LinearLayout中有关CheckBox的处理

Question

I am new to android and I'm trying to set a style to all check boxes in my application. My application style is set to Theme.Holo which is dark and I would like the check boxes on my list view to be of style Theme.Holo.Light. I am not trying to create a custom style. The code below doesn't seem to work, nothing happens at all. I need to do this because my list view has a light paper texture and the check box and check box text is white which i would like dark.

<style name="CustomActivityTheme" parent="@android:style/Theme.Holo">
    <item name="android:checkboxStyle">@style/customCheckBoxStyle</item>
</style>

<style name="customCheckBoxStyle" parent="@android:style/Widget.Holo.Light.CompoundButton.CheckBox">
</style>

Also can you set styles to individual widgets if you set a style to the application?

MH. · Answer 1 · 2012-04-16 10:49:52Z

My application style is set to Theme.Holo which is dark and I would like the check boxes on my list view to be of style Theme.Holo.Light. I am not trying to create a custom style. The code below doesn't seem to work, nothing happens at all.

At first it may not be apparent why the system exhibits this behaviour, but when you actually look into the mechanics you can easily deduce it. Let me take you through it step by step.

First, let's take a look what the Widget.Holo.Light.CompoundButton.CheckBox style defines. To make things more clear, I've also added the 'regular' (non-light) style definition.

<style name="Widget.Holo.Light.CompoundButton.CheckBox" parent="Widget.CompoundButton.CheckBox" />

<style name="Widget.Holo.CompoundButton.CheckBox" parent="Widget.CompoundButton.CheckBox" />

As you can see, both are empty declarations that simply wrap Widget.CompoundButton.CheckBox in a different name. So let's look at that parent style.

<style name="Widget.CompoundButton.CheckBox">
    <item name="android:background">@android:drawable/btn_check_label_background</item>
    <item name="android:button">?android:attr/listChoiceIndicatorMultiple</item>
</style>

This style references both a background and button drawable. btn_check_label_background is simply a 9-patch and hence not very interesting with respect to this matter. However,?android:attr/listChoiceIndicatorMultiple indicates that some attribute based on thecurrent theme (this is important to realise) will determine the actual look of theCheckBox.

As listChoiceIndicatorMultiple is a theme attribute, you will find multiple declarations for it - one for each theme (or none if it gets inherited from a parent theme). This will look as follows (with other attributes omitted for clarity):

<style name="Theme">
    <item name="listChoiceIndicatorMultiple">@android:drawable/btn_check</item>
    ...
</style>

<style name="Theme.Holo">
    <item name="listChoiceIndicatorMultiple">@android:drawable/btn_check_holo_dark</item>
    ...
</style>

<style name="Theme.Holo.Light" parent="Theme.Light">
    <item name="listChoiceIndicatorMultiple">@android:drawable/btn_check_holo_light</item>
    ...
</style>

So this where the real magic happens: based on the theme's listChoiceIndicatorMultiple attribute, the actual appearance of theCheckBox is determined. The phenomenon you're seeing is now easily explained: since the appearance is theme-based (andnot style-based, because that is merely an empty definition) and you're inheriting fromTheme.Holo, you will always get the CheckBox appearance matching the theme.

Now, if you want to change your CheckBox's appearance to the Holo.Light version, you will need to take a copy of those resources, add them to your local assets and use a custom style to apply them.

As for your second question:

Also can you set styles to individual widgets if you set a style to the application?

Absolutely, and they will override any activity- or application-set styles.

Is there any way to set a theme(style with images) to the checkbox widget. (...) Is there anyway to use this selector:link?

Update:

Let me start with saying again that you're not supposed to rely on Android's internal resources. There's a reason you can't just access the internal namespace as you please.

However, a way to access system resources after all is by doing an id lookup by name. Consider the following code snippet:

int id = Resources.getSystem().getIdentifier("btn_check_holo_light", "drawable", "android");
((CheckBox) findViewById(R.id.checkbox)).setButtonDrawable(id);

The first line will actually return the resource id of the btn_check_holo_light drawable resource. Since we established earlier that this is the button selector that determines the look of theCheckBox, we can set it as 'button drawable' on the widget. The result is aCheckBox with the appearance of the Holo.Light version, no matter what theme/style you set on the application, activity or widget in xml. Since this sets only the button drawable, you will need to manually change other styling; e.g. with respect to the text appearance.

Below a screenshot showing the result. The top checkbox uses the method described above (I manually set the text colour to black in xml), while the second uses the default theme-basedHolo styling (non-light, that is).

Screenshot showing the result

Thank you for taking the time to respond. I see the issue here and I'm still wondering if this can be done with out me having to do a lot of work. Is there any way to set a theme(style with images) to the checkbox widget. I know that I can find the images and include them in my project but it seems like over kill. Is there anyway to use this selector:github.com/android/platform_frameworks_base/blob/master/core/…
@user1330739: Yes and no. You're not supposed to rely on internal resources as Google may decide to change them in future releases. Including a copy of the drawables in your local resources is really your best option. That being said, there is another (ugly) solution I'm aware of, but that only works at runtime (meaning you cannot reference it in your xml files). Please see the edit to my answer above.

Praveen · Answer 2 · 2012-04-13 05:13:15Z

Maybe this will satisfies you -

something.xml

<CheckBox
    android:text="Custom CheckBox"
    android:button="@drawable/checkbox_selector"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"/>

Selector

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_checked="true" android:drawable="@drawable/star_down" />
    <item android:state_checked="false" android:drawable="@drawable/star" />
</selector>

For, the reference just refer here

Edwin Evans · Answer 3 · 2012-04-25 22:34:48Z

Perhaps you want something like:

<style name="CustomActivityTheme" parent="@android:style/Theme.Holo">
    <item name="android:checkboxStyle">@style/customCheckBoxStyle</item>
</style>

<style name="customCheckBoxStyle" parent="@android:style/Widget.CompoundButton.CheckBox">
    <item name="android:textColor">@android:color/black</item>
</style>

Note, the textColor item.

LinearLayout中有关CheckBox的处理

Android checkbox style

4 Answers