Is it possible to set a virtual resolution of a screen, meaning increasing its resolution over its normal resolution (say, I've got a 1920x1080 screen, can I use it like it was a 3640x2160 screen)?
With X it was easy, just xrandr --scale 2x2, but with wayland I can't seem to find a way to do it...
It would be to set up a multi-screen environment, with one good screen and a bad screen, and I need to double the resolution of the bad screen, to have the windows about the same size in both screens, which is my goal.
I've read somewhere about multi-screen scaling, but couldn't fine more informations about
Thank you for your help
If you are using weston compositor then you can specify the "scale" factor in weston.ini file under [ouput] section please refer here http://manpages.ubuntu.com/manpages/bionic/man5/weston.ini.5.html
scale=factor
The scaling multiplier applied to the entire output, in support of high resolution("HiDPI" or "retina") displays, that roughly corresponds to the pixel ratio of the display's physical resolution to the logical resolution. Applications that do not support high resolution displays typically appear tiny and unreadable. Weston will scale the output of such applications by this multiplier, to make them readable.Applications that do support their own output scaling can draw their content in high resolution, in which case they avoid compositor scaling. Weston will not scale the output of such applications, and they are not affected by this multiplier.
An integer, 1 by default, typically configured as 2 or higher when needed, denoting
the scaling multiplier for the output.
Related
When using "setMinimumHeight(...)/setMinimumWidth(...)" what units are the arguments in? I'm not turning up anything online, the book I bought doesn't address it and based on my experiments the units certainly aren't pixels. Thanks in advance.
Those parameters are measured in pixels, but there are other things at play here as well that unfortunately are harder to deal with and may be complicating your measurments.
Take a look at the following two images. The resolution of my screen remains at 3840x2160 but the "Scale Factor" that Windows suggests varies between 100% and 250%.
Scale Factor = 100%
Scale Factor = 250%
The ruler has actually changed size which could give you the impression that the size policy of these isn't equivalent to the pixel size. Note the size of each of these widgets starts at the grey, not at the blue. Additionally, even though Qt maintains the size of the widget in pixels independently from Windows' "Scale Factor", the same can't be said for the label in the center which does change in size depending on the scaling.
I don't know exactly how you are taking your measurements, what the GUI is, or what your display setting is, but those all can contribute to the confusion around sizing in Qt.
I'm told that DPI and Points are no longer relevant in terminology involving graphical displays on computer screens and mobile devices yet we use the term "High DPI Aware" and in Windows you can set the various DPI levels (96, 120, 144, 192).
Here is my understanding of the various terms that are used in displaying images on computer monitors and devices:
DPI = number of dots in one linear inch. But DPI refers to printers and printed images.
Resolution = the number of pixels that make up a picture whether it is printed on paper or displayed on a computer screen. Higher resolution provides the capability to display more detail. Higher DPI = Higher resolution, however, resolution does not refer to size, it refers to the number of pixels in each dimension.
DPI Awareness = an app takes the DPI setting into account, making it possible for an application to behave as if it knew the real size of the pixels.
Points and Pixels: (There are 72 points per inch.)
At 300 DPI, there are 300 pixels per inch. So 4.16 Pixels = 1 point.
At 96 DPI there are 1.33 pixels in one point.
Is there a nice way to "crisply" describe the relationship between DPI, PPI, Points, and Resolution?
You are correct that DPI refers to the maximum amount of detail per unit of physical length.
Computer screens are devices that have a physical size, so we speak of the number of pixels per inch they have. Traditionally this value has been around 80 PPI, but now it can be up to 400 PPI.
The notion of "High DPI Aware" (e.g. Retina) is based on the fact that physical screen sizes don't change much over time (for example, there have been 10-inch tablets for more than a decade), but the number of pixels we pack into the screens is increasing. Because the size isn't increasing, it means the density - or the PPI - must be increasing.
Now when we want to display an image on a screen has more pixels than an older screen, we can either:
Map the old pixels 1:1 onto the new screen. The physical image is smaller due to the increased density. People start to complain about how small the icons and text are.
Stretch the old image and fill in the extra details. The physical image is the same size, but now there are more pixels to represent the content. For example, this results in font curves being smoother and photographs showing more fine details.
The term DPI (Dots Per Inch) to refer to device or image resolution came into common use well before the invention of printers that could print multiple dots per pixel. I remember using it in the 1970's. The term PPI was invented later to accommodate the difference, but the old usage still lingers in places such as Windows which was developed in the 1980's.
The DPI assigned in Windows rarely corresponds to the actual PPI of the screen. It's merely a way to specify the intended scaling of elements such as fonts.
DPI vs. resolution – What’s the difference?
The acronym dpi stands for dots per inch. Similarly, ppi stands for pixels per inch. So, why have two different acronyms for measuring roughly the same thing? Because there is a key difference between the two and if you don’t understand this difference it can have a negative impact on your digital signage project.
Part of the confusion between the two terms stems from the fact that many people who use them are lazy and tend to use the terms interchangeably. The simplest way of thinking about them is that one is digital (ppi) and represents what you see on the computer screen and the other is physical (dpi) for example, how an image appears when you print it out on a piece of paper.
I suggest you to check this in-depth article talking about the technicality of this topic.
https://blog.viewneo.com/blog/72-dpi-resolution-vs-300-dpi-for-digital-solutions/
Is there any relation (preferably an equation) between the number of polygons in a 3D object and the rendering workload? I want to see how much the rendering workload would be increased if for instance the number of polygons doubles.
There is no clear connection between the arbitrary number of polygons and the mythical "workload".
See the following samples:
You render a cube with 6 faces composed of 12 triangles. You get, say, 1000fps (without vsync). When you tesselate the cube into 120 triangles, most likely the fps counter remains 1000.
You render a single fullscreen-sized quad with a heavy fragment shader with a lot of calculation. You get 0.5fps (or more, but I hope you get the point).
Another extreme. You are rendering a thousand of similar cubes, each with different texture. The rendering state change will take most of the time, not the actual rendering.
So, polygons may have different screen area and they may be rendered not within a single primitive. If you're talking about one big vertex array with a large number of polygons, then for some certain scenarios the performance change must be something like linear. "Something" because the videocard and the drivers are clipping the invisible polys and perfrom the early-out tests for each pixel being rendered.
Could you define 'workload'? – Erno yesterday
Well, I mean working
calculations. I want to see how much overhead (for GPU, CPU,
memory,...) would be increased. Actually I want to conclude the energy
usage of the device – user1196937 2 hours ago
If that is the actual question, a comparison of energy usage:
You will have to pick specific configurations and test those. Energy usage is very different from GPU to GPU and machine to machine.
Some GPU manufactures give very detailed information on the performance of their processors but when you want to compare those you will need an actual machine.
I took a look at the phone specifications and is says something like this
"HTC Desire. It comes with a 3.7" LCD screen (480 x 800 pixels of resolution)"
ok the screen is 480x800 pixels but how many dips it has ? and how do I calculate that.
Also it is confusing for me the fact that Desire HD has the same resolution 480x800 pixcels, and they both use hdpi images. I have application and when I install myApp they both use the images from hdpi folder
can someone tall me what is the resolution in dips in desire and desireHD ?
You can get information about display, such as size, density, and font scaling using DisplayMetrics.
Documentation gives a usage example.
Is there a recommended smallest button size under normal conditions?
By "recommended" I mean prescribed by some document like:
Apple HCI Guidelines
Windows UX Guidelines
or some ISO standard..
By "normal" conditions I mean:
desktop/office use
standard 96dpi monitor resolution
mouse/touchpad for pointing (no touchscreen)
non-disabled or visually impaired users
standard "theme" (no large fonts/icons)
Microsoft's UX Guide for Windows 7 and Vista recommends:
"Make click targets at least 16x16 pixels so that they can be easily clicked by any input device. For touch, the recommended minimum control size is 23x23 pixels (13x13 DLUs)." where"A dialog unit (DLU) is a device-independent metric where one horizontal dialog unit equals one-fourth of the average character width for the current font and one vertical dialog unit equals one-eighth of the character height for the current font. Because characters are roughly twice as high as they are wide, a horizontal DLU is roughly the same size as a vertical DLU, but it's important to realize that DLUs are not a square unit."
You may also want to look up Fitts' Law, which calculates the time necessary to complete an action as a function of the target size. That can help mathematically determine the trade-offs of different button sizes.
Well, I try to make important/common mouse targets as large as possible without looking bad, something about 20 pixels (assuming 96 DPI) height, and as much width as needed to accomodate labels. If the button has no labels, which is very rare, I found out it's actually comfortable to have an aspect like 20w/50h (with the icon on top, not center), since the mouse is easier to move horizontally. So it's also good to keep them in the same row.
In addition to what MsLis suggested the UX Guide also suggests a minimum width of 75 pixels specifically for Command Buttons.
UX Guide - Recommended sizing and spacing