Merge lp:~verzegnassi-stefano/ubuntu-docviewer-app/fix-zoom-performance into lp:ubuntu-docviewer-app/trunk

[Stefano Verzegnassi]

Fixed zoom performance

QQuickView::releaseResources() is a bit expensive.

In the current trunk code, it's called whenever _zoomHelper.scale value changes, one call for each delegate currently loaded.
That means that (on phones) we have ~5 calls for each pinchUpdated event, and it's too much.

In the proposed patch, QQuickView::releaseResources() has been moved in the onPinchFinished slot, so that it's called just one time per zoom event.

[Ubuntu Phone Apps Jenkins Bot (ubuntu-phone-apps-jenkins-bot)]

PASSED: Continuous integration, rev:77
http://91.189.93.70:8080/job/ubuntu-docviewer-app-ci/166/
Executed test runs:
    SUCCESS: http://91.189.93.70:8080/job/generic-mediumtests-vivid/1040
        deb: http://91.189.93.70:8080/job/generic-mediumtests-vivid/1040/artifact/work/output/*zip*/output.zip
    SUCCESS: http://91.189.93.70:8080/job/ubuntu-docviewer-app-vivid-amd64-ci/69

Click here to trigger a rebuild:
http://91.189.93.70:8080/job/ubuntu-docviewer-app-ci/166/rebuild

review: Approve (continuous-integration)

[Alan Pope 🍺🐧🐱 🦄 (popey)]

LGTM

review: Approve

[Ubuntu Phone Apps Jenkins Bot (ubuntu-phone-apps-jenkins-bot)]

FAILED: Autolanding.
More details in the following jenkins job:
http://91.189.93.70:8080/job/ubuntu-docviewer-app-autolanding/52/
Executed test runs:
    UNSTABLE: http://91.189.93.70:8080/job/generic-mediumtests-vivid/1109
        deb: http://91.189.93.70:8080/job/generic-mediumtests-vivid/1109/artifact/work/output/*zip*/output.zip
    SUCCESS: http://91.189.93.70:8080/job/ubuntu-docviewer-app-vivid-amd64-autolanding/29

review: Needs Fixing (continuous-integration)

[Ubuntu Phone Apps Jenkins Bot (ubuntu-phone-apps-jenkins-bot)]

FAILED: Autolanding.
More details in the following jenkins job:
http://91.189.93.70:8080/job/ubuntu-docviewer-app-autolanding/53/
Executed test runs:
    UNSTABLE: http://91.189.93.70:8080/job/generic-mediumtests-vivid/1113
        deb: http://91.189.93.70:8080/job/generic-mediumtests-vivid/1113/artifact/work/output/*zip*/output.zip
    SUCCESS: http://91.189.93.70:8080/job/ubuntu-docviewer-app-vivid-amd64-autolanding/30

review: Needs Fixing (continuous-integration)

[Ubuntu Phone Apps Jenkins Bot (ubuntu-phone-apps-jenkins-bot)]

review: Approve (continuous-integration)

=== modified file 'src/app/qml/PdfView.qml'
--- src/app/qml/PdfView.qml	2015-02-05 19:30:53 +0000
+++ src/app/qml/PdfView.qml	2015-02-09 12:10:55 +0000
@@ -37,25 +37,24 @@
     PDF.VerticalView {
         id: pdfView
         objectName: "pdfView"
-
         anchors.fill: parent
         spacing: units.gu(2)
 
         clip: true
         boundsBehavior: Flickable.StopAtBounds
-
-        cacheBuffer: height * poppler.providersNumber * _zoomHelper.scale * 0.5
-
         flickDeceleration: 1500 * units.gridUnit / 8
         maximumFlickVelocity: 2500 * units.gridUnit / 8
 
+        contentWidth: parent.width * _zoomHelper.scale
+        cacheBuffer: height * poppler.providersNumber * _zoomHelper.scale * 0.5
+        interactive: !pinchy.pinch.active
+
         model: poppler
         delegate: PdfViewDelegate {
-            onWidthChanged: QQuickView.releaseResources()
             Component.onDestruction: QQuickView.releaseResources()
         }
 
-        contentWidth: parent.width * _zoomHelper.scale
+        // FIXME: On zooming, keep the same content position.
         PinchArea {
             id: pinchy
             anchors.fill: parent
@@ -66,14 +65,13 @@
                 maximumScale: 2.5
             }
 
-            onPinchStarted: pdfView.interactive = false;
-
-            // FIXME: On zooming, keep the same content position.
-            // onPinchUpdated: {}
-
             onPinchFinished: {
-                pdfView.interactive = true;
                 pdfView.returnToBounds();
+
+                // This is a bit expensive, so it's safer to put it here.
+                // It won't be called on desktop (where PinchArea is not used),
+                // but it's not a problem at the moment (our target is phone).
+                QQuickView.releaseResources();
             }
         }