我正在开发一个 Android 应用程序。在我的应用程序中，我同时使用了 CardView 和 ImageView。但是我在 CardView 中设计 ImageView 时遇到了问题。问题出在 ImageView 的圆角半径上。

我有这样的适配器项的 XML 布局。

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:card_view="http://schemas.android.com/apk/res-auto"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_marginTop="5dp"
    android:layout_marginLeft="5dp"
    android:layout_marginRight="5dp"
    card_view:cardCornerRadius="5dp"
    android:layout_width="match_parent"
    android:id="@+id/di_card_container"
    android:layout_height="wrap_content">

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ImageView
            android:id="@+id/di_iv_image"
            android:scaleType="centerCrop"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

        <RelativeLayout
            android:padding="10dp"
            android:layout_below="@id/di_iv_image"
            android:layout_alignParentLeft="true"
            android:layout_alignParentBottom="true"
            android:id="@+id/di_name_container"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
            <TextView
                android:textSize="15dp"
                android:textColor="@color/textColorPrimary"
                android:id="@+id/di_tv_name"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />
        </RelativeLayout>
    </RelativeLayout>
</android.support.v7.widget.CardView>

如您所见，我将 CardView 的角半径设置为 5dp 并且 ImageView 适合其父元素的宽度 卡片 View 。问题是 ImageView 的两个顶角都没有像其父级 CardView 的角那样弯曲。

这是截图

如果适合父 CardView，CardView 的 subview 的角通常会像其父角一样自动弯曲。那正确吗？那么，为什么我的 ImageView 不工作？

最佳答案

所以这是 pre lollipop 上的常见行为。以下是修复它的步骤:

第 1 步:将以下属性添加到您的 cardView

card_view:cardUseCompatPadding="true"
card_view:cardPreventCornerOverlap="false"
card_view:cardCornerRadius="10dp"

第 2 步:使用自定义 ImageView 将其顶部边框四舍五入:

public class RoundedTopImageView extends ImageView {
private Paint                       mPaint;
private Path                        mPath;
private Bitmap                      mBitmap;
private Matrix                      mMatrix;
private int                         mRadius = DisplayUtils.convertDpToPixel(10);
private int                         mWidth;
private int                         mHeight;
private Drawable                    mDrawable;

public RoundedTopImageView(Context context) {
    super(context);
    init();
}

public RoundedTopImageView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init();
}

public RoundedTopImageView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init();
}

private void init() {
    mPaint = new Paint();
    mPaint.setColor(Color.WHITE);

    mPath = new Path();
}

@Override
public void setImageDrawable(Drawable drawable) {
    mDrawable = drawable;
    if (drawable == null) {
        return;
    }
    mBitmap = drawableToBitmap(drawable);

    int bDIWidth = mBitmap.getWidth();
    int bDIHeight = mBitmap.getHeight();

    //Fit to screen.
    float scale;
    if ((mHeight / (float)bDIHeight) >= (mWidth / (float)bDIWidth)){
        scale =  mHeight / (float)bDIHeight;
    } else {
        scale = mWidth / (float)bDIWidth;
    }

    float borderLeft = (mWidth - (bDIWidth * scale)) / 2;
    float borderTop = (mHeight - (bDIHeight * scale)) / 2;

    mMatrix = getImageMatrix();
    RectF drawableRect = new RectF(0, 0, bDIWidth, bDIHeight);
    RectF viewRect = new RectF(borderLeft, borderTop, (bDIWidth * scale) + borderLeft, (bDIHeight * scale) + borderTop);
    mMatrix.setRectToRect(drawableRect, viewRect, Matrix.ScaleToFit.CENTER);
    invalidate();
}

private Bitmap drawableToBitmap(Drawable drawable) {
    Bitmap bitmap;

    if (drawable instanceof BitmapDrawable) {
        BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
        if(bitmapDrawable.getBitmap() != null) {
            return bitmapDrawable.getBitmap();
        }
    }

    if(drawable.getIntrinsicWidth() <= 0 || drawable.getIntrinsicHeight() <= 0) {
        bitmap = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888); // Single color bitmap will be created of 1x1 pixel
    } else {
        bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
    }

    Canvas canvas = new Canvas(bitmap);
    drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
    drawable.draw(canvas);
    return bitmap;
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    mWidth = MeasureSpec.getSize(widthMeasureSpec);
    mHeight = MeasureSpec.getSize(heightMeasureSpec);
    if ((mDrawable != null) && (mHeight > 0) && (mWidth > 0)) {
        setImageDrawable(mDrawable);
    }
}

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

    if (mBitmap == null) {
        return;
    }

    canvas.drawColor(Color.TRANSPARENT);

    mPath.reset();
    mPath.moveTo(0, mRadius);
    mPath.lineTo(0, canvas.getHeight());
    mPath.lineTo(canvas.getWidth(), canvas.getHeight());
    mPath.lineTo(canvas.getWidth(), mRadius);
    mPath.quadTo(canvas.getWidth(), 0, canvas.getWidth() - mRadius, 0);
    mPath.lineTo(mRadius, 0);
    mPath.quadTo(0, 0, 0, mRadius);


    canvas.drawPath(mPath, mPaint);
    canvas.clipPath(mPath);
    canvas.drawBitmap(mBitmap, mMatrix, mPaint);
}

}

第 3 步:只需将 xml 中的 ImageView 替换为 RoundedTopImageView

第 4 步:在您的代码中将其用作常规 imageView，例如 Picasso:

RoundedTopImageView image = (RoundedTopImageView) findViewById(R.id.di_iv_image);
Picasso.with(context)
                    .load("Some cool Url")
                    .into(image);

编辑:添加了 convertDpToPixel 函数

抱歉，我忘了添加它，它是 Util 类的一部分，您可以将其添加到任何您想要的地方(在我的例子中是 DisplayUtils 类):

public static int convertDpToPixel(int dp) {
    DisplayMetrics displayMetrics = Resources.getSystem().getDisplayMetrics();
    return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, displayMetrics);
}

关于android - Corners ImageView 适合 CardView 没有像 CardView 在 Android 中的角那样的半径，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37549204/