السحب والتمرير والدفع

Dragging means tracking how far a finger moves and updating the UI to match. Compose makes this smooth with dedicated drag detectors. ✋

Inside pointerInput, call detectDragGestures. Its onDrag lambda fires repeatedly with the change and the distance moved since the last event.

Keep a state Offset and add each drag delta to it. Then feed that offset into a Modifier so the element follows your finger.

Use the offset modifier to move a composable by your tracked pixels. Convert with roundToInt so it positions cleanly on screen.

Call change.consume() in your drag handler. This tells parents you handled the event so they do not also react to it.

Need only sideways motion? Use detectHorizontalDragGestures, or detectVerticalDragGestures for up and down. They report a single Float delta.

A swipe is just a drag you judge at the end. If the finger traveled far enough, treat it as a dismiss instead of snapping back.

For simple single-axis dragging, the draggable modifier is easier. Pair it with rememberDraggableState to collect the delta.

A fling keeps moving after release based on speed. Track velocity with a VelocityTracker as the finger moves to capture that momentum.

Feed the release velocity into an Animatable with a decay spec. It glides to a natural stop, mimicking real physics. 🌀

detectDragGestures also gives you onDragEnd and onDragCancel. Use them to snap back, settle, or kick off your fling animation.

What does a fling animation need that a plain drag does not?

You tracked drags with detectDragGestures, accumulated an offset, judged swipes, and used velocity for a fling. Touch now feels alive. 🎉