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Improve drag handling and animation #38

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3e66843
Respect isDragging flag in updates
rustobi Oct 8, 2025
9c5a6be
Use start offset to smooth drag animation
rustobi Oct 8, 2025
3857cb9
Fix offset calculation
rustobi Oct 8, 2025
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34 changes: 25 additions & 9 deletions lib/src/core/animation/animation_strategy.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ abstract class AnimationStrategy {
DragStartDetails details, BuildContext context, SlideDirection direction);

void handleDragUpdate(DragUpdateDetails details, BoxConstraints constraints,
SliderDrawerController controller);
SliderDrawerController controller, double sliderOpenSize);
}

class SliderAnimationStrategy implements AnimationStrategy {
Expand All @@ -30,17 +30,33 @@ class SliderAnimationStrategy implements AnimationStrategy {

@override
void handleDragUpdate(DragUpdateDetails details, BoxConstraints constraints,
SliderDrawerController controller) {
SliderDrawerController controller, double sliderOpenSize) {
if (controller.isHorizontalSlide) {
var position =
(details.globalPosition.dx).clamp(0.0, constraints.maxWidth) /
constraints.maxWidth;
var xOffsetSinceStart = details.globalPosition.dx -
(controller.globalStartOffset != null
? controller.globalStartOffset!.dx
: 0);

if (controller.slideDirection == SlideDirection.rightToLeft) {
position = 1 - position;
}
double adjustedOffset;
double percent = 0.0;
if (controller.slideDirection == SlideDirection.leftToRight) {
// if drawer is open, dragging needs to go into the negative direction,
// so we shift the offset by sliderOpenSize to keep it normalized
adjustedOffset = controller.wasDrawerOpen
? xOffsetSinceStart + sliderOpenSize
: xOffsetSinceStart;

percent = (adjustedOffset).clamp(0.0, sliderOpenSize) / sliderOpenSize;
} else if (controller.slideDirection == SlideDirection.rightToLeft) {
// same here but in the other direction
adjustedOffset = controller.wasDrawerOpen
? xOffsetSinceStart - sliderOpenSize
: xOffsetSinceStart;

controller.updatePosition(position);
percent =
(adjustedOffset).clamp(-sliderOpenSize, 0.0) / -sliderOpenSize;
}
controller.updatePosition(percent);
}
}

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15 changes: 14 additions & 1 deletion lib/src/core/animation/slider_drawer_controller.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,8 @@ class SliderDrawerController extends ChangeNotifier {
final double threshold;

bool _isDragging = false;
bool _wasDrawerOpen = false;
Offset? _globalStartOffset;
double _percent = 0.0;

SliderDrawerController({
Expand All @@ -19,6 +21,10 @@ class SliderDrawerController extends ChangeNotifier {

bool get isDragging => _isDragging;

bool get wasDrawerOpen => _wasDrawerOpen;

Offset? get globalStartOffset => _globalStartOffset;

bool get isDrawerOpen => animationController.isCompleted;

bool get isHorizontalSlide =>
Expand All @@ -31,18 +37,25 @@ class SliderDrawerController extends ChangeNotifier {

void closeSlider() => animationController.reverse();

void startDragging() {
void startDragging(DragStartDetails details) {
_wasDrawerOpen = isDrawerOpen;
_isDragging = true;
_globalStartOffset = details.globalPosition;
notifyListeners();
}

void stopDragging() {
if (!_isDragging) return;

_globalStartOffset = null;
_isDragging = false;
_percent > threshold ? openSlider() : closeSlider();
notifyListeners();
}

void updatePosition(double percent) {
if (!_isDragging) return;

_percent = percent;
animationController.value = percent;
notifyListeners();
Expand Down
4 changes: 2 additions & 2 deletions lib/src/slider_drawer.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -209,7 +209,7 @@ class SliderDrawerState extends State<SliderDrawer>
void _handleDragStart(DragStartDetails details) {
if (_animationStrategy.shouldStartDrag(
details, context, widget.slideDirection)) {
_controller.startDragging();
_controller.startDragging(details);
}
}

Expand All @@ -219,7 +219,7 @@ class SliderDrawerState extends State<SliderDrawer>

void _handleDragUpdate(
DragUpdateDetails details, BoxConstraints constraints) {
_animationStrategy.handleDragUpdate(details, constraints, _controller);
_animationStrategy.handleDragUpdate(details, constraints, _controller, widget.sliderOpenSize);
}

@override
Expand Down