Added placeholder support (#4897)

* Added placeholder suport

* Updated per CR comments

source/ios/AdaptiveCards/ADCIOSVisualizer/ADCIOSVisualizer/ADCResolver.m

@@ -14,24 +14,31 @@ @implementation ADCResolver
 - (UIImageView *)resolveImageViewResource:(NSURL *)url
 {
     __block UIImageView *imageView = [[UIImageView alloc] init];
-    NSURLSessionDownloadTask *downloadPhotoTask = [[NSURLSession sharedSession]
-        downloadTaskWithURL:url
-          completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {
-              // iOS uses NSInteger as HTTP URL status
-              NSInteger status = 200;
-              if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
-                  status = ((NSHTTPURLResponse *)response).statusCode;
-              }
-              if (!error && status == 200) {
-                  UIImage *image = [UIImage imageWithData:[NSData dataWithContentsOfURL:location]];
-                  if (image) {
-                      dispatch_async(dispatch_get_main_queue(), ^{
-                          imageView.image = image;
-                      });
+    // check if custom scheme bundle exists
+    if ([url.scheme isEqualToString:@"bundle"]) {
+        // if bundle scheme, load an image from sample's main bundle
+        UIImage *image = [UIImage imageNamed:url.pathComponents.lastObject];
+        imageView.image = image;
+    } else {
+        NSURLSessionDownloadTask *downloadPhotoTask = [[NSURLSession sharedSession]
+            downloadTaskWithURL:url
+              completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {
+                  // iOS uses NSInteger as HTTP URL status
+                  NSInteger status = 200;
+                  if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
+                      status = ((NSHTTPURLResponse *)response).statusCode;
                   }
-              }
-          }];
-    [downloadPhotoTask resume];
+                  if (!error && status == 200) {
+                      UIImage *image = [UIImage imageWithData:[NSData dataWithContentsOfURL:location]];
+                      if (image) {
+                          dispatch_async(dispatch_get_main_queue(), ^{
+                              imageView.image = image;
+                          });
+                      }
+                  }
+              }];
+        [downloadPhotoTask resume];
+    }
     return imageView;
 }
 

source/ios/AdaptiveCards/ADCIOSVisualizer/ADCIOSVisualizer/ViewController.m

@@ -168,6 +168,8 @@ - (void)viewDidLoad
     [_resolvers setResourceResolver:resolver scheme:@"http"];
     [_resolvers setResourceResolver:resolver scheme:@"https"];
     [_resolvers setResourceResolver:resolver scheme:@"data"];
+    // register a custom scheme bundle with resolver
+    [_resolvers setResourceResolver:resolver scheme:@"bundle"];
     _enableCustomRenderer = NO;
     self.curView = nil;
 

source/ios/AdaptiveCards/AdaptiveCards/AdaptiveCards/ACRImageRenderer.mm

@@ -46,16 +46,38 @@ - (UIView *)render:(UIView<ACRIContentHoldingView> *)viewGroup
     BOOL isAspectRatioNeeded = !(pixelWidth && pixelHeight);
     CGSize cgsize = [acoConfig getImageSize:imgElem->GetImageSize()];
 
-    NSString *key = [NSString stringWithCString:imgElem->GetUrl().c_str() encoding:[NSString defaultCStringEncoding]];
+    // makes parts for building a key to UIImage, there are different interfaces for loading the images
+    // we list all the parts that are needed in building the key.
+    NSString *number = [[NSNumber numberWithUnsignedLongLong:(unsigned long long)(elem.get())] stringValue];
+    NSString *urlString = [NSString stringWithCString:imgElem->GetUrl().c_str() encoding:[NSString defaultCStringEncoding]];
+    NSDictionary *pieces = @{
+        @"number" : number,
+        @"url" : urlString
+    };
+
+    NSString *key = makeKeyForImage(acoConfig, @"image", pieces);
     NSMutableDictionary *imageViewMap = [rootView getImageMap];
-    NSURL *url = [NSURL URLWithString:key];
+    UIImage *img = imageViewMap[key];
+
+    // try get an UIImageView
+    view = [rootView getImageView:key];
+    if (!view && img) {
+        // if an UIImage is available, but UIImageView is missing, create one
+        ACRUIImageView *acrImageView = [[ACRUIImageView alloc] initWithFrame:CGRectMake(0, 0, cgsize.width, cgsize.height)];
+        acrImageView.image = img;
+        if (imgElem->GetImageStyle() == ImageStyle::Person) {
+            acrImageView.isPersonStyle = YES;
+            [acrImageView setNeedsLayout];
+        }
+        view = acrImageView;
+    }
 
-    if (ACOImageViewIF == [acoConfig getResolverIFType:[url scheme]]) {
-        NSNumber *number = [NSNumber numberWithUnsignedLongLong:(unsigned long long)(elem.get())];
-        key = [number stringValue];
+    if (view && img) {
+        // if we already have UIImageView and UIImage, configures the constraints and turn off the notification
+        [rootView removeObserverOnImageView:@"image" onObject:view keyToImageView:key];
+        [self configUpdateForUIImageView:acoElem config:acoConfig image:img imageView:view];
     }
 
-    UIImage *img = imageViewMap[key];
     ImageSize size = ImageSize::None;
     CGSize intrinsicContentSize;
     if (!hasExplicitMeasurements) {
@@ -85,22 +107,6 @@ - (UIView *)render:(UIView<ACRIContentHoldingView> *)viewGroup
         }
     }
 
-
-    if (img) {
-        ACRUIImageView *acrImageView = [[ACRUIImageView alloc] initWithFrame:CGRectMake(0, 0, cgsize.width, cgsize.height)];
-        acrImageView.image = img;
-        if (imgElem->GetImageStyle() == ImageStyle::Person) {
-            acrImageView.isPersonStyle = YES;
-            [acrImageView setNeedsLayout];
-        }
-        view = acrImageView;
-        [self configUpdateForUIImageView:acoElem config:acoConfig image:img imageView:view];
-    } else {
-        NSNumber *number = [NSNumber numberWithUnsignedLongLong:(unsigned long long)imgElem.get()];
-        NSString *key = [number stringValue];
-        view = [rootView getImageView:key];
-    }
-
     ACRContentHoldingUIView *wrappingview = [[ACRContentHoldingUIView alloc] initWithFrame:view.frame];
 
     if (!view) {

source/ios/AdaptiveCards/AdaptiveCards/AdaptiveCards/ACRMediaRenderer.mm

@@ -43,26 +43,41 @@ - (UIView *)render:(UIView<ACRIContentHoldingView> *)viewGroup
     std::shared_ptr<Media> mediaElem = std::dynamic_pointer_cast<Media>(elem);
 
     NSMutableDictionary *imageViewMap = [rootView getImageMap];
-    NSString *key = [NSString stringWithCString:mediaElem->GetPoster().c_str() encoding:[NSString defaultCStringEncoding]];
-    UIImage *img = imageViewMap[key];
+
+    // makes parts for building a key to UIImage, there are different interfaces for loading the images
+    // we list all the parts that are needed in building the key.
+    NSString *urlString = [NSString stringWithCString:mediaElem->GetPoster().c_str() encoding:[NSString defaultCStringEncoding]];
+    NSString *numberString = [[NSNumber numberWithUnsignedLongLong:(unsigned long long)(elem.get())] stringValue];
+    NSString *piikey = [NSString stringWithCString:[acoConfig getHostConfig] -> GetMedia().playButton.c_str() encoding:[NSString defaultCStringEncoding]];
+    NSString *piikeyViewIF = [NSString stringWithFormat:@"%llu_playIcon", (unsigned long long)elem.get()];
+
+    NSDictionary *pieces = @{
+        @"number" : numberString,
+        @"url" : urlString,
+        @"playicon-url-imageView" : piikey,
+        @"playicon-url-viewIF" : piikeyViewIF
+    };
+
+    NSString *mediaKey = makeKeyForImage(acoConfig, @"media-poster", pieces);
+    UIImage *img = imageViewMap[mediaKey];
     UIImageView *view = nil;
-    CGFloat heightToWidthRatio = 0.0f;
     ACRContentHoldingUIView *contentholdingview = nil;
 
     // if poster is available, restrict the image size to the width of superview, and adjust the height accordingly
     if (img) {
-        view = [[UIImageView alloc] initWithImage:img];
-
-        if (img.size.width > 0) {
-            heightToWidthRatio = img.size.height / img.size.width;
+        contentholdingview = (ACRContentHoldingUIView *)[rootView getImageView:mediaKey];
+        if (contentholdingview) {
+            view = contentholdingview.subviews[0];
+        } else {
+            view = [[UIImageView alloc] initWithImage:img];
+            contentholdingview = [[ACRContentHoldingUIView alloc] init];
+            [contentholdingview addSubview:view];
         }
-        contentholdingview = [[ACRContentHoldingUIView alloc] init];
-        [contentholdingview addSubview:view];
+        // if we already have UIImageView and UIImage, configures the constraints and turn off the notification
         [self configUpdateForUIImageView:acoElem config:acoConfig image:img imageView:view];
+        [rootView removeObserverOnImageView:@"image" onObject:view keyToImageView:mediaKey];
     } else {
-        NSNumber *number = [NSNumber numberWithUnsignedLongLong:(unsigned long long)mediaElem.get()];
-        NSString *key = [number stringValue];
-        contentholdingview = (ACRContentHoldingUIView *)[rootView getImageView:key];
+        contentholdingview = (ACRContentHoldingUIView *)[rootView getImageView:mediaKey];
         if (contentholdingview) {
             view = contentholdingview.subviews[0];
         }
@@ -81,16 +96,16 @@ - (UIView *)render:(UIView<ACRIContentHoldingView> *)viewGroup
     view.contentMode = UIViewContentModeScaleAspectFill;
     contentholdingview.isMediaType = YES;
 
+
     // process play icon image
-    NSString *piikey = [NSString stringWithCString:[acoConfig getHostConfig] -> GetMedia().playButton.c_str() encoding:[NSString defaultCStringEncoding]];
-    UIImage *playIconImage = imageViewMap[piikey];
+    NSString *playIconKey = makeKeyForImage(acoConfig, @"media-playicon-image", pieces);
+    UIImage *playIconImage = imageViewMap[playIconKey];
     UIImageView *playIconImageView = nil;
     BOOL hideDefaultPlayIcon = NO;
 
-    if (!playIconImage) {
-        NSString *key = [NSString stringWithFormat:@"%llu_playIcon", (unsigned long long)elem.get()];
-        playIconImageView = [rootView getImageView:key];
-    } else {
+    playIconImageView = [rootView getImageView:playIconKey];
+
+    if (playIconImage && !playIconImageView) {
         playIconImageView = [[UIImageView alloc] initWithImage:playIconImage];
     }
 

source/ios/AdaptiveCards/AdaptiveCards/AdaptiveCards/ACRView.mm

@@ -216,6 +216,8 @@ - (void)processBaseCardElement:(std::shared_ptr<BaseCardElement> const &)elem
                 ^(NSObject<ACOIResourceResolver> *imageResourceResolver, NSString *key, std::shared_ptr<BaseCardElement> const &elem, NSURL *url, ACRView *rootView) {
                     UIImageView *view = [imageResourceResolver resolveImageViewResource:url];
                     if (view) {
+                        // check image already exists in the returned image view and register the image
+                        [self registerImageFromUIImageView:view key:key];
                         [view addObserver:self
                                forKeyPath:@"image"
                                   options:NSKeyValueObservingOptionNew
@@ -240,6 +242,8 @@ - (void)processBaseCardElement:(std::shared_ptr<BaseCardElement> const &)elem
                     ^(NSObject<ACOIResourceResolver> *imageResourceResolver, NSString *key, std::shared_ptr<BaseCardElement> const &elem, NSURL *url, ACRView *rootView) {
                         UIImageView *view = [imageResourceResolver resolveImageViewResource:url];
                         if (view) {
+                            // check image already exists in the returned image view and register the image
+                            [self registerImageFromUIImageView:view key:key];
                             [view addObserver:self
                                    forKeyPath:@"image"
                                       options:NSKeyValueObservingOptionNew
@@ -268,6 +272,8 @@ - (void)processBaseCardElement:(std::shared_ptr<BaseCardElement> const &)elem
                         UIImageView *view = [imageResourceResolver resolveImageViewResource:url];
                         ACRContentHoldingUIView *contentholdingview = [[ACRContentHoldingUIView alloc] initWithFrame:view.frame];
                         if (view) {
+                            // check image already exists in the returned image view and register the image
+                            [self registerImageFromUIImageView:view key:key];
                             [contentholdingview addSubview:view];
                             contentholdingview.isMediaType = YES;
                             [view addObserver:self
@@ -288,6 +294,8 @@ - (void)processBaseCardElement:(std::shared_ptr<BaseCardElement> const &)elem
                     ^(NSObject<ACOIResourceResolver> *imageResourceResolver, NSString *key, std::shared_ptr<BaseCardElement> const &elem, NSURL *url, ACRView *rootView) {
                         UIImageView *view = [imageResourceResolver resolveImageViewResource:url];
                         if (view) {
+                            // check image already exists in the returned image view and register the image
+                            [self registerImageFromUIImageView:view key:key];
                             [view addObserver:rootView
                                    forKeyPath:@"image"
                                       options:NSKeyValueObservingOptionNew
@@ -575,12 +583,25 @@ - (void)observeValueForKeyPath:(NSString *)path ofObject:(id)object change:(NSDi
     }
 }
 
+// remove observer from UIImageView
+- (void)removeObserverOnImageView:(NSString *)KeyPath onObject:(NSObject *)object keyToImageView:(NSString *)key
+{
+    if ([object isKindOfClass:[UIImageView class]]) {
+        if (_imageViewContextMap[key]) {
+            [self removeObserver:self forKeyPath:KeyPath onObject:object];
+        }
+    }
+}
+
 - (void)removeObserver:(NSObject *)observer forKeyPath:(NSString *)path onObject:(NSObject *)object
 {
-    _numberOfSubscribers--;
-    [object removeObserver:self forKeyPath:path];
-    [_setOfRemovedObservers addObject:object];
-    [self callDidLoadElementsIfNeeded];
+    // check that makes sure that there are subscribers, and the given observer is not one of the removed observers
+    if (_numberOfSubscribers && ![_setOfRemovedObservers containsObject:object]) {
+        _numberOfSubscribers--;
+        [object removeObserver:self forKeyPath:path];
+        [_setOfRemovedObservers addObject:object];
+        [self callDidLoadElementsIfNeeded];
+    }
 }
 
 - (void)loadBackgroundImageAccordingToResourceResolverIF:(std::shared_ptr<BackgroundImage> const &)backgroundImage key:(NSString *)key observerAction:(ObserverActionBlock)observerAction
@@ -785,4 +806,12 @@ - (ACRColumnView *)peekCurrentShowCard
     return showcard;
 }
 
+// check if UIImageView already contains an UIImage, if so, add it the image map.
+- (void)registerImageFromUIImageView:(UIImageView *)imageView key:(NSString *)key
+{
+    if (imageView.image) {
+        self->_imageViewMap[key] = imageView.image;
+    }
+}
+
 @end

source/ios/AdaptiveCards/AdaptiveCards/AdaptiveCards/ACRViewPrivate.h

@@ -45,6 +45,8 @@ typedef void (^ObserverActionBlockForBaseAction)(NSObject<ACOIResourceResolver>
                                            key:(NSString *)key
                                 observerAction:(ObserverActionBlock)observerAction;
 
+- (void)removeObserverOnImageView:(NSString *)KeyPath onObject:(NSObject *)object keyToImageView:(NSString *)key;
+
 - (void)updatePaddingMap:(std::shared_ptr<CollectionTypeElement> const &)collection view:(UIView *)view;
 
 - (UIView *)getBleedTarget:(InternalId const &)internalId;

source/ios/AdaptiveCards/AdaptiveCards/AdaptiveCards/UtiliOS.h

@@ -85,3 +85,5 @@ void configVerticalAlignmentConstraintsForBackgroundImageView(const BackgroundIm
 void configWidthAndHeightAnchors(UIView *superView, UIImageView *imageView, bool isComplimentaryAxisHorizontal);
 
 NSMutableAttributedString *initAttributedText(ACOHostConfig *acoConfig, const std::string &text, const AdaptiveCards::RichTextElementProperties &textElementProperties, ACRContainerStyle style);
+
+NSString *makeKeyForImage(ACOHostConfig *acoConfig, NSString *keyType, NSDictionary<NSString *, NSString *> *pieces);

source/ios/AdaptiveCards/AdaptiveCards/AdaptiveCards/UtiliOS.mm

@@ -751,3 +751,26 @@ void configWidthAndHeightAnchors(UIView *superView, UIImageView *imageView, bool
 
     return [[NSMutableAttributedString alloc] initWithString:[NSString stringWithCString:text.c_str() encoding:NSUTF8StringEncoding] attributes:@{NSFontAttributeName : font, NSForegroundColorAttributeName : foregroundColor}];
 }
+
+NSString *makeKeyForImage(ACOHostConfig *acoConfig, NSString *keyType, NSDictionary<NSString *, NSString *> *pieces)
+{
+    ACOResolverIFType resolverType = ACODefaultIF;
+    NSString *urlString = pieces[@"url"], *key = urlString;
+    NSURL *url = nil;
+
+    if (urlString) {
+        url = [NSURL URLWithString:urlString];
+        resolverType = [acoConfig getResolverIFType:[url scheme]];
+    }
+
+    if ([keyType isEqualToString:@"image"] || [keyType isEqualToString:@"media-poster"]) {
+        if (ACOImageViewIF == resolverType) {
+            key = pieces[@"number"];
+        }
+    } else if ([keyType isEqualToString:@"media-playicon-image"]) {
+        key = (ACOImageViewIF == resolverType) ? pieces[@"playicon-url-viewIF"] : pieces[@"playicon-url"];
+    } else if ([keyType isEqualToString:@"media-playicon-imageView"]) {
+        key = (ACOImageViewIF == resolverType) ? pieces[@"playicon-url-imageView-viewIF"] : pieces[@"playicon-url-imageView"];
+    }
+    return key;
+}