Fix loading m.image events in encrypted rooms

Fix bug introduced in 11fb32:

When loading an encrypted thumbnail, QML lacks the decryption dict for
half a second at first.

When calling python like this, python calls the wrong matrix API
for fetching the encrypted thumbnail, and the added retry code
would be forever stuck.

The retry code has been moved to QML, and now works for all HImage.

TODO.md

@@ -1,14 +1,17 @@
 # TODO
 
 - Image viewer: 
+    - support http urls
     - open externally in context menu in timeline thumbnail
     - fix: gif always closes?
     - hflickable support kinetic scrolling disabler and speed/decel settings
     - buttons 
     - keyboard controls
 
+- clipboard preview doesn't update when copied image changes until second time
 - Avatar tooltip can get displayed in front of presence menu
 - Use loading cursorShape
+- Increase keyboard page scroll speed
 
 - global presence control
 

src/backend/media_cache.py

@@ -12,7 +12,6 @@ from dataclasses import dataclass, field
 from pathlib import Path
 from typing import TYPE_CHECKING, Any, DefaultDict, Dict, Optional
 from urllib.parse import urlparse
-from .errors import MatrixError
 
 from PIL import Image as PILImage
 
@@ -134,20 +133,8 @@ class Media:
     async def create(self) -> Path:
         """Download and cache the media file to disk."""
 
-        retries = 0
-
-        while True:
-            try:
         async with CONCURRENT_DOWNLOADS_LIMIT:
             data = await self._get_remote_data()
-            except MatrixError as err:
-                if err.http_code != 404 and err.http_code < 500:
-                    raise
-            else:
-                break
-
-            await asyncio.sleep(min(30, 0.2 * (2 ** (min(1000, retries) - 1))))
-            retries += 1
 
         self.local_path.parent.mkdir(parents=True, exist_ok=True)
 

src/gui/Base/HAvatar.qml

@@ -83,7 +83,6 @@ Rectangle {
             )
 
             visible: ! avatarImage.broken &&
-                     avatarImage.status !== Image.Error &&
                      avatarImage.width < dimension * 0.75 &&
                      (toolTipSourceOverride || toolTipMxc) &&
                      hoverHandler.hovered

src/gui/Base/HImage.qml

@@ -7,7 +7,7 @@ Image {
     id: image
 
     property bool circle: radius === circleRadius
-    property bool broken: false
+    property bool broken: image.status === Image.Error
     property bool animate: true
     property bool animated:
         utils.urlExtension(image.source).toLowerCase() === "gif"
@@ -20,6 +20,13 @@ Image {
     readonly property int circleRadius:
         Math.ceil(Math.max(image.width, image.height))
 
+    function reload() {
+        // Can be reimplemented in components inheriting HImage
+        const oldSource = source
+        source          = ""
+        source          = oldSource
+    }
+
 
     autoTransform: true
     asynchronous: true
@@ -122,7 +129,7 @@ Image {
 
     HIcon {
         anchors.centerIn: parent
-        visible: broken || image.status === Image.Error
+        visible: image.broken
         svgName: "broken-image"
         colorize: theme.colors.negativeBackground
     }
@@ -132,4 +139,18 @@ Image {
         anchors.fill: parent
         visible: false
     }
+
+    Timer {
+        property int retries: 0
+
+        running: image.broken
+        repeat: true
+        interval:
+            Math.min(60, 0.2 * Math.pow(2, Math.min(1000, retries) - 1)) * 1000
+
+        onTriggered: {
+            image.reload()
+            retries += 1
+        }
+    }
 }

src/gui/Base/HMxcImage.qml

@@ -20,7 +20,7 @@ HImage {
 
     readonly property bool isMxc: mxc.startsWith("mxc://")
 
-    function update() {
+    function reload() {
         if (! py || ! canUpdate) return  // component was destroyed
 
         const w = sourceSize.width || width
@@ -46,7 +46,7 @@ HImage {
                 if (! image) return
                 if (image.cachedPath !== path) image.cachedPath = path
 
-                image.broken = false
+                image.broken = Qt.binding(() => image.status === Image.Error)
                 image.show   = image.visible
 
             }, (type, args, error, traceback) => {
@@ -61,9 +61,9 @@ HImage {
     showProgressBar:
         (isMxc && status === Image.Null) || status === Image.Loading
 
-    onWidthChanged: Qt.callLater(update)
-    onHeightChanged: Qt.callLater(update)
-    onVisibleChanged: Qt.callLater(update)
-    onMxcChanged: Qt.callLater(update)
+    onWidthChanged: Qt.callLater(reload)
+    onHeightChanged: Qt.callLater(reload)
+    onVisibleChanged: Qt.callLater(reload)
+    onMxcChanged: Qt.callLater(reload)
     Component.onDestruction: if (getFuture) getFuture.cancel()
 }