harbour-fernschreiber/qml/components/messageContent/mediaAlbumPage/ZoomArea.qml

148 lines
5.2 KiB
QML

import QtQuick 2.6
import Sailfish.Silica 1.0
SilicaFlickable {
// id
id: flickable
// property declarations
property real zoom
property bool zoomed
// override if needed
property bool zoomEnabled: true
property real minimumZoom: fitZoom
property real maximumZoom: 4 //Math.max(fitZoom, 1) * 3
default property alias zoomContentItem: zoomContentItem.data
property alias implicitContentWidth: zoomContentItem.implicitWidth
property alias implicitContentHeight: zoomContentItem.implicitHeight
// factor for "PreserveAspectFit"
readonly property real fitZoom: implicitContentWidth > 0 && implicitContentHeight > 0
? Math.min(maximumZoom, width / implicitContentWidth, height / implicitContentHeight)
: 1.0
readonly property int minimumBoundaryAxis: (implicitContentWidth / implicitContentHeight) > (width / height) ? Qt.Horizontal : Qt.Vertical
// JavaScript functions
function zoomOut(animated) {
if (zoomed) {
if(animated) { zoomOutAnimation.start() }
else {
zoom = fitZoom
zoomed = false
}
}
}
// object properties
contentWidth: Math.max(width, zoomContentItem.width)
contentHeight: Math.max(height, zoomContentItem.height)
enabled: !zoomOutAnimation.running && implicitContentWidth > 0 && implicitContentHeight > 0
flickableDirection: Flickable.HorizontalAndVerticalFlick
interactive: zoomed
// According to Jolla, otherwise pinching would sometimes not work:
pressDelay: 0
Binding { // Update zoom on orientation changes and set as default
target: flickable
when: !zoomed
property: "zoom"
value: minimumZoom
}
// child objects
PinchArea {
id: pinchArea
parent: flickable.contentItem
width: flickable.contentWidth
height: flickable.contentHeight
enabled: zoomEnabled && minimumZoom !== maximumZoom && flickable.enabled
onPinchUpdated: {
scrollDecoratorTimer.restart()
var f = flickable;
var requestedZoomFactor = 1.0 + pinch.scale - pinch.previousScale;
var previousWidth = f.contentWidth
var previousHeight = f.contentHeight
var targetWidth
var targetHeight
var targetZoom = requestedZoomFactor * f.zoom;
if (targetZoom < f.minimumZoom) {
f.zoom = f.minimumZoom;
f.zoomed = false;
f.contentX = 0;
f.contentY = 0;
return
} else if(targetZoom >= f.maximumZoom) {
f.zoom = f.maximumZoom;
targetHeight = f.implicitContentHeight * f.zoom
targetWidth = f.implicitContentWidth * f.zoom
}
else if(targetZoom < f.maximumZoom) {
if (f.minimumBoundaryAxis == Qt.Horizontal) {
targetWidth = f.contentWidth * requestedZoomFactor
f.zoom = targetWidth / f.implicitContentWidth
targetHeight = f.implicitContentHeight * f.zoom
} else {
targetHeight = f.contentHeight * requestedZoomFactor
f.zoom = targetHeight / f.implicitContentHeight
targetWidth = f.implicitContentWidth * f.zoom
}
}
// calculate center difference
f.contentX += pinch.previousCenter.x - pinch.center.x
f.contentY += pinch.previousCenter.y - pinch.center.y
// move to new (zoomed) center. this jumps a tiny bit, but is bearable:
if (targetWidth > f.width)
f.contentX -= (previousWidth - targetWidth)/(previousWidth/pinch.previousCenter.x)
if (targetHeight > f.height)
f.contentY -= (previousHeight - targetHeight)/(previousHeight/pinch.previousCenter.y)
f.zoomed = true
}
onPinchFinished: {
returnToBounds()
}
Item {
id: zoomContentItem
anchors.centerIn: parent
implicitWidth: flickable.width
implicitHeight: flickable.height
width: Math.ceil(implicitWidth * zoom)
height: Math.ceil(implicitHeight * zoom)
}
}
// enable zoom to minimumZoom on click
ParallelAnimation {
id: zoomOutAnimation
NumberAnimation {
target: flickable
properties: "contentX, contentY"
to: 0
}
NumberAnimation {
target: flickable
property: "zoom"
to: fitZoom
}
onRunningChanged: {
if(!running) {
zoomed = false
}
}
}
// show scroll decorators when scrolling OR zooming
Timer {
id: scrollDecoratorTimer
readonly property bool moving: flickable.moving
readonly property bool showing: moving || running
onMovingChanged: restart()
interval: 300
}
VerticalScrollDecorator {
flickable: flickable
opacity: scrollDecoratorTimer.showing ? 1.0 : 0.0
}
HorizontalScrollDecorator {
flickable: flickable
opacity: scrollDecoratorTimer.showing ? 1.0 : 0.0
}
}