[List] Support vertically centered image views in MDCSelfSizingStereo…

…Cell

PiperOrigin-RevId: 349420776

components/List/src/MDCSelfSizingStereoCell.h

@@ -15,6 +15,7 @@
 #import <UIKit/UIKit.h>
 
 #import "MDCBaseCell.h"
+#import "MDCSelfSizingStereoCellImageViewVerticalPosition.h"
 
 /**
  MDCSelfSizingStereoCell is intended to be an easy to use readymade implementation of a basic
@@ -42,11 +43,23 @@ __attribute__((objc_subclassing_restricted)) @interface MDCSelfSizingStereoCell
  */
 @property(nonatomic, strong, readonly) UIImageView *leadingImageView;
 
+/**
+ This property influences the positioning of @c leadingImageView. The default value is @c .top.
+ */
+@property(nonatomic, assign)
+    MDCSelfSizingStereoCellImageViewVerticalPosition leadingImageViewVerticalPosition;
+
 /**
  The UIImageView responsible for displaying the trailing image.
  */
 @property(nonatomic, strong, readonly) UIImageView *trailingImageView;
 
+/**
+ This property influences the positioning of @c trailingImageView. The default value is @c .top.
+ */
+@property(nonatomic, assign)
+    MDCSelfSizingStereoCellImageViewVerticalPosition trailingImageViewVerticalPosition;
+
 /**
  The UILabel responsible for displaying the title text. By default, `numberOfLines` is set to 0 so
  the label wraps and the self-sizing capabilities of the cell are best utilized.

components/List/src/MDCSelfSizingStereoCell.m

@@ -172,12 +172,15 @@ - (MDCSelfSizingStereoCellLayout *)layoutForCellWidth:(CGFloat)cellWidth {
   CGFloat flooredCellWidth = floor(cellWidth);
   MDCSelfSizingStereoCellLayout *layout = self.cachedLayouts[@(flooredCellWidth)];
   if (!layout) {
-    layout = [[MDCSelfSizingStereoCellLayout alloc] initWithLeadingImageView:self.leadingImageView
-                                                           trailingImageView:self.trailingImageView
-                                                               textContainer:self.textContainer
-                                                                  titleLabel:self.titleLabel
-                                                                 detailLabel:self.detailLabel
-                                                                   cellWidth:flooredCellWidth];
+    layout = [[MDCSelfSizingStereoCellLayout alloc]
+                 initWithLeadingImageView:self.leadingImageView
+         leadingImageViewVerticalPosition:self.leadingImageViewVerticalPosition
+                        trailingImageView:self.trailingImageView
+        trailingImageViewVerticalPosition:self.trailingImageViewVerticalPosition
+                            textContainer:self.textContainer
+                               titleLabel:self.titleLabel
+                              detailLabel:self.detailLabel
+                                cellWidth:flooredCellWidth];
     self.cachedLayouts[@(flooredCellWidth)] = layout;
   }
   return layout;

components/List/src/MDCSelfSizingStereoCellImageViewVerticalPosition.h

@@ -0,0 +1,31 @@
+// Copyright 2020-present the Material Components for iOS authors. All Rights Reserved.
+//
+// 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.
+
+#import <UIKit/UIKit.h>
+
+/**
+ This enum represents different positions for the side image views in an @c
+ MDCSelfSizingStereoCell.
+ */
+typedef NS_ENUM(NSUInteger, MDCSelfSizingStereoCellImageViewVerticalPosition) {
+  /**
+   This value results in the image view being positioned at the top of the cell.
+   */
+  MDCSelfSizingStereoCellImageViewVerticalPositionTop,
+  /**
+   This value results in the image view being positioned in the vertical center of the
+   cell.
+   */
+  MDCSelfSizingStereoCellImageViewVerticalPositionCenter,
+};

components/List/src/MaterialList.h

@@ -15,3 +15,4 @@
 #import "MDCBaseCell.h"
 #import "MDCSelfSizingLayoutAttributes.h"
 #import "MDCSelfSizingStereoCell.h"
+#import "MDCSelfSizingStereoCellImageViewVerticalPosition.h"

components/List/src/private/MDCSelfSizingStereoCellLayout.h

@@ -17,6 +17,8 @@
 #import <Foundation/Foundation.h>
 #import <UIKit/UIKit.h>
 
+#import "MDCSelfSizingStereoCellImageViewVerticalPosition.h"
+
 @interface MDCSelfSizingStereoCellLayout : NSObject
 
 @property(nonatomic, assign, readonly) CGFloat cellWidth;
@@ -28,7 +30,11 @@
 @property(nonatomic, assign, readonly) CGRect trailingImageViewFrame;
 
 - (instancetype)initWithLeadingImageView:(UIImageView *)leadingImageView
+        leadingImageViewVerticalPosition:
+            (MDCSelfSizingStereoCellImageViewVerticalPosition)leadingImageViewVerticalPosition
                        trailingImageView:(UIImageView *)trailingImageView
+       trailingImageViewVerticalPosition:
+           (MDCSelfSizingStereoCellImageViewVerticalPosition)trailingImageViewVerticalPosition
                            textContainer:(UIView *)textContainer
                               titleLabel:(UILabel *)titleLabel
                              detailLabel:(UILabel *)detailLabel