editor: dynamic padding

lib/widgets/editor/transform/cropper.dart

@@ -90,7 +90,7 @@ class _CropperState extends State<Cropper> with SingleTickerProviderStateMixin {
 
   void _registerWidget(Cropper widget) {
     _subscriptions.add(widget.magnifierController.stateStream.listen(_onViewStateChanged));
-    _subscriptions.add(widget.magnifierController.scaleBoundariesStream.map((v) => v.viewportSize).listen(_onViewportSizeChanged));
+    _subscriptions.add(widget.magnifierController.scaleBoundariesStream.map((v) => v.viewportSize).distinct().listen(_onViewportSizeChanged));
     _subscriptions.add(widget.transformController.activityStream.listen(_onTransformActivity));
     _subscriptions.add(widget.transformController.transformationStream.map((v) => v.orientation).distinct().listen(_onOrientationChanged));
     _subscriptions.add(widget.transformController.transformationStream.map((v) => v.straightenDegrees).distinct().listen(_onStraightenDegreesChanged));
@@ -454,13 +454,41 @@ class _CropperState extends State<Cropper> with SingleTickerProviderStateMixin {
     if (boundaries != null) {
       magnifierController.setScaleBoundaries(
         boundaries.copyWith(
-          padding: const EdgeInsets.all(double.infinity),
+          padding: _getBoundariesPadding,
         ),
       );
     }
     _showRegion();
   }
 
+  EdgeInsets _getBoundariesPadding(double scale) {
+    // TODO TLAD handle orientation
+    if (transformation.orientation != TransformOrientation.normal) {
+      return const EdgeInsets.all(double.infinity);
+    }
+    // TODO TLAD handle straightening
+    if (transformation.straightenDegrees != 0) {
+      return const EdgeInsets.all(double.infinity);
+    }
+
+    final viewState = _getViewState();
+    if (viewState != null) {
+      final viewportSize = viewState.viewportSize;
+      final contentSize = viewState.contentSize;
+      if (viewportSize != null && contentSize != null) {
+        final fullRegion = CropRegion.fromRect(Offset.zero & contentSize);
+        final fullOutline = _containingOutlineFromRegion(viewState, fullRegion);
+        final cropOutline = _outlineNotifier.value;
+
+        final paddingWidth = max(0.0, (min(fullOutline.width, viewportSize.width) - cropOutline.width) / 2);
+        final paddingHeight = max(0.0, (min(fullOutline.height, viewportSize.height) - cropOutline.height) / 2);
+        return EdgeInsets.symmetric(vertical: paddingHeight, horizontal: paddingWidth);
+      }
+    }
+
+    return EdgeInsets.zero;
+  }
+
   ViewState? _getViewState() {
     final scaleBoundaries = magnifierController.scaleBoundaries;
     if (scaleBoundaries == null) return null;
@@ -560,6 +588,16 @@ class _CropperState extends State<Cropper> with SingleTickerProviderStateMixin {
     return clampedRegion;
   }
 
+  Rect _containingOutlineFromRegion(ViewState viewState, CropRegion region) {
+    final regionToOutlineMatrix = _getRegionToOutlineMatrix(viewState);
+    final points = region.corners.map(regionToOutlineMatrix.transformOffset).toList();
+    final dxSet = points.map((v) => v.dx).toSet();
+    final dySet = points.map((v) => v.dy).toSet();
+    final topLeft = Offset(dxSet.reduce(min), dySet.reduce(min));
+    final bottomRight = Offset(dxSet.reduce(max), dySet.reduce(max));
+    return Rect.fromPoints(topLeft, bottomRight);
+  }
+
   Rect _containedOutlineFromRegion(ViewState viewState, CropRegion region) {
     final regionToOutlineMatrix = _getRegionToOutlineMatrix(viewState);
     final points = region.corners.map(regionToOutlineMatrix.transformOffset).toList();

plugins/aves_magnifier/lib/src/scale/scale_boundaries.dart

@@ -16,7 +16,7 @@ class ScaleBoundaries extends Equatable {
   final ScaleLevel _initialScale;
   final Size viewportSize;
   final Size contentSize;
-  final EdgeInsets padding;
+  final EdgeInsets Function(double scale)? padding;
   final Matrix4? externalTransform;
 
   static const Alignment basePosition = Alignment.center;
@@ -31,7 +31,7 @@ class ScaleBoundaries extends Equatable {
     required ScaleLevel initialScale,
     required this.viewportSize,
     required this.contentSize,
-    this.padding = EdgeInsets.zero,
+    this.padding,
     this.externalTransform,
   })  : _allowOriginalScaleBeyondRange = allowOriginalScaleBeyondRange,
         _minScale = minScale,
@@ -45,7 +45,7 @@ class ScaleBoundaries extends Equatable {
     initialScale: ScaleLevel(ref: ScaleReference.contained),
     viewportSize: Size.zero,
     contentSize: Size.zero,
-    padding: EdgeInsets.zero,
+    padding: null,
   );
 
   ScaleBoundaries copyWith({
@@ -55,7 +55,7 @@ class ScaleBoundaries extends Equatable {
     ScaleLevel? initialScale,
     Size? viewportSize,
     Size? contentSize,
-    EdgeInsets? padding,
+    EdgeInsets Function(double scale)? padding,
     Matrix4? externalTransform,
   }) {
     return ScaleBoundaries(
@@ -115,7 +115,8 @@ class ScaleBoundaries extends Equatable {
 
     final minX = ((positionX - 1).abs() / 2) * widthDiff * -1;
     final maxX = ((positionX + 1).abs() / 2) * widthDiff;
-    return EdgeRange(minX - padding.left, maxX + padding.right);
+    final _padding = padding?.call(scale) ?? EdgeInsets.zero;
+    return EdgeRange(minX - _padding.left, maxX + _padding.right);
   }
 
   EdgeRange getYEdges({required double scale}) {
@@ -127,7 +128,8 @@ class ScaleBoundaries extends Equatable {
 
     final minY = ((positionY - 1).abs() / 2) * heightDiff * -1;
     final maxY = ((positionY + 1).abs() / 2) * heightDiff;
-    return EdgeRange(minY - padding.top, maxY + padding.bottom);
+    final _padding = padding?.call(scale) ?? EdgeInsets.zero;
+    return EdgeRange(minY - _padding.top, maxY + _padding.bottom);
   }
 
   double clampScale(double scale) {