I have a QGraphicPixmapItem as a game piece in my program. It has three main states: red, blue, and blank. The problem is, when blank, the piece is not clickable.
When red, I change the pixmap of the piece to a red, vaguely checker-like png. When blue, I do the same. When blank, I use a completely transparent png.
This blank, completely transparent pixmap is why (as far as I can tell) events are passing right through it. When I redid it by changing the pixmap to the red checker, then manually resetting the opacity to zero, the same thing happened. When I left even 0.01 opacity in the newly-red piece, however, the event triggered.
Clearly, being transparent means events pass through you for a QGraphicPixmapItem. How do I change that and make it receive events? Or is my conclusion wrong?
What you're seeing is the correct behaviour as described by the shapeMode.
You can change it to use QGraphicsPixmapItem::BoundingRectShape which, as the documentation states:-
...does not take into account any transparent areas on the pixmap.
If you still need to obey transparency, then you could inherit from QGraphicsPixmap item and reimplement the shape function to set the opacity to 0.1, call the base class shape function and set it back afterwards.
Related
I was trying to add some transparency to a text and oddly enough I noticed it was only transparent on one side while being opaque on the other.
The expected behavior was transparent on both sides. Any idea why this happens?
Thank you.
https://aframe.io/docs/0.8.0/components/material.html#transparency-issues
With opacity, A-Frame sets three.js renderer to sortObjects: false. Transparency ordering is based on when objects are added / defined in the scene. Shuffle the order of the text in like the HTML or when they are injected and it should work.
I'm using Qt3D with a combination of this offscreen renderer and modified the framegraph to include a background image, like here.
Unfortunately, adding transparency to the objects drawn over the background image using QPhongAlphaMaterial only works unsatisfactorily.
This is th result:
What you can't see here is that the whole circle part is actually transparent, i.e. the renderer wrote the transparency value of the object for the whole pixel instead of adding it transparently on top of the background.
This is what the rendered object looks like wihtout transparency:
And this is the background:
The framegraph has two branches: one for the backgroun image, which is processed first, and one for the objects. I added a QRenderStateSet for the objects that contains a QBlendEquation with the blend function set to add and a QBlendEquationArguments with source RGB and alpha set to 1, and destination RGB and alpha set to 1 minus source alpha.
Any ideas how to fix this problem?
(For anyone wondering, I took the images from the T-Less dataset and wrote a program to create ground-truth data for 6D pose estimation)
Similarly to this question, the format of the texture that is being rendered to needs to be set to RGB8_UNorm and not RGBA8_UNorm, i.e. without the alpha channel.
I’ve searched and I haven’t found a way to get a certain level of transparency in a colored button while the text of the button is 100% visible.
There has been options to get certain levels of transparency in a button, but the text also becomes transparent and that’s not what I want.
Any pointers?
Do do it in code, you can use:
yourButtonName.getBackground().setAlpha(int alpha)
where alpha is an int between 0 and 255.
Do do it in XML, you would add something like this to your button attributes:
android:background="#8000FF00"
This would yield a 50% opaque green color.
To better understand how we arrive at the code "#8000FF00" , look here.
:)
I have a transparent QGraphicsWebview inside a QGraphicsView with the following settings:
The QGraphicsView is the high level widget, and is shown in full screen mode
The graphics view uses a QGLWidget as its view port (to use opengl-es)
Alpha channel and double buffering are enabled in this QGLWidget
Transparency is achieved by graphicsView->setStyleSheet("background:transparent")
Following attributes are set for QGraphicsView and QGraphicsWebview
WA_TranslucentBackground = true
WA_NoSystemBackground = true
WA_OpaquePaintEvent = false
The QPalette::Base and QPalette::Window brushes of webview and webview->page() are set to Qt::transparent
At the beginning, the transparency works fine. But as the screen get updated (when I scroll), it looks like the new bitmap is blended on top of the existing one to get a superimposed picture. After about 5-6 screen updates, this blending causes the colors to accumulate and form an opaque rectangle (with a corrupted image). Following images show first, second and final stages of the problem.
How do I tell qt/opengl to stop blending and just draw the new image to the frame buffer?
I tried calling fillRect(boundRect(), Qt::transparent) from overridden Webview::paint and GraphicsView::paintEvent; but it didn't work except for making the updates slower.
I am new to Qt and OpenGl, so I might be missing some basic flags or settings.
I tried all the methods mentioned above. They did not work for me. I then debugged into qtbase code and found that setting the Opacity level make the top browser layer transparent.
this->setOpacity(0.1);
this pointer points to the QGraphicsWebView object.
With this method, the whole front browser contents including background will be transparent. To separate header, paragraph and background and to specify different transparent levels for them, I will have to dig into webkit code a little further to figure out the problem. But for now, setOpacity() did the trick and is good enough for what I am doing.
It turns out the problem is graphicsView->setStyleSheet("background:transparent");. Who would have guessed?!
Yeah, the line that I thought made transparency work was actually causing troubles with transparency. The application works fine without that line (or if you change it to background:none)
In short, steps to get a transparent QGraphicsWebview using QGLWidget:
Set the Base palettes of QGraphicsWebview, QWebpage and the outer QGraphicsView to Qt::transparent
scene->setBackgroundBrush(QBrush(Qt::transparent));
You should also make sure that html body background is set to transparent values:
html, body {
background-color: rgba(127, 127, 0, 0.5);
}
I am building an App in which I had given background to my mainWindow only and all other widgets are used without any background, but when I run the app they are not 100% transparent they are somewhat translucent, is there any way to make them 100 % transparent so that only foreground can appear with no background hint.
Could you post the code you are using to get transparancy at the moment? If you say that you get "something translucent" I think that you created a tool window which is not what you really want.
A really transparent main window could be achieved by removing the title bar (give the QWidget constructor Qt::FramelessWindowHint as second parameter - WindowFlags), draw everything in the widget that should be transparent in a uncommon color (like 255,0,255) and then cut it off.
A very primitive example of cutting off parts of a QWidget:
QBitmap b(100, 100);
b.fill(Qt::black);
setMask(b);
QBitmap must be black on that pixels that shall be visible and white on that are not. In this example just the 100,100 area starting at 0,0 will be visible, the rest of your window will be invisible.