给控件添加阴影

2019-11-20 19:15:56

代码来自github，忘记是谁写的了，底子不错，适当做了点修改

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ShadowContainer

package com.example.android_research;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.RectF;
import android.os.Build;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;

/**
 * <p>
 * Created by weiwei22 on 2019-11-20.
 */
public class ShadowContainer extends ViewGroup {
    private final float topDeltaLength;
    private final float bottomDeltaLength;
    private final float leftDeltaLength;
    private final float rightDeltaLength;
    private final float cornerRadius;
    private final Paint mShadowPaint;
    private boolean drawShadow;

    public ShadowContainer(Context context) {
        this(context, null);
    }

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

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

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ShadowContainer);
        topDeltaLength = a.getDimension(R.styleable.ShadowContainer_topDeltaLength, 0);
        bottomDeltaLength = a.getDimension(R.styleable.ShadowContainer_bottomDeltaLength, 0);
        leftDeltaLength = a.getDimension(R.styleable.ShadowContainer_leftDeltaLength, 0);
        rightDeltaLength = a.getDimension(R.styleable.ShadowContainer_rightDeltaLength, 0);
        cornerRadius = a.getDimension(R.styleable.ShadowContainer_containerCornerRadius, 0);
        drawShadow = a.getBoolean(R.styleable.ShadowContainer_enable, true);
        float dx = a.getDimension(R.styleable.ShadowContainer_deltaX, 0);
        float dy = a.getDimension(R.styleable.ShadowContainer_deltaY, 0);
        float shadowRadius = a.getDimension(R.styleable.ShadowContainer_containerShadowRadius, 0);
        int shadowColor = a.getColor(R.styleable.ShadowContainer_containerShadowColor, Color.RED);
        a.recycle();

        mShadowPaint = new Paint();
        mShadowPaint.setStyle(Paint.Style.FILL);
        mShadowPaint.setAntiAlias(true);
        mShadowPaint.setColor(shadowColor);
        mShadowPaint.setShadowLayer(shadowRadius, dx, dy, shadowColor);
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        if (drawShadow) {
            if (getLayerType() != LAYER_TYPE_SOFTWARE) {
                setLayerType(LAYER_TYPE_SOFTWARE, null);
            }
            View child = getChildAt(0);
            int left = child.getLeft();
            int top = child.getTop();
            int right = child.getRight();
            int bottom = child.getBottom();
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                canvas.drawRoundRect(left, top, right, bottom, cornerRadius, cornerRadius, mShadowPaint);
            } else {
                Path drawablePath = new Path();
                drawablePath.moveTo(left + cornerRadius, top);
                drawablePath.arcTo(new RectF(left, top, left + 2 * cornerRadius, top + 2 * cornerRadius), -90, -90, false);
                drawablePath.lineTo(left, bottom - cornerRadius);
                drawablePath.arcTo(new RectF(left, bottom - 2 * cornerRadius, left + 2 * cornerRadius, bottom), 180, -90, false);
                drawablePath.lineTo(right - cornerRadius, bottom);
                drawablePath.arcTo(new RectF(right - 2 * cornerRadius, bottom - 2 * cornerRadius, right, bottom), 90, -90, false);
                drawablePath.lineTo(right, top + cornerRadius);
                drawablePath.arcTo(new RectF(right - 2 * cornerRadius, top, right, top + 2 * cornerRadius), 0, -90, false);
                drawablePath.close();
                canvas.drawPath(drawablePath, mShadowPaint);
            }
        }
        super.dispatchDraw(canvas);
    }

    public void setDrawShadow(boolean drawShadow) {
        if (this.drawShadow == drawShadow) {
            return;
        }
        this.drawShadow = drawShadow;
        postInvalidate();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (getChildCount() != 1) {
            throw new IllegalStateException("Child view must be ony one!");
        }
        int measuredWidth = getMeasuredWidth();
        int measuredHeight = getMeasuredHeight();
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        View child = getChildAt(0);
        ShadowLayoutParams layoutParams = (ShadowLayoutParams) child.getLayoutParams();
        int childBottomMargin = (int) bottomDeltaLength;
        int childLeftMargin = (int) leftDeltaLength;
        int childRightMargin = (int) rightDeltaLength;
        int childTopMargin = (int) topDeltaLength;
        int widthMeasureSpecMode;
        int widthMeasureSpecSize;
        int heightMeasureSpecMode;
        int heightMeasureSpecSize;
        if (widthMode == MeasureSpec.UNSPECIFIED) {
            widthMeasureSpecMode = MeasureSpec.UNSPECIFIED;
            widthMeasureSpecSize = MeasureSpec.getSize(widthMeasureSpec);
        } else {
            if (layoutParams.width == ShadowLayoutParams.MATCH_PARENT) {
                widthMeasureSpecMode = MeasureSpec.EXACTLY;
                widthMeasureSpecSize = measuredWidth - childLeftMargin - childRightMargin;
            } else if (ShadowLayoutParams.WRAP_CONTENT == layoutParams.width) {
                widthMeasureSpecMode = MeasureSpec.AT_MOST;
                widthMeasureSpecSize = measuredWidth - childLeftMargin - childRightMargin;
            } else {
                widthMeasureSpecMode = MeasureSpec.EXACTLY;
                widthMeasureSpecSize = layoutParams.width;
            }
        }
        if (heightMode == MeasureSpec.UNSPECIFIED) {
            heightMeasureSpecMode = MeasureSpec.UNSPECIFIED;
            heightMeasureSpecSize = MeasureSpec.getSize(heightMeasureSpec);
        } else {
            if (layoutParams.height == ShadowLayoutParams.MATCH_PARENT) {
                heightMeasureSpecMode = MeasureSpec.EXACTLY;
                heightMeasureSpecSize = measuredHeight - childBottomMargin - childTopMargin;
            } else if (ShadowLayoutParams.WRAP_CONTENT == layoutParams.height) {
                heightMeasureSpecMode = MeasureSpec.AT_MOST;
                heightMeasureSpecSize = measuredHeight - childBottomMargin - childTopMargin;
            } else {
                heightMeasureSpecMode = MeasureSpec.EXACTLY;
                heightMeasureSpecSize = layoutParams.height;
            }
        }
        measureChild(child, MeasureSpec.makeMeasureSpec(widthMeasureSpecSize, widthMeasureSpecMode), MeasureSpec.makeMeasureSpec(heightMeasureSpecSize, heightMeasureSpecMode));
        int parentWidthMeasureSpec = MeasureSpec.getMode(widthMeasureSpec);
        int parentHeightMeasureSpec = MeasureSpec.getMode(heightMeasureSpec);
        int height = measuredHeight;
        int width = measuredWidth;
        int childHeight = child.getMeasuredHeight();
        int childWidth = child.getMeasuredWidth();
        if (parentHeightMeasureSpec == MeasureSpec.AT_MOST) {
            height = childHeight + childTopMargin + childBottomMargin;
        }
        if (parentWidthMeasureSpec == MeasureSpec.AT_MOST) {
            width = childWidth + childRightMargin + childLeftMargin;
        }
        if (width < childWidth + leftDeltaLength + rightDeltaLength) {
            width = (int) (childWidth + leftDeltaLength + rightDeltaLength);
        }
        if (height < childHeight + topDeltaLength + bottomDeltaLength) {
            height = (int) (childHeight + topDeltaLength + bottomDeltaLength);
        }
        if (height != measuredHeight || width != measuredWidth) {
            setMeasuredDimension(width, height);
        }
    }

    public static class ShadowLayoutParams extends MarginLayoutParams {

        public ShadowLayoutParams(Context c, AttributeSet attrs) {
            super(c, attrs);
        }

        public ShadowLayoutParams(int width, int height) {
            super(width, height);
        }

        public ShadowLayoutParams(MarginLayoutParams source) {
            super(source);
        }

        public ShadowLayoutParams(ViewGroup.LayoutParams source) {
            super(source);
        }
    }

    @Override
    protected ViewGroup.LayoutParams generateDefaultLayoutParams() {
        return new ShadowLayoutParams(ShadowLayoutParams.WRAP_CONTENT, ShadowLayoutParams.WRAP_CONTENT);
    }

    @Override
    protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) {
        return new ShadowLayoutParams(p);
    }

    @Override
    public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) {
        return new ShadowLayoutParams(getContext(), attrs);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        View child = getChildAt(0);
        int measuredWidth = getMeasuredWidth();
        int measuredHeight = getMeasuredHeight();
        int childMeasureWidth = child.getMeasuredWidth();
        int childMeasureHeight = child.getMeasuredHeight();
//        child.layout((measuredWidth - childMeasureWidth) / 2, (measuredHeight - childMeasureHeight) / 2, (measuredWidth + childMeasureWidth) / 2, (measuredHeight + childMeasureHeight) / 2);
        child.layout((int) leftDeltaLength, (int) topDeltaLength, (int) (leftDeltaLength + childMeasureWidth), (int) (topDeltaLength + childMeasureHeight));
    }
}

使用方式：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <FrameLayout
        android:id="@+id/top"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:layout_marginRight="10dp"
        android:visibility="gone">

        <View
            android:id="@+id/layer"
            android:layout_width="match_parent"
            android:layout_height="200dp"
            android:background="#7fff00ff" />

        <TextView
            android:id="@+id/tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="10dp"
            android:layout_marginTop="10dp"
            android:text="默认竖屏"
            android:textColor="#00ff00"
            android:textSize="23sp" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="top|right"
            android:layout_marginTop="10dp"
            android:layout_marginRight="10dp"
            android:text="右上角"
            android:textColor="#00ff00"
            android:textSize="23sp" />

        <TextView
            android:id="@+id/btn"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom|right"
            android:layout_marginRight="10dp"
            android:layout_marginBottom="10dp"
            android:text="点击"
            android:textColor="#00ff00"
            android:textSize="23sp" />
    </FrameLayout>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:background="@drawable/ala_wish_list_bg"
        android:orientation="vertical"
        android:padding="30dp">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="四周等距离发散阴影" />

        <com.example.android_research.ShadowContainer
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:bottomDeltaLength="12dp"
            app:containerCornerRadius="13dp"
            app:containerShadowColor="#70B5041A"
            app:containerShadowRadius="6dp"
            app:leftDeltaLength="12dp"
            app:rightDeltaLength="12dp"
            app:topDeltaLength="12dp">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="100dp"
                android:background="@drawable/ala_my_wish_list_item_bg" />
        </com.example.android_research.ShadowContainer>

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="30dp"
            android:text="底部阴影区较大，顶部及两侧较小" />

        <com.example.android_research.ShadowContainer
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:bottomDeltaLength="12dp"
            app:containerCornerRadius="13dp"
            app:containerShadowColor="#70B5041A"
            app:containerShadowRadius="6dp"
            app:deltaY="3dp"
            app:leftDeltaLength="4dp"
            app:rightDeltaLength="4dp"
            app:topDeltaLength="4dp">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="100dp"
                android:background="@drawable/ala_my_wish_list_item_bg" />
        </com.example.android_research.ShadowContainer>


        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="30dp"
            android:text="圆形右下角运营区" />

        <com.example.android_research.ShadowContainer
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:bottomDeltaLength="10dp"
            app:containerCornerRadius="80dp"
            app:containerShadowColor="#ffff00"
            app:containerShadowRadius="6dp"
            app:deltaX="3dp"
            app:deltaY="6dp"
            app:rightDeltaLength="10dp"
            app:topDeltaLength="0dp">

            <TextView
                android:layout_width="100dp"
                android:layout_height="100dp"
                android:background="@drawable/circle" />
        </com.example.android_research.ShadowContainer>
    </LinearLayout>


</RelativeLayout>