How to threading data in app?

Quote:

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Originally Posted by wysota

How is the gradient implemented?

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Code:

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gradient: Gradient {
        id: id0
        GradientStop {
            position: 0.0
            id: id1
            SequentialAnimation on color {
                id: update1
                loops: Animation.Infinite
                ColorAnimation { from: "red"; to: "magenta"; duration: 1000}
                ColorAnimation { from: "magenta"; to: "blue"; duration: 1000}
                ColorAnimation { from: "blue"; to: "cyan"; duration: 1000}
                ColorAnimation { from: "cyan"; to: "lime"; duration: 1000}
                ColorAnimation { from: "lime"; to: "yellow"; duration: 1000}
                ColorAnimation { from: "yellow"; to: "red"; duration: 1000}
            }
        }
        GradientStop {
            position: 1
            id: id2
            SequentialAnimation on color {
                id: update2
                loops: Animation.Infinite
                ColorAnimation { from: "yellow"; to: "red"; duration: 1000}
                ColorAnimation { from: "red"; to: "magenta"; duration: 1000}
                ColorAnimation { from: "magenta"; to: "blue"; duration: 1000}
                ColorAnimation { from: "blue"; to: "cyan"; duration: 1000}
                ColorAnimation { from: "cyan"; to: "lime"; duration: 1000}
                ColorAnimation { from: "lime"; to: "yellow"; duration: 1000}
            }
 
        }

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This is one example. I have get color pixel of screen another effect.

It seems quite easy to calculate the color from such definition. You know the starting color, the ending color and the percentage of the gradient you are currently in.

Quote:

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Originally Posted by wysota

It seems quite easy to calculate the color from such definition. You know the starting color, the ending color and the percentage of the gradient you are currently in.

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Yes! I can calculate gradient the color from the starting color and ending color. But random effect, I can't calculate color.
As this video
https://www.youtube.com/watch?v=vL7p-IsObj4
So I want get color of screen

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Added after 15 minutes:

My problem is when I put <150 object to get color pixel of screen, it work ok. But when I put 500 - 1000 object, it's shaking shock
I need get color all object in 30 millisecond or less but 30 milisecond not enough to calculate all the object in list.
So I think threading data.

Then do as I told you in the beginning -- render the scene to an FBO, convert that to a QImage and use QImage::pixel() to get the color.

Quote:

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Originally Posted by wysota

Then do as I told you in the beginning -- render the scene to an FBO, convert that to a QImage and use QImage::pixel() to get the color.

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it can get a large number of pixels in a small period of time?

I have to get color by function

Code:

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HWND name = FindWindow(NULL,L"Lighting Player");
        HDC dc = GetDC(name);
        COLORREF color = GetPixel(dc, _x, _y );

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But it but 30 millisecond not enough to calculate large object
I don't know what is "render the scene to an FBO"? Can you explain more?

Quote:

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Originally Posted by tanthinh1510

it can get a large number of pixels in a small period of time?

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I bet it can.

Quote:

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Originally Posted by wysota

Then do as I told you in the beginning -- render the scene to an FBO, convert that to a QImage and use QImage::pixel() to get the color.

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Can you for me example "render the scene to an FBO"?

QQuickWindow::setRenderTarget() (make sure you understand the warning in the docs) and optionally you can see if QQuickWindow::grabWindow() is fast enough for you.

Quote:

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Originally Posted by wysota

QQuickWindow::setRenderTarget() (make sure you understand the warning in the docs) and optionally you can see if QQuickWindow::grabWindow() is fast enough for you.

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I used QQuickWindow::grabWindow() and my code

Code:

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void getScreen::getpixel(int _x, int _y)
{
    QQuickWindow screen;
    QImage imageScreen = screen.grabWindow();
    COLORREF color = imageScreen.pixel(_x,_y);
    int _red = GetRValue(color);
    int _green = GetGValue(color);
    int _blue = GetBValue(color);
    QColor c1;
    c1.setRgb(_red, _green, _blue);
    qDebug() << c1.name();
}

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result is

Code:

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QQuickWindow::grabWindow: scene graph already in use
QImage::pixel: coordinate (39,72) out of range

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I don't know warning

Quote:

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Warning: This function can only be called from the GUI thread

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Where are you calling this function? What is COLORREF? How in God's name am I supposed to make anything out of the code you post?

Quote:

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Originally Posted by wysota

Where are you calling this function?

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I call when I click in rectangle

Code:

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Rectangle {
    width: 360
    height: 360
    MouseArea {
        anchors.fill: parent
        onClicked: {
            _getScreen.getpixel(mouse.x,mouse.y)
        }
    }
}

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Thanks wysota!
I used QQuickWindow::grabWindow() and it work ok. However when I minimize app, it do not work. How to it work when minimize app?

Render the scene to an FBO :)

Quote:

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Originally Posted by wysota

Render the scene to an FBO :)

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I'm trying used it but I can't find document or example about it. Maybe a don't understand about it.

Did you try using setRenderTarget as advised?