I have 2 widgets:
One of them is background(semi-transparent), second contains other widgets(without background)
Can I make a blur behind window like this?
I have 2 widgets:
One of them is background(semi-transparent), second contains other
widgets(without background)
QLCDNumber is a widget of such kind.
That is doable and one of the good examples is: C++,Qt QMainWindow Transparent Background Example. But if you need to make it semi-transparent or lower the transparency you can do something like:
// mind the last component of rgba
mainwindow->setStyleSheet("QMainWindow{background-color: rgba(255, 255, 255, 127)};");
Related
In my paintEvent method for a custom widget for a game I'm writing, After calling the various model objects' render() methods to render them to the widget, I am trying to render the "Hi-Score" text. Here's the general code for just the text drawing:
painter.fillRect(event->rect(), QColor(0, 0, 0));
painter.drawImage(QRectF(event->rect().x(), event->rect().y() + 30, 512, 512), getGameBoardImage());
//...rendering other model components
painter.setBrush(QBrush(QColor(255, 255, 255)));
//painter.setFont(getGameFont());
painter.setFont(QFont("Times New Roman", 16, QFont::Bold));
painter.drawText(0, 0, "HI-SCORE");
I 'was' trying to draw the text in a custom font loaded from resource (I found an answer on here for that) but it wouldn't even display, even with a white brush. I thought maybe it was because it was because I didn't 'set' a font, but setting it to Times New Roman doesn't display anything either. What might I be doing wrong? As you can see the background is a black background with the game board painted on top but leaving a small buffer at the top and bottom. Do I need to do something special to display the text? Please don't suggest using a QLabel because I am trying to keep it all in one widget if possible. If I must, I will split the Hi-Score and 1-Ups into 2 other label sets with specialty fonts.
you code look ok, but you are drawing at 0,0 which is the top left corner of the widget canvas AND the text is actually there but not visible...
draw instead at
painter.drawText(margin, y+margin, "HI-SCORE");
where y is the high of the font used to draw the text and margin is you know a little margin border to make it look better something like 5 units
update
you can get the value of the text you are painting doing somthing like
QFont font("times", 25);
QFontMetrics fm(font);
int pixelsW{fm.width("HI-SCORE")};
int pixelsH{fm.height()};
How can I get the pressed background color of a QPushButton?
if (isDown())
_BGColor = <pressed background color>; // how to get this???
else
_BGColor = palette().color(QPalette::Background); // this is to get the idle backcolor
Thanks in advance!!!
It's very difficult (if not impossible) to find a way to get the backgound color of a button when it's pressed, because it depends on the style, and it's not guaranteed that the style respects the palette.
However I suggest two different approaches:
You can set you own background color using style sheets (simpler) or implement the painting of the button yourself, using styles or reimplementing paintEvent(). See Customizing QPushButton
To paint over the button with the inverse color, you can set a composition mode to the painter in order to get the inverse color.
For example:
painter.setPen(QColor(255, 255, 255));
painter.setCompositionMode(QPainter::RasterOp_SourceAndNotDestination);
(note that using this example, the inverse color of middle grey (128, 128, 128) is exactly the same color)
See QPainter::CompositionMode
I am fairly new to Qt and have been doing a lot of reading and practicing exercises.
I have searched for this one quite a lot but I could not find any examples.
I have a QPixmap object to which I load a .png image.
I need to create a copy of this QPixmap with a dark mask applied to it.
Basically I want this QPixmap's image to be covered with a layer of solid black of which the opacity is set to 50%.
I know how to set the opacity of a QPixmap's image but how can I add a layer of solid black with opacity on it?
Thank you!
You can use a QPainter and you a semi-transparent QBrush to paint that dark layer onto your QPixmap.
Assuming pic is a QPixmap loaded with your image:
QPainter p(&pic);
QBrush b(QColor(0,0,0,128)); // adjust color and alpha to taste
p.setBrush(b);
p.drawRect(0, 0, 200, 200);
Effect (before/after):
vs
The opaque black border can be removed by setting an semi-transparent pen before painting.
Copy the pixmap before applying the "mask" if you want to preserve the original.
I tried to add a gradient background on my main QWidget by adding (background-image:url(images/background.png) to its stylesheet but I noticed HUGE performance drops and I haven't written any code yet.
background image is a gradient , 16bit 1x800 px png.
So my question is, how can I add a nice gradient to my QWidgets / QFrames without slowing down the program? Using only the designer.
Try this:
QPalette thePalette = this->palette();
QLinearGradient gradient(0, 0, 0, 50);
gradient.setColorAt(0, QColor(227,177,27));
gradient.setColorAt(0.25, QColor(170,177,167));
gradient.setColorAt(1, Qt::white);
QBrush brush(gradient);
thePalette.setBrush(QPalette::Window, brush);
setPalette(thePalette);
and modify freely the colors and the positions. Although that this is code, it might be useful.
I'm trying to draw a semi-transparent rectangle on top of an image to act as a highlight. Unfortunately, nothing I try seems to be able to perform the transparency effect I want. Instead I just get solid filled rectangles, with no transparency.
Here's what I'm doing right now:
void PageView::paintEvent(QPaintEvent *event)
{
QPainter painter(this);
QImage img=...;
painter.drawImage(0, 0, img);
...
// draw a light blue, transparent rectangle to highlight
QRect rect=...;
painter.fillRect(rect, QColor(128, 128, 255, 128));
...
}
Unfortunately, for me, this draws a solid blue rectangle, instead of the semi-transparent one I expect due to giving the QBrush an alpha value.
I've also tried drawing to an intermediate QImage or QPixMap, playing around with painter.setCompositionMode(...). No luck so far.
Thus my question: How can I convince Qt to draw a semi-transparent rectangle to my PageView?
EDIT: If it's relevant, I'm building this under Qt 4.8.1 on Windows.
The code works for me with a slight modification as it does not compile as you have it:
painter.fillRect(rect, QBrush(QColor(128, 128, 255, 128)));
NOTE:
The OP was painting the semi transparent rectangle in a loop causing the same area to be painted multiple times. This will result in an additive effect which will eventually cause that area to look the same as a solid fill.