint has no reserved word
    /// there today, and a one-word property that might become one is not worth
    /// the bet on a panel this small.
    in property <bool> showing: false;
    /// Index into `PeakSensitivity`, in the order Rust declares it.
    in property <int> sensitivity: 1;
    /// Index into `PeakColour`, likewise.
    in property <int> colour: 0;

    callback toggled(bool);
    callback sensitivity-picked(int);
    callback colour-picked(int);

    background: Theme.surface;

    /// TRACES: FR-UI-2
    /// How wide this panel has to be before it clips itself. The develop
    /// column is the largest of these and nothing else; see `SpotPanel` and
    /// `HistogramPanel` for the whole protocol.
    ///
    /// Both chip rows wrap at three, which is what keeps this number at the
    /// narrowest column the application supports rather than at four chips
    /// abreast — a single row of four would set the width of the entire
    /// sidebar for every other panel in it.
    out property <length> content-width: layout.preferred-width;
    min-width: root.content-width;

    // Flat rather than nested, for the reason `SpotPanel` and `MaskPanel` both
    // give: a nested conditional layout under-reports its height here and the
    // rows below it get drawn on top of one another. Every row carries its own
    // `if`.
    layout := VerticalLayout {
        padding: Theme.gap;
        spacing: Theme.gap-sm;
        alignment: start;

        PanelHeading { text: "FOCUS"; }

        if !root.available: Caption {
            text: "This device could not build the overlay.";
            wrap: word-wrap;
        }

        if root.available: Button {
            // The label states the action rather than the state, as the mask
            // overlay's does: a photographer reads a button for what pressing
            // it will do.
            text: root.showing ? "Hide focus peaking" : "Show focus peaking";
            active: root.showing;
            clicked => { root.toggled(!root.showing); }
        }

        if root.available && root.showing: Segmented {
            label: "Sensitivity";
            hint: "lower on a noisy frame";
            options: ["Low", "Medium", "High"];
            selected: root.sensitivity;
            columns: 3;
            picked(i) => { root.sensitivity-picked(i); }
        }

        if root.available && root.showing: Segmented {
            label: "Marks";
            hint: "pick what the subject is not";
            options: ["Red", "Yellow", "Cyan", "Magenta"];
            selected: root.colour;
            columns: 3;
            picked(i) => { root.colour-picked(i); }
        }

        if root.available && root.showing: Caption {
            // Said once, here, rather than left to be discovered: the marks go
            // away while a control is moving because a half-resolution draft
            // frame cannot be measured for sharpness (see `FocusPeakPass`).
            //
            // Kept to one short sentence on purpose. A wrapping Text reports
            // its *unwrapped* width as its preferred one, and this panel's
            // `content-width` is what the develop column sizes itself from —
            // a paragraph here would hold the whole sidebar open.
            text: "Marks pause while a control is dragged.";
            wrap: word-wrap;
        }
    }
}