Develop Reference

How to implement modern Card component (a'la Material Design 3.0) in Jetpack Compose

How can I implement using Compose these modern, subtle Card components, seen in updated Google apps?
They don't have border, they are a little bit elevated, with a subtle shadow behind. I tried fiddling with modifiers on standard Card, but didn't come close to this result.
Similar versions of them (elevated Filled?) appear on Material Design 3.0 docs, but its implementation is not yet available for Compose.

I cannot see much differences with previous card. Maybe the border radius and the elevation are higher. In the image you posted looks like they are using a background color similar to the shadow color to reduce contrast.
Anyway here you can find the new Material Design 3 for Compose: https://developer.android.com/jetpack/androidx/releases/compose-material3

How to Remove white Background from icon?

I have an app on android that create home shortcut icon.
The image of the icon is image that i set programmatically from the drawable
Now the problem is, when the shortcut was created on the home screen it's created with white background.
How do i remove that white backgroubd and set image to full size of icon?
Thank you all..
EDIT: the app i was talking about is app that i developed using android studio and just want to set full size of image when i create home shortcut

This is highly dependent on the launcher you use. The image looks like the standard google android 8+ (?) icon shape.
I theory it could be part of the icon you created but since you are asking this I doubt it.
In older versions of android the outer shape of the icons were individual, while rather cool and the outline correctly shown while dragging them etc many complained about the lack of a uniform look of all the icons in the app drawer etc.
It was introduced to make all icons seem more uniform.
Long pressing an empty space in the Google Pixel launcher for example shows a choice to go into the settings for the launcher and there you can change the shape all icons should have:
In addition to this, apps can take advantage of the various shapes and adapt to them and fill them out so to speak. See for example the Chrome icon while changing the icon shapes in the launcher settings.
Introduced in android 8: The feature is called adaptive icons.
See the docs about adaptive icons here:
https://developer.android.com/guide/practices/ui_guidelines/icon_design_adaptive

That is because of adaptive icons - a feature of Android 8 and can't or shouldn't be changed. You can at best change the colour of the background.

i removed the white background from the launcher icon by following these guidelines https://developer.android.com/studio/write/image-asset-studio
a few more points
in the background layer, move the slider to resize the icon until you see no what would have been the white background.
in the manifest file, change the icons to reference the mipmap folder;
android:icon="#mipmap/yourlogo"
android:roundIcon="#mipmap/yourlogo"

Get rid of the margin on Image Asset for launcher icons on Android Studio

I am trying hard to get rid of the extra margin around the ic launcher icons generated by Android Studio without luck. I know this is one of Google's material design trends. Though, the icons are so small on devices which is ugly.
I have Googled for around three hours and the only workaround I could find is to generate the clipart with a transparent background and photoshop the background with rounded corners which is pretty slow.
Is there a better solution than this?
Thank you.

Per the Designing adaptive icons blog post, the adaptive icon images created in the drawable directory for use on API 26+ devices follow the adaptive icon size and shape:
You'll note that while the entire image must be 108dp by 108dp, the actual visual area is only the center 72dp - the outer edge is only seen when dragging the icons around (where parallax effects may cause it be visible).
The Pixel Launcher, as well as many third party launchers, enforce the use of adaptive icons on API 26+ devices, so you should always design with that requirement in mind - the alternative, in the Pixel Launcher's case for instance, is to place your non-adaptive icon within a white circle.
Therefore you should always design your icon such that the background layer takes up the full size, but any foreground image you put on top of that background layer should be contained within that center area.
You can't just remove that margin without the foreground image being messed up, but as per the Implementing Adaptive Icons follow up blog post, you can remove any white excess around the foreground by putting your trimmed image within a transparent drawable of 108dp x 108dp by using an InsetDrawable.
<!-- Center a 54x54dp image in the 108x108dp size of adaptive icons -->
<inset
android:drawable="#mipmap/ic_fg_trimmed"
android:insetLeft="25%"
android:insetTop="25%"
android:insetRight="25%"
android:insetBottom="25%" />
Although this would have to be something you'd need to do to the ic_launcher_foreground image yourself after the fact.
A better solution, in most cases, is to use vector drawable images as the input to the Android Studio Image Asset wizard - this will ensure they are always the right size and don't take up any additional space in your APK.

I think i had the same problem as you. I solved this with a nasty hack, in the AndroidManifest.xml I just changed the roundIcon to point to the standard icon.
<application
…
android:icon="#mipmap/ic_launcher"
android:roundIcon="#mipmap/ic_launcher"
See more from the docs.

Use VectorDrawables in a Bitmap XML and tint them

We are trying to move all our app icon resources to VectorDrawables to reduce the size of the app and manage the app icon kit easily.
We already have an Icon Kit with all the icons of our app, all in a black color and the idea is to use them and tint in each usage with the appropriate color. This works (more or less) perfectly until you try to made the same in a layer-list/selector/similar, where you need to include an item with a <bitmap> or similar and... I don't find how to tint a VectorDrawable that also works in <21 devices
The pre-requisite is to not need to make it programmatically, I know that is possible but made it programmatically breaks all the easy usage of the icons and, also, not has sense.
In resume, Is there any form to use VectorDrawable in a <Bitmap> XML and tint it working in <21 devices and not programmatically?

The short answer: No, you can't do that.
The extended version:
Copy the SVG and apply color:
icon_a.xml
icon_b.xml (with color changed)

Detecting the background color of the option menu

I have realized that there are at least two background colors on Option menu of Android. On the HTC Hero, the background is white and on Samsung Galaxy S II, the background is black.
This became a problem when I set the icons for the background menus. Is there some way to detect the background color of the Option menus in Android?

Possible solutions:
Don't use icons.
Design icons according to the guidelines - http://developer.android.com/guide/practices/ui_guidelines/icon_design_menu.html. There are three different guidelines for up to 2.2 (white background), 2.3 (black background) and 3.0+, so it's a lot of work...
As Profete162 suggested, use #android:drawable/ic_menu_*
For Android 4.0+, you can also set the light / dark Holo theme, which is guaranteed (at least in theory) to remain unchanged across different phone manufacturers - so it'll look the same in HTC Sense, Samsung TouchWiz etc.

That's indeed a very annoying issue.
On my implementation, I always try to use standards icons from android.R.drawable.IC_menu_*, so I am sure these icons are part of the framework and users are always positively surprised to see their generic icons in my app!
That gives a really good continuity in the user experience on the device, but that doesn't answer your question, but at least provide a workaround.
Here are for instance all android 2.2 icons: http://androiddrawableexplorer.appspot.com/
You can trust me, using these icons will always fit your colors.

First of all to answer your title question:
You can reference and read the background of the options menu by reading the attributes of the current theme. The attribute for this is panelFullBackground. E.g. set it as the background of a textview in XML¹:
<TextView android:background="?android:attr/panelFullBackground"
... />
Note that the background seems to be a solid color, but it's not - it's actually a bitmap. If you look closely you can see a grey border at the top (android 2.3+), or a drop shadow (<= android 2.2), so its'a bit difficult. Luckily there is a different attribute called panelColorBackground which matches the background color of the drawable as close as possible. So if you want just the normal background color, use this instead.
¹ This can surely also be read from code, but I don't know how from the top of my head at the moment, maybe I'll look it up and edit it in later.
Regarding icons
So you have the color as stated above, but you still have to process it to know if it's a dark or a bright color. You can do that, but that's not the usual way to deal with these icons and probably a good bit of work until you cover all the possible cases - not to mention that you have to create icons for each variant.
Normally you should adopt the platform menu icon style. This works across all devices and looks familiar to your users (custom icons that dont follow this often look "wrong" - e.g. astro file manager does this I believe).
You can do that by hand (see the guidelines), but the way better alternative is the Android Asset Studio.
It comes in two flavors:
As a webapp
Integrated in the latest version of the ADT plugin for eclipse
(under File->New->Other->Android Icon Set)
The workflow for both is pretty similar, select the point "Menu Icon" and follow the wizard. It will promt you to enter a simple, black and white bitmap of your desired icon that just outlines it's shape. After you specified one, the asset studio will generate everything for you. Play a bit around with the "clipart" option, that has a few example bitmaps ready to see how it works. When finished, the webapp gives you a simple zip which can be extracted into your project directory, the eclipse version adds it directly to the project that you select in the wizard.

The background color can be anything, because its implemented in Framework by manufacturer. You can't read it, in fact you will never need to read it.
Just create your custom menu layout in res/menu folder, set style and use it.