android - 如何选择矢量绘图？

Question

背景

我制作了以下 ImageView，以支持选择器作为“src”:

public class CheckableImageView extends ImageView implements Checkable {
    private boolean mChecked;

    private static final int[] CHECKED_STATE_SET = { android.R.attr.state_checked };

    public CheckableImageView(final Context context, final AttributeSet attrs) {
        super(context, attrs);
        final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.com_app_CheckableImageView, 0, 0);
        setChecked(a.getBoolean(R.styleable.com_app_CheckableImageView_com_app_checked, false));
        a.recycle();
    }

    @Override
    public int[] onCreateDrawableState(final int extraSpace) {
        final int[] drawableState = super.onCreateDrawableState(extraSpace + 1);
        if (isChecked())
            mergeDrawableStates(drawableState, CHECKED_STATE_SET);
        return drawableState;
    }

    @Override
    public void toggle() {
        setChecked(!mChecked);
    }

    @Override
    public boolean isChecked() {
        return mChecked;
    }

    public interface OnCheckStateListener {
        void onCheckStateChanged(boolean checked);
    }

    private OnCheckStateListener mOnCheckStateListener;

    public void setOnCheckStateListener(OnCheckStateListener onCheckStateListener) {
        mOnCheckStateListener = onCheckStateListener;
    }

    @Override
    public void setChecked(final boolean checked) {
        if (mChecked == checked)
            return;
        mChecked = checked;
        refreshDrawableState();
        if (mOnCheckStateListener != null) 
            mOnCheckStateListener.onCheckStateChanged(checked);
    }
}

问题

上面的代码适用于普通选择器，它们将图像文件作为每个状态的可绘制项。

问题是，它根本不适用于矢量绘图(使用“srcCompat”)。相反，它显示的是空内容。

这是我尝试过的:

        <...CheckableImageView
         ...
            app:srcCompat="@drawable/selector"/>

选择器(例如)是:

<?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/test"/>
    <item  android:state_pressed="true" android:drawable="@drawable/test" />
    <item android:drawable="@drawable/test2" />
</selector>

示例矢量可绘制对象:

<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
        android:width="48dp"
        android:height="48dp"
        android:viewportWidth="48"
        android:viewportHeight="48">

    <path
        android:fillColor="#0000ff"
        android:strokeColor="#000000"
        android:pathData="M 0 0 H 48 V 48 H 0 V 0 Z" />

    <path
        android:fillColor="#ff0000"
        android:strokeColor="#000000"
        android:pathData="M14.769224,32.692291l5.707315,-17.692275l3.073244,17.479182l6.585245,-16.413424l2.634209,16.200186l-4.170761,-8.526356l-5.048693,7.247362l-5.268419,-8.100027l-3.51214,9.805351z" />
</vector>

问题

为什么不起作用？我做的有什么问题吗？我该如何解决？

Answer 1

看起来，这是支持库工作方式中的一个错误，并且没有以任何方式记录。

我试图发布有关它的错误报告，但 Google 将其标记为 UserError，即使我没有看到它的记录，也没有任何类型的警告:

Working as intended. Vectors are not supported in containers unless you turn on AppComaptDelegate.setCompatVectorFromResourcesEnabled(true).

https://code.google.com/p/android/issues/detail?id=210745

因此，如果您看到一个选择器没有显示，或者导致此日志崩溃:

引起:android.content.res.Resources$NotFoundException:来自可绘制资源 ID #0x7f02004f 的文件 res/drawable/selector.xml

您应该避免在选择器中使用 vectorDrawable，或者避免使用 vectorDrawables.useSupportLibrary=true 行。

您可以使用 AppComaptDelegate.setCompatVectorFromResourcesEnabled(true) ，但是 according to the docs ，这可能是错误的(主要是内存/性能问题)，根本不建议使用:

Sets whether vector drawables on older platforms (< API 21) can be used within DrawableContainer resources.

When enabled, AppCompat can intercept some drawable inflation from the framework, which enables implicit inflation of vector drawables within DrawableContainer resources. You can then use those drawables in places such as android:src on ImageView, or android:drawableLeft on TextView.

This feature defaults to disabled, since enabling it can cause issues with memory usage, and problems updating Configuration instances. If you update the configuration manually, then you probably do not want to enable this. You have been warned.

Even with this disabled, you can still use vector resources through setImageResource(int) and it's app:srcCompat attribute. They can also be used in anything which AppComapt inflates for you, such as menu resources.

Please note: this only takes effect in Activities created after this call.