removing backgroundcolor of a view in android

removing backgroundcolor of a view in android - android

Removing Background color in Android
I have set backgroundColor in code like this,
View.setBackgroundColor(0xFFFF0000);
How to remove this background color on some event?

You should try setting the background color to transparent:
view.setBackgroundColor(0x00000000);

You can use
View.setBackgroundColor(Color.TRANSPARENT);
or
View.setBackgroundColor(0);
or even
View.setBackground(null);
Please remember that almost everything visible on the screen extends View, like a Button, TextView, ImageView, any kind of Layout, so this can be done to almost everything.
Bonus point!
Instead of using View.setBackgroundColor(0xFFFF0000); it is sooooooooo much better to create a color filter with android.graphics.PorterDuff.MULTIPLY option and, if needed, just clear the filter.
Using the color filter, colors look much better because it won't be that "flat" color but a nicer tone of the chosen color.
A light red background would be
View.getBackground().setColorFilter(0x3FFF0000, PorterDuff.Mode.MULTIPLY);
To "remove" the color, just use
View.getBackground().clearColorFilter();

All of the answers about setting color to transparent will work technically. But there are two problems with these approaches:
You'll end up with overdraw.
There is a better way:
If you look at how View.setBackgroundColor(int color) works you'll see a pretty easy solution:
/**
* Sets the background color for this view.
* #param color the color of the background
*/
#RemotableViewMethod
public void setBackgroundColor(#ColorInt int color) {
if (mBackground instanceof ColorDrawable) {
((ColorDrawable) mBackground.mutate()).setColor(color);
computeOpaqueFlags();
mBackgroundResource = 0;
} else {
setBackground(new ColorDrawable(color));
}
}
The color int is just converted to a ColorDrawable and then passed to setBackground(Drawable drawable). So the solution to remove background color is to just null out the background with:
myView.setBackground(null);

View.setBackgroundColor(0); also works. It isn't necessary to put all those zeros.

Choose Any one
View.setBackgroundColor(Color.TRANSPARENT);
or
View.setBackgroundColor(0x00000000);

Related

Change background colour of view programatically

I am trying to change the background colour of my View programatically, using a colour that I defined in my resources. Other SO posts explain to do it like this:
int color = ContextCompat.GetColor(this.context, Resource.Color.my_color_background);
this.myView.SetBackgroundColor(color);
But this doesn't work for me, because SetBackgroundColor takes a Color, not an int... what am I doing wrong here?

I solved it by just creating the Color object myself and setting it with that:
int color = ContextCompat.GetColor(context, Resource.Color.my_color);
this.view.SetBackgroundColor(new Color(color));
Not sure why the constructor is different in Xamarin though...

Color set by setColorFilter disappears on prelollipop devices

I have a TabLayout which has icons. The idea is to change the colors runtime.
I have and xml drawable file with states: state_pressed, state_selected and default with the same white picture so I can put color later.
I take the drawables for different states:
Drawable[] drawables = stateListDrawable.getConstantState();
and the for every drawable state I put color from another array:
drawables[i].setColorFilter(colors[i], PorterDuff.Mode.MULTIPLY);
The issue is that the color is visible in the beginning, but when I start to click on the icons all the icons becomes white again and I lose the tint.
Everything is working as expected on lollipop and above.

Use the tint method from the v4 Support library
drawables[i] = DrawableCompat.wrap(drawables[i])
DrawableCompat.setTint(drawables[i], colors[i])

I have found my solution, which does not look clean at all, but at least it is working :)
I have created CustomStateListDrawable which extends from StateListDrawable and added the drawables for the different states. Then I have overridden all the methods in the class to see which ones are called and tried to change the colors there. The called late enough(my changes will not be overridden after I make them) was getState(). I have created also a ColorStateList object to hold my colors so the code will look like this:
private ColorStateList colorStateList;
public int[] getState() {
if (colorStateList != null) {
// Resolve the color for the current state
int color = colorStateList.getColorForState(super.getState(), 0);
// Get the current drawable and changed its color.
if (getCurrent() != null) {
getCurrent().setColorFilter(color, PorterDuff.Mode.MULTIPLY);
}
}
return super.getState();
}
Basically every time when there is a change in the state I get the current drawable and change its color.

After updating background drawable from host, set a contrast color for text

Let me make this clear: I create a fragment which is used for playing music. I blur the artwork of album and set it as the background of the fragment. And I need to show the music name and artist name on the fragment. Sometimes the updated artwork background has the pretty close color with text (like both them are black). In this case, I want to change the text color to another contrast color to make the text clear. The ios has the similar function when you set the wall paper.
Does anyone know how to achieve that?

Use palette: https://guides.codepath.com/android/Dynamic-Color-using-Palettes
Palette.from(bitmap).maximumColorCount(16).generate(new Palette.PaletteAsyncListener() {
#Override
public void onGenerated(Palette palette) {
// Get the "vibrant" color swatch based on the bitmap
Palette.Swatch vibrant = palette.getVibrantSwatch();
if (vibrant != null) {
// Set the background color of a layout based on the vibrant color
containerView.setBackgroundColor(vibrant.getRgb());
// Update the title TextView with the proper text color
titleView.setTextColor(vibrant.getTitleTextColor());
}
}
});
This is an example of using it. Mess around with grabbing different swatches to see what works best.

If u need black or white theme for text please go through Determine font color based on background color
or otherwise use palette for vibrent colours
https://guides.codepath.com/android/Dynamic-Color-using-Palettes

How to control the contrast of text?

How do you change the color contrast of text when the background changes? for example If I was to have a black background, black text would not be visible.

This might be helpful: http://developer.android.com/guide/topics/resources/color-list-resource.html
It is a way you can set a color that will change based on certain circumstances.
For example, say you have a TextView that you want to have white text while it is enabled and black text when it is disabled. You can set that up in a xml file using the references in the link above, and then in your xml layout where you define the TextView set the android:textColor to #color/my_text_color. (my_text_color being the xml color list file you created)
Then, as the TextView changes from enabled to disabled (or whatever you end up setting up in the xml file) the color will change automatically as well.
That's one way to do it. However, you might want to try to clarify what you are looking for as it isn't perfectly clear in your question.
Update
After Matt's comment, here is a method you could use to get an inverted color value. There is probably a better way but this should work.
private int getInverseColor(int color){
int red = Color.red(color);
int green = Color.green(color);
int blue = Color.blue(color);
int alpha = Color.alpha(color);
return Color.argb(alpha, 255-red, 255-green, 255-blue);
}
You could programmaticly get the color int from a view such as a TextView using one of the getTextColor() methods. You may have to tinker with a Color State List like I linked to above to get the color you want. Then pass that color to the method above to get the inverted color int and set it with one of the setTextColor() methods.

How to set background color of a View

I'm trying to set the background color of a View (in this case a Button).
I use this code:
// set the background to green
v.setBackgroundColor(0x0000FF00 );
v.invalidate();
It causes the Button to disappear from the screen. What am I doing wrong, and what is the correct way to change the background color on any View?
Thanks.

You made your button transparent. The first byte is the alpha.
Try v.setBackgroundColor(0xFF00FF00);

When you call setBackgoundColor it overwrites/removes any existing background resource, including any borders, corners, padding, etc.
What you want to do is change the color of the existing background resource...
View v;
v.getBackground().setColorFilter(Color.parseColor("#00ff00"), PorterDuff.Mode.DARKEN);
Experiment with PorterDuff.Mode.* for different effects.

Several choices to do this...
Set background to green:
v.setBackgroundColor(0x00FF00);
Set background to green with Alpha:
v.setBackgroundColor(0xFF00FF00);
Set background to green with Color.GREEN constant:
v.setBackgroundColor(Color.GREEN);
Set background to green defining in Colors.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="myGreen">#00FF00</color>
<color name="myGreenWithAlpha">#FF00FF00</color>
</resources>
and using:
v.setBackgroundResource(R.color.myGreen);
and:
v.setBackgroundResource(R.color.myGreenWithAlpha);
or the longer winded:
v.setBackgroundColor(ContextCompat.getColor(getContext(), R.color.myGreen));
and:
v.setBackgroundColor(ContextCompat.getColor(getContext(), R.color.myGreenWithAlpha));

You can set the hex-color to any resource with:
View.setBackgroundColor(Color.parseColor("#e7eecc"));

// set the background to green
v.setBackgroundColor(0x0000FF00 );
v.invalidate();
The code does not set the button to green. Instead, it makes the button totally invisible.
Explanation: the hex value of the color is wrong. With an Alpha value of zero, the color will be invisible.
The correct hex value is 0xFF00FF00 for full opacity green. Any Alpha value between 00 and FF would cause transparency.

For setting the first color to be seen on screen, you can also do it in the relevant layout.xml (better design) by adding this property to the relevant View:
android:background="#FF00FF00"

and what is the correct way to change
the background color on any View?
On any View? What you have is correct, though you should drop the invalidate() call.
However, some Views already have backgrounds. A Button, for example, already has a background: the face of the button itself. This background is a StateListDrawable, which you can find in android-2.1/data/res/drawable/btn_default.xml in your Android SDK installation. That, in turn, refers to a bunch of nine-patch bitmap images, available in multiple densities. You would need to clone and modify all of that to accomplish your green goals.
In short, you will be better served finding another UI pattern rather than attempting to change the background of a Button.

try to add:
setBackgroundColor(Color.parseColor("#FF0000"));

I use at API min 16 , target 23
Button WeekDoneButton = (Button) viewWeeklyTimetable.findViewById(R.id.week_done_button);
WeekDoneButton.setBackgroundColor(ContextCompat.getColor(getActivity(), R.color.colorAccent));

mButton.setBackgroundColor(getResources().getColor(R.color.myColor));

You can simple use :
view.setBackgroundColor(Color.parseColor("#FFFFFF"));

You can simple use :
view.setBackgroundColor(Color.rgb(0, 198, 255));

This question talks about changing the background color of a view. In one of the answers, the person explains how to change the background color during runtime. Obviously you are going to look into how to modify other objects on the screen, but this should give you a good start by at least allowing you to modify the background color of the view on button click.

Stating with Android 6 use ContextCompact
view.setBackgroundColor( ContextCompat.getColor(this, R.color.your_color));

This works for me
v.getBackground().setTint(Color.parseColor("#212121"));
That way only changes the color of the background without change the background itself. This is usefull for example if you have a background with rounded corners.

In kotlin you could do it like this:
val backgroundColor = R.color.whatever_color_you_like
view.setBackgroundColor(getColorCompat(backgroundColor))
Where getColorCompat() is an extension function:
/**
* Extension method to provide simpler access to {#link ContextCompat#getColor(int)}.
*/
fun Context.getColorCompat(color: Int) = ContextCompat.getColor(this, color)

view.setBackgroundColor(R.color.primaryColor);
Adds color to previous color value, so i have a different color.
What works for me is :
view.setBackgroundResource(R.color.primaryColor);

Let suppose we have a primary color in values=>colors.xml as:
<resources>
<color name="primary">#FDD835</color>
</resources>
so if we want to use our custom color into setBackgroundColor(#ColorInt int Color) then we just need an annotation #SuppressLint("ResourceAsColor") with constructor/method which will be used as:
#SuppressLint("ResourceAsColor")
public _LinearLayout(Context context) {
super(context);
// Formatting our layout : )
super.setBackgroundColor(R.color.primary);
....
}

You must pass an int in the argument.
First Example:
view.setBackgroundColor(-500136)
Second Example:
int colorId = R.color.green;
view.setBackgroundResource(colorId);

This should work fine: v.setBackgroundColor(0xFF00FF00);

I tried all the above ways. But I havent achieve what i need. Here is my try.
If you are using hexcode for color and want to set the color as background of image, then this is the kotlin code.
val bitmap = Bitmap.createBitmap(30, 30, Bitmap.Config.ARGB_8888)
val canvas = Canvas(bitmap)
val colorCode = "#ffffff"
canvas.drawColor(Color.parseColor(colorCode))
mImageViewLogo.setImageBitmap(bitmap)

When calling setBackgroundColor on a view you need to set the alpha value to a non-zero value (e.g. 0xFF), otherwise the color will not show up.
TextView tv = (TextView)findViewById(R.id.myTextview);
int rgb = 0xF05922; // Orange
tv.setBackgroundColor(0xFF000000|rgb); // Use bitwise OR to add alpha to RGB value

Develop Reference

The Android operating system is a mobile operating system that was developed by Google (GOOGL?) to be primarily used for touchscreen devices, cell phones, and tablets.

removing backgroundcolor of a view in android - android

Removing Background color in Android I have set backgroundColor in code like this, View.setBackgroundColor(0xFFFF0000); How to remove this background color on some event?

You should try setting the background color to transparent: view.setBackgroundColor(0x00000000);

View.setBackgroundColor(0); also works. It isn't necessary to put all those zeros.

Choose Any one View.setBackgroundColor(Color.TRANSPARENT); or View.setBackgroundColor(0x00000000);

Related

Change background colour of view programatically

Color set by setColorFilter disappears on prelollipop devices

After updating background drawable from host, set a contrast color for text

How to control the contrast of text?

How to set background color of a View

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