Develop Reference

How to set background color of an image, but within the border?

My goal is to display a circular image, and allow the user to set its foreground and background colors respectively, for example:
My attempt was to create an image asset with transparent background, then use ImageView::setColorFilter to change its foreground, and use ImageView::setBackgroundColor to set its background. The image asset looks like this:
My problem is that pixels outside of what we humans call 'border' are also transparent, so the result looks like this:
How do people usually deal with this issue? Although I was doing Android development, but any ideas or code snippets in any language are appreciated!

at the first, you must create a new drawable file and write below code for creating the circle with yellow color with blue border:
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="oval">
<solid android:color="#cab816" />
<size android:width="50dp"
android:height="50dp"/>
<stroke android:width="2dp"
android:color="#color/darkBlue"/>
</shape>
and now you must set this drawable to the background of your imageview and set your image with src.
if your image covered all of this circle, use padding for decrease image size.

Make Seekbar thumb easier to grab

So I have a SeekBar but the little circle thumb thing is kind of hard to grab. Is there a way to make the hitbox larger? I don't necessarily care if the graphic itself looks any different -- I just want it to be grabbable.

You can customize the seekbar, Answered by Andrew, by changing the size of the Thumb.
create layered-drawable with shape as placeholder thumb_image.xml
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item>
<shape>
<size
android:height="40dp"
android:width="40dp" />
<solid android:color="#android:color/transparent" />
</shape>
</item>
<item android:drawable="#drawable/scrubber_control_normal_holo"/>
</layer-list>
The example shows the result below.
<SeekBar
android:id="#+id/seekBar1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:thumb="#drawable/thumb_image" />
Another good example here of Thumb customization.

Check out this cool library for Seekbar DiscreteSeekBar
And can be added without much complexity by the following
<org.adw.library.widgets.discreteseekbar.DiscreteSeekBar
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:dsb_min="2"
app:dsb_max="15"
/>
Which has the following attributes as well.
dsb_progressColor: color/colorStateList for the progress bar and thumb drawable
dsb_trackColor: color/colorStateList for the track drawable
dsb_indicatorTextAppearance: TextAppearance for the bubble indicator
dsb_indicatorColor: color/colorStateList for the bubble shaped drawable
dsb_indicatorElevation: related to android:elevation. Will only be used on API level 21+
dsb_rippleColor: color/colorStateList for the ripple drawable seen when pressing the thumb. (Yes, it does a kind of "ripple" on API levels lower than 21 and a real RippleDrawable for 21+.
dsb_trackHeight: dimension for the height of the track drawable.
dsb_scrubberHeight: dimension for the height of the scrubber (selected area) drawable.
dsb_thumbSize: dimension for the size of the thumb drawable.
dsb_indicatorSeparation: dimension for the vertical distance from the thumb to the indicator.
Other SeekBar components in the library are these

You want an inset drawable resource. This answer to the question "Offset shape within a ShapeDrawable" https://stackoverflow.com/a/3674134/3175580 happens to be the same thing, you're asking. Like the other answer, you'll still need to copy the target drawable if it's private.
The advantage (or disadvantage) is that this shows you exactly how much you're increasing the size by, instead of the total size. Plus, I think it saves memory because using a Transparent shape will create a transparent bitmap of that size (?).

Draw rectangle with empty partial fill

Here's what I want to do: Click
I have a progressBar and I want to overlay this onto it so that I can achieve rounded corners. Problem is, if I use a 9patch image, it doesn't scale down, and scaling up pixelates the corners. Also, the corners when I increase the size of the progressBar, don't look sharp enough.
So I thought maybe drawing such a rectangle on top would make it 100% precise with crisp quality. Unfortunately, I've never used that before and there's no tutorial similar to what I want to achieve.
Thanks for all the help.

If you apply a shape drawable, you should be able to achieve what you want. You reference it just like any other drawable (android:src/android:background).
Let's name this file rounded_rect.xml:
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<corners android:radius="20dp" />
<solid android:color="#80ffffff" />
</shape>
The radius can be more or less than 20dp, it will actually scale down if the container that it's drawn in requires less for the sides to be perfectly rounded; the color is white with a bit of transparency (#80).
Save it to your drawable folder and refer to it as you usually would with any png/jpg/etc drawable:
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/rounded_rect" />

How to add corners to a view

I added a full border around a view but I need to add just the corner as shown image below :
I mean the red corner only .
I tried to adjust the below border xml , but it didn't work :
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<stroke android:width="10dp" android:height="10dp" android:color="#B22222" />
<solid android:color="#FCE6C9" />
<corners android:radius="20dp" />
</shape>
Any help will be appreciated

I don't think it's possible to do this using a ShapeDrawable, as it would require you to use some sort of margin or padding on the drawable itself. There actually is a padding attribute, but unfortunately that only has effect on the content of the View, and not the drawable itself.
That being said, an easy solution would be to create a 9-patch in stead and apply that as background to the TextView. Just for demonstration purposes: make the 9-patch look somewhat like this:
Edit:
On second thought, there's actually another option that relies on using a LayerDrawable to create the desired effect. It's a bit tedious to create and I have my doubts it'll be more efficient than using a 9-patch, but at least you don't have to render out images, which means that if you need to make e.g. a change in colours, it's more straightforward.
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="#drawable/rounded" />
<item android:drawable="#android:color/white" android:left="30dp"
android:right="30dp" />
<item android:bottom="30dp" android:drawable="#android:color/white"
android:top="30dp" />
<item android:bottom="30dp" android:left="10dp" android:right="10dp"
android:drawable="#color/pink" android:top="30dp" />
<item android:bottom="10dp" android:left="30dp" android:right="30dp"
android:drawable="#color/pink" android:top="10dp" />
</layer-list>
Some details: #drawable/rounded is the code snippet you posted yourself. The following two items are simply white rectangles with an offset, to create the white edges. Now, since these will also overlay the pink surface, we need two more pink rectangles (again with specific offsets) to counter that. The result is a background that looks exactly like what you're showing in your question.
Note that you might want to see if you can optimise this a bit. At the least I'd recommend not hardcoding the offsets (like I did for simplicity), but store them in a dimens.xml file so you can keep these values centralized and consistent by referencing them from both the ShapeDrawable and LayerDrawable.
Addendum: On pre-ICS (or perhaps pre-Honeycomb) devices, there appears to be an issue with directly referencing colours with the android:drawable attribute. You can however easily get around this by setting up another drawable (be it either a 9-patch or ShapeDrawable) to represent this colour. For example, in the snippet above, you would replace android:drawable="#color/pink" with android:drawable="#drawable/color_pink", where color_pink can simply be an xml file containing:
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid android:color="#FCE6C9" />
</shape>
Obviously you will need to do the same for all other colours referenced in the LayerDrawable. Tested on Gingerbread 2.3.7.

I would create a 9-patch file and set it to be the background of the main container. The steps to do that would be.
You create the background you would like roughly in fireworks, illustrator, or whatever image editing software you prefer.
Then crop the artwork so that there is only a 1 pixel border around the artwork. Save it as a png.
Open the draw9patch.bat file in your android sdk folder on your computer C:\Program Files (x86)\Android\android-sdk\tools.
Open your png file. You can then use your mouse to click on the outer 1 pixel border which will turn the clicked pixels black. The areas that you have black pixels on both the top and bottom or on the left and right will be the area that is stretched. In your case you just want to have the middle area where there is no red stretched.
My personal preference is to just open the file above and save it as a 9 patch file. Then open it in my photo editing software to create a 1 pixel thick line in the same fashion as above. It is quicker and more precise.
Finally add the file to your drawable folder. Then set the background of your main view container to the drawable.
That should be it. Hope that helps.

How do I create the equivalent of a css outset border in Android?

If you create an outset border in CSS the browser varies the border colour for each edge to make the shape appear to protrude from its parent.
Is there an easy way to do this in an android layout or do I need to set each line colour manually?
Update - added example below:
Example http://www.witzelsucht.co.uk/googleplusheader.png

Set the background of an ImageView to a 9 patched drawable resource with the desired shadow/bevel around the edge. Lets say it takes 5 pixels to create the effect you want. Then set the padding of the ImageView to 5 pixels. Then set the bitmap to any image.
ImageView.setBackgroundDrawable
ImageView.setPadding
ImageView.setImageBitmap
Even easier, use a shape with a stroked border and set it as the background of the view:
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#00000000" />
<stroke android:width="1px" android:color="#ffffff" /></shape>

I'm not aware of any native support for Views to have borders. Your question reminded me of this question that I was looking at recently:
Is there an easy way to add a border to the top and bottom of an Android View?