Add no-image image in ContentSuggestions

ios/chrome/browser/ui/content_suggestions/cells/content_suggestions_article_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_article_item.h"
 
 #include "base/time/time.h"
 #import "ios/chrome/browser/ui/colors/MDCPalette+CrAdditions.h"
 #import "ios/chrome/browser/ui/uikit_ui_util.h"
 #import "ios/chrome/browser/ui/util/i18n_string.h"
+#import "ios/third_party/material_components_ios/src/components/Palettes/src/MaterialPalettes.h"
 #import "ios/third_party/material_components_ios/src/components/Typography/src/MaterialTypography.h"
 #include "url/gurl.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 namespace {
 const CGFloat kImageSize = 72;
 // When updating this, make sure to update |layoutSubviews|.
 const CGFloat kStandardSpacing = 16;
+// Size of the icon displayed when there is not image.
+const CGFloat kIconSize = 24;
+// Name of the image.
+NSString* const kImageName = @"content_suggestions_no_image";

[jif, 2017/03/28 09:04:58]

kImageName can be made more precise. Possible replacements:
kNoThumbnailImageName.

[gambard, 2017/03/28 09:40:29]

The backend service use "fetchSuggestionImage". I have added comments to make it
clearer.

+// No image icon percentage of white.
+const CGFloat kImageWhite = 0.38;
+// No image background percentage of white.
+const CGFloat kBackgroundWhite = 0.95;
+const CGFloat kAnimationDuration = 0.3;
 }
 
 @interface ContentSuggestionsArticleItem ()
 
 @property(nonatomic, copy) NSString* subtitle;
 // Used to check if the image has already been fetched. There is no way to
 // discriminate between failed image download and nonexitent image. The article
 // tries to download the image only once.
 @property(nonatomic, assign) BOOL imageFetched;
 
@@ skipping 18 matching lines @@
                     subtitle:(NSString*)subtitle
                     delegate:(id<ContentSuggestionsArticleItemDelegate>)delegate
                          url:(const GURL&)url {
   self = [super initWithType:type];
   if (self) {
     self.cellClass = [ContentSuggestionsArticleCell class];
     _title = [title copy];
     _subtitle = [subtitle copy];
     _articleURL = url;
     _delegate = delegate;
-    _image = [self emptyImageBackground];
   }
   return self;
 }
 
 - (void)configureCell:(ContentSuggestionsArticleCell*)cell {
   [super configureCell:cell];
   if (!self.imageFetched) {
     self.imageFetched = YES;
     // Fetch the image. During the fetch the cell's image should still be set.
     [self.delegate loadImageForArticleItem:self];
   }
   cell.titleLabel.text = self.title;
   cell.subtitleLabel.text = self.subtitle;
-  cell.imageView.image = self.image;
+  if (self.image)

[jif, 2017/03/28 09:04:58]

we are already checking in |setContentImage| if its parameter is nil.

Either define |setContentImage| as never taking in a nil parameter (and put a
DCHECK inside), or have |setContentImage| support taking in nil parameters.

[gambard, 2017/03/28 09:40:29]

Done.

+    [cell setContentImage:self.image];
   [cell setPublisherName:self.publisher date:self.publishDate];
 }
 
-#pragma mark - Private
-
-- (UIImage*)emptyImageBackground {
-  // TODO(crbug.com/698171): Remove this function once we have real background
-  // image.
-  UIColor* color = [UIColor lightGrayColor];
-  CGRect rect = CGRectMake(0, 0, 1, 1);
-  UIGraphicsBeginImageContext(rect.size);
-  [color setFill];
-  UIRectFill(rect);
-  UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
-  UIGraphicsEndImageContext();
-  return image;
-}
-
 @end
 
 #pragma mark - ContentSuggestionsArticleCell
 
 @interface ContentSuggestionsArticleCell ()
 
 @property(nonatomic, strong) UILabel* publisherLabel;
+@property(nonatomic, strong) UIView* imageContainer;
+@property(nonatomic, strong) UIImageView* noImageIcon;
+@property(nonatomic, strong) UIImageView* contentImageView;
 
 // Applies the constraints on the elements. Called in the init.
 - (void)applyConstraints;
 
 @end
 
 @implementation ContentSuggestionsArticleCell
 
 @synthesize titleLabel = _titleLabel;
 @synthesize subtitleLabel = _subtitleLabel;
-@synthesize imageView = _imageView;
+@synthesize imageContainer = _imageContainer;
+@synthesize noImageIcon = _noImageIcon;
 @synthesize publisherLabel = _publisherLabel;
+@synthesize contentImageView = _contentImageView;
 
 - (instancetype)initWithFrame:(CGRect)frame {
   self = [super initWithFrame:frame];
   if (self) {
     _titleLabel = [[UILabel alloc] initWithFrame:CGRectZero];
     _subtitleLabel = [[UILabel alloc] initWithFrame:CGRectZero];
-    _imageView = [[UIImageView alloc] initWithFrame:CGRectZero];
+    _imageContainer = [[UIView alloc] initWithFrame:CGRectZero];
+    _noImageIcon = [[UIImageView alloc] initWithFrame:CGRectZero];
     _publisherLabel = [[UILabel alloc] initWithFrame:CGRectZero];
 
     _titleLabel.numberOfLines = 2;
     _subtitleLabel.numberOfLines = 2;
     [_subtitleLabel setContentHuggingPriority:UILayoutPriorityDefaultHigh
                                       forAxis:UILayoutConstraintAxisVertical];
     [_titleLabel setContentHuggingPriority:UILayoutPriorityDefaultHigh
                                    forAxis:UILayoutConstraintAxisVertical];
-    _imageView.contentMode = UIViewContentModeScaleAspectFill;
-    _imageView.clipsToBounds = YES;
 
-    _imageView.translatesAutoresizingMaskIntoConstraints = NO;
+    _imageContainer.translatesAutoresizingMaskIntoConstraints = NO;
+    _noImageIcon.translatesAutoresizingMaskIntoConstraints = NO;
     _titleLabel.translatesAutoresizingMaskIntoConstraints = NO;
     _subtitleLabel.translatesAutoresizingMaskIntoConstraints = NO;
     _publisherLabel.translatesAutoresizingMaskIntoConstraints = NO;
 
-    [self.contentView addSubview:_imageView];
+    [self.contentView addSubview:_imageContainer];
     [self.contentView addSubview:_titleLabel];
     [self.contentView addSubview:_subtitleLabel];
     [self.contentView addSubview:_publisherLabel];
 
+    [_imageContainer addSubview:_noImageIcon];
+
+    _imageContainer.backgroundColor =
+        [UIColor colorWithWhite:kBackgroundWhite alpha:1];
+    _noImageIcon.image = [[UIImage imageNamed:kImageName]
+        imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
+    [_noImageIcon setTintColor:[UIColor colorWithWhite:kImageWhite alpha:1]];
+
     _titleLabel.font = [MDCTypography subheadFont];
     _subtitleLabel.font = [MDCTypography body1Font];
     _publisherLabel.font = [MDCTypography captionFont];
 
     _subtitleLabel.textColor = [[MDCPalette greyPalette] tint700];
     _publisherLabel.textColor = [[MDCPalette greyPalette] tint700];
 
     [self applyConstraints];
   }
   return self;
 }
 
+- (void)setContentImage:(UIImage*)image {
+  if (!image)
+    return;
+  self.contentImageView = [[UIImageView alloc] initWithFrame:CGRectZero];
+  self.contentImageView.translatesAutoresizingMaskIntoConstraints = NO;
+  self.contentImageView.contentMode = UIViewContentModeScaleAspectFill;
+  self.contentImageView.clipsToBounds = YES;
+  self.contentImageView.image = image;
+
+  self.contentImageView.alpha = 0;
+  [self.imageContainer addSubview:self.contentImageView];
+  AddSameSizeConstraint(self.contentImageView, self.imageContainer);
+
+  [UIView animateWithDuration:kAnimationDuration
+                   animations:^{
+                     self.contentImageView.alpha = 1;
+                   }];
+}
+
 - (void)setPublisherName:(NSString*)publisherName date:(base::Time)publishDate {
   NSDate* date = [NSDate dateWithTimeIntervalSince1970:publishDate.ToDoubleT()];
   NSString* dateString =
       [NSDateFormatter localizedStringFromDate:date
                                      dateStyle:NSDateFormatterMediumStyle
                                      timeStyle:NSDateFormatterNoStyle];
 
   self.publisherLabel.text = AdjustStringForLocaleDirection(
       [NSString stringWithFormat:@"%@ - %@.", publisherName, dateString]);
 }
 
+- (void)prepareForReuse {
+  [self.contentImageView removeFromSuperview];
+}
+
 #pragma mark - UIView
 
 // Implements -layoutSubviews as per instructions in documentation for
 // +[MDCCollectionViewCell cr_preferredHeightForWidth:forItem:].
 - (void)layoutSubviews {
   [super layoutSubviews];
 
   // Adjust the text label preferredMaxLayoutWidth when the parent's width
   // changes, for instance on screen rotation.
   CGFloat parentWidth = CGRectGetWidth(self.contentView.bounds);
 
   self.titleLabel.preferredMaxLayoutWidth =
       parentWidth - kImageSize - 3 * kStandardSpacing;
   self.subtitleLabel.preferredMaxLayoutWidth =
       parentWidth - kImageSize - 3 * kStandardSpacing;
 
   // Re-layout with the new preferred width to allow the label to adjust its
   // height.
   [super layoutSubviews];
 }
 
 #pragma mark - Private
 
 - (void)applyConstraints {
   [NSLayoutConstraint activateConstraints:@[
-    [_imageView.widthAnchor constraintEqualToConstant:kImageSize],
-    [_imageView.heightAnchor constraintEqualToAnchor:_imageView.widthAnchor],
-    [_imageView.topAnchor constraintEqualToAnchor:_titleLabel.topAnchor],
+    [_imageContainer.widthAnchor constraintEqualToConstant:kImageSize],
+    [_imageContainer.heightAnchor
+        constraintEqualToAnchor:_imageContainer.widthAnchor],
+    [_imageContainer.topAnchor constraintEqualToAnchor:_titleLabel.topAnchor],
     [_publisherLabel.topAnchor
-        constraintGreaterThanOrEqualToAnchor:_imageView.bottomAnchor
+        constraintGreaterThanOrEqualToAnchor:_imageContainer.bottomAnchor
                                     constant:kStandardSpacing],
     [_publisherLabel.topAnchor
         constraintGreaterThanOrEqualToAnchor:_subtitleLabel.bottomAnchor
                                     constant:kStandardSpacing],
+
+    // No image icon.
+    [_noImageIcon.centerXAnchor
+        constraintEqualToAnchor:_imageContainer.centerXAnchor],
+    [_noImageIcon.centerYAnchor
+        constraintEqualToAnchor:_imageContainer.centerYAnchor],
+    [_noImageIcon.widthAnchor constraintEqualToConstant:kIconSize],
+    [_noImageIcon.heightAnchor constraintEqualToAnchor:_noImageIcon.widthAnchor]
   ]];
 
   ApplyVisualConstraintsWithMetrics(
       @[
         @"H:|-(space)-[title]-(space)-[image]-(space)-|",
         @"H:|-(space)-[text]-(space)-[image]",
         @"V:|-(space)-[title]-[text]",
         @"H:|-(space)-[publish]-(space)-|",
         @"V:[publish]-|",
       ],
       @{
-        @"image" : _imageView,
+        @"image" : _imageContainer,
         @"title" : _titleLabel,
         @"text" : _subtitleLabel,
         @"publish" : _publisherLabel,
       },
       @{ @"space" : @(kStandardSpacing) });
 }
 
 @end