glass_forge 0.1.1

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• The README's GIFs and screenshots load on pub.flutter-io.cn. They are linked from the repository by absolute URL, since the images are kept out of the package, and so are its links to the example app, the changelog and the license.

First release.

Rendering #

• GlassLayer captures the backdrop once per material, and every Glass under it registers into one shared signed-distance matte.
• Two refraction models. GlassMaterial.regular(brightness:) and GlassMaterial.clear() bend only inside a band at the rim, fitted against iOS 27 captures. GlassMaterial.dome() refracts across the whole surface. The band's displacement is what refracting through its surface's slope gives: strongest at the rim, easing to zero with no seam. It reads the backdrop bilinearly wherever it bends it; the flat interior keeps a single tap.
• Shapes: GlassRoundedRectangle, GlassOval and GlassSuperellipse. GlassBlendGroup smooth-mins shapes into one another.
• Any number of shapes per material. A pass's shapes are sorted into clusters, groups of shapes whose mattes could meet plus any blend group, and each cluster is a draw of its own, up to kMaxShapes (8) shapes.
• A shape that is laid out but not drawn stays out of the matte, its clusters and the diagnostics until it is: under an Opacity at zero, in an Offstage, in a lazy list's cache region.
• A pass whose material changes only in shading (tint, frost, highlight) keeps its matte, and a GlassTextField's focus is a uniform on its pass, so neither rebakes anything.

Presence and host awareness #

• GlassPresence and GlassPresenceScope fade a Glass in and out, driven by a controller, an Animation<double> or a route transition, without rebaking its matte on every frame.
• GlassHostScope.isOnGlass(context) tells a widget it is drawn on glass rather than on content, so it can paint instead of stacking glass on glass.

Motion #

• InteractiveGlass handles press, drag, fling and spring-home. Squash and stretch are read off the spring's own velocity (GlassJiggle, a 1.08 ceiling at a 2000 px/s half-speed).
• Springs take a duration and a bounce, the way SwiftUI specifies them: GlassMotion.bouncy, .snappy, .smooth and .interactive. A press runs on snappy 250 ms / bounce 0.25 and lets go on its own spring, pressReleaseMotion, bouncy 280 ms / bounce 0.45.
• A press grows the surface by pressGrowth, 6 pt on its longest side, held to a ratio of 1.02 to 1.10. pressScale fixes a ratio instead.
• A pulled surface gives the way a native button does (GlassPressStretch). The stretch comes from how far the finger has moved since it went down, never from where it rests, so a tap does not deform anything. The first 3 pt are ignored and the rest is rubber-banded. At the defaults a surface reaches about 1.5x along the pull with no squash across it, follows the finger up to 10 pt, and the label or glyph on it stretches with the glass. It takes on a white sheen as it stretches (sheen), and letting go bounces it softly back through rest (rebound).
• Touch glow (GlassGlow): a soft lift under the finger, 0.10 at full press (0.05 in dark mode), over one and a half times the pressed surface's longest side. It belongs to the pass, so neighbouring glass catches a little of it, and it stays on the pressed surface however far the finger pulls. InteractiveGlass.glow turns it off for one surface.
• Under Reduce Motion every spring settles at once and nothing stretches; the surface still answers the pointer.

Controls #

Five controls, each resolving GlassSurfaceRole.control for its shape and label colour. On content each draws real glass: in the control role's material, except the switch knob, which is always GlassMaterial.dome(). Painted parts such as a switch track or a slider fill leave a hole where that glass is. Under GlassHostScope, on a glass toolbar say, a control paints a flat tint instead, so there is never glass on glass.

Every control but the text field shares one frame:

• One semantics node with the visible text as its label, Enter and Space activation, a 44 x 44 minimum hit target that grows the tap area rather than the glass, and a focus ring for keyboard focus.
• The owner decides. A control moves as soon as it is touched and then reports. If the owner does not rebuild with the new value, the control goes back to the value it was given.

And all five have:

• autofocus, and a focusNode on all but the segmented control, whose segments are each a focus stop of their own.
• A disabled state that dims the glass as well as the paint, and ignores touches. Disabling a control mid-drag ends the drag.
• Right-to-left layouts, mirrored the way Flutter's own controls mirror.
• A debug error naming the control when it is given an unbounded width.
• Labels that name their own size, so they never fall back to WidgetsApp's debug text style outside a Material.

The controls:

• GlassButton and GlassButton.icon, with toggled for a button that reports an on/off state, pressStretch, glow and semanticLabel. Labels are iOS's 17-point button text.
• GlassSwitch: a painted 63 x 28 track and a 37 x 24 glass knob, sized to iOS 27's Toggle, that drags, flicks and settles to the side it ends up past. activeTrackColor defaults to the theme's accent.
• GlassSlider, with min, max, divisions, onChangeStart, onChangeEnd and semanticValueFormatter. It can be dragged from anywhere in its hit area, a tap sets it (in a scroll view too), and it reports only real changes. Arrow keys step it, onto the division grid when it has one.
• GlassSegmentedControl and GlassSegment, a travelling pill you can drag: a 32-point track under a 28-point pill inset 2, sized to iOS 27, centred in a hit area 44 tall. Labels are 13 points, semibold when selected. The control is a named semantics group, each segment a selectable button with its own semanticLabel. Left and right arrows move the selection; up and down are left to the page.
• GlassTextField, built on EditableText. Options: controller, placeholder, leading, trailing, shape, enabled, keyboardType, textInputAction, obscureText, semanticLabel, onChanged and onSubmitted. contextMenuBuilder defaults to the system selection menu (SystemContextMenu) where the device has one, and selectionControls takes an app's own drag handles. Focus lights the glass rather than drawing a ring. In a scroll view the field scrolls clear of the keyboard and of a bar riding it, and it grows with the reader's text size.

Large text: the fixed-height controls and bars let labels grow to 1.5x and stop there. The text field grows instead.

Chrome #

• GlassScaffold puts the composition rules in place for you. Each bar sits in a layer of its own, the size of the bar, whose glass is clipped to the bar, so a bar's filter never reaches over body glass. The body gets one layer, which draws glass only between the bars. The bars are laid out before the body, so the body's padding and its glass band are right from the first frame. The body is padded to clear the bars, and its viewInsets.bottom is 0 under a bottom bar that rides the keyboard. Each bar fades out over the first 40% of any route that covers the page, so the bar and the covering glass are never two backdrop filters over the same pixels. material is what a bare Glass in either layer inherits.
• GlassScaffold, showGlassSheet and GlassDetentSheet give their content a text style and icon colour of their own, iOS's 17-point body in the theme's label colour, the way Material's Scaffold does.
• GlassTabBar and GlassTab, a floating capsule whose selection is always a clear glass lens. Only the selection is glass: the bar is painted, a translucent capsule in the role's tint at its legible step (about 54% in dark mode, 35% in light, or backgroundColor) with a hairline rim and the role's shadow, and no blur, so the lens is never glass over glass. The fill is light enough for the content behind to show through for the lens to bend, and still keeps every label at 3:1 over any backdrop. The default lens is bright and bends far (highlight 2.8, edge refraction 26, a 14% white tint, chromatic aberration 0.3), and a faint selectionMaterial is raised to minimumSelectionHighlight (2), minimumSelectionTintOpacity (0.12) and minimumSelectionEdgeRefraction (14), so a clear preset never hides the selection. A bouncy spring moves the lens, and it squashes along its travel with its speed, to at most 116% of its height. A drag carries it under the finger, clicks once per tab crossed, and commits the tab under the finger on release; a cancelled drag sends it back. Reduce Motion moves it at once, still glass. GlassTabBar.height and GlassTabBar.margin are public for laying out around it. GlassTab.semanticLabel names icon-only tabs. In debug it reports a bar too narrow for 44-point tabs. maxWidth caps the bar, centred, at GlassTabBar.defaultMaxWidth (480 points) unless you pass another, so on a tablet it stays a capsule rather than a strip.
• GlassAppBar: leading, a 17-point semibold title centred iOS style and marked as a header, actions, the top safe area, and material.
• showGlassSheet presents a modal glass sheet from the bottom edge. It takes isDismissible, material, barrierLabel, useRootNavigator and routeSettings, and completes with what it is popped with. The sheet rises over the keyboard, and Reduce Motion presents it instantly, even mid-presentation.
• GlassDetentSheet, a persistent bottom sheet dragged between fixed heights, à la Apple Maps: floating with an inset and a large-radius corner below its top detent, flush with the display's own corners at it, with a scroll handoff to the content it carries. Detents are GlassDetent.fraction, .height or .content. material replaces the sheet role's material, and bottomGap sets the floating bottom inset apart from the side ones, for a sheet that has to clear a bar beneath it. GlassDetentSheetController drives it from outside, including presenceUnder, which hands a covered surface's GlassPresence off before the sheet's own glass reaches it. GlassSheetScrollPhysics lets one drag cross from the sheet to its list and back without a lifted finger.
• GlassSurface takes a material on every constructor. Placed on glass, it paints its tint instead of drawing glass, and inside a GlassPresence it fades its content with the glass.

Backdrop sampling #

• GlassBackdropSampler, GlassBackdropSource and GlassBackdropBuilder measure what is behind a surface, so adaptation needs no caller-supplied backdrop. The source is snapshotted at low resolution (1/8 scale, at most 96 px on its long side), asynchronously, at most every 200 ms and only after it repainted; each surface takes the mean colour under its own rect, with a luminance band so it does not flicker between schemes. GlassSurface, GlassAppBar, GlassTabBar, GlassDetentSheet and every control use it when no backdrop is given. An explicit backdrop still wins. Nothing is sampled where the tier renders no glass, under Reduce Transparency, or on glass.

Tiering and accessibility #

• GlassTierScope picks a tier from GPU capability, thermal state, frame health and accessibility settings. ResolvedTier.describe() says why.
• Reduce Transparency is read through a native channel and reported as unknown where the platform has no answer. Reduce Motion honours both engine bits. Increase Contrast drives surfaces toward opaque with a border.
• Skia and web backends fall back to frost without refraction.

Design system #

• Tokens for blur, radius, depth and tint, five GlassSurface roles, and GlassTheme.
• The controls' colours come from the theme: GlassTokens.controls, a GlassControlPalette of light and dark GlassControlColors — accent (the switch's on-track), knob (the knob, thumb and pill painted on glass), and fill and focus (the slider's fill and the focus ring, null for the label colour). GlassSwitch.activeTrackColor still wins for one switch.
• The chrome's painted colours do too: GlassTokens.chrome, a GlassChromeColors with scrim (under showGlassSheet, black at 32% by default) and handle (both sheets' grab handle, null for the sheet's label colour).

Debug tooling #

• A warning when shapes in different render passes overlap on screen, surfacing the artifact behind flutter/flutter#187820 before it reaches a release build. It reports every overlapping pair once, not every frame.
• A warning when more shapes sit in one cluster than a single draw can carry (kMaxShapes).

Known limits #

• kMaxShapes is 8 per cluster: shapes whose mattes could meet, and every shape in one blend group. Past eight the extras are not drawn.
• The backdrop sampler misses a repaint behind a repaint boundary inside the source until GlassBackdropSampler.markNeedsSample, and a surface that moves while nothing repaints or scrolls keeps its last reading.
• Benchmark budgets are seed values, not measurements from real hardware.