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bapuji_4469
Inspiring
September 11, 2025
Answered

Help: Qt Widget Not Occupying Full AI Panel Space

  • September 11, 2025
  • 1 reply
  • 631 views

Hello Everyone,

I am writing a C++ plugin using the latest SDK (v1-Aug 2025) for Adobe Illustrator 2025 (version 29.8.1). My requirement is to display a Qt UI inside an AI Panel. I have taken the EmptyPanel sample as a reference and added my Qt widgets to the panel.

I am able to see the Qt widget in the panel, and it resizes when the panel resizes. However, the Qt widget is not fully occupying the panel space, even though I set the widget size to match the AI Panel size using the sAIPanel->GetSize API. I am also updating the size when the window size changes through PanelSizeChangedNotifyProc.

 

To isolate the issue, I created a simple QWidget and explicitly set its geometry to the panel size, but I still see the same problem.

Below is the code snippet. Also attached the screenshot of my Plugin panel view. Could someone shed some light on what I might be missing or doing wrong?

Thanks in advance!

ASErr EasyVariantsPlugin::StartupPlugin(SPInterfaceMessage* message)
{
//Initialization code

    AISize pnSize = { 2000, 2000 };
    AIErr error = sAIPanel->Create(fPluginRef, ai::UnicodeString("MyTestPlugin"), ai::UnicodeString("MyTestPlugin"), 1, pnSize, true, NULL, this, fPanel);

    AISize minSize = { 200, 200 };
    AISize maxSize = { 2000, 2000 };
    AISize prefConstSize = { 500, 500 };
    AISize prefUnconstSize = { 500, 500 };

    error = sAIPanel->SetSizes(fPanel, minSize, prefUnconstSize, prefConstSize, maxSize);
    CHECK_ERROR	
    error = sAIPanel->Show(fPanel, true);
    CHECK_ERROR	
    error = sAIPanel->SetVisibilityChangedNotifyProc(fPanel, PanelVisibilityChangedNotifyProc);
    CHECK_ERROR
        error = sAIPanel->SetSizeChangedNotifyProc(fPanel, PanelSizeChangedNotifyProc);
    CHECK_ERROR
        error = sAIPanel->SetClosedNotifyProc(fPanel, PanelClosedNotifyProc);
    CHECK_ERROR
	
	AddQtWidgets();
}

AIErr EasyVariantsPlugin::AddQtWidgets()
{
    AIErr error = kNoErr;
    _hDlg = nullptr;
    error = sAIPanel->GetPlatformWindow(fPanel, _hDlg);
    if (error != kNoErr || !_hDlg)
        return error;
    
    _containerWidget = new QWidget();
    _containerWidget->setStyleSheet("background-color: green;");

    SetParent((HWND)_containerWidget->winId(), _hDlg);
    SetWindowLong((HWND)_containerWidget->winId(), GWL_STYLE, WS_CHILD | WS_VISIBLE); 

    AISize panelSize = { 0, 0 };
    error = sAIPanel->GetSize(fPanel, panelSize);
    _containerWidget->setGeometry(0, 0, panelSize.width, panelSize.height);
    _containerWidget->show();
    return error;
}

Calling below function from "void PanelSizeChangedNotifyProc(AIPanelRef inPanel)" callback

void UpdateUIOnPanelResize(AISize& outSize)
{
    if (_containerWidget != nullptr)
    {
        _containerWidget->setGeometry(0, 0, outSize.width, outSize.height);
    }
}

 

Correct answer bapuji_4469

Hi @A. Patterson, I have increased the size(Hard-coded to 1500 X 1500) but no luck. I will debug further and update here my solution later. I am also a windows guy. Thank you for the feedback and inputs.


Hi @A. Patterson, Good day. Finally, I figured out the solution. To fix this, we need to add the following line before instantiating QApplication:

QApplication::setAttribute(Qt::AA_PluginApplication);

The root cause is that after creating a Qt application in the plugin, Qt takes over the event loop and does not return it to Illustrator. 

1 reply

A. Patterson
A. Patterson
Inspiring
September 11, 2025

FIrst thing is to make sure that AI doesn't have any UI scaling going on. If so, you can tell Qt to match the UI scaling (it has a similar feature) and that might solve your problem.

 

We do exactly what you're doing and I don't see any obivous reason why it wouldn't work at first blush. If you find it's not the scaling, reply and I'll poke around our internals a bit and see if there's something we've got that you're missing.

B
bapuji_4469Author
Inspiring
September 12, 2025

Thank you, A. Patterson, for taking the time to read my lengthy post and respond. Your feedback is greatly appreciated. As you suggested, I attempted to set the scaled value to my QWidget; however, it is still not functioning as expected. I have applied a scale factor of 1.3333f, based on the conversion from points to pixels, but this has not resolved the issue. Could you please advise on how I can adjust the widget so that it occupies the available panel space? Maintaining the aspect ratio is not necessary in this case. My Dev setup details are: Windows 10, VS2022 and Adobe Illustrator 2025.

void UpdateUIOnPanelResize(AISize& outSize){
    if (_containerWidget != nullptr){
        const float kiUIScaleFactor = 1.3333f;
        const int kiNewWidth = outSize.width * kiUIScaleFactor;
        const int kiNewHeight = outSize.height * kiUIScaleFactor;
        _containerWidget->setGeometry(0, 0, kiNewWidth, kiNewHeight);
    }
}

  

A. Patterson
A. Patterson
Inspiring
September 23, 2025

Hi @A. Patterson, Good day. Finally, I figured out the solution. To fix this, we need to add the following line before instantiating QApplication:

QApplication::setAttribute(Qt::AA_PluginApplication);

The root cause is that after creating a Qt application in the plugin, Qt takes over the event loop and does not return it to Illustrator. 


Crap, I should have thought to check that stuff. I was so focused on the panel part. I haven't thought about the plugin part in years (we went to Qt about 20+ years ago and dealt with all of this then).


Glad you figured it out! Good luck with the rest, I hope it goes smoothly! I appreciate you letting me know!

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