Merge lp:~jamesh/camera-app/pre-cache-video-thumbnails into lp:camera-app

[James Henstridge]

After shooting a video, request a thumbnail so that it will be available in the cache when needed (e.g. by the Gallery or Dash).

Due to the bad performance of thumbnailing H.264 video files (on the order of a 1.4 seconds) I started investigating whether we could improve the user experience with a modification to camera-app.

This branch requests a small thumbnail after shooting a video with the camera-app, which will prime the thumbnailer-service's full-size image cache with a screenshot of the video, ready to provide thumbnails for whatever asks for one later (e.g. the "My Videos" scope on the dash, gallery-app, etc).

With this patch applied and an updated camera-app installed on my phone, I can see a thumbnail request in ~/.cache/upstart/dbus.log when I shoot a video. If I switch back to the dash, the video shows up almost instantly rather than the old delay.

It wasn't clear where best to put this code, so if there is a better location I can update the branch.

[PS Jenkins bot (ps-jenkins)]

FAILED: Continuous integration, rev:581
http://jenkins.qa.ubuntu.com/job/camera-app-ci/434/
Executed test runs:
    SUCCESS: http://jenkins.qa.ubuntu.com/job/camera-app-vivid-amd64-ci/130
    SUCCESS: http://jenkins.qa.ubuntu.com/job/camera-app-vivid-armhf-ci/130
        deb: http://jenkins.qa.ubuntu.com/job/camera-app-vivid-armhf-ci/130/artifact/work/output/*zip*/output.zip
    SUCCESS: http://jenkins.qa.ubuntu.com/job/camera-app-vivid-i386-ci/130
    UNSTABLE: http://jenkins.qa.ubuntu.com/job/generic-click-autopilot-vivid-touch/275
    UNSTABLE: http://jenkins.qa.ubuntu.com/job/generic-click-autopilot-runner-mako/929
    SUCCESS: http://jenkins.qa.ubuntu.com/job/generic-click-builder-vivid-armhf/756
    SUCCESS: http://s-jenkins.ubuntu-ci:8080/job/touch-flash-device/23984

Click here to trigger a rebuild:
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review: Needs Fixing (continuous-integration)

[Florian Boucault (fboucault)]

Functionally, it's great and achieves what the description promises with a very minimal cost. Very nice improvement indeed!
Code wise, only a couple of details:
- it would be nice to unload the Image once the thumbnail has been loaded; although it is a very small save of a 32x32 image
- the Image {}'s id could be more explicit than just 'thumbnail', for example 'preCachingThumbnail' or something
- also a small comment next to the Image explaining its purpose and specifically why a sourceSize of 32x32 suffices to provide all the benefits would be extra useful

Thanks a lot!

[lp:~jamesh/camera-app/pre-cache-video-thumbnails]

582. By James Henstridge on 2015-10-23

Updates based on Florian's review.

[James Henstridge (jamesh)]

Thanks for the review.

> Functionally, it's great and achieves what the description promises with a
> very minimal cost. Very nice improvement indeed!
> Code wise, only a couple of details:
> - it would be nice to unload the Image once the thumbnail has been loaded;
> although it is a very small save of a 32x32 image

I've added an onStatusChanged handler to the image that resets the filename to "" whenever the status changes to Image.Ready.

> - the Image {}'s id could be more explicit than just 'thumbnail', for example
> 'preCachingThumbnail' or something

Done.

> - also a small comment next to the Image explaining its purpose and
> specifically why a sourceSize of 32x32 suffices to provide all the benefits
> would be extra useful

Done.

[PS Jenkins bot (ps-jenkins)]

FAILED: Continuous integration, rev:582
http://jenkins.qa.ubuntu.com/job/camera-app-ci/440/
Executed test runs:
    SUCCESS: http://jenkins.qa.ubuntu.com/job/camera-app-vivid-amd64-ci/136
    SUCCESS: http://jenkins.qa.ubuntu.com/job/camera-app-vivid-armhf-ci/136
        deb: http://jenkins.qa.ubuntu.com/job/camera-app-vivid-armhf-ci/136/artifact/work/output/*zip*/output.zip
    SUCCESS: http://jenkins.qa.ubuntu.com/job/camera-app-vivid-i386-ci/136
    FAILURE: http://jenkins.qa.ubuntu.com/job/generic-click-autopilot-vivid-touch/281/console
    FAILURE: http://jenkins.qa.ubuntu.com/job/generic-click-builder-vivid-armhf/762/console

Click here to trigger a rebuild:
http://s-jenkins.ubuntu-ci:8080/job/camera-app-ci/440/rebuild

review: Needs Fixing (continuous-integration)

[Florian Boucault (fboucault)]

Perfect!

review: Approve

=== modified file 'GalleryView.qml'
--- GalleryView.qml	2015-02-12 19:25:00 +0000
+++ GalleryView.qml	2015-10-23 05:21:20 +0000
@@ -17,6 +17,7 @@
 import QtQuick 2.2
 import Ubuntu.Components 1.1
 import Ubuntu.Content 0.1
+import Ubuntu.Thumbnailer 0.1
 import CameraApp 0.1
 import "MimeTypeMapper.js" as MimeTypeMapper
 
@@ -51,6 +52,10 @@
         galleryView.model.prependFile(filePath);
     }
 
+    function precacheThumbnail(filePath) {
+        preCachingThumbnail.filename = filePath;
+    }
+
     function exitUserSelectionMode() {
         model.clearSelection();
         model.singleSelectionOnly = true;
@@ -226,6 +231,27 @@
         }
     }
 
+    // This image component is used to pre-load thumbnails of recently
+    // created files.  This is primarily to hide the delays in
+    // thumbnailing videos.
+    Image {
+        id: preCachingThumbnail
+        property string filename
+
+        visible: false
+        asynchronous: true
+        cache: false
+        sourceSize.width: 32
+        sourceSize.height: 32
+        source: filename ? "image://thumbnailer/%1".arg(filename) : ""
+
+        onStatusChanged: {
+            if (status == Image.Ready) {
+                filename = "";
+            }
+        }
+    }
+
     state: galleryView.gridMode ? "GRID" : "SLIDESHOW"
     states: [
         State {
 
=== modified file 'GalleryViewLoader.qml'
--- GalleryViewLoader.qml	2015-01-24 12:52:12 +0000
+++ GalleryViewLoader.qml	2015-10-23 05:21:20 +0000
@@ -31,6 +31,9 @@
         loader.item.prependMediaToModel(filePath);
     }
 
+    function precacheThumbnail(filePath) {
+        loader.item.precacheThumbnail(filePath);
+    }
 
     asynchronous: true
 
 
=== modified file 'camera-app.qml'
--- camera-app.qml	2015-07-03 10:32:14 +0000
+++ camera-app.qml	2015-10-23 05:21:20 +0000
@@ -245,6 +245,7 @@
             onVideoShot: {
                 galleryView.prependMediaToModel(filePath);
                 galleryView.showLastPhotoTaken();
+                galleryView.precacheThumbnail(filePath);
             }
         }