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The Page Editor draws. Pick a brush, drag on the page, and the mark lands on a Drawing layer as a stroke — a margin scribble, a crossed-out line, a highlighted passage, a map sketched on the back of a letter. Every brush is drawn procedurally. Inkwell ships no brush images, no noise textures, and no shaders for this: a brush’s look is only ever how many passes it lays down, how far they wander, and how transparent each one is. That is why strokes cost nothing to ship and why they bake identically at any resolution.
A strip of sample strokes, one per Inkwell brush

One stroke per brush: pen, pencil, marker, crayon, highlighter.

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The five brushes

EInkBrushType, in the order the Brush dropdown lists them. Every brush that jitters seeds its randomness from the stroke’s own points, so a stroke looks the same every time it is drawn — in the editor preview, in the bake, and after a reload. Nothing is rolled fresh at paint time.

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The Drawing Tools panel

Bottom of the Page Editor’s left column, under Default Text Style.
The Drawing Tools panel in the Inkwell Page Editor

Drawing Tools: the tool toggles, the brush, and the ink it lays down.

1

Brush / Erase

The two tools. Clicking either one switches the page into Draw mode immediately — reaching for a brush and then having to find a mode button somewhere else is not how a brush works.
2

Brush

Which of the five brushes the next stroke uses. Default Pen. The brush, the ink color, and the opacity all disappear while Erase is selected — Size px is the only one of them the eraser uses.
3

Ink color

The color of the next stroke, alpha included. Strokes keep the color they were drawn with — changing this never restyles a mark already on the page. Default is the same warm near-black the document’s default text color uses, (0.02, 0.017, 0.025).
4

Size px

Stroke width in page pixels — pixels of the document’s Page Size Pixels, not screen pixels, so a stroke keeps its proportions however the page is scaled. Range 1–120, default 6. This is also the eraser’s width, and the ring under the cursor is drawn at this size.
5

Opacity

Multiplies the brush’s own transparency. A highlighter is already faint before this touches it. Range 0.05–1, default 1.
Nothing in this panel is undoable, because nothing in it touches the document: the palette is the toolbox, not the picture. The hint line at the bottom of the panel tells you where the next stroke will land — into the selected drawing layer, or into a new one it is about to make.

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Drawing on the page

The page surface in Draw mode with strokes on it

Draw mode. The banner is the reminder that typing is suspended.

1

Enter Draw mode

Click Draw in the toolbar’s Mode group, or pick a tool in Drawing Tools — that arms Draw mode by itself. The banner across the page reads DRAW MODE — draw on the page. Esc returns to Text Mode., and the cursor becomes a crosshair with a ring at the current brush size.
2

Add or select a drawing layer

Click + Drawing in the Layers panel, or select an existing Drawing layer’s row. You can skip this: drawing on the page with no drawing layer selected makes one, inserted in front of the current selection, and the new layer plus the stroke are a single undo step. Entering Draw mode when nothing suitable is selected also picks up the frontmost usable drawing layer for you.
3

Choose the brush, color, and size

Set them before you draw. A stroke is stamped from the palette at mouse-down, so changing the palette mid-stroke never re-styles the line in progress.
4

Draw

Press, drag, release. You see the real mark as you drag — the live stroke goes through the same renderer the bake uses, so the line you drag is the line that comes out of the oven. Nothing is written to the document until you let go, which is what makes one stroke one undo step (“Draw Stroke”). A click with no drag is still a mark: it draws a dot.
5

Erase

Click Erase and sweep over the ink. See below.
6

Undo

Ctrl+Z, through the normal editor undo stack. One stroke is one step; one eraser sweep is one step, however much it took out. An eraser sweep that touched nothing leaves no undo step at all.
7

Back to typing

Esc, or click Text in the Mode group.
Strokes land on the side of the sheet being edited. Flip the sheet with the Front / Back toggle under the page list and Draw mode works the same on the back — a map sketched on the back of a letter really is on the back, and drawing the first mark on an untouched back is one of the ways a back becomes authored.

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The eraser

The eraser rubs out the ink under the cursor, not the stroke that ink belongs to. This matters more than it sounds:
  • A stroke erased through the middle becomes two strokes, each keeping the original’s brush, color, width, and opacity. It is the same mark with a bite out of it, not a new one.
  • A stroke erased at one end comes back shorter. A stroke erased everywhere goes away.
  • Untouched stretches come back with exactly the points they were authored with — the eraser does not resample ink it never reached.
  • One sweep is one undo step. The transaction opens on the first real cut and every later cut in the same sweep joins it.
The eraser’s reach is half the Size px value (with a floor of 3 page pixels), plus half the width of whatever stroke it is testing — so a fat crayon line is bitten when the eraser reaches its edge, not its center line. Erasing works along the whole path the cursor travelled between mouse events, so a fast sweep does not leave untouched ink between bites. The eraser never invents a layer. It works on the selected Drawing layer if there is one, otherwise on the frontmost visible, unlocked Drawing layer — which is also the one whose strokes are on top of the cursor.
A hidden or locked Drawing layer is neither a stroke target nor an erase target. Drawing with one selected creates a new layer instead of adding to it, and the eraser skips it entirely. If your marks keep landing on a fresh layer, check the eye and the padlock on the row you meant to draw into.
To wipe a layer completely, select it and use Clear Strokes in the layer properties — one undo step, and it tells you the stroke count above the button.

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The stroke data model

Useful if you generate marks from Blueprint or from C++ — a signature stamped at runtime, a crossed-out line revealed by a quest, a scribble whose position depends on save data.

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FInkStroke — one continuous mark

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FInkStrokePoint — one sample along it

Normalized coordinates are why strokes survive everything: the same points bake at full page resolution, bake clamped down on a huge document, and preview at whatever size the editor pane has room for. WidthPx is the one value that is not normalized, so it is scaled by the widget’s real width over the document’s Page Size Pixels X when it is painted.
Pressure comes from touch input only. Slate reports touch force from 1.0 for an ordinary press up to 10 for a hard one, which Inkwell clamps into the 0.05–1 range Pressure uses; a mouse has no pressure at all and every point it produces gets a flat 1.0. Strokes you build in Blueprint can vary it freely — tapering the last few points is what makes a generated mark look drawn rather than plotted.
The editor drops points that are barely apart (the threshold rides on the stroke width: half of it, clamped to 1–24 page pixels) and caps a single stroke at 4096 points. Generated strokes are not held to that, but a stroke with hundreds of points per centimeter is bytes in the asset for nothing — the renderer resamples the curve anyway.

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Recipe: add a stroke from Blueprint

  1. Build the points: for each sample, Make Ink Stroke Point with a normalized Position and a Pressure, into an array.
  2. Make Ink Stroke — set Brush, Color, Width Px, Opacity, and the Points array.
  3. Make Ink Drawing — set its Strokes array (existing strokes first; the list is drawn oldest first).
  4. Make Ink Page Layer — Type = Drawing, Name = something readable, and the Drawing member from step 3.
  5. Add Page Layer (PageIndex, the layer) to put it at the front of the page, or Move Page Layer afterwards to drop it behind the writing. The Side pin defaults to Front; pass Back to scribble on the back of the sheet instead.
  6. Refresh on any Ink Page Display showing that page. (Add Page Layer bumps the document’s content revision, so cached bakes are already invalidated.)
To add to an existing Drawing layer instead, Get Page Layers, edit the copy’s Drawing.Strokes, and write the whole array back with Set Page Layers — the getter hands you a copy, so nothing changes until you do.

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Next

Layers

Where strokes live, and how to stack a highlight under the words.

Paper

The stock the ink sits on — textures, generated sheets, or your own materials.

Page Editor

Modes, the toolbar, and the rest of the window.

Rendering reference

How strokes, text, and images become one baked ink texture.