Android 設置圓角View

核心ViewHelper，使用ViewOutlineProvider實現圓角

<?xml version="1.0" encoding="utf-8"?>
<resources>


    <declare-styleable name="viewOutLineStrategy">
        <attr name="clip_radius" format="dimension"></attr>
        <attr name="clip_side" format="enum">
            <enum name="all" value="0"></enum>
            <enum name="left" value="1"></enum>
            <enum name="top" value="2"></enum>
            <enum name="right" value="3"></enum>
            <enum name="bottom" value="4"></enum>
        </attr>
    </declare-styleable>
</resources>

ViewHelper.java

import android.annotation.TargetApi;
import android.content.res.TypedArray;
import android.graphics.Outline;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewOutlineProvider;


public class ViewHelper {

    public static final int RADIUS_ALL = 0;
    public static final int RADIUS_LEFT = 1;
    public static final int RADIUS_TOP = 2;
    public static final int RADIUS_RIGHT = 3;
    public static final int RADIUS_BOTTOM = 4;

    public static void setViewOutline(View view, AttributeSet attributes, int defStyleAttr, int defStyleRes) {
        TypedArray array = view.getContext().obtainStyledAttributes(attributes, R.styleable.viewOutLineStrategy, defStyleAttr, defStyleRes);
        int radius = array.getDimensionPixelSize(R.styleable.viewOutLineStrategy_clip_radius, 0);
        int hideSide = array.getInt(R.styleable.viewOutLineStrategy_clip_side, 0);
        array.recycle();
        setViewOutline(view, radius, hideSide);
    }

    public static void setViewOutline(View owner, final int radius, final int radiusSide) {
        owner.setOutlineProvider(new ViewOutlineProvider() {
            @Override
            @TargetApi(21)
            public void getOutline(View view, Outline outline) {
                int w = view.getWidth(), h = view.getHeight();
                if (w == 0 || h == 0) {
                    return;
                }

                if (radiusSide != RADIUS_ALL) {
                    int left = 0, top = 0, right = w, bottom = h;
                    if (radiusSide == RADIUS_LEFT) {
                        right += radius;
                    } else if (radiusSide == RADIUS_TOP) {
                        bottom += radius;
                    } else if (radiusSide == RADIUS_RIGHT) {
                        left -= radius;
                    } else if (radiusSide == RADIUS_BOTTOM) {
                        top -= radius;
                    }
                    outline.setRoundRect(left, top, right, bottom, radius);
                    return;
                }

                int top = 0, bottom = h, left = 0, right = w;
                if (radius <= 0) {
                    outline.setRect(left, top, right, bottom);
                } else {
                    outline.setRoundRect(left, top, right, bottom, radius);
                }
            }
        });
        //開啓剪裁
        owner.setClipToOutline(radius > 0);
        owner.invalidate();
    }
}

CornerFrameLayout

import android.content.Context;
import android.util.AttributeSet;
import android.widget.FrameLayout;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

public class CornerFrameLayout extends FrameLayout {
    public CornerFrameLayout(@NonNull Context context) {
        this(context, null);
    }

    public CornerFrameLayout(@NonNull Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public CornerFrameLayout(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        this(context, attrs, defStyleAttr, 0);
    }

    public CornerFrameLayout(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);

        ViewHelper.setViewOutline(this, attrs, defStyleAttr, defStyleRes);
    }

    public void setViewOutline(int radius, int radiusSide) {
        ViewHelper.setViewOutline(this, radius, radiusSide);
    }
}

CornerLinearLayout

import android.content.Context;
import android.util.AttributeSet;
import android.widget.LinearLayout;

import androidx.annotation.Nullable;

public class CornerLinearLayout extends LinearLayout {
    public CornerLinearLayout(Context context) {
        this(context, null);
    }

    public CornerLinearLayout(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public CornerLinearLayout(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        this(context, attrs, defStyleAttr, 0);
    }

    public CornerLinearLayout(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);

        ViewHelper.setViewOutline(this, attrs, defStyleAttr, defStyleRes);
    }
}