iOS: implement slider style gallery

doric-iOS/Pod/Classes/Shader/DoricSliderLayout.m

@@ -0,0 +1,60 @@
+/*
+ * Copyright [2023] [Doric.Pub]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+//
+//  DoricSliderNode.m
+//  Doric
+//
+//  Created by jingpeng.wang on 2023/6/13.
+//
+#import "DoricSliderLayout.h"
+
+@implementation DoricSliderLayout
+
+- (NSArray<UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect {
+    NSArray *attributes = [super layoutAttributesForElementsInRect:rect];
+    CGRect visitRect = {self.collectionView.contentOffset,self.collectionView.bounds.size};
+    NSMutableArray *attributesCopy = [NSMutableArray array];
+    for (UICollectionViewLayoutAttributes *attribute in attributes) {
+        UICollectionViewLayoutAttributes *attributeCopy = [attribute copy];
+        [attributesCopy addObject:attributeCopy];
+    }
+    
+    for (UICollectionViewLayoutAttributes *attribute in attributesCopy) {
+        CGFloat distance = CGRectGetMidX(visitRect) - attribute.center.x;
+        float diff = fabs(distance);
+        CATransform3D scaleTransform = CATransform3DIdentity;
+        
+        if (diff >= 0 && diff <= self.galleryItemWidth) {
+            float scale = 1 - (1 - self.galleryMinScale) * (diff / self.galleryItemWidth);
+            scaleTransform = CATransform3DMakeScale(scale, scale, scale);
+            attribute.alpha = 1 - (1 - self.galleryMinAlpha) * (diff / self.galleryItemWidth);
+        } else {
+            float scale = self.galleryMinScale;
+            scaleTransform = CATransform3DMakeScale(scale, scale, scale);
+            attribute.alpha = self.galleryMinAlpha;
+        }
+        
+        attribute.transform3D = scaleTransform;
+    }
+    return attributesCopy;
+}
+
+- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds {
+    return YES;
+}
+
+@end
+