How to save an image from QML Image element?

DonRico

Hi

Little help please. That piece of code probably works on Qt 4.7 but in 5.3 it doesn't. -The problem lays in qobject_cast -ing since it requires the source to inherit QObject, but QML Image is based on QtObject class.-

My bad QtObject inherits QObject but I'm still getting empty object after casting. By debugging the source imageobject seems to be normal QQuickImage object. Any ideas?

Since I'm really inexperienced in Qt c++ part, could anyone help with that problem.

Thanx.

Djay96

QDeclarativeView *view = new QDeclarativeView();
QPixmap::grabWidget(view).save(outputFile, 0, 100);

create view and grab image file in outputFile

DonRico

Sorry, I'm not quite sure how to implement your solution. Also QDeclarativeView isn't used in Qt5 and Pixmap::grapWidget() also depricated.

But thnx anyways :)

Djay96

sorry I am using older version (As per requirement ) I appreciate your reply

DonRico

Hi

Does anybody have an idea why I can't pass the Image object to the save function. The path comes over nicely but "imageObj" pointer in save() function turns out empty?

qomg

Hi

I also have an empty pointer. I do not know where to look to solve this problem.

jeremy_k

For Qt 5 and later, "Canvas":http://qt-project.org/doc/qt-5/qml-qtquick-canvas.html has loadImage(url) and save(filename) functions.

Vincent007

wait for QQuickRenderControl

qomg

I tried to use the Canvas, and also I could not save.
I'll try again tomorrow ..

jeremy_k

Image loading and saving via Canvas:

@import QtQuick 2.2
import QtQuick.Window 2.1

Window {
width: imgLoader.sourceSize.width
height: imgLoader.sourceSize.height
visible: true
property string loadUrl: "file://tmp/image.png"
property string saveUrl: "/tmp/i2.png"

Canvas {
    id: root
    anchors.fill: parent
    onPaint: {
        var ctx = getContext("2d")
        ctx.drawImage(imgLoader, 0, 0)
    }
}
MouseArea {
    anchors.fill: parent
    onClicked: {
        if (root.save(saveUrl)) {
            console.log("save succeeded")
        }
        else {
            console.log("save failed")
        }
    }
}
Image {
    id: imgLoader
    visible: false
    source: loadUrl
}

}@

Note that the parameter to Canvas::save() is a filename, not a URL. It fails when "file://tmp/i2.png" is used.

qomg

jeremy_k thanks it works great.

beemaneni

Hi
does the above code really draw an image in the given path?
For me the file gets created but nothing in it... i have given save url as "/storage/sdcard0/a1.png".

Can u help me ?

Thanks in Advance,,

DonRico

Hi

I decided to solve this a bit differently. I created a new QML type (c++ class) that takes in image url (local or remote) and spits out local url. In case of beginning http:// or https:// class checks if image is already downloaded from the remote server and in that case spits the local url right out w/o wasting the precious mobile data bandwidth.And then there a QML component that fills out the Image type source property when the local url is returned from my so called "Caching class". If anybody's interest I can strip it out of my project and put it up to github with decent comments.

beemaneni

Hi DonRico
If u can post that code that would be an great help for me...can u?

Thanks

DonRico

Ok, I'll try to find some spare time to separate it and put it.

DonRico

Ok, the exmaple project is available in https://github.com/DonRico/QT-Image-Caching . There might be some issues since I've written QT for 2mos for now but it should give you the general idea.

jeremy_k

Caching can also be handled with a "QQuickImageProvider":https://qt-project.org/doc/qt-5/qquickimageprovider.htmlQQuickImageProvider.

After defining and register a provider, image urls can be written as "image://ProviderName/path/to/image".

The same concept exists for Qt 4 in the form of QDeclarativeImageProvider.

chuahanmandis

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