photo_zoom 1.2.3

photo_zoom: ^1.2.3 copied to clipboard

• A figure for the wheel hand-off. The desktop section described it in a sentence, and it is the feature nobody knows to look for because both ways of getting it wrong fail silently: always claiming the wheel traps a reader in the post, never claiming it means no desktop zoom at all. Two feeds side by side say which one gets the event. Generated by tool/wheel_handoff_figure.dart.

• A figure for contained, covered and 1.0. The scale-limits section reached for two computed scales before anything had shown what they do, and they are the part of this API people get wrong. Drawn by tool/scale_states_figure.dart, with the widget tests' own fixture, so the 2.0 and 4.0 in it are numbers you can check.
• Drops the fractal zoom from the archive. It was a screenshot entry only, and pub.dev renders screenshots as still thumbnails, so 3.4 MB bought one static frame of something that taught nothing about using the package. The archive goes from 4 MB to 997 KB.

• Tests for the desktop and web input path, which had none: mouse wheel zoom, trackpad two-finger pan, trackpad pinch, and the hand-off where a view already pinned at a scale limit leaves the wheel event unclaimed so a list it sits inside keeps scrolling. No behaviour changed; all of it was already correct, and none of it was pinned.

• The sampling filter now follows the zoom. Magnifying and shrinking want different filters, and which applies changes as the reader zooms, so it is decided per frame from the scale on screen in device pixels: FilterQuality.high when the image is drawn larger than its own pixels, FilterQuality.medium when it is not, and medium throughout a gesture or a fling, where the frame budget matters more than the last of the sharpness. Passing filterQuality still overrides all of it.
• The recording in the README now shows the drag and the two-finger pinch as well as the double tap, and the demonstration keeps moving rather than parking on a still frame: a frame diff of the previous cut came back 87% unchanged, this one 47%.

• Fixed a crash-adjacent error when a PhotoView is mounted from inside a layout callback while something else listens to the same PhotoViewController. The view resolves its scale from initState, and writing the resolved value there notified the listener mid-build, which the framework rejects. The write is now held until the frame is done; the frame still paints at the right scale. The combination is the one the controller's own documentation suggests, so it had to hold.
• The example gained a second screen showing where a double tap sends the zoom, on a numbered grid, with a live scale readout. Open it directly with flutter run --dart-define=start=compare.
• The README leads with that recording and answers InteractiveViewer and photo_view in its first screen rather than a hundred lines down.

• The example demonstrates enableScrollZoom. A toolbar button turns it off, which is the behaviour photo_view has no switch for, and the difference is a trackpad gesture away. The feature was the reason to pick this package and the example never touched it.

• Stop shipping build output in the published archive. This version downloads as 3 MB. 1.0.1 downloaded 32,418,118 bytes, and 93,092,107 of its 96,897,275 unpacked bytes were under build/; two build/test_cache/*.cache.dill.track.dill files account for 92,965,256 of those, which is what flutter test left on the machine that published the release. No library code changed, and lib/ is byte-identical to 1.0.1.

  The cause was one file in the wrong directory. pub replaces .gitignore with .pubignore per directory rather than layering the two, so a .pubignore at the repository root switched the root .gitignore off for the whole tree, and build/ is named only in .gitignore. The rule now lives in doc/.pubignore, beside the doc/blog/ directory it was written for; doc/ has no .gitignore for it to shadow, so the root one stays in force.

  Checked with build/ on disk rather than absent, since an absent build/ would hide the bug instead of testing the fix: 3 MB here, against 17 MB with the old layout restored in a scratch copy.

• Call the package an alternative to photo_view rather than a drop-in. Moving across is usually just a change of import, but the migration table in the readme lists cases that need an edit: minScale: 0.5 becomes minScale: PhotoViewScale.value(0.5), the controller is a ValueNotifier instead of a stream, and tightMode is gone. "Drop-in" promised none of that. Description only; no code change.

First stable release. The API below is what 1.0 freezes.

• Fix PhotoViewComputedScale's operators accepting scales the absolute scale refuses. PhotoViewScale.value has always asserted on a negative or a NaN, but contained * x and covered / x took anything. A NaN — the realistic source is a caller's own arithmetic, contained * (a / b) with both zero — travelled into the widget and came back out as Invalid argument(s): NaN from clamp, or Unsupported operation: Infinity or NaN toInt from layout, depending on which parameter carried it. Neither message names the parameter, so the error surfaces far from its origin. Both operators now assert with a message that says which one produced what. Infinity stays legal: it is maxScale's default and means "no upper limit".

Verified unchanged for this release, by driving each case rather than reading for it: a zero-size viewport, an external controller or scale-state controller disposed before the view, a gallery built with itemCount: 0, a gallery whose itemCount shrinks while the last page is showing, writes to a controller that outlives its view, extreme controller values (scale 0 and 1e9, position 1e9, rotation 1e9), five double-taps interrupting each other's animations, a dispose mid-animation, and an orientation change while zoomed in. None misbehaved.

• Fix swipe to dismiss going dead once the view is zoomed out below the initial scale. The gate compared the scale to scaleBoundaries.initialScale instead of checking whether the child had room to pan, and the default minScale is PhotoViewScale.value(0), so a pinch or a controller write into zoomedOut left the drag unable to dismiss. It also could not pan: clampPosition collapses every write to Offset.zero once the child no longer overflows the viewport, so the drag produced no visible feedback either.

• Add opt-in swipe to dismiss. Pass onDismiss to PhotoView, PhotoViewGallery or PhotoViewGalleryPageOptions and a single-finger drag at the rest scale slides the image and fades the background; releasing past dismissThreshold (a fraction of the viewport height, 0.2 by default) calls it, usually to pop the route, and a shorter drag springs back. A drag while zoomed still pans. Off by default: with no onDismiss nothing changes.

• Declare the demo in pubspec.yaml so pub.dev shows it on the package page. The recording was already in the repository and in the README, but pub.dev only renders what the screenshots: field points at, so anyone landing on the page from search saw text where the demo should have been.

• Docs: sharpen the pub.dev description to lead with the value and the terms people search.

• Docs: tightened the README wording and visuals.

• Correct the migration table. Only the double tap recenters in photo_view: a pinch updates the scale state through setInvisibly, which notifies no listener, so it never reaches the recentering path. The table claimed both.

Initial release.

• PhotoView: pan, pinch zoom, double tap cycle, optional rotation, hero transitions, loading and error builders, and PhotoView.customChild for zooming an arbitrary widget.
• PhotoViewGallery: a PageView of photos, from a list or built on demand. Each page keeps its own zoom, and hands a drag to the page view once its photo is panned to the edge.
• PhotoViewController and PhotoViewScaleStateController: ValueNotifiers that read and drive the transform and the double tap cycle.
• PhotoViewScale: typed scale limits, either PhotoViewScale.value or a PhotoViewComputedScale.contained / .covered, with * and / to offset them.
• Zoom anchors at the touch, pointer or tap, rather than at basePosition.
• enableScrollZoom: mouse wheel zooms at the pointer and a two-finger trackpad scroll pans. Events that would change nothing are left to an ancestor scrollable.
• Zoom level and zoom actions exposed to screen readers; reduced motion honoured.

The API follows the photo_view package by Renan C. Araújo. See "Migrating from photo_view" in the README for the differences.