Disable an ImageButton | 易学教程

问题

This looks easy, but I'm not able to disable an ImageButton. It continues to receive click events, and its appearance don't change like a standard Button would.

There are some similar questions on SO, but they don't help me.

Even with a very simple layout like this :

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical">

    <ImageButton
        android:id="@+id/btn_call"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:clickable="false"
        android:enabled="false"
        android:src="@android:drawable/sym_action_call" />

</LinearLayout>

The button is still enabled and I can click it.

What's strange is that if I change the ImageButton to a simple Button, then it works as expected. The button becomes disabled and unclickable. I don't understand. Does anyone have an idea?

回答1:

ImageButton has different inheritance chain meaning it does not extend Button:

ImageButton < ImageView < View

It continues to receive click events

Here is what happens when you set a click listener for the View:

public void setOnClickListener(OnClickListener l) {
    if (!isClickable()) {
        setClickable(true);
    }
    mOnClickListener = l;
}

So if you set a listener the android:clickable="false" changes to android:clickable="true".

and its appearance don't change like a standard Button would

You should supply a drawable state list to the view so it could set an appropriate image based on android:enabled. Do you have this? Or you have the only image for your button?

EDIT: You can find info on StateListDrawable here. android:state_enabled is what you need to use in the list in order to tell the OS what image to use for that state.

EDIT2: Since you really need to add a listener you can make a check inside of the listener if (!isEnabled()) { return; } else { /* process the event */ }.

回答2:

Here's the code I use to disable an ImageButton and make it look grayed out:

/**
 * Sets the specified image buttonto the given state, while modifying or
 * "graying-out" the icon as well
 * 
 * @param enabled The state of the menu item
 * @param item The menu item to modify
 * @param iconResId The icon ID
 */
public static void setImageButtonEnabled(Context ctxt, boolean enabled, ImageButton item,
        int iconResId) {
    item.setEnabled(enabled);
    Drawable originalIcon = ctxt.getResources().getDrawable(iconResId);
    Drawable icon = enabled ? originalIcon : convertDrawableToGrayScale(originalIcon);
    item.setImageDrawable(icon);
}

/**
 * Mutates and applies a filter that converts the given drawable to a Gray
 * image. This method may be used to simulate the color of disable icons in
 * Honeycomb's ActionBar.
 * 
 * @return a mutated version of the given drawable with a color filter
 *         applied.
 */
public static Drawable convertDrawableToGrayScale(Drawable drawable) {
    if (drawable == null) {
        return null;
    }
    Drawable res = drawable.mutate();
    res.setColorFilter(Color.GRAY, Mode.SRC_IN);
    return res;
}

Simply call setImageButtonEnabled(); the only downside is you need the image's resource ID in here because it's not possible to revert a transformed icon back into the original.

回答3:

Make sure there is no view with same id in your view hierarchy and you do not add any click listener to that view.

回答4:

if you want to disable an image button,on click event, set the the property "setEnabled" to false

Ex: imgButton.setEnabled(false);

回答5:

Taking advantage of the Oleg Vaskevich's answer. Can be made an answer for Kotlin.

Make a Extension Function for ImageButton, this way:

/**
 * Sets the specified image buttonto the given state, while modifying or
 * "graying-out" the icon as well
 *
 * @param enabled The state of the menu item
 * @param iconResId The icon ID
 */
fun ImageButton.setButtonEnabled(enabled: Boolean, iconResId: Int) {
    isEnabled = enabled
    val originalIcon = context.resources.getDrawable(iconResId)
    val icon = if (enabled) originalIcon else convertDrawableToGrayScale(originalIcon)
    setImageDrawable(icon)
}

And you get a little less reliant on providing Context

回答6:

I managed to build a solution inspired by Oleg Vaskevich's answer, but without the need to pass drawable resource ID to setEnabled().

Here is Kotlin code, inside of utility module:

fun Drawable.deepCopy(): Drawable =
    constantState?.newDrawable()?.mutate() ?:
        throw RuntimeException("Called on null Drawable!")

fun Drawable.toGrayscale(): Drawable =
        deepCopy().apply { setColorFilter(Color.GRAY, PorterDuff.Mode.SRC_IN) }

fun ImageButton.setAndShowEnabled(enabled: Boolean) {
    if (enabled == isEnabled)
        return

    isEnabled = enabled

    if (enabled) {
        setImageDrawable(tag as Drawable)
    }
    else {
        if (tag == null)
            tag = drawable

        setImageDrawable(drawable.toGrayscale())
    }
}

It can be used like this:

val button: ImageButton = findViewById(...)
// ...
button.setAndShowEnabled(false)

// launch async operation
GlobalScope.launch {
    // do work here

    // unblock button
    button.setAndShowEnabled(true)
}

回答7:

As other answers have said, you cannot disable an ImageButton in the layout XML as you can a Button, but you can disable both the same way at runtime:

In Java:

button.setEnabled(false);     // setEnabled(boolean) on TextView
imgButton.setEnabled(false);  // setEnabled(boolean) on View

In both cases the button is disabled -- no click events get to its onClickListener.

You can also change the icon color of the disabled ImageButton the same way you change the text color on a disabled Button, assuming the icon is tintable.

In the layout XML:

<Button
    ...
    android:textColor="@drawable/button_color_selector" />


<ImageButton
    ...
    android:tint="@drawable/button_color_selector" />

Now setEnable(boolean) on the Button or ImageButton changes the text or icon color according to the states in your button_color_selector.xml

来源：https://stackoverflow.com/questions/8196206/disable-an-imagebutton

标签

android

imagebutton