Click through windows

Vunnm

Hi,

How do I create a transparent window with mouse events going through the window? Actually I try to set transparency with this in the constructor:

setAttribute(Qt::WA_TranslucentBackground, true);

But it only works on linux, under Windows I get a black background and I still don't know how to make mouse click going through my window.
I hope someone will know how to fix it :)

SGaist

Hi and welcome to devnet,

Looks like you want: widget->setAttribute(Qt::WA_TransparentForMouseEvents).

Vunnm

@SGaist I already try it:

here is my code:

#include "transparentwindow.h"

TransparentWindow::TransparentWindow() : QWidget()
{
    setFixedSize(300, 150);

    m_b= new QPushButton("Ok", this);
    //setWindowFlag(Qt::X11BypassWindowManagerHint);
    setAttribute(Qt::WA_NoSystemBackground, true);
    setAttribute(Qt::WA_TranslucentBackground, true);
    setAttribute(Qt::WA_TransparentForMouseEvents);
}

header of the file:

#ifndef TRANSPARENTWINDOW_H
#define TRANSPARENTWINDOW_H

#include <QObject>
#include <QWidget>
#include <QPushButton>

class TransparentWindow : public QWidget
{
public:
    TransparentWindow();

protected:
    QPushButton *m_b;
};

#endif // TRANSPARENTWINDOW_H

and my main.cpp:

#include <iostream>
#include <QApplication>
#include <transparentwindow.h>

int main(int argc, char**argv)
{
QApplication app(argc, argv);
TransparentWindow f;
f.show();

return app.exec();

}

but here is the result:

mrjj

Hi
Being drawn transparently or have mouse event passthrough is not the same.
Anyway, i used this to have a 100% invisible window and clicks went through it.
(win 10, not tried on linux)

class Overlay : public QWidget {
  Q_OBJECT
public:
  explicit Overlay ( QWidget* parent = 0 ) :
    QWidget ( parent ) {
    setPalette ( Qt::transparent );
    setAttribute ( Qt::WA_TransparentForMouseEvents );
  }
protected:
  void paintEvent ( QPaintEvent* event ) {} // draw nothing ( i did draw some stuff) not 100% sure its needed.
};

Vunnm

@mrjj I simply copy/paste your code but I still get the same result: a black window and the click don't go through the window (I try it on both Windows and linux).

mrjj

@Vunnm

Works here. (win 10)
You can try my sample
https://www.dropbox.com/s/v74riecj5zq1t3t/trans.zip?dl=0

Vunnm

Well your project don't work for my, perhaps because I am using a 64 bits Windows 7 on virtual machine and compiling my project in 32 bits. But anyway I find a solution on another forum, here.

here the constructor of my transparent and click-through window:

MyWindows::MyWindows() : QWidget()
{
    //setWindowFlag(Qt::X11BypassWindowManagerHint); 
    setAttribute(Qt::WA_TranslucentBackground, true);
    setAttribute(Qt::WA_TransparentForMouseEvents);

    setWindowFlags(Qt::FramelessWindowHint);
    setWindowFlags(Qt::FramelessWindowHint | Qt::WindowStaysOnTopHint); //we can add Qt::Tool
    //setFixedSize(300,300);

}

so thanks everyone for your help!

dschiller

@Vunnm What I also do - I know it's Python code, but that changed a lot for me.

self.setStyleSheet('background: transparent')

With setting the style sheet background to transparent:

And without:

Here the full code of my UI Init method:

from PyQt5.QtWidgets import QVBoxLayout
from PyQt5.QtCore import Qt
from ..Scene import Scene
from ..GraphicsView import GraphicsView
from ..properties import Properties


def initUI(self):
    """Initialize the user interface of the window."""

    props = Properties()

    self.setGeometry(0, 0, int(self.screen_.width(0)), int(self.screen_.height(0)))
    self.setStyleSheet('background: transparent')
    self.setWindowFlag(Qt.WindowType.FramelessWindowHint)

    # Only necessary on Windows
    self.setAttribute(Qt.WidgetAttribute.WA_TranslucentBackground)

    self.layout = QVBoxLayout()
    self.layout.setContentsMargins(0, 0, 0, 0)
    self.setLayout(self.layout)

    props.scene = Scene()

    self.view = GraphicsView(props.scene.grScene, self)
    self.layout.addWidget(self.view)

It has come to my attention that the proper arrangement of Window Flags holds significance as well.

Having the flags in this order:

self.setWindowFlag(Qt.WindowType.FramelessWindowHint)
self.setAttribute(Qt.WidgetAttribute.WA_TransparentForMouseEvents)

Makes the WA_TransparentForMouseEvents useless and it doesn't show any effect.

Whereas this order works and I can click trough the window:

self.setAttribute(Qt.WidgetAttribute.WA_TransparentForMouseEvents)
self.setWindowFlag(Qt.WindowType.FramelessWindowHint)

SamiV123

On Win7 (at least) transparent windows are are feature of the Windows window compositor (Aero) and you need to enable transparency in Windows graphics/system settings.