I have a fixed strip I'm drawing, 50 pixels in height and as wide as my application main window.
I'd like to place text on that strip.
My problem is that even with the same font and size (arial 15 for example), the font will have a different height under OSX and Windows.
Is there a way to make this more predictable? I know I can use the QFont measuring mechanism until the extent of the text I need will match my target projection area, more or less. but is there another way to set size that'll be identical across operating systems? Just want to make sure I'm not missing something here.
You can specify font heights in pixels using QFont::setPixelSize(). It's particularly handy when drawing text over fixed sized bitmaps.
Related
Learning about rem and try to make whole website responsive.
According to the value of 1rem, should I be scaling:
Font sizes and margins/paddings around text
margins/paddings/size of elements that do not directly contain text like components and images
Does this depend on the layout?
For example, I have an image in a card component. As user increases the font size, image or space around it might stay small next to a larger font.
Should I let this happen or scale image with the font size? I know the setting in the browser only changes font size. On Facebook, for instance, font size from browser settings does not affect the images or component sizes.
Should I then only worry about text?
I think this is entirely based on context/preference but,
Generally yes, if you are using 'em' for padding/margin (which you should be) this will scale automatically however to the font-size of its element.
Depends on the element, text is hard to read for some people as its small lines in unique shapes so this makes the most sense to scale however images and other elements are generally a lot easier to look at. - if the content of the element is something like an icon for button I would probably scale it with text as it is likely to be adjacent to some text so would look weird if the text scaled but the element didn't. Otherwise I would just use responsive web design such as flex/grid to fill the space of a page, this is "scaling" however less for accessibility and more for design.
I'm working on a website over here:
venuslabs.org
Some of the tabs, such as "Technology Details (pdf)" and "Venus Needs Advocates (Take Part!)" create a number of subwindows in the middle. Their sizes are based on em, so that they scale properly if the user changes their font size / zoom level (as I understand is "best practices" today).
The way they are looks fine... most of the time. But when viewed on a cell phone in horizontal (not vertical) layout, they're just too big and overlap the top bar. So it appears that the current layout is fine down to a certain height, but below that height I need to have the font size scale linearly with page height (with the subwindows scaling along with the font size).
Obviously I could do that with javascript, but I know you're supposed to do things in pure CSS where possible. What would be the recommended approach? I've been trying a number of things and none have really played out.
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what is the difference px,em and ex?
I have a question for all the coding geniuses on StackOverflow.
I am a newbie, and I am about to start building my third website. Being that I had some problems with the layouts of my first two websites, I am asking this question before I start on my third:
What measurement is it best to use for
the css elements? Percents,EM's or Px?
Which form of measurement will ensure that I have a site that will not get distorted on different browser sizes/resolutions? Is there anything else that I have to be careful of when building my site so that it will not get distorted when a user zooms, or looks at the site from a different browser size/ resolution? (as was he case on my other sites)
Thanks for your time, guys. Any help would be greatly appreciated!!
Thank you.
Whichever is easier for you to work with.
Modern browsers (i.e. everything in use today except for IE6 and IE7) have a concept of "CSS pixels" which is different from "actual pixels," so e.g. zooming changes the size of a "CSS pixel." Fonts will scale just fine; if you say the font is 14px, it will start out that way, but if the user zooms it'll get bigger. Thus, if it's easy for you to measure in pixels, for example to size page elements relative to an image of a given pixel size, you should do pixels.
Sometimes you want to size things relative to text, though. If the width of an em-dash is a useful measurement, somewhat representing the "longest possible character," go ahead and use ems.
And finally, if you're trying for a fluid layout, percentages can be great: a gradient that starts fading 50% across the page is often what you want, as opposed to one that starts fading after some fit number of pixels. Even if you're not fluid, and the width of your container is fixed to e.g. 900px, it's still often useful to say "this goes at the 50% mark" or "I have one thing at the 33% mark and one at the 66% mark." That's much easier to work with than figuring out what the corresponding pixel offset is every time, and makes your intent clearer to anyone reading your code.
Short answer: it depends.
Longer answer:
There is a place for all three units, frequently in the same design. There is no "best" unit; they serve different purposes.
Pixel units generally offer the most precise control over the size of the elements in the user interface, but also restrict that size such that it does not change with regard to the other elements of the page design. The size of pixels themselves may change. For example, a Retina display packs more pixels into the same physical space as a non-Retina display, so images which were designed for traditional displays get scaled up. Similarly, traditional desktop web browsers may adjust the size of pixel in response to the user zooming the size of a page. In these cases however, the pixels change sizes throughout the entire document, and retain the same proportions with regard to one another, so you can use px values and expect them to work sanely in most conditions.
EM units vary according to the size of the text. They're most commonly used for setting the size of text, and for line heights; but there have been some interesting things done with "elastic" layouts such as the elastic lawn zen garden (turn off page zoom for this site; switch to text-only zoom and change the size a few times).
Percentages vary according to the size of the containing element, expanding and contracting depending on how much room is available to them.
And, really, it's very common to see web designs that use all of these. For example, suppose you have a site with two columns. The main column must expand and contract with the browser width, but the secondary column needs to stay the same width. The main column might have a width of 100%, but also a margin set in pixels for the secondary column to float in. And the text and line height might be set in ems.
So, the real answer is: they all have their uses. Keep practicing, and pretty soon you'll figure out how it all fits together.
EDIT: In the example above, I should have said "a width of auto" -- meaning take up all available space after margins, padding, and borders are accounted for. Sorry, I tend to think of that as a percentage even though it's actually a keyword.
from accessability point of view need to use EM's. You need you layout to adapt to very different fonts sizes so if allmeasurements are in EM's everything will scale as accessability tools increase font size
When creating liquid layouts, it makes sense to use percentages for the widths of your blocks, so they shrink and grow with browser size changes.
For heights, pts have a specific spatial value, and em are related to your current point size. This is useful because things specified in those units will be roughly the same size on everyone's display (unless they have different zoom factors applied). em are also useful when working with a dimension driven by an amount of text.
Browsers will also scale values specified in pixels, so they are not any more a "trap", but they are rarely the "natural" choice for layouts, unless working with raster images.
As Will and Domenic say: use all three, when appropriate. As you get more experience, you'll get a better feel for when to use which.
If you want to design a fixed layout website then use px or em.
If you want to design a fluid layout website then use percentages.
Percentage is always relative so page content with dimensions in percentage will automatically resize on window resize and on different screen resolutions.
px and em are one and the same thing. Same in their nature. They define the absoluteness of the dimensions. Btw for the difference, 1em=current font size. So if your html or body has css font-size:19px; then 1em=19px.
I have windows that are fixed in size, under which I have textual labels. Although I use the same font, the fonts look different on windows, mac and linux, up to the point where I can't rely on where a label will end, even though the string and the font size are a constant in my application.
Is there any solution to that? Someone mentioned embedding TTF fonts and using them, but is that really necessary?
There is no font you can rely on being available on all platforms, and height/width ratios for different strings will differ for different fonts (fixed-width being slightly better). Additionally, things like different DPI settings will cause you headaches even if using the same font. I would rather reconsider whether your widgets really should be fixed size and you need those assumptions about the font size at all. In almost all cases, your UI will be more usable, readable and consistent with the rest of the desktop if you use flexible layouts and stick to whatever font and font size the platform suggests.
You can use QFont::setPixelSize to guarantee a consistent font size across platforms.
Since the goal is to keep a line of text label from drawing over and out of the window bounds, one solution is to adjust the font size used at runtime.
QFontMetrics provides boundingRect() family of calls to find how must space a text string will take when drawing in a given font. With those, you can test if the string can fit in the space. If it doesn't fit, reduce the font size and test again.
I read somewhere on a site :
In principle, using a px measurement for font-size is not a good idea. A handful of browsers will prevent the font from being resized by the user if you do this.
Is this right??
Is this right??
Well, yes, certainly there are a few (generally older) browsers that won't let you resize the text when it's sized in px, pt, in, mm and so on.
But even in browsers with a working zoom, it's polite to work relative to the user's stated preference for font size, so they don't have to resize the text or zoom the page manually to make it comfortable. (Fixed fonts plus fixed width page can be particularly bad for this in page-zooming browsers as zooming up is likely to make the columns of text too wide to fit the screen.)
In principle, using a px measurement for font-size is not a good idea.
I wouldn't go so far as to say it's always a bad idea.
There are often elements on the page where you want the text to be sized to match an image (say, a header with text below it that should fit more-or-less without wrapping, or text above a background image made to fit it). In that case you should use px to make fonts and images line up nicely.
For the page's main body text, yes, it's nicer to use em/% and let the user decide the size. But for text that plays a part in the page's graphical layout, px fonts are typically the best bet.
The issue is mainly with aspect ratio. Let's say my resolution is 1024x768 for an aspect ratio of 1.33. For 1920x1080, the aspect ratio becomes 1.77, meaning that any image displayed at a specific pixel width and height will be a different size in inches due to the scaling effect of the aspect ratio. The same basic issue exists if you zoom as you are effectively using the aspect ratio in the zoom window.
Most websites get around this by using em which, to be honest, suffers from some of the same downfalls as any other rendering mode. Even "device independent pixels" are based on the DPI of a monitor. So, use em knowing that it just has less faults than px, not because it's perfect.
Read the following article if you want a more in depth study.
http://www.w3.org/WAI/GL/css2em.htm
Yes, at least IE6 & IE7 do that. Take a look at How to Size Text in CSS.
Quoting CSS: The Definitive Guide by Eric Meyer
There is one more value that is
potentially the same as 36pt, and
that's 36px, which would be the same
physical distance if the display
medium is 72 pixels-per-inch (ppi).
However, there are very few monitors
with that setting anymore. Most are
much higher, in the range of 96ppi to
120ppi. Many very old Macintosh web
browsers treat points and pixels as
though they are equivalent, so the
values 14pt and 14px may look the same
on them. This is not, however, the
case for Windows and other platforms,
including Mac OS X, which is one of
the primary reasons why points can be
a very difficult measurement to use in
document design.
Because of these variations between
operating systems, many authors choose
to use pixel values for font sizes.
This approach is especially attractive
when mixing text and images on a web
page, since text can (in theory) be
set to the same height as graphic
elements on the page by declaring
font-size: 11px; or something similar,
as illustrated by Figure 5-15.
Using pixel measurements for font-size
is certainly one way to get
"consistent" results with font-size
(and, indeed, with any length at all),
but there is a major drawback.
Internet Explorer for Windows up
through Version 6.0 does not allow
users to easily resize text that has
been set with pixels. Other browsers,
including Mozilla, Netscape 6+,
IE5+/Mac, Opera, and even IE7, allow
the user to resize text no matter how
it's been set. Thus, using pixels to
size text is no more of a guarantee
that it will stay the same size than
is any other method. The other
approaches discussed in this chapter,
such as keywords and percentages, are
a much more robust (and user-friendly)
way to go, as they can be used to
scale text from the user's default
font size.
That said, the issue here is what unit to use for your body element. In most cases, you should use the em unit for other elements like headings and paragraphs.