Implement Mode.ANIMATED_THUMBNAIL used for autoplaying animated images

This patch introduces a new `ImageContentRenderer` mode used for
autoplaying animated images. The mode shares url resolving semantics
with `FULL_SIZE` and `STICKER`, as such not just fetching thumbnail data
but shares sizing semantics with `THUMBNAIL` (scaling by image height).

This change fixes animated images not playing in cases in which only a
static thumbnail would be loaded.

This new mode will only be chosen if the message content is actually a
playable image, as such limiting bandwith usage to the required amount
by avoiding to load normal images fully (still fetching animated images
will increase bandwith usage as a whole of course).

Signed-off-by: networkException <git@nwex.de>

vector/src/main/java/im/vector/app/features/home/room/detail/timeline/factory/MessageItemFactory.kt

@@ -453,12 +453,15 @@ class MessageItemFactory @Inject constructor(
                 maxWidth = maxWidth,
                 allowNonMxcUrls = informationData.sendState.isSending()
         )
+
+        val playable = messageContent.mimeType == MimeTypes.Gif
+
         return MessageImageVideoItem_()
                 .attributes(attributes)
                 .leftGuideline(avatarSizeProvider.leftGuideline)
                 .imageContentRenderer(imageContentRenderer)
                 .contentUploadStateTrackerBinder(contentUploadStateTrackerBinder)
-                .playable(messageContent.mimeType == MimeTypes.Gif)
+                .playable(playable)
                 .highlighted(highlight)
                 .mediaData(data)
                 .apply {
@@ -472,6 +475,10 @@ class MessageItemFactory @Inject constructor(
                             callback?.onImageMessageClicked(messageContent, data, view, emptyList())
                         }
                     }
+                }.apply {
+                    if (playable && vectorPreferences.autoplayAnimatedImages()) {
+                        mode(ImageContentRenderer.Mode.ANIMATED_THUMBNAIL)
+                    }
                 }
     }
 

vector/src/main/java/im/vector/app/features/media/ImageContentRenderer.kt

@@ -85,6 +85,7 @@ class ImageContentRenderer @Inject constructor(
 
     enum class Mode {
         FULL_SIZE,
+        ANIMATED_THUMBNAIL,
         THUMBNAIL,
         STICKER
     }
@@ -231,6 +232,7 @@ class ImageContentRenderer @Inject constructor(
             val contentUrlResolver = activeSessionHolder.getActiveSession().contentUrlResolver()
             val resolvedUrl = when (mode) {
                 Mode.FULL_SIZE,
+                Mode.ANIMATED_THUMBNAIL,
                 Mode.STICKER -> resolveUrl(data)
                 Mode.THUMBNAIL -> contentUrlResolver.resolveThumbnail(data.url, size.width, size.height, ContentUrlResolver.ThumbnailMethod.SCALE)
             }
@@ -269,6 +271,7 @@ class ImageContentRenderer @Inject constructor(
                     finalHeight = height
                     finalWidth = width
                 }
+                Mode.ANIMATED_THUMBNAIL,
                 Mode.THUMBNAIL -> {
                     finalHeight = min(maxImageWidth * height / width, maxImageHeight)
                     finalWidth = finalHeight * width / height