DarkRoom/docs/gestures.md

How the application is driven

Every entry here is extracted from the comment beside the code that implements it, so this file cannot describe a gesture the application does not have. Add one by writing a GESTURE: block next to the implementation; there is nowhere else to write it.

37 gestures, in 4 places.

Develop

Set the white balance from the photograph

• Touch — Press "pick" in the group's heading, then tap something neutral in the picture
• Pointer — Press "pick", then click something neutral

Sampling a neutral is the first move of the tonal pass — every colour judgement afterwards is measured against where the grey was put — and guessing at two sliders until a wall stops looking green is the wrong way round. One click is one sample and one step to undo; the sliders stay, because a sampled neutral is where the decision starts rather than where it ends.

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Magnify the photograph by any amount

• Touch — Pinch it with two fingers
• Pointer — The scroll wheel over it

Anchored on the fingers' midpoint, and on the pointer, so the gesture reads as magnifying the picture rather than sliding it about. Double-tap is the way to an exact 1:1; this is the way to everything in between.

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Move a magnified photograph about

• Touch — Drag it
• Pointer — Drag it

Only once there is something outside the viewport to reach, which is why the cursor becomes a hand exactly then. The view is clamped to the frame: panning past the edge would show undefined area beside the photograph, and that reads as a rendering fault rather than as the end of the picture.

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Paint a mask by hand

• Touch — Choose Paint or Erase, then drag on the photograph
• Pointer — Choose Paint or Erase, then drag

A model's mask stops inside a shoulder and leaks into the hair, and no single edge control fixes two errors that go opposite ways. The whole stroke is one step in the history, so taking a mark back costs one press however long it took to make.

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Take back the last change

• Touch — Tap the step above the current one in the History list
• Pointer — Click it, or press Undo in the History header
• Keyboard — Ctrl+Z

A whole drag is one step, so undo takes back a decision rather than a frame of a gesture. The list is there because arriving six steps back costs what arriving from one does.

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Do it again after taking it back

• Touch — Tap the step below the current one in the History list
• Pointer — Click it, or press Redo in the History header
• Keyboard — Ctrl+Shift+Z

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Copy the settings from this photograph

• Touch — Press Copy in the Settings panel
• Pointer — Press Copy in the Settings panel
• Keyboard — Ctrl+C

The panel is the copy that has to work: a tablet has no modifier key to hold and no menu bar to hang the action from. The shortcut is an accelerator for a control that is on screen either way.

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Paste the settings onto this photograph

• Touch — Press Paste in the Settings panel
• Pointer — Press Paste in the Settings panel
• Keyboard — Ctrl+V

The button names what would be pasted — "3 adjustments", and whether the crop is coming with it — which the shortcut cannot say. Both paste the same scope.

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Change which group of adjustments is on screen

• Touch — Tap a group in the rail down the left
• Pointer — Click a group in the strip above the develop column
• Keyboard — [ and ] step through them, wrapping round through "everything"

The groups are whatever the operation set declares itself to be about, so there are as many as the pipeline has and no key can be assigned to one of them by name. Stepping is the binding that survives a node being added.

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Look at the photograph at 1:1

• Touch — Double-tap the photograph
• Pointer — Double-click it, or press the zoom readout floating over the canvas
• Keyboard — Z

Noise reduction and capture sharpening are judgements about single pixels, and a fitted view averages several of the file's into each one on screen — so the frame looks softer than it is and the correction goes too far. The point and the magnification survive opening the next photograph, which is what makes checking the same eye across forty portraits forty keystrokes rather than forty pans.

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Move to the next or previous photograph

• Touch — Tap a frame in the roll along the foot of the canvas
• Pointer — Click a frame in the roll
• Keyboard — Right arrow or space for the next, left arrow for the one before

The edit on screen is saved on the way out, so stepping through a folder is as much a departure as going back to the grid and loses nothing.

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See the photograph before you edited it

• Touch — Press and hold "Before"
• Pointer — Press and hold "Before"
• Keyboard — Hold \

Held rather than toggled, and no split screen: a split halves the working image on the tablet the column was sized for, and the comparison photographers describe making is a flick back and forth. It takes no history step, so checking whether a frame is overcooked costs nothing to undo afterwards.

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Put one control back to its default

• Touch — Double-tap its track
• Pointer — Double-click its track, or right-click it

The column is 280px wide and the colour mixer alone puts thirty-six of these in it, so a reset button per row would be most of the width. Two ways in with a pointer because right-click is the one a hand already reaches for and double-click is the one that needs no second button. A group's own reset is in its heading; this is the single control.

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Show or hide one mask layer

• Touch — Tap the ring at the head of its row
• Pointer — Click the ring at the head of its row

Disabling a layer is the before-and-after a local edit constantly wants, so it is one press away rather than inside the row. It is an edit and does take a history step, unlike holding "Before" — the layer really is off until it is switched back on.

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Show or hide one mask on the photograph

• Touch — Tap the eye on its row
• Pointer — Click the eye on its row

A mask is judged by seeing where it falls, and two are judged by seeing where they meet — so each row has its own eye rather than the panel having one, and the eye is drawn in the colour the mask shows in, so the row says which shape on the picture is its. Nothing about the edit changes: this is how the photograph is looked at, and takes no history step.

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Collections sidebar

Pick a collection up to rearrange the tree

• Touch — Press and hold it until it lifts, then drag it
• Pointer — Drag it, or hold it until it lifts and then drag

The tree is inside a Flickable, which claims any drag beginning inside it — so with a finger a drag on a row is a scroll until something says otherwise. The hold is that something, and it is what every mobile list already uses to pick a row up. The row lifts the moment it fires, so the gesture says it has been understood before anything moves.

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Act on a collection — rename, nest, un-nest, delete

• Touch — Press and hold the collection, then let go without moving
• Pointer — Right-click it

The hold arms a drag and opens this menu, and which one you get is decided by whether you moved — the same fork the grid uses. One menu for everything done to a row, because there is one hold per row: while the hold opened the offline question by itself, nothing else the tree can do had a touch route.

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Take a collection back out of the one it is nested in

• Touch — Hold it, then drag it onto "All photographs" — or let go and choose "Move to top level"
• Pointer — Drag it onto "All photographs", or right-click it and choose "Move to top level"

Nesting is a drag of one row onto another, and its inverse had no gesture at all: "All photographs" refused every drop, which is right for a photograph — it is already in the library — and wrong for a collection, which has a top level to be returned to. Without it a collection dragged into another was in there permanently.

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Rename a collection

• Touch — Hold the collection, then "Rename"
• Pointer — Double-click its name, or right-click it and choose "Rename"

Double-click is what a file manager and a Lightroom panel use for the same thing, so it needs no discovering — but nothing on screen says so, which is what the menu item is for.

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People

Pull a face out of the wrong person

• Touch — Tap the faces that do not belong, then "Split off"
• Pointer — Click the faces that do not belong, then "Split off"

Grouping over-merges on siblings, on parents and children, and on the same person a decade apart, so splitting is as prominent as merging. A tool that can only merge makes its own errors permanent.

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Rule on a suggested face

• Touch — Tick to confirm it, cross to reject it
• Pointer — Tick to confirm it, cross to reject it

A face is either the system's guess or the user's judgement, and the two are never conflated. A rejection is remembered, so the face is not suggested for that person again. The gesture note above is the whole label: a tick and a cross are only "confirm" and "reject" to someone who can see the suggestion they sit beside, and IconButton's fallback would announce them as "check" and "cross" — two icon names that say nothing about which person is being ruled on.

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See a person's photographs

• Touch — Choose them in the rail, then "Show photos"
• Pointer — Choose them in the rail, then "Show photos"

This is the point of having identified anybody. Without it the screen is a filing cabinet with no drawer handles.

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Change how faces are grouped

• Touch — "Grouping…", move the dials, then Regroup
• Pointer — "Grouping…", move the dials, then Regroup

The right match confidence is a property of your library, not of the model. "What would this do?" answers for this library without writing anything; names, confirmations and the groups you have set aside are kept whatever the dials say.

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Library grid

Start selecting several photographs

• Touch — Press and hold a photograph, or press Select in the header
• Pointer — Ctrl-click, or press Select in the header

Touch has no ctrl, so without a mode there is no way to select a second photograph — the first tap would open it. The hold is the fast way in and the button is the one that can be found.

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Add or remove one photograph

• Touch — While selecting, tap it
• Pointer — Ctrl-click it

While selecting, a tap never opens. That is the whole point of the mode: one meaning per gesture at a time. Press Done to get tap-to-open back.

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Leave selecting

• Touch — Press Done in the header
• Pointer — Press Done in the header
• Keyboard — Escape

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Pick a photograph up to drag it

• Touch — Press and hold it until a ring opens around it, then drag
• Pointer — Drag it

A finger on a photograph might be starting a scroll, and for the first half-second the grid assumes it is. Holding says otherwise, and the ring is the grid saying it heard — from there the drag cannot be lost to a scroll. A mouse never waits: the cursor is precise enough that a sideways drag is unambiguous from the first pixel.

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Select a range

• Touch — While selecting, press "Select to…", then tap the last photograph of the run
• Pointer — Shift-click the last photograph of the run

This replaced a double tap, which had no visible state and could take forty photographs by accident. The run is resolved by the catalog rather than by what is on screen, so the grid can scroll between the two taps — the ranges that hurt on a tablet are longer than a screenful, which is exactly where a finger sweep runs out.

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Find photographs with two people in them

• Touch — Open the People chip on the filter bar, tap each name, then switch the chip beside them to "all of them"
• Pointer — Open the People chip on the filter bar, click each name, then switch the chip beside them to "all of them"

"Any of them" is a union and "all of them" is an intersection. The tray is where both terms and the choice between them live, because a filter belongs on the filter bar.

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Resize the thumbnails

• Touch — Pinch the grid with two fingers
• Pointer — Ctrl and the scroll wheel

There is no wheel on a tablet, so without the pinch the cell size could only be changed by a control a finger cannot reach.

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File photographs in a collection

• Touch — Drag a photograph — or a whole selection — onto a collection in the sidebar. Starting a drag stops the press becoming a hold, so it cannot leave you in selection mode.
• Pointer — Drag a photograph — or a whole selection — onto a collection in the sidebar

The selection is what the drag carries, which is why selecting several is worth the mode: forty photographs file in one gesture.

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Open a photograph

• Touch — Tap it — a single tap, any length
• Pointer — Click it

A tap opens; a tap that moved does not. Travel is what separates a deliberate tap from a hand brushing past, and it is the only thing that does: the two are the same length. An earlier version required the finger to dwell 120 ms instead, and that rejected ordinary taps — a real tap is often quicker than a brush.

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Rate a photograph without opening it

• Touch — Tap a star on the cell
• Pointer — Hover the cell, then click a star
• Keyboard — 0 to 5 on the selection

A star has to take the press without it also reaching the cell, or every rating throws the user into develop.

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Choose the frame a folded burst shows

• Touch — Open the burst, then tap the ring on the frame you want
• Pointer — Open the burst, then click the ring on the frame you want

A folded burst draws its earliest frame, which is a fact about the clock and not a judgement about the photograph — nothing in this application ranks a frame (FR-CULL-5). But the point of a burst is that one of the twelve is better than the other eleven, and the photographer is the only one who knows which. So the choice is offered on the frames themselves, while they are open and side by side, which is the one moment the alternatives are on screen to be compared.

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Drop the selection but keep selecting

• Touch — Press Clear in the selection strip
• Pointer — Press Clear in the selection strip

Distinct from Done, which leaves the mode entirely. Clearing keeps it, so the next selection can start straight away.

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Select everything the grid is showing

• Touch — While selecting, press "Select all"
• Pointer — While selecting, press "Select all"

A scoped grid of two hundred frames is two hundred taps otherwise, and "all of them, except those three" is a far more common shape than the taps it took to say it.

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Take photographs out of a collection

• Touch — Select them, then "Collections…" in the selection bar
• Pointer — Select them, then "Collections…" in the selection bar

The badge on a cell says a photograph is filed in three collections and never which. This is the sheet that names them, and the only way out of one the grid is not currently scoped to.

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