stash

frontend/src/assets/fonts/pixel/LICENSE.md

@@ -0,0 +1,9 @@
+# Pixel fonts used for small label text (see ../../../scss/_pixel-fonts.scss)
+
+- **Tom Thumb** (`TomThumb.ttf`) - by Brian Swetland, TTF conversion by gheja
+  (https://github.com/gheja/tom-thumb-ttf). Licensed CC0 or CC-BY 3.0 (original:
+  https://robey.lag.net/2010/01/23/tiny-monospace-font.html).
+- **PICO-8** (`PICO-8.ttf`) - reproduction by Jacob Pierce
+  (https://github.com/jacobpierce/pico-8-font). MIT License, Copyright (c) 2016 Jacob Pierce.
+- **Silkscreen** (`Silkscreen-Regular.woff2`) - by Jason Kottke, served via Google Fonts
+  (https://fonts.google.com/specimen/Silkscreen). SIL Open Font License 1.1.

frontend/src/label-layouts.js

@@ -8,33 +8,33 @@ const GAP = {type: "empty", "min-width": "1mm", "min-height": "1mm"};
 export const LABEL_TEMPLATES = [
     {
         id: "qr", name: "QR code only", description: "Just the code - smallest label, prints fastest.",
-        required_vars: ["value"],
+        required_vars: ["text"],
-        layout: [{type: "qrcode", content: c => c.value}]
+        layout: [{type: "qrcode", content: c => c.text}]
     },
     {
         id: "qr-text", name: "QR code + text", description: "The code with the encoded text printed next to it.",
-        required_vars: ["value"],
+        required_vars: ["text"],
-        layout: [{type: "qrcode", content: c => c.value}, GAP, {type: "text", content: c => c.value?.split("\n")}]
+        layout: [{type: "qrcode", content: c => c.text}, GAP, {type: "text", content: c => c.text?.split("\n")}]
     },
     {
         id: "qr-text-below", name: "QR code + text below",
         description: "The code with the encoded text printed below it.",
-        required_vars: ["value"],
+        required_vars: ["text"],
-        layout: [[{type: "qrcode", content: c => c.value}, GAP, {type: "text", content: c => c.value?.split("\n")}]]
+        layout: [[{type: "qrcode", content: c => c.text}, GAP, {type: "text", content: c => c.text?.split("\n")}]]
     },
     {
         id: "id-qr-text-vertical", name: "ID + QR code + text below",
         description: "The code with the encoded text printed below it.",
-        required_vars: ["itemId", "value", "userHandle"],
+        required_vars: ["itemId", "text", "userHandle"],
         layout: [[{type: "text", content: c => "Item: "+c.itemId}, GAP, {
             type: "qrcode",
-            content: c => c.value
+            content: c => c.text
         }, GAP, {type: "text", content: c => c.userHandle}]]
     },
     {
         id: "text", name: "Text only", description: "No code, just the text itself, as large as it fits.",
-        required_vars: ["value"],
+        required_vars: ["text"],
-        layout: [{type: "text", content: c => c.value?.split("\n")}]
+        layout: [{type: "text", content: c => c.text?.split("\n")}]
     },
     {
         id: "item-handle", name: "Item handle",
@@ -105,10 +105,19 @@ export const KNOWN_VARS = [...new Set(LABEL_TEMPLATES.flatMap(t => t.required_va
 // A derived var is a format string calculated from other vars rather than typed directly - it
 // doesn't get its own input, just a read-only, live-recalculated display next to the ones that
 // do (see Print.vue and withDerivedVars below). `inputs` names every var (base or, in principle,
-// derived) `calc` reads - declared up front rather than inferred from calc's body so BASE_VARS
+// another derived one - see itemUrl/itemHandle below, which both read the derived userHandle)
-// below can include a var like "webdomain" that only feeds a calculation and that no template
+// `calc` reads - declared up front rather than inferred from calc's body so BASE_VARS below can
-// ever references directly.
+// include a var like "webdomain" that only feeds a calculation and that no template ever
+// references directly. Declaration order matters here: withDerivedVars runs these in a single
+// pass, so a derived var must be declared after every other derived var it depends on.
 export const DERIVED_VARS = {
+    // The full owner handle (see federation.md's Unique Handles section / ToolshedUser's
+    // separate username/domain columns) - kept as two base vars (user, domain) rather than one,
+    // since that's how the account itself is actually shaped, with this just the display/URL form.
+    userHandle: {
+        inputs: ["user", "domain"],
+        calc: (f) => `${f.user}@${f.domain}`,
+    },
     // The self-contained Item URL (see docs/design-in-progress/items-labels.md) - what a printed
     // label actually encodes, since scanning it has to resolve the right frontend/backend/item
     // with no other context, not just this browser's history. `webdomain` defaults to this

frontend/src/label.js

@@ -1,4 +1,5 @@
 import QRCode from "qrcode";
+import {encodeHandleForUrl} from "@/handle-url";
 
 const TRAILING_PADDING_PX = 3;		/* blank columns after the cut, same idea as the leading margin */
 
@@ -40,7 +41,26 @@ export function tapeFromStatus(status) {
 */
 const QR_ASPECT = 1;			/* a QR code is always square */
 const TEXT_REFERENCE_PX = 100;		/* font size text leaves measure their natural aspect ratio at */
-const MIN_READABLE_TEXT_PX = 8;	/* below this, a layout is rejected rather than rendered unreadably small */
+
+// Below 10px, a general-purpose sans-serif gets blurry/illegible, so drawTextLeaf switches to
+// whichever of these bitmap-style fonts (see ../scss/_pixel-fonts.scss) is designed closest to -
+// and no smaller than - the box's actual effective size. Ordered smallest first; fontFamilyFor
+// below picks the first tier whose belowPx clears the requested size, sans-serif once none do.
+const PIXEL_FONT_TIERS = [
+    {belowPx: 6, family: "Tom Thumb"},	/* designed for ~5px */
+    {belowPx: 7, family: "PICO-8"},	/* designed for ~6px */
+    {belowPx: 10, family: "Silkscreen"},	/* designed for ~7-8px */
+];
+
+function fontFamilyFor(fontPx) {
+    return PIXEL_FONT_TIERS.find(t => fontPx < t.belowPx)?.family ?? "sans-serif";
+}
+
+// A pixel font (see PIXEL_FONT_TIERS above) is what makes a size down here still legible - a
+// plain sans-serif this small would fail the old MIN_READABLE_TEXT_PX=8 floor that predates them.
+// Below this, drawTextLeaf leaves that one field blank rather than drawing illegible ink - see
+// there for why that's a quieter failure than rejecting the whole label over it.
+const MIN_READABLE_TEXT_PX = 5;
 
 function isSplit(node) {
     return Array.isArray(node);
@@ -134,26 +154,6 @@ function positionTree(node, ownAxis, x, y) {
     }
 }
 
-/* Walks the tree once it's been sized (layoutTree) and given a hard minimum to check against -
-   this is the text-too-small-to-read validation, kept as one pass over the already-final boxes
-   rather than scattered through the drawing code, so nothing gets mutated on the canvas before
-   every leaf is confirmed to fit. The equivalent QR-doesn't-fit check already happened earlier,
-   in snapQrToCrispSize. */
-function assertLeavesFit(node) {
-    if (isSplit(node)) {
-        node.forEach(child => assertLeavesFit(child));
-        return;
-    }
-    if (node.type === "text") {
-        const fontPx = TEXT_REFERENCE_PX * (node.box.height / node.naturalHeight);
-        if (fontPx < MIN_READABLE_TEXT_PX) {
-            throw new Error("This text doesn't fit this layout even at the smallest readable size — "
-                + "try a shorter value, a wider tape, or a different layout.");
-        }
-    }
-    // "qrcode"/"empty" leaves have nothing left to check by this point.
-}
-
 /* A QR code needs an integer number of pixels per module to render crisply rather than blurring
    at a fractional scale, so its true size is whatever that rounds down to - almost never the
    scale-free square a bare aspect ratio of 1 would suggest. Called once every qrcode leaf has a
@@ -180,6 +180,12 @@ function snapQrToCrispSize(node) {
     }
 }
 
+// Always measures in sans-serif at the fixed reference size, even though drawTextLeaf may end up
+// actually drawing in one of PIXEL_FONT_TIERS' fonts - the final effective size (and so which
+// font applies) isn't known until layoutTree has already sized the box this aspect ratio feeds
+// into. The pixel fonts are close enough in proportion for basic Latin/digits that the tiny
+// resulting mismatch is invisible in practice at these sizes, and the MIN_READABLE_TEXT_PX check
+// still catches anything that genuinely doesn't fit.
 function measureTextBlock(ctx, lines, referencePx) {
     ctx.font = `${referencePx}px sans-serif`;
     const width = Math.max(...lines.map(line => ctx.measureText(line).width));
@@ -224,10 +230,28 @@ function drawQrLeaf(ctx, node) {
     }
 }
 
+// Returns the effective font size drawn at (or that would have been, if it's too small to draw -
+// see below) - drawTree collects these into drawLabel/drawFallbackLabel's textSizesPx.
 function drawTextLeaf(ctx, node, referencePx) {
     const fontPx = referencePx * (node.box.height / node.naturalHeight);
+    // Even the smallest PIXEL_FONT_TIERS entry stops being legible below this - rather than
+    // reject the whole label over one field that's too small (the old behavior), just leave this
+    // leaf blank; its box was already accounted for, so nothing else in the layout shifts.
+    if (fontPx < MIN_READABLE_TEXT_PX) {
+        return fontPx;
+    }
     const lineHeight = node.box.height / node.lines.length;
-    ctx.font = `${fontPx}px sans-serif`;
+    const family = fontFamilyFor(fontPx);
+    ctx.font = `${fontPx}px "${family}"`;
+    // A @font-face family already in use elsewhere on the page loads in time for this, but canvas
+    // text silently falls back to the next font in the stack (there isn't one here, so the
+    // browser default) if drawn before its first-ever load finishes - unlike DOM text, a canvas
+    // fillText never waits or repaints on its own once the real font arrives. Kicking off the load
+    // here means only that very first draw at a given size risks the fallback; every redraw after
+    // it (Print.vue's live preview redraws on every keystroke) picks up the real font.
+    if (family !== "sans-serif") {
+        document.fonts.load(ctx.font);
+    }
     ctx.textBaseline = "middle";
     ctx.textAlign = "center";
     const centerX = node.box.x + node.box.width / 2;
@@ -238,6 +262,7 @@ function drawTextLeaf(ctx, node, referencePx) {
         ctx.fillText(line, centerX, y);
         y += lineHeight;
     }
+    return fontPx;
 }
 
 // Flip this to true (in a debugger or a local edit) to outline every leaf's box - including
@@ -256,15 +281,19 @@ function drawDebugBorder(ctx, node) {
     ctx.restore();
 }
 
-function drawTree(ctx, node, referencePx) {
+// `textSizesPx` collects each "text" leaf's effective font size as drawTree walks the tree - see
+// drawLabel/drawFallbackLabel, which hand it back to the caller (Print.vue shows it alongside the
+// tape width) so a field rendering blank (see drawTextLeaf's MIN_READABLE_TEXT_PX check) shows up
+// as a suspiciously small size here rather than just silently not being there.
+function drawTree(ctx, node, referencePx, textSizesPx) {
     if (isSplit(node)) {
-        node.forEach(child => drawTree(ctx, child, referencePx));
+        node.forEach(child => drawTree(ctx, child, referencePx, textSizesPx));
         return;
     }
     if (node.type === "qrcode") {
         drawQrLeaf(ctx, node);
     } else if (node.type === "text") {
-        drawTextLeaf(ctx, node, referencePx);
+        textSizesPx.push(drawTextLeaf(ctx, node, referencePx));
     }
     // "empty" leaves carry no ink - their box just reserves the space.
     if (DEBUG_LEAF_BORDERS) {
@@ -298,12 +327,13 @@ function layoutContent(ctx, content, height, maxLength, referencePx, pxPerMm) {
             + "try a shorter value, a different layout, or a bigger label.");
     }
     layoutTree(tree, false, width, height, pxPerMm);
-    assertLeavesFit(tree);
     return {tree, width};
 }
 
 /* The tape-fed layout - draws a fully resolved content tree (see templateContent) at the tape's
-   real pixel dimensions. See DEBUG_LEAF_BORDERS above to outline every leaf's box. */
+   real pixel dimensions. See DEBUG_LEAF_BORDERS above to outline every leaf's box. Returns
+   {textSizesPx}: each "text" leaf's effective font size, in the tree's own left-to-right,
+   top-to-bottom order. */
 export function drawLabel(canvas, tape, content) {
     const maxLength = tape.printLengthPx
         ? tape.printLengthPx - tape.leadPx - TRAILING_PADDING_PX
@@ -324,7 +354,9 @@ export function drawLabel(canvas, tape, content) {
 
     const originX = tape.leadPx + Math.floor((width - tape.leadPx - TRAILING_PADDING_PX - contentWidth) / 2);
     positionTree(tree, false, originX, 0);
-    drawTree(ctx, tree, TEXT_REFERENCE_PX);
+    const textSizesPx = [];
+    drawTree(ctx, tree, TEXT_REFERENCE_PX, textSizesPx);
+    return {textSizesPx};
 }
 
 const FALLBACK_LABEL_HEIGHT_PX = 200;	/* reference height the no-webusb preview/PNG scales from */
@@ -333,7 +365,7 @@ const FALLBACK_DPI = 203;		/* reference resolution for turning "empty" leaves' m
 /* The no-webusb preview/PNG - same layout tree and renderer as drawLabel, just scaled from a
    fixed reference height instead of a real tape's, and with no maxLength (there's no physical
    tape to run out of, so the canvas just grows to fit) and no printer feed margin, since there's
-   no real print head here to keep clear of. */
+   no real print head here to keep clear of. Returns {textSizesPx}, see drawLabel. */
 export function drawFallbackLabel(canvas, content) {
     const measureCtx = canvas.getContext("2d");
     const pxPerMm = FALLBACK_DPI / 25.4;
@@ -349,7 +381,9 @@ export function drawFallbackLabel(canvas, content) {
     ctx.fillStyle = "#000";
 
     positionTree(tree, false, 0, 0);
-    drawTree(ctx, tree, TEXT_REFERENCE_PX);
+    const textSizesPx = [];
+    drawTree(ctx, tree, TEXT_REFERENCE_PX, textSizesPx);
+    return {textSizesPx};
 }
 
 // Turns a {kind, components} prefill (see Print.vue's `prefill` prop) into the literal string a
@@ -360,7 +394,7 @@ export const LABEL_CONTENT_BUILDERS = {
     // The self-contained Item URL (see docs/design-in-progress/items-labels.md) - what a
     // printed label actually encodes, since scanning it has to resolve the right
     // frontend/backend/item with no other context, not just this browser's history.
-    "item-url": ({user, id}) => `${window.location.origin}/i/${user}/${id}`,
+    "item-url": ({user, id}) => `${window.location.origin}/i/${encodeHandleForUrl(user)}/${id}`,
 };
 
 export function buildLabelContent(prefill) {
@@ -378,11 +412,20 @@ export function buildLabelContent(prefill) {
 // (rather than present-but-empty) is what label-layouts.js's templateIsAvailable treats as "not
 // available", so builders should only include a field once its inputs actually check out.
 const LABEL_FIELD_BUILDERS = {
+    // `user` here is already a full "user@domain" handle (that's the form login usernames take -
+    // see Login.vue/store.js), so it's split into label-layouts.js's separate `user`/`domain`
+    // base vars the same way store.js's own lookupServer does, rather than stuffing the whole
+    // handle into one field the way userHandle (now derived from these two) used to be.
     "item-url": ({user, id}) => {
         if (!user || !id) {
             return {};
         }
-        return {userHandle: user, itemId: String(id)};
+        const at = user.indexOf("@");
+        return {
+            user: at === -1 ? user : user.slice(0, at),
+            domain: at === -1 ? "" : user.slice(at + 1),
+            itemId: String(id),
+        };
     },
 };
 

frontend/src/scss/_pixel-fonts.scss

@@ -0,0 +1,21 @@
+// Specialized bitmap-style fonts label.js's drawTextLeaf switches to below an effective text
+// size of 10px, where a general-purpose sans-serif gets blurry/illegible - each is designed for
+// (and named after) roughly the pixel size it's used at. See
+// ../assets/fonts/pixel/LICENSE.md for sources/licenses.
+@font-face {
+    font-family: "Tom Thumb";
+    src: url("../assets/fonts/pixel/TomThumb.ttf") format("truetype");
+    font-display: block;
+}
+
+@font-face {
+    font-family: "PICO-8";
+    src: url("../assets/fonts/pixel/PICO-8.ttf") format("truetype");
+    font-display: block;
+}
+
+@font-face {
+    font-family: "Silkscreen";
+    src: url("../assets/fonts/pixel/Silkscreen-Regular.woff2") format("woff2");
+    font-display: block;
+}

frontend/src/scss/toolshed.scss

@@ -92,6 +92,7 @@ $body-color: $gray-700;
 @import "forms";
 @import "tags";
 @import "dropdown";
+@import "pixel-fonts";
 
 #root, body, html {
   height: 100%;

frontend/src/views/Print.vue

@@ -20,9 +20,9 @@
                             </div>
                             <div class="card-body">
                                 <div class="row g-3">
-                                    <div :class="v === 'value' ? 'col-12' : 'col-md-6'" v-for="v in baseVars" :key="v">
+                                    <div :class="v === 'text' ? 'col-12' : 'col-md-6'" v-for="v in baseVars" :key="v">
                                         <label class="form-label">{{ varLabel(v) }}</label>
-                                        <textarea v-if="v === 'value'" class="form-control" rows="3"
+                                        <textarea v-if="v === 'text'" class="form-control" rows="3"
                                                   v-model="varValues[v]"
                                                   placeholder="https://example.com/…"></textarea>
                                         <input v-else type="text" class="form-control" v-model="varValues[v]">
@@ -88,7 +88,7 @@
                         <div class="card">
                             <div class="card-header d-flex justify-content-between align-items-center">
                                 <h5 class="card-title mb-0">Label</h5>
-                                <small v-if="tape" class="text-muted">{{ tape.mediaWidthMm }} mm tape</small>
+                                <small v-if="tape" class="text-muted">{{ tape.mediaWidthMm }} mm tape{{ textSizesSummary }}</small>
                             </div>
                             <div class="card-body">
                                 <p v-if="!tape" class="text-muted">
@@ -99,7 +99,7 @@
                                         <div class="ruler-v">
                                             <div class="ruler-v-corner"></div>
                                             <div class="ruler ruler-v-ticks"
-                                                 :style="{height: (tape.printAreaPx * zoom) + 'px'}">
+                                                 :style="{height: (tape.mediaWidthMm * tapePxPerMm) + 'px'}">
                                                 <span v-for="t in verticalRulerTicks" :key="'tick-' + t.mm"
                                                       class="tick" :class="{'tick-major': t.major}"
                                                       :style="{top: t.pos + 'px'}"></span>
@@ -108,7 +108,7 @@
                                                       :style="{top: t.pos + 'px'}">{{ t.mm }}</span>
                                             </div>
                                         </div>
-                                        <div class="preview-scroll">
+                                        <div class="preview-track">
                                             <div class="ruler ruler-h"
                                                  :style="{width: (printedWidthPx * zoom) + 'px'}">
                                                 <span v-for="t in horizontalRulerTicks" :key="'tick-' + t.mm"
@@ -118,8 +118,15 @@
                                                       :key="'label-' + t.mm" class="tick-label"
                                                       :style="{left: t.pos + 'px'}">{{ t.mm }}</span>
                                             </div>
-                                            <div class="label-preview">
+                                            <!-- The tape's full physical width, printable area included - the
-                                                <canvas ref="labelCanvas"></canvas>
+                                                 print head can't mark all the way to the tape's outer edges, so
+                                                 the canvas (printAreaPx tall) is narrower than this and centered
+                                                 within it; the rest is real, if unprintable, tape margin. -->
+                                            <div class="tape-full"
+                                                 :style="{height: (tape.mediaWidthMm * tapePxPerMm) + 'px'}">
+                                                <div class="label-preview">
+                                                    <canvas ref="labelCanvas"></canvas>
+                                                </div>
                                             </div>
                                         </div>
                                     </div>
@@ -207,8 +214,17 @@ const BLOB_URL = "/vendor/libweblabel.js";
 
 const MAX_ZOOM = 4;			/* never magnify the preview more than this */
 const MAX_PREVIEW_HEIGHT_PX = 300;	/* never let the on-screen preview grow taller than this */
-const RULER_TICK_MM = 1;		/* finest tick spacing the mm ruler draws */
+// How far apart plain and labeled/major ticks sit, both coarser the longer the ruler itself runs
-const RULER_MAJOR_EVERY_MM = 5;	/* every Nth tick is taller and labeled with its mm value */
+// - tightly spaced ticks (and their labels) get too cramped to read/render once there are enough
+// of them. Ordered smallest threshold first; rulerTicks below uses the last entry whose `aboveMm`
+// the ruler's own length clears, so add a finer/coarser tier here rather than growing a pile of
+// separate constants. Every tier's majorEveryMm is a multiple of its own tickMm, so major ticks
+// always land on a tick that's actually drawn.
+const RULER_TIERS = [
+    {aboveMm: 0, tickMm: 1, majorEveryMm: 5},
+    {aboveMm: 100, tickMm: 1, majorEveryMm: 10},
+    {aboveMm: 500, tickMm: 5, majorEveryMm: 25},
+];
 
 export default {
     name: "Print",
@@ -244,17 +260,21 @@ export default {
             // either one changes.
             zoom: 1,
             printedWidthPx: 0,
+            // Each "text" leaf's effective font size in the current render (see label.js's
+            // drawLabel) - shown alongside the tape width so a field rendering blank (too small
+            // even for the smallest pixel font) shows up as a suspiciously tiny number here rather
+            // than just silently not being there.
+            textSizesPx: [],
 
             // One input per *base* template variable (see label-layouts.js's BASE_VARS) - the
-            // derived ones (itemUrl, itemHandle) are format strings calculated from these, not
+            // derived ones (userHandle, itemUrl, itemHandle) are format strings calculated from
-            // typed directly, so they're only ever shown (see the `fields` computed below), never
+            // these, not typed directly, so they're only ever shown (see the `fields` computed
-            // stored here. Prefilled from the ?kind=…&… query params where
+            // below), never stored here. Prefilled from the ?kind=…&… query params where
             // buildLabelContent/buildLabelFields have a value for them, editable from there so a
-            // template needing e.g. userHandle isn't stuck depending on a prefill that never
+            // template needing e.g. domain isn't stuck depending on a prefill that never arrives.
-            // arrives.
             varValues: {
                 ...Object.fromEntries(BASE_VARS.map(v => [v, ""])),
-                value: buildLabelContent(this.prefill),
+                text: buildLabelContent(this.prefill),
                 // Defaults to wherever this page itself is being served from - editable since any
                 // frontend can resolve any handle (see label-layouts.js's DERIVED_VARS.itemUrl),
                 // so a label doesn't have to point back at this particular one.
@@ -327,17 +347,46 @@ export default {
         tapePxPerMm() {
             return this.tape ? (this.tape.dpi / 25.4) * this.zoom : 0;
         },
+        // The physical length, in mm, each ruler axis actually needs to cover - see
+        // horizontalRulerTicks/verticalRulerTicks below for what each one measures and why.
+        horizontalTotalMm() {
+            return (this.tape && this.printedWidthPx) ? this.printedWidthPx / (this.tape.dpi / 25.4) : 0;
+        },
+        verticalTotalMm() {
+            return this.tape ? this.tape.mediaWidthMm : 0;
+        },
+        // The single RULER_TIERS entry both rulers draw from, keyed off whichever axis is
+        // physically longer - so a long label's ruler doesn't end up coarser (or finer) than the
+        // tape-width ruler right next to it just because the other axis happens to be shorter.
+        rulerTier() {
+            return RULER_TIERS.filter(t => Math.max(this.horizontalTotalMm, this.verticalTotalMm) >= t.aboveMm)
+                .at(-1);
+        },
         // Ticks along the tape's length (the printed bitmap's actual width, lead/trailing feed
         // margin included, since that's real physical tape too).
         horizontalRulerTicks() {
             if (!this.tape || !this.printedWidthPx) {
                 return [];
             }
-            return this.rulerTicks(this.printedWidthPx / (this.tape.dpi / 25.4));
+            return this.rulerTicks(this.horizontalTotalMm);
         },
-        // Ticks across the tape's fixed physical width.
+        // Ticks across the tape's full physical width, mediaWidthMm - not printAreaPx/dpi: a
+        // print head can't reach the tape's outer edges, so the printable area (see .tape-full in
+        // the template) is genuinely narrower than the tape itself, by an amount that isn't a
+        // fixed/predictable fraction of it. The ruler still has to show the *whole* tape - its
+        // container is sized from mediaWidthMm too (see the template's inline height) precisely so
+        // these ticks can't run past it, the way they did when both were sized from printAreaPx.
         verticalRulerTicks() {
-            return this.tape ? this.rulerTicks(this.tape.mediaWidthMm) : [];
+            return this.tape ? this.rulerTicks(this.verticalTotalMm) : [];
+        },
+        // "(5px, 23px)" for the current render's text leaves (see data's textSizesPx), or "" once
+        // there's nothing to show - appended straight onto the tape-width <small>, so the blank
+        // string here just means that text is left with no trailing space.
+        textSizesSummary() {
+            if (!this.textSizesPx.length) {
+                return "";
+            }
+            return ` (${this.textSizesPx.map(px => Math.round(px) + "px").join(", ")})`;
         },
     },
     watch: {
@@ -377,12 +426,15 @@ export default {
             return v.replace(/([a-z])([A-Z])/g, "$1 $2").replace(/^./, c => c.toUpperCase());
         },
 
-        // One tick per RULER_TICK_MM from 0 up to totalMm, each positioned in on-screen pixels
+        // Ticks from 0 up to totalMm, each positioned in on-screen pixels via tapePxPerMm - shared
-        // via tapePxPerMm - shared by the horizontal/vertical ruler computeds above.
+        // by the horizontal/vertical ruler computeds above. Both the plain tick spacing and the
+        // labeled/major one come from the shared rulerTier (see above), not from this totalMm, so
+        // both rulers always coarsen together once *either* axis is long enough to need it.
         rulerTicks(totalMm) {
+            const {tickMm, majorEveryMm} = this.rulerTier;
             const ticks = [];
-            for (let mm = 0; mm <= totalMm; mm += RULER_TICK_MM) {
+            for (let mm = 0; mm <= totalMm; mm += tickMm) {
-                ticks.push({mm, pos: mm * this.tapePxPerMm, major: mm % RULER_MAJOR_EVERY_MM === 0});
+                ticks.push({mm, pos: mm * this.tapePxPerMm, major: mm % majorEveryMm === 0});
             }
             return ticks;
         },
@@ -463,13 +515,15 @@ export default {
                 return;
             }
             this.resizeObserver.observe(canvas.parentElement);
+            let textSizesPx;
             try {
-                drawLabel(canvas, this.tape, content);
+                ({textSizesPx} = drawLabel(canvas, this.tape, content));
             } catch (e) {
                 this.error = e.message;
                 return;
             }
             this.error = null;
+            this.textSizesPx = textSizesPx;
             const bitmap = canvasToBitmap(canvas);
             bitmapToCanvas(canvas, bitmap);
             this.labelBitmap = bitmap;
@@ -593,7 +647,7 @@ export default {
 .label-preview {
     overflow-x: auto;
     padding: .75rem;
-    background: rgba(127, 127, 127, .08);
+    //background: rgba(127, 127, 127, .08);
     border-radius: .35rem;
     text-align: center;
     max-height: 300px;
@@ -602,7 +656,7 @@ export default {
 .label-preview canvas {
     display: inline-block;
     background: #fff;
-    box-shadow: 0 0 0 1px rgba(127, 127, 127, .5);
+    //box-shadow: 0 0 0 1px rgba(127, 127, 127, .5);
 }
 
 /* The tape-fed preview's mm ruler (see Print.vue's template/script) - a horizontal track above
@@ -613,22 +667,38 @@ export default {
     align-items: flex-start;
 }
 
-/* The single horizontal scroll region for a label wider than its card - the horizontal ruler and
+/* Holds the horizontal ruler and the canvas - deliberately never scrollable (no overflow-x:auto):
-   the canvas are both direct children of this, so they scroll in lockstep with no JS needed to
+   fitZoom's zoom always satisfies `canvas.width * zoom <= available`, so the canvas can never
-   keep them in sync. */
+   actually be wider than this has room for, and a scrollbar here would let the ruler and canvas
-.preview-scroll {
+   drift apart (or just look broken) for no reason. min-width:0 only lets this flex item shrink
+   to the card's real available width - it doesn't enable scrolling. */
+.preview-track {
     flex: 1 1 auto;
     min-width: 0;
-    overflow-x: auto;
 }
 
-/* Overrides the standalone rule above: nested here, .label-preview must neither clip nor center
+/* Overrides the standalone rule above: nested here, .label-preview must neither scroll nor center
-   its canvas - overflow-x:visible lets the canvas's true width "bubble up" to .preview-scroll's
+   its canvas - overflow-x:visible (never auto) rules out a second, inner scrollbar, and
-   own scrollbar instead of scrolling twice, and text-align:left keeps the canvas flush with the
+   text-align:left keeps the canvas flush with the ruler's zero tick instead of drifting to the
-   ruler's zero tick instead of drifting to the middle of whatever spare width this card has. */
+   middle of whatever spare width this card has. padding:0 so the canvas's own edges are exactly
-.preview-scroll .label-preview {
+   this box's edges too - the ruler's ticks (see .ruler-h/.ruler-v-ticks below) line up with those
+   same edges, so any padding here would leave the ticks and the actual canvas misaligned. */
+.preview-track .label-preview {
     overflow-x: visible;
     text-align: left;
+    padding: 0;
+}
+
+/* The tape's full physical width (see the template) - a print head can't mark all the way to a
+   tape's outer edges, so .label-preview/the canvas is narrower than this and centered within it
+   (the print area sits centered on the tape, with equal margin on both sides); a faint tint
+   distinguishes the margin as real (if blank, unprintable) tape rather than empty space. */
+.tape-full {
+    display: flex;
+    flex-direction: column;
+    justify-content: center;
+    background: rgba(127, 127, 127, .08);
+    border-radius: .35rem;
 }
 
 .ruler-v {
@@ -645,13 +715,11 @@ export default {
 
 .ruler-v-ticks {
     position: relative;
-    margin-top: .75rem;	/* .label-preview's own padding, so tick 0 meets the canvas, not its box */
 }
 
 .ruler-h {
     position: relative;
     height: 1.6rem;
-    margin-left: .75rem;	/* .label-preview's own padding, so tick 0 meets the canvas, not its box */
     color: rgba(127, 127, 127, .9);
 }