Develop Reference

Bitmap otained is transparent but when set to imageview becomes non-transparent

I'm using OpenCV to implement something simple, that if Mat has color of pixel(x,y) equal to white, it turns to transparent (alpha = 0). After that convert Mat to bitmap.
When debugging the bitmap returned is correct, but when i set it to imageview, the image returned still has white background (as in the original image) instead of the transparent image.
This is the original image (with white background)
And debugging image, with transparent background
Please help me to fix it :(

Add following line in your ImageView,
android:background="#android:color/transparent"

Using ClipDrawable to hide a part of and ImageView

I am trying to hide a part of an image so that the user does not see it. Initially I copied the Bitmap pixels on another Bitmap, without copying only the pixels that I needed and making the second bitmap the correct size at creation. That worked, but I have many large images and that results in OOMs unfortunately. So instead of doing that I thought on using a ClipDrawable to draw the image, and making the pixels that I don't need invisible.
The code is as follows
ClipDrawable clipDrawable = new ClipDrawable(new BitmapDrawable(resources, bitmap), gravity, orientation);
clipDrawable.setLevel(level);
// Cannot use as the imageview source. Must use background or else we don't get anything on the screen.
picture.setBackground(clipDrawable);
// This is super important. Do not modify this! Without it you will not get the fullscreen image working and the ImageView will be deleted
// from the parent layout.
picture.setImageResource(android.R.color.transparent);
The idea is that I calculate the level based on the image size so that I hide the pixels that I don't need. And it's working. Except I don't understand why I need to use
picture.setBackground(clipDrawable);
picture.setImageResource(android.R.color.transparent);
instead of the more normal:
picture.setImageDrawable(clipDrawable);
If I do the second more normal example then I don't get anything in the ImageView, but if I set it as a background and put a transparent image over it, then it works. Since I want to further manipulate the ImageView using a zooming class that needs the picture set as the src and not as background, I cannot have both, either I get the ClipDrawable showing or I get to have zoom on the image.
Any help would be appreciated!

picture.setImageDrawable(new
ClipDrawable(new BitmapDrawable(resources, bitmap), gravity, orientation
));
ClipDrawable clipDrawable = (ClipDrawable) picture.getDrawable();
clipDrawable.setLevel(level);

CircularImageView with a solid color

The CircularImageView, https://github.com/Pkmmte/CircularImageView, works great when setting an image bitmap like so...
circularImageView.setImageBitmap(bitmap);
However, there are times where I just want to set a solid color instead of a bitmap. If I do something like this,
circularImageView.setBackgroundResource(R.color.blue);
The color of the view is set but the image is never made circular, so it fill the entire rectangular view. I'm assuming the getDrawable() is returning null so it can't actually manipulate the view. Anyone ran into this problem or any suggestions on what to do?
Edit:
I can do this but it seems a bit flimsy:
Bitmap image = Bitmap.createBitmap(50, 50, Bitmap.Config.ARGB_8888);
image.eraseColor(android.graphics.Color.GREEN);
circularImageView.setImageBitmap(image);

You should call circularImageView.setImageResource(R.color.blue) instead.
The code you wrote sets the background of the view, not the content image. Looking at the code on github, this view will only clip the content image to the circle--it has no effect on the background at all.

Give a try for ColorDrawable;
int decode = Integer.decode("FF6666");
ColorDrawable colorDrawable = new ColorDrawable(decode);

Converting bitmap to drawable in Android

I'm downloading the image from server and storing it in bitmap object. I want to set this image as background for button. But the button doesn't have the property setImageBitmap. So is there anyway I can set the background of button with the downloaded bitmap image? Like by converting the bitmap to drawable? Sorry, I'm new to Android, please bear with my mistakes (if any).
P.S : I want to use button control only. Because I want some text at the bottom of each buttons and I'm creating these buttons dynamically.

The best way to convert a Bitmap to drawable in android is as follows,
Drawable drawable = new BitmapDrawable(getResources(), bitmap);
where bitmap is the name the Bitmap. Then set the drawable as your Button background as follows,
btn.setBackground(drawable);
N.B: Without specifying getResources() as the first argument, you may experience inconsistent image sizing across different screen densities.
for more info refer this
http://developer.android.com/reference/android/graphics/drawable/BitmapDrawable.html

Simply use BitmapDrawable.
Drawable drawable=new BitmapDrawable(contact_pic);

Convert Bitmap to BitmapDrawable like this
Drawable drawable = new BitmapDrawable(getResources(),your_bitmap);
and then set it as background to button as ,
button.setBackgroundDrawable(drawable);
P.S. You can also do the same inline as ,
button.setBackgroundDrawable(new BitmapDrawable(getResources(),your_bitmap));

This is how to do it, I've used several times:
Drawable drawable = (Drawable)new BitmapDrawable(Bitmap);
Button button= new Button(this);
button.setBackground(drawable);

Programmatically set the Background color of a Drawable in Android?

I have an image in a resource file.
Drawable draw = getResources().getDrawable(R.drawable.my_icon);
The image has a transparent background.
Is there a way to programmatically set the background color to the Drawable before using the end product further in my code?

I think Drawing with PorterduffXferMode may help you in your case. This way you can merge two images (your image and a overlay completly in your color you want to replace the transparent pixels with) in many different ways.
Different porterduff modes explaned:
http://www.ibm.com/developerworks/java/library/j-mer0918/
Android example:
http://www.vogella.com/code/ApiDemos/src/com/example/android/apis/graphics/Xfermodes.html
This way you draw the result inside a new Bitmap. (SRC_OVER should work in your case if your image is the src and the background is used as the dst)

setColorFilter() with Porterduff SRC will break the transparent of drawable.
I used this in my code, and it work
disabledIcon = ContextCompat.getDrawable(getContext(), resId);
disabledIcon = DrawableCompat.wrap(disabledIcon);
disabledIcon.mutate(); // to not share its state with any other drawable
DrawableCompat.setTint(disabledIcon, ContextCompat.getColor(getContext(), R.color.button_text_disabled));