Dealing with animations

J.Hilk

HI, let me see if I can help you.
@tomy said in Dealing with animations:

1- Why isn't the property on x or y but a string with a floating point value 0.0?
The property property is basicaly the reference what property shall be targeted for the animation, its referenced as a string.
Would you want to change the x value you would have to write property: "x" for y property: "y" for x and y properties: "x,y"

Why is it a string instead of the property, well no idea, but my best guess is, if its a propery you would have to reference it with an ID e.g myItem.x. But that is lost of you convoluted QML obejects. And everything but an Item is convoluted.

2- Why isn't there any change if we don't use 0.0 but a negative number, say, -5, or a positive one, say, +5, or farther?

3- Why isn't there any change when we alter the duration and make big difference?

No idea, I find this example very confusing and hard to read.
Have you tried the Qt Quick Examples - Animation ? I think that would be better for getting started in QML-Animations

tomy

@J-Hilk
Hi, Thanks, you did.

but my best guess is, if its a propery you would have to reference it with an ID e.g myItem.x.

Did you mean that 'value' acts here like a unique property making the property independent of need to refer to a specific item's property?

No idea, I find this example very confusing and hard to read.

So do I. I'm highly astonished why there isn't any good reference appropriate for newcomers of QML!! It's a hardship.
Thanks also for the example. I'm appreciative of that but it's too long for this level of me (hundreds of lines of code with several components including many types and new items). I would need a simpler one.
Anyway, if Docs is the only reference for learning QML in your point of view too, which is better than that online book, where to start from? Some point that much resembles a step-by-step route from beginning to the end (similar to a book).

J.Hilk

@tomy said in Dealing with animations:

Did you mean that 'value' acts here like a unique property making the property independent of need to refer to a specific item's property?

It basically looks for a specific property name, in this case value of your QML-Object and all its "base-classes" and binds the animation to that property, if it can find one appropriatly named.

I would guess a process similar to Qt4 SignalSlot

Thanks also for the example. I'm appreciative of that but it's too long for this level of me (hundreds of lines of code with several components including many types and new items). I would need a simpler one.

of course the example covers more or less the whole area of property animations. For your current case, you should simply look into Transitions.qml. Thats 133 Lines of code dealing with 3 Rectangels a logo and NumberAnimation and states. You should be able to simply copy and paste that into a clean new project.

Anyway, if Docs is the only reference for learning QML in your point of view too, which is better than that online book, where to start from? Some point that much resembles a step-by-step route from beginning to the end (similar to a book).

In the end it really depends on you, your time available and the money you're willing to spend.

There are a couple Qt-certificated Partners that offer small group training sessions, KDAB comes to my mind here. Really good and usually on the point, but very expensive.

What I usually do is the following:

I set in mind a specific goal I want to archive.
If its new territory, do a quick google search on the topic.
Spend some time going through examples, trying to understand them.
Create a basic working program with the examples and/or the docu
If that is more difficult than expected => recreate the example by hand
Refine and expand the code until the previously set goal is reached

this usually takes some time, but I can also remember stuff years later ;-)

mrjj

Hi
Maybe this one is is worth checking out
https://www.amazon.com/Getting-started-Quick-multidevice-applications-ebook/dp/B01B9DV54G

tekojo

@tomy
You might want to take a look at the QML book https://qmlbook.github.io/en/
Chapter 5 talks about animations.

mrjj

@tekojo
I think he is already using the book but feels its not as detailed step by step as he would like.
As far as I could find, it is the book for learning QML.

mostefa

@tomy said in Dealing with animations:

@mrjj
Hi,
Thanks for your time. But that example is much more complicated the my own one! :)

If you answer the questions (I've asked more than three times here on this thread) about simple things, I think it would also be helpful. :)

1- Why isn't the property on x or y but a string with a floating point value 0.0?
2- Why isn't there any change if we don't use 0.0 but a negative number, say, -5, or a positive one, say, +5, or farther?

3- Why isn't there any change when we alter the duration and make big difference?

Easing is the curve that is used during your animation, have a look at this doc about easing.

I advise you also to run this example , and to see how easing change your animation.

1- Why isn't the property on x or y but a string with a floating point value 0.0?

The string is used in property to know which property we need to animate , see this link

property : string

These properties are used as a set to determine which properties should be animated. The singular and plural forms are functionally identical, e.g.

NumberAnimation { target: theItem; property: "x"; to: 500 }

2- Why isn't there any change if we don't use 0.0 but a negative number, say, -5, or a positive one, say, +5, or farther?

Because the -5 that you are writing is just an initial value, after that you are telling in NumberAnimation that value must be from 0 to 1.

NumberAnimation {
    id: anim
    target: root
    property: 'value'
    from: 0
    to: 1
    duration: 3000
}

3- Why isn't there any change when we alter the duration and make big difference?

Cause your animation is driven by AnimationController (in your case the timer is not used at all) and the Qt Doc says that :

Normally animations are driven by an internal timer, but the AnimationController allows the given animation to be driven by a progress value explicitly.

As @tekojo said qmlbook is a good one to start qml.

I don't know what are you doing exactly , but for my personal opinion you don't have to use AnimationController at all. you can do a lot of funny animation only with (NumberAnimation , SequentialAnimation, ParallelAnimation)

Take a look in this Qt Quick Example

I hope this can help you , and if not ,you can tell me what do you want to achieve , and i will try to help you !

tomy

@J.Hilk
Thank you for all of your suggestions. I appreciate them.

tomy

@tekojo
Thanks, but I think I'm reading that book and getting stuck in it often! :)

tomy

@mostefa
Thank you very much. It was helpful and I appreciate you.
The book you (and the other guy) suggested is the one I'm currently reading.

tomy

@mostefa

I want to explain the first parts of the code based on my understanding and if possible, you please state your idea on it.

Rectangle {
    id: root
    width: 100
    height: 100
    clip: true
    property real value: 0.0
    property int pointCount: 100
    property string title
    signal clicked()

    property alias easingType: anim.easing.type


    Image {
        anchors.fill: parent
        source: "blueprint.jpg"
    }

    Rectangle {
        anchors.fill: view
        anchors.leftMargin: -8
        anchors.rightMargin: -8
        color: 'transparent'
        border.color: "#53d769"
        border.width: 4
        opacity: 0.5

    }

    NumberAnimation {
        id: anim
        target: root
        property: "value"
        from: 0
        to: 1
    }

First we have a squared rectangle (100, 100) that limits all painting to its borders. And it has some properties (of types real, int, string, signal and alias) which will be used later on the code. Until now that rectangle won't be shown because it hasn't a color.

On Image, the blue square like one of these will fit onto the previous rectangle.

After these two items, we reach the next Rectangle with the color transparent. This rectangle is mostly for drawing two top and down lines to act like two x-axes for the curve.
The next object is NumberAnimation. It specifies the root as its target and the property as 'value' to be used by the AnimationController. It also sets the range to be used for making the curve from 0 to 1. I remove the duration property.

Up to this point, is all of the above comprehension about each section correct please?

mostefa

@tomy said in Dealing with animations:

@mostefa

I want to explain the first parts of the code based on my understanding and if possible, you please state your idea on it.
Rectangle {
    id: root
    width: 100
    height: 100
    clip: true
    property real value: 0.0
    property int pointCount: 100
    property string title
    signal clicked()

    property alias easingType: anim.easing.type


    Image {
        anchors.fill: parent
        source: "blueprint.jpg"
    }

    Rectangle {
        anchors.fill: view
        anchors.leftMargin: -8
        anchors.rightMargin: -8
        color: 'transparent'
        border.color: "#53d769"
        border.width: 4
        opacity: 0.5

    }

    NumberAnimation {
        id: anim
        target: root
        property: "value"
        from: 0
        to: 1
    }
First we have a squared rectangle (100, 100) that limits all painting to its borders. And it has some properties (of types real, int, string, signal and alias) which will be used later on the code. Until now that rectangle won't be shown because it hasn't a color.

On Image, the blue square like one of these will fit onto the previous rectangle.

After these two items, we reach the next Rectangle with the color transparent. This rectangle is mostly for drawing two top and down lines to act like two x-axes for the curve.
The next object is NumberAnimation. It specifies the root as its target and the property as 'value' to be used by the AnimationController. It also sets the range to be used for making the curve from 0 to 1. I remove the duration property.

Up to this point, is all of the above comprehension about each section correct please?

For me i think that all your explanation is correct ! =)

tomy

@mostefa
Thank you.

mostefa

@tomy said in Dealing with animations:

@mostefa
Thank you.

You are welcome =)

Eeli K

@tomy This is going to be off-topic, but I thought maybe I could help in another way.

Maybe the problem is not so much the book (which really is problematic in some ways) but your learning strategy. You seem to want to understand every detail when you see it. It's a good thing but can lead to situation where you get stuck with things which are actually irrelevant for you at the moment. You have said you need and want to learn QML. Why? For what do you need it? Do you want to learn to animate cool visual things? Or do you want to create a working and practical user interface for some application which you need? If it's the latter, you don't need animations at all and can read the animation part of the book with a cursory glance. Nobody can expect to read a book with a new subject area and understand it all. There's much in Qt or even just in the QML part of it which you will never need or use. There's also much you don't need to know actively, for example you don't need to create grouped properties or attached properties right away, you just need to recognize them when you see them and use something which someone else has created.

It's important to learn meta-learning skills, i.e. learn to how to learn effectively. One part of it is knowing what to not learn at the moment and just let some things be and go forward. Sometimes I read a book (not necessarily about programming) of which I understand maybe 10% or less. But when I read more and more I will understand those things which I didn't previously understood, and I wouldn't have understood them if I hadn't previously read that 90% which I didn't understand back then. Giving up isn't a bad thing if you know when and how to do it. Don't give up your greater goals, learn to give up some details if they hinder you from going forward.

Another important thing is that if you don't have a personal task it's more difficult to learn. Just going through some examples which someone has made up is tedious, at least for me. I need some short-term goal, for example a user interface which does something for me which I actually want or need. Then I can search for things which are actually relevant for me and I can integrate them into my own task. The feeling when you get something done for your own needs is much better than when going through made-up examples. Do you have something specific you want to do with QML?

tomy

@Eeli-K

I appreciate your good talks. That's very kind of you.
I will make them remained in my mind.

tomy

I want to express my understanding on the rest of the code.
On the way, we reach the ListModel type. It's like a container. After that is AnimationController, which executes its body instructions. So it first clears the container and then adds a hundred floating point numbers (0.0, 0.01, 0.02, ..., 0.99) to the container (using append).

The next executed type (according to the from-top-to-down order) is PathView. Its job is displaying the data (those 100 floating point numbers stored in the ListModel). So the actual draw/design/display of the curve is done by PathView). On delegate it defines how data should be displayed by creating 4x4 orangish rectangles. In fact, it wants to put 100 4x4 rectangles to display the cure. By Path, the type creates a horizontal line (0, 100 to 100, 100). And then it finishes.

The Text type is used for allowing the type EasyingType to have a text property. The MouseArea is used on the component to receive clicks.

What about this part please? Is what I've understood mentioned-above correct?

Eeli K

@tomy I think you have understood the purpose of almost all parts correctly, although terminology isn't very clear. Here are some details which aren't crucial:

Types aren't "executed", I'd rather say that objects of those types are created. As I have said earlier (at least I remember having said), the creation order isn't necessarily top-down in implementation, but it's enough for understanding the logic. On the other hand it may be important to understand that Component.onCompleted functions are executed only after the object tree has been created to some point so that objects and their properties can be used in those Component.onCompleted functions, and the order of executing different objects' Component.onCompleted functions is undefined (it's explicitly told in the documentation) and I actually have stumbled on this fact, so it may be important in some situations.

You make one mistake: the last Text element isn't a property. It's just an object which is added to its parent's children list and is one visible object amongst the Image, Rectangle and PathView objects.

tomy

@Eeli-K

the last Text element isn't a property. It's just an object which is added to its parent's children list and is one visible object amongst the Image, Rectangle and PathView objects.

Hi,
Yes, I meant that object is used for populating the alias property of the root making it capable of having a property with the name 'title' on its use on the other component.

Would you please take another look at the AnimationControler?

AnimationController {
        id: controller
        animation: anim
        Component.onCompleted: {
            valueModel.clear()
            for(var i=0; i<root.pointCount; i++) {
                progress = i/root.pointCount
                valueModel.append({value: root.value})
            }
        }
    }

In valueModel.append({value: root.value}), the progress values aren't used apparently! What is appended is a constant value, 0.0, which is the value of root!

tomy

Still I can't create a good story based on what I comprehended from that component.