I'm a bit confused about how device screen emulation works in chrome and how to use it to write affordable media-query. e.g.
IPhone X
Real device screen-size: 1125x2436px
Emulated device screen-size: 375x812px
I know that a resolution like that easily take two full-hd screen to be shown at 1:1 scale with the actual monitor resolution (pixel density), but the emulated res is not simply the result of a zoom-out, because if I zoom in or out the view, pixel size is about the same, and this make me think that chrome is suggesting me that the emulated resolution should be my reference for layout, like it is the real-device res.
But if it is, how this resolution is calculated? Why I should use this instead of the actual device screen-size?
While phone screens are usually high resolution like Full HD or Quad HD, their browser viewports are not, instead they are the resolutions Chrome shows you in the developer tools.
This helps you when setting up your CSS media-queries as you don't have to handle every single resolution of every specific device.
But if it is, how this resolution is calculated?
It is just a scaled down version of the actual screen resolution for that given device.
Why I should use this instead of the actual device screen-size?
Because the actual resolution of the viewport is that one and not the device screen size.
You can read more about this here: https://mediag.com/blog/popular-screen-resolutions-designing-for-all/
Related
I'm a bit confused about CSS pixels and whether they translate into pure resolution or physical width of devices.
My question is, will content displayed on a 1080p 13 inch laptop be the same as content on a 4k 13 inch laptop? Or will everything be scaled down?
(I'm using (max-width)/(min-width) media queries and not (max-device-width)/(min-device-width)
I'd be glad if you guys could clear this up for me.
Yes, it should render the same.
CSS uses “px” to relate “...the pixel unit to the reference pixel...”, thus a single CSS “px” could represent more than one physical pixel as different devices (ie. HD vs. 4K) have different pixel densities.
A single “px” in CSS should always be about 1/96 of an inch though. You may see variations in rendering based on browser rendering and/or monitor resolution quirks.
For most cases, desktop and laptop displays will use the same pixels their resolution is set to for CSS pixels. In these cases, a 4k 13" laptop without scaling will display more content, at a smaller physical size, than a 1080p 13" laptop.
That said, there are some cases where this isn't quite true. With mobile devices the browser will use a scaled down resolution so that elements are rendered at a more natural physical size. This scaling can be determined by the devicePixelRatio - which is the ratio of physical pixels to CSS pixels.
Further reading about devicePixelRatio: https://www.quirksmode.org/blog/archives/2012/07/more_about_devi.html
Details on sizes for mobile devices: https://mydevice.io/devices/
I am trying to create website in kiosk device. It is working fine when I test it in my browsers(chrome). But when it comes, to kiosk device, the page is fully distorted. The kiosk screen resolution is 1980 x 1020. Actually my page has two columns width 50% each. And each column has some fields arranged.Can somebody please guide me as how to start with the media queries for this resolution.
If you have made the website for smaller resolutions and then you will put kiosk resolution, the images and other elements are going to be bigger (so will be distorted).
You need to implement in your website different resolutions (thinking in different devices) and in this case you need to think in the big resolution that you can put your web, ie: Full HD and then resize to smaller resolutions.
I'm trying to make sense of CSS media queries for a mobile-only page. My final goal is to have the font size on my page be about the same in physical units (inches/centimeters) regardless of decice physical size and resolution. But what I see reported by the media queries has nothing to do with the device specs.
I'm testing on an HTC One M7, which is 1080x1920, 467dpi - manufacturer specs.
The precise numbers reported by the media queries is:
width (as reported by min-width/max-width): 1080px
resolution (as reported by min-resolution/max-resolution): 288dpi or 3.0dppx
First, shouldn't the pixels reported for the width be in logical pixels, not physical? I mean both iPhone3GS and iPhone4 report a width of 320px, even though the latter is actually 640 physical pixels. See How to target iPhone 3GS AND iPhone 4 in one media query?
How should I know what the browser meant by "pixel" when it matches a given query?
Second, the reported 288dpi has nothing to do with the actual device 467dpi. And how is this 3dppx calculated?
This is an interesting question. I'm familiar with the way media queries work for iOS devices, but less so with Android devices. I'll take a stab at it anyway.
Let's start with dppx, which you probably know is a measurement of how many physical dots fit into each pixel (let's use your terms "physical pixels" and "logical pixels"). 3dppx means that each of the screen's logical pixels is composed of a 3x3 grid of physical pixels. To use iOS terminology, your display has a #3x resolution, like the iPhone 6 Plus.
You can see a list of various device dppx values here:
http://bjango.com/articles/min-device-pixel-ratio/
(The site refers to -webkit-min-device-pixel-ratio, which predates dppx, but I think means exactly the same thing.)
If you know a device's physical width and dppx you can use the following formula to calculate its logical width, which you can use in media queries:
device width / dppx = logical width
For your device this should be:
1080 / 3 = 360
I would therefore expect the following media query to target your device in portrait mode:
#media only screen and (max-width: 360px) { }
As for the 288dpi: A 1dppx device has 96dpi, and 3 x 96 = 288. I'm not sure where the manufacturer's 467dpi comes from, but it doesn't seem relevant to writing media queries.
Are there any sorts of desktop tools or browser plugins that are able to simulate various mobile and tablet devices in order to properly test responsive designs? And I'm not just talking about changing the browser window size. Other items would need to be simulated as well:
device-width
min-device-width
max-device-width
orientation (landscape/portrait)
-webkit-min-device-pixel-ratio
resolution
ppi
I typically try Opera Mobile Emulator. It's fairly accurate, and will imitate high DPI displays, etc, and will handle most the media queries just fine. Just pick your display characteristics, or a device to emulate, and it will attempt to render in that manner.
this is mentioned every article about mobile web, but nowhere I can found an explanation of what exactly does this attribute measure.
Can anyone please elaborate what does queries like this check?
#media only screen and (-webkit-min-device-pixel-ratio: 1.5),
only screen and (min--moz-device-pixel-ratio: 1.5),
only screen and (-o-device-pixel-ratio: 3/2),
only screen and (min-device-pixel-ratio: 1.5) {
//high resolution images go here
}
Short answer
The device pixel ratio is the ratio between physical pixels and logical pixels. For instance, the iPhone 4 and iPhone 4S report a device pixel ratio of 2, because the physical linear resolution is double the logical linear resolution.
Physical resolution: 960 x 640
Logical resolution: 480 x 320
The formula is:
Where:
is the physical linear resolution
and:
is the logical linear resolution
Other devices report different device pixel ratios, including non-integer ones. For example, the Nokia Lumia 1020 reports 1.6667, the Samsumg Galaxy S4 reports 3, and the Apple iPhone 6 Plus reports 2.46 (source: dpilove). But this does not change anything in principle, as you should never design for any one specific device.
Discussion
The CSS "pixel" is not even defined as "one picture element on some screen", but rather as a non-linear angular measurement of viewing angle, which is approximately of an inch at arm's length. Source: CSS Absolute Lengths
This has lots of implications when it comes to web design, such as preparing high-definition image resources and carefully applying different images at different device pixel ratios. You wouldn't want to force a low-end device to download a very high resolution image, only to downscale it locally. You also don't want high-end devices to upscale low resolution images for a blurry user experience.
If you are stuck with bitmap images, to accommodate for many different device pixel ratios, you should use CSS Media Queries or the HTML picture Element to provide different sets of resources for different groups of devices. Combine this with nice tricks like background-size: cover or explicitly set the background-size to percentage values.
Example
#element { background-image: url('lores.png'); }
#media only screen and (min-device-pixel-ratio: 2) {
#element { background-image: url('hires.png'); }
}
#media only screen and (min-device-pixel-ratio: 3) {
#element { background-image: url('superhires.png'); }
}
This way, each device type only loads the correct image resource. Also keep in mind that the px unit in CSS always operates on logical pixels.
A case for vector graphics
As more and more device types appear, it gets trickier to provide all of them with adequate bitmap resources. In CSS, media queries is currently the only way, and in HTML5, the picture element lets you use different sources for different media queries, but the support is still not 100 % since most web developers still have to support IE11 for a while more (source: caniuse).
If you need crisp images for icons, line-art, design elements that are not photos, you need to start thinking about SVG, which scales beautifully to all resolutions.
Device Pixel Ratio == CSS Pixel Ratio
In the world of web development, the device pixel ratio (also called CSS Pixel Ratio) is what determines how a device's screen resolution is interpreted by the CSS.
A browser's CSS calculates a device's logical (or interpreted) resolution by the formula:
For example:
Apple iPhone 6s
Actual Resolution: 750 x 1334
CSS Pixel Ratio: 2
Logical Resolution:
When viewing a web page, the CSS will think the device has a 375x667 resolution screen and Media Queries will respond as if the screen is 375x667. But the rendered elements on the screen will be twice as sharp as an actual 375x667 screen because there are twice as many physical pixels in the physical screen.
Some other examples:
Samsung Galaxy S4
Actual Resolution: 1080 x 1920
CSS Pixel Ratio: 3
Logical Resolution:
iPhone 5s
Actual Resolution: 640 x 1136
CSS Pixel Ratio: 2
Logical Resolution:
Why does the Device Pixel Ratio exist?
The reason that CSS pixel ratio was created is because as phones screens get higher resolutions, if every device still had a CSS pixel ratio of 1 then webpages would render too small to see.
A typical full screen desktop monitor is a roughly 24" at 1920x1080 resolution. Imagine if that monitor was shrunk down to about 5" but had the same resolution. Viewing things on the screen would be impossible because they would be so small. But manufactures are coming out with 1920x1080 resolution phone screens consistently now.
So the device pixel ratio was invented by phone makers so that they could continue to push the resolution, sharpness and quality of phone screens, without making elements on the screen too small to see or read.
Here is a tool that also tells you your current device's pixel density:
http://bjango.com/articles/min-device-pixel-ratio/
Boris Smus's article High DPI Images for Variable Pixel Densities has a more accurate definition of device pixel ratio: the number of device pixels per CSS pixel is a good approximation, but not the whole story.
Note that you can get the DPR used by a device with window.devicePixelRatio.
https://developer.mozilla.org/en/CSS/Media_queries#-moz-device-pixel-ratio
-moz-device-pixel-ratio
Gives the number of device pixels per CSS pixel.
this is almost self-explaining. the number describes the ratio of how much "real" pixels (physical pixerls of the screen) are used to display one "virtual" pixel (size set in CSS).
Device Pixel Ratio has direct correlation with Pixel density of the device.
Best concise description I could find:
Purpose of DPR is to keep consistent size of CSS pixels and therefore
consistent size of letters, symbols, images and everything else on
screen, across a variety of devices with different physical pixel
densities.
Source: screenresolutiontest