Create a MostVisited cell for ContentSuggestions

ios/chrome/browser/ui/content_suggestions/cells/content_suggestions_most_visited_item.mm

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/chrome/browser/ui/content_suggestions/cells/content_suggestions_most_visited_item.h"
+
+#import "ios/chrome/browser/ui/content_suggestions/cells/content_suggestions_most_visited.h"
+#import "ios/chrome/browser/ui/content_suggestions/cells/content_suggestions_most_visited_tile.h"
+#import "ios/chrome/browser/ui/favicon/favicon_attributes.h"
+#import "ios/chrome/browser/ui/favicon/favicon_view.h"
+#include "ios/chrome/browser/ui/ui_util.h"
+#import "ios/chrome/browser/ui/uikit_ui_util.h"
+#include "url/gurl.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+namespace {
+const CGFloat kSpacingIPhone = 16;
+const CGFloat kSpacingIPad = 24;
+}
+
+#pragma mark - ContentSuggestionsMostVisitedItem
+
+@implementation ContentSuggestionsMostVisitedItem
+
+@synthesize suggestionIdentifier = _suggestionIdentifier;
+@synthesize suggestions = _suggestions;
+
+- (instancetype)initWithType:(NSInteger)type {
+  self = [super initWithType:type];
+  if (self) {
+    self.cellClass = [ContentSuggestionsMostVisitedCell class];
+  }
+  return self;
+}
+
+- (void)configureCell:(ContentSuggestionsMostVisitedCell*)cell {
+  [super configureCell:cell];
+  [cell setSuggestions:self.suggestions];
+}
+
+@end
+
+#pragma mark - ContentSuggestionsMostVisitedCell
+
+@interface ContentSuggestionsMostVisitedCell ()
+
+// The Most Visited tiles to be displayed.
+@property(nonatomic, strong)
+    NSMutableArray<ContentSuggestionsMostVisitedTile*>* tiles;
+
+// The first line of Most Visited tiles.
+@property(nonatomic, strong) UIStackView* firstLine;
+
+// The second line of Most Visited tiles, displayed below the first one.
+@property(nonatomic, strong) UIStackView* secondLine;
+
+// Contains both stack views.
+@property(nonatomic, copy) NSArray<UIStackView*>* stackViews;
+
+// Superview for the stack views, used to center them.
+@property(nonatomic, strong) UIView* stackContainer;
+
+// Width of the |stackContainer|, allowing resizing.
+@property(nonatomic, strong) NSLayoutConstraint* containerWidth;
+
+// Number of tiles per line during the previous layout.
+@property(nonatomic, assign) NSUInteger previousNumberOfTilesPerLine;
+
+@end
+
+@implementation ContentSuggestionsMostVisitedCell : MDCCollectionViewCell
+
+@synthesize tiles = _tiles;
+@synthesize firstLine = _firstLine;
+@synthesize secondLine = _secondLine;
+@synthesize stackViews = _stackViews;
+@synthesize stackContainer = _stackContainer;
+@synthesize containerWidth = _containerWidth;
+@synthesize previousNumberOfTilesPerLine = _previousNumberOfTilesPerLine;
+
+#pragma mark - Public
+
+- (instancetype)initWithFrame:(CGRect)frame {
+  self = [super initWithFrame:frame];
+  if (self) {
+    _tiles = [NSMutableArray array];
+    _firstLine = [[UIStackView alloc] init];
+    _secondLine = [[UIStackView alloc] init];
+    _stackViews = @[ _firstLine, _secondLine ];
+    _stackContainer = [[UIView alloc] init];
+    _previousNumberOfTilesPerLine = 0;
+
+    for (UIStackView* row in self.stackViews) {
+      row.axis = UILayoutConstraintAxisHorizontal;
+      row.spacing = [self spacing];
+      row.translatesAutoresizingMaskIntoConstraints = NO;
+      [_stackContainer addSubview:row];
+      row.layoutMarginsRelativeArrangement = YES;
+    }
+
+    _stackContainer.translatesAutoresizingMaskIntoConstraints = NO;
+
+    [self.contentView addSubview:_stackContainer];
+
+    [_stackContainer.centerXAnchor
+        constraintEqualToAnchor:self.contentView.centerXAnchor]
+        .active = YES;
+    _containerWidth = [_stackContainer.widthAnchor constraintEqualToConstant:0];
+    _containerWidth.active = YES;
+
+    ApplyVisualConstraints(@[ @"V:|[container]|" ],
+                           @{ @"container" : _stackContainer });
+    ApplyVisualConstraints(
+        @[
+          @"V:|[first][second]|", @"H:|[first]-(>=0)-|",
+          @"H:|[second]-(>=0)-|"
+        ],
+        @{ @"first" : _firstLine,
+           @"second" : _secondLine });
+  }
+  return self;
+}
+
+- (void)setSuggestions:(NSArray<ContentSuggestionsMostVisited*>*)suggestions {
+  [self.tiles removeAllObjects];
+  for (ContentSuggestionsMostVisited* suggestion in suggestions) {
+    [self.tiles addObject:[ContentSuggestionsMostVisitedTile
+                              tileWithTitle:suggestion.title
+                                 attributes:suggestion.attributes]];
+  }
+}
+
+- (NSUInteger)numberOfTilesPerLine {
+  CGFloat availableWidth = self.contentView.bounds.size.width;
+
+  if (availableWidth > [self widthForNumberOfItem:4])
+    return 4;
+  if (availableWidth > [self widthForNumberOfItem:3])
+    return 3;
+  if (availableWidth > [self widthForNumberOfItem:2])
+    return 2;
+
+  NOTREACHED();
+  return 2;
+}
+
+#pragma mark - UIView
+
+// Implements -layoutSubviews as per instructions in documentation for
+// +[MDCCollectionViewCell cr_preferredHeightForWidth:forItem:].
+- (void)layoutSubviews {
+  [super layoutSubviews];
+
+  [self applyLayout];
+
+  [super layoutSubviews];
+}
+
+#pragma mark - Private
+
+// Layouts the tiles. The view is modified only if the number of tiles per line
+// changes.
+- (void)applyLayout {
+  NSUInteger numberOfTilesPerLine = [self numberOfTilesPerLine];
+
+  if (numberOfTilesPerLine == self.previousNumberOfTilesPerLine) {
+    return;
+  }
+  self.previousNumberOfTilesPerLine = numberOfTilesPerLine;
+
+  for (UIStackView* row in self.stackViews) {
+    while (row.arrangedSubviews.count > 0) {
+      UIView* view = row.arrangedSubviews.firstObject;
+      [row removeArrangedSubview:view];
+      [view removeFromSuperview];
+    }
+  }
+
+  NSUInteger numberOfTilesFirstLine =
+      MIN(numberOfTilesPerLine, self.tiles.count);
+  for (NSUInteger i = 0; i < numberOfTilesFirstLine; i++) {
+    [self.firstLine addArrangedSubview:self.tiles[i]];
+  }
+  if (self.tiles.count > numberOfTilesPerLine) {
+    NSUInteger totalNumberOfTiles =
+        MIN(2 * numberOfTilesPerLine, self.tiles.count);
+    for (NSUInteger i = numberOfTilesPerLine; i < totalNumberOfTiles; i++) {
+      [self.secondLine addArrangedSubview:self.tiles[i]];
+    }
+  }
+
+  self.containerWidth.constant =
+      [self widthForNumberOfItem:numberOfTilesPerLine];
+}
+
+// Returns the spacing between tiles, based on the device.
+- (CGFloat)spacing {
+  return IsIPadIdiom() ? kSpacingIPad : kSpacingIPhone;
+}
+
+// Returns the width necessary to fit |numberOfItem| items.
+- (CGFloat)widthForNumberOfItem:(NSUInteger)numberOfItem {
+  return (numberOfItem - 1) * [self spacing] +
+         numberOfItem * [ContentSuggestionsMostVisitedTile width];
+}
+
+@end