QtQuick.qtquick-demos-photosurface-example

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Photo Surface demonstrates how to use a Repeater with a FolderListModel and a FileDialog to access images from a folder selected by a user and how to handle dragging, rotation and pinch zooming within the same item using a PinchArea that contains a MouseArea.

All the app code is contained in one QML file, photosurface.qml. Inline JavaScript code is used to place, rotate, and scale images on the photo surface.

Running the Example

To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

Creating the Main Window

To create the main window for the Photo Surface app, we use the Window QML type as the root item. It automatically sets up the window for use with Qt Quick graphical types:

Window {
id: root
visible: true
width: 1024; height: 600
color: "black"
property int highestZ: 0
property real defaultSize: 200
property var currentFrame: undefined

To use the Window type, we must import it:

import QtQuick.Window 2.1

Accessing Folder Contents

We use a Repeater QML type together with the FolderListModel to display GIF, JPG, and PNG images located in a folder:

    Repeater {
model: FolderListModel {
id: folderModel
objectName: "folderModel"
showDirs: false
nameFilters: [".png", ".jpg", ".gif"]
}

To use the FolderListModel type, we must import it:

import Qt.labs.folderlistmodel 1.0

We use a FileDialog to enable users to select the folder that contains the images:

    FileDialog {
id: fileDialog
title: "Choose a folder with some images"
selectFolder: true
onAccepted: folderModel.folder = fileUrl + "/"
}

To use the FileDialog type, we must import Qt Quick Dialogs:

import QtQuick.Dialogs 1.0

We use the fileDialog.open() function to open the file dialog when the app starts:

Component.onCompleted: fileDialog.open()

Users can also click the file dialog icon to open the file dialog. We use an Image QML type to display the icon. Inside the Image type, we use a MouseArea with the onClicked signal handler to call the fileDialog.open() function:

    Image {
anchors.top: parent.top
anchors.left: parent.left
anchors.margins: 10
source: "resources/folder.png"
MouseArea {
anchors.fill: parent
anchors.margins: -10
onClicked: fileDialog.open()
}
}

Displaying Images on the Photo Surface

We use a Rectangle as a delegate for a Repeater to provide a frame for each image that the FolderListModel finds in the selected folder. We use JavaScript Math() methods to place the frames randomly on the photo surface and to rotate them at random angles, as well as to scale the images:

        Rectangle {
id: photoFrame
width: image.width  image.scale + 20
height: image.height  image.scale + 20
border.color: "black"
border.width: 2
smooth: true
antialiasing: true
x: Math.random()  root.width - defaultSize
y: Math.random()  root.height - defaultSize
rotation: Math.random()  13 - 6
Image {
id: image
anchors.centerIn: parent
fillMode: Image.PreserveAspectFit
source: folderModel.folder + fileName
scale: defaultSize / Math.max(sourceSize.width, sourceSize.height)
antialiasing: true
}

Handling Pinch Gestures

We use a PinchArea that contains a MouseArea in the photo frames to handle dragging, rotation and pinch zooming of the frame:

            PinchArea {
anchors.fill: parent
pinch.target: photoFrame
pinch.minimumRotation: -360
pinch.maximumRotation: 360
pinch.minimumScale: 0.1
pinch.maximumScale: 10
onPinchStarted: setFrameColor();

We use the pinch group property to control how the photo frames react to pinch gestures. The pinch.target sets photoFrame as the item to manipulate. The rotation properties specify that the frames can be rotated at all angles and the scale properties specify that they can be scaled between 0.1 and 10.

In the MouseArea's onPressed signal handler, we raise the selected photo frame to the top by increasing the value of its z property. The root item stores the z value of the top-most frame. The border color of the photo frame is controlled in the onEntered signal handler to highlight the selected image:

                MouseArea {
id: dragArea
hoverEnabled: true
anchors.fill: parent
drag.target: photoFrame
onPressed: {
photoFrame.z = ++root.highestZ;
parent.setFrameColor();
}
onEntered: parent.setFrameColor();

To enable you to test the example on the desktop, we use the MouseArea's onWheel signal handler to simulate pinch gestures by using a mouse:

                    onWheel: {
if (wheel.modifiers & Qt.ControlModifier) {
photoFrame.rotation += wheel.angleDelta.y / 120  5;
if (Math.abs(photoFrame.rotation) < 4)
photoFrame.rotation = 0;
} else {
photoFrame.rotation += wheel.angleDelta.x / 120;
if (Math.abs(photoFrame.rotation) < 0.6)
photoFrame.rotation = 0;
var scaleBefore = image.scale;
image.scale += image.scale  wheel.angleDelta.y / 120 / 10;
photoFrame.x -= image.width  (image.scale - scaleBefore) / 2.0;
photoFrame.y -= image.height  (image.scale - scaleBefore) / 2.0;
}
}
}

The onWheel signal handler is called in response to mouse wheel gestures. Use the vertical wheel to zoom and Ctrl and the vertical wheel to rotate frames. If the mouse has a horizontal wheel, use it to rotate frames.

Files:

  • demos/photosurface/photosurface.qml
  • demos/photosurface/main.cpp
  • demos/photosurface/photosurface.pro
  • demos/photosurface/photosurface.qmlproject
  • demos/photosurface/photosurface.qrc

See also QML Applications.

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