Android 如何在API中的图标周围绘制圆形涟漪<；21?

当我想要API<21中的涟漪效应时，我通常使用前景视图-下面是我用于文本视图的

foregroundtextview

。如果是图像，则会有一个

foregroundimageview

，该代码也可以在互联网上下载：

/*
 * Copyright 2014 DogmaLabs
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


import android.annotation.TargetApi;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.NinePatchDrawable;
import android.os.Build;
import android.support.annotation.NonNull;
import android.util.AttributeSet;
import android.widget.TextView;

import com.bekwaai.activities.R;

public class ForegroundTextView extends TextView {

    private Drawable mForegroundSelector;
    private Rect mRectPadding;
    private boolean mUseBackgroundPadding = false;


    public ForegroundTextView (Context context) {
        super(context);
    }


    public ForegroundTextView (Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }


    public ForegroundTextView (Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ForegroundTextViewLayout, defStyle, 0);

        final Drawable d = a.getDrawable(R.styleable.ForegroundTextViewLayout_android_foreground);

        if (d != null) {
            setForeground(d);
        }


        a.recycle();


        if (this.getBackground() instanceof NinePatchDrawable) {
            final NinePatchDrawable npd = (NinePatchDrawable) this.getBackground();
            mRectPadding = new Rect();
            if (npd.getPadding(mRectPadding)) {
                mUseBackgroundPadding = true;
            }
        }
    }


    @Override
    protected void drawableStateChanged() {
        super.drawableStateChanged();


        if (mForegroundSelector != null && mForegroundSelector.isStateful()) {
            mForegroundSelector.setState(getDrawableState());
        }
    }


    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);


        if (mForegroundSelector != null) {
            if (mUseBackgroundPadding) {
                mForegroundSelector.setBounds(mRectPadding.left, mRectPadding.top, w - mRectPadding.right, h - mRectPadding.bottom);
            } else {
                mForegroundSelector.setBounds(0, 0, w, h);
            }
        }
    }


    @Override
    protected void dispatchDraw(@NonNull Canvas canvas) {
        super.dispatchDraw(canvas);


        if (mForegroundSelector != null) {
            mForegroundSelector.draw(canvas);
        }
    }


    @Override
    protected boolean verifyDrawable(Drawable who) {
        return super.verifyDrawable(who) || (who == mForegroundSelector);
    }


    @Override
    public void jumpDrawablesToCurrentState() {
        super.jumpDrawablesToCurrentState();
        if (mForegroundSelector != null) mForegroundSelector.jumpToCurrentState();
    }


    public void setForeground(Drawable drawable) {
        if (mForegroundSelector != drawable) {
            if (mForegroundSelector != null) {
                mForegroundSelector.setCallback(null);
                unscheduleDrawable(mForegroundSelector);
            }


            mForegroundSelector = drawable;


            if (drawable != null) {
                setWillNotDraw(false);
                drawable.setCallback(this);
                if (drawable.isStateful()) {
                    drawable.setState(getDrawableState());
                }
            } else {
                setWillNotDraw(true);
            }
            requestLayout();
            invalidate();
        }
    }


    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    @Override
    public void drawableHotspotChanged(float x, float y) {
        super.drawableHotspotChanged(x, y);
        if (mForegroundSelector != null) {
            mForegroundSelector.setHotspot(x, y);
        }
    }
}

它就像一个符咒，请参见下面的gif：

现在，我在

卡片视图中有一个图标：


您可以在android studio visual editor中看到图标的边界是一个正方形。如果我对其应用前景图像视图，涟漪将延伸到正方形的边界，因此最终效果将是相机图标下的白色方形块

我真的不想那样。我希望最终在相机下方显示圆形白色波纹，类似于单击工具栏中的图标时：


API<21有没有办法做到这一点？
我在instamaterial应用程序上找到了一个解决方案，但这并不是我想要的，但它必须做到

他们所做的只是将选择器链接为imageButton的背景：

<?xml version="1.0" encoding="utf-8"?>
<!--drawable/btn_feed_action.xml-->
<selector xmlns:android="http://schemas.android.com/apk/res/android" android:enterFadeDuration="200" android:exitFadeDuration="200">
    <item android:state_pressed="false">
        <shape android:shape="oval">
            <solid android:color="@android:color/transparent" />
        </shape>
    </item>
    <item android:state_pressed="true">
        <shape android:shape="oval">
            <solid android:color="@color/white45" />
        </shape>
    </item>
</selector>



然后，每次按下图像时，45%的透明白色圆圈进入并投射为图像背景。一旦你的手指被移开，圆圈就会消失

解决方案不是“涟漪”效应，更多的是淡入淡出效应。有谁能想出更好的解决办法吗