explode_widget

Shatters any widget into thousands of fragments of its own pixels.

ExplodeWidget(
  child: Card(child: ListTile(title: Text('Tap me'))),
)

Tap it. The widget is captured, cut into a grid, and every piece is thrown with its own velocity, spin and fade then it is gone.

The pieces are rectangles of the widget's own snapshot, so what flies apart is the widget itself: its text, its gradient, its border. Not a cloud of dots in matching colours.

How it works, and why that matters

The whole thing lives in one RenderObject.

RenderExplode makes itself a repaint boundary, which means it owns an OffsetLayer — and a layer can rasterise itself with toImageSync, synchronously, in the same frame as the tap. No GlobalKey, no RepaintBoundary for you to remember, and no async gap where the widget is neither whole nor exploding.

Every fragment is then one sprite in a single Canvas.drawRawAtlas call. That is the primitive built for exactly this: a thousand rotated, scaled, faded rectangles of one texture, drawn in one go. A per-particle drawRect loop is what makes a thousand particles stutter; this is why the default is 600 fragments and 2400 is a reasonable ask.

And nothing rebuilds while it runs. The animation's only side effect is markNeedsPaint, so no widget in your tree is asked to build a frame of the explosion.

The child also stays in the tree the whole time — it is hidden, not removed. So its state, its controllers and its scroll positions are all still there, and putting it back is instant:

final ExplodeController controller = ExplodeController();
// ...
ExplodeWidget(controller: controller, explodeOnTap: false, child: MyForm());
// ...
controller.explode();
controller.reset();   // the form is back, with everything the user typed

Settings

ExplodeWidget(
  settings: const ExplodeSettings(
    duration: Duration(milliseconds: 900),
    grid: ExplodeGrid.auto(600),        // or ExplodeGrid(columns: 30, rows: 20)
    origin: ExplodeOrigin.tap(),        // or .at(Alignment.topLeft)
    minSpeed: 120,                      // logical pixels per second
    maxSpeed: 520,
    gravity: 1400,                      // pixels per second squared
    spin: 6,                            // radians per second, either way
    shrink: 0.4,                        // how much size a fragment loses
    stagger: 0.25,                      // the far side leaves a little later
    fade: Curves.easeInQuad,
    pixelRatio: null,                   // defaults to the view's
    seed: null,                         // fix it and it shatters the same way
    collapseWhenGone: false,
  ),
  child: child,
)

ExplodeSettings.dust and ExplodeSettings.shatter are ready-made: many small pieces drifting, and few big ones thrown hard.

duration does not slow the motion down

Speeds are in pixels per second, so doubling the duration does not halve the speed — it gives the fragments twice as long to leave the screen, and you watch an empty hole fade. To slow an explosion down, bring the speeds and the gravity down with it:

// Four seconds of drifting, rather than four seconds of nothing.
const ExplodeSettings(
  duration: Duration(milliseconds: 4000),
  minSpeed: 15, maxSpeed: 60, gravity: 50,
);

ExplodeGrid.auto follows the widget's aspect ratio, so a 300x100 widget asked for 300 fragments becomes 30x10, not 17x17 — square debris rather than a glitch.

origin decides where the blast comes from. ExplodeOrigin.tap() uses the point that was touched, which is why the near side of the widget leaves first and the far side follows.

What it will not do

• Platform views do not rasterise. A map, a web view or a camera preview captures as nothing, so it explodes into transparent fragments. That is a limit of photographing the layer tree, not of this package.
• A child with its own tap handler wins the gesture arena. Wrapping a button and leaving explodeOnTap: true presses the button. Use the controller for those.
• One controller drives one widget. Give two live widgets the same controller and it drives the most recently built one. There is deliberately no assertion: a widget whose key just changed is built before the old one is unmounted, and the two cases cannot be told apart from inside.
• Dashed edges, non-rectangular shards, physics between fragments. The grid is what drawAtlas can draw in one call, and that is the whole trick.

Example

/example is a Flutter app with four presets, a widget whose counter survives the explosion, and a reset button. Run it and tap things.

License

MIT.