Better ImageProvider->ThumbnailProvider

The class handles avatars in a special way now - when passed a room id
and, optionally, a user id for a member of that room, it spawns
a newly introduced AvatarResponse that can retrieve the possibly
already cached avatar from the respective Room/User object. This
required some changes in QML, with common code moved out to the special
Avatar specialisation of Image component.

What warranted a dedicated QML component is that Quotient::Avatar
returns the first (possibly empty or smaller resolution) image
immediately while requesting the right one behind the scenes; so
QML Avatar listens on the respective signals from the library and
updates the image when the new avatar arrives - which (i.e. updating) is
in turn somewhat "idiomatic" because of QTBUG-14900. QML Avatar
encapsulates these two peculiarities.

CMakeLists.txt

@@ -155,7 +155,7 @@ message( STATUS )
 set(quaternion_SRCS
     client/quaternionroom.cpp
     client/htmlfilter.cpp
-    client/imageprovider.cpp
+    client/thumbnailprovider.cpp
     client/activitydetector.cpp
     client/dialog.cpp
     client/logindialog.cpp

client/logging_categories.h

@@ -16,7 +16,7 @@ QUO_LOGGING_CATEGORY(EVENTMODEL, "quaternion.models.events")
 QUO_LOGGING_CATEGORY(TIMELINE, "quaternion.timeline")
 QUO_LOGGING_CATEGORY(HTMLFILTER, "quaternion.htmlfilter")
 QUO_LOGGING_CATEGORY(MSGINPUT, "quaternion.messageinput")
-QUO_LOGGING_CATEGORY(IMAGEPROVIDER, "quaternion.imageprovider")
+QUO_LOGGING_CATEGORY(THUMBNAILS, "quaternion.thumbnails")
 
 // Only to be used in QML; shows up here for documentation purpose only
 [[maybe_unused]] QUO_LOGGING_CATEGORY(TIMELINEQML, "quaternion.timeline.qml")

client/qml/Avatar.qml

@@ -0,0 +1,27 @@
+import QtQuick 2.15
+
+Image {
+    readonly property var forRoom: root.room
+    /* readonly */ property var forMember
+
+    property string sourceId: forRoom ? "image://thumbnail/" + forRoom.id
+                                     + (forMember ? '/' + forMember.id : "")
+                                   : ""
+    source: sourceId
+    cache: false // Quotient::Avatar takes care of caching
+    fillMode: Image.PreserveAspectFit
+
+    function reload() {
+        source = ""
+        source = Qt.binding(function() { return sourceId })
+    }
+
+    Connections {
+        target: forRoom
+        function onAvatarChanged() { parent.reload() }
+        function onMemberAvatarChanged(member) {
+            if (member === parent.forMember)
+                parent.reload()
+        }
+    }
+}

client/qml/Timeline.qml

@@ -42,7 +42,7 @@ Page {
 
         property bool showTopic: true
 
-        Image {
+        Avatar {
             id: roomAvatar
             anchors.verticalCenter: headerText.verticalCenter
             anchors.left: parent.left
@@ -53,13 +53,9 @@ Page {
             width: Math.min(headerText.height / implicitHeight * implicitWidth,
                             parent.width / 2.618) // Golden ratio - just for fun
 
-            source: room && room.avatarMediaId
-                    ? "image://mtx/" + room.avatarMediaId : ""
             // Safe upper limit (see also topicField)
             sourceSize: Qt.size(-1, settings.lineSpacing * 9)
 
-            fillMode: Image.PreserveAspectFit
-
             AnimationBehavior on width {
                 NormalNumberAnimation { easing.type: Easing.OutQuad }
             }

client/qml/TimelineItem.qml

@@ -216,10 +216,10 @@ Item {
 
                 text: "<" + time + ">"
             }
-            Image {
+            Avatar {
                 id: authorAvatar
                 visible: (authorSectionVisible || settings.timelineStyleIsXChat)
-                         && settings.show_author_avatars && author.avatarMediaId
+                         && settings.show_author_avatars && paintedHeight > 0
                 anchors.left: timelabel.right
                 anchors.leftMargin: 3
                 height: visible ? settings.minimalTimelineItemHeight
@@ -228,11 +228,9 @@ Item {
                 width: settings.show_author_avatars
                        * settings.minimalTimelineItemHeight
 
-                fillMode: Image.PreserveAspectFit
                 horizontalAlignment: Image.AlignRight
 
-                source: author.avatarMediaId
-                        ? "image://mtx/" + author.avatarMediaId : ""
+                forMember: author
                 sourceSize: Qt.size(width, -1)
 
                 AuthorInteractionArea { }
@@ -427,7 +425,7 @@ Item {
                               ? ""
                               : content.info && content.info.thumbnail_info
                                 && !autoload
-                                ? "image://mtx/" + content.thumbnailMediaId
+                                ? "image://thumbnail/" + content.thumbnailMediaId
                                 : ""
                     maxHeight: chatView.height - textField.height -
                                authorLabel.height * !settings.timelineStyleIsXChat

client/resources.qrc

@@ -22,5 +22,6 @@
         <file>qml/AnimatedTransition.qml</file>
         <file>qml/ScrollFinisher.qml</file>
         <file>qml/Logger.qml</file>
+        <file>qml/Avatar.qml</file>
     </qresource>
 </RCC>