Android直播源码APP开发中阴影效果实现

Android直播源码APP开发中阴影效果实现的相关代码
为View添加阴影，其实就是为View提供一个有阴影的背景而已，所以有2中实现方式：
1.重写View的onDraw()方法；
2.自定义Drawable；
第一种明显不合理，我们不可能重写每个需要设置阴影的View的onDraw()，所以这里选择自定义Drwable（通过设置Paint的ShadowLayer）来实现。需要注意的是：这种方式实现的阴影，其目标View需要关闭硬件加速。

view.setLayerType(View.LAYER_TYPE_SOFTWARE, null);

需求点
可设置阴影颜色，圆角，面积，偏移量；
可设置View的背景形状，颜色，圆角；
实现

public class ShadowDrawable extends Drawable {

private Paint mPaint;
private int mShadowRadius; // 阴影圆角
private int mShape; // 背景形状
private int mShapeRadius; // 背景圆角
private int mOffsetX; // 阴影的水平偏移量
private int mOffsetY; // 阴影的垂直偏移量
private int mBgColor[]; // 背景颜色
private RectF mRect;

public final static int SHAPE_ROUND = 1; // 表示圆角矩形
public final static int SHAPE_CIRCLE = 2; // 表示圆

private ShadowDrawable(int shape, int[] bgColor, int shapeRadius, int shadowColor, int shadowRadius, int offsetX, int offsetY) {
this.mShape = shape;
this.mBgColor = bgColor;
this.mShapeRadius = shapeRadius;
this.mShadowRadius = shadowRadius;
this.mOffsetX = offsetX;
this.mOffsetY = offsetY;
mPaint = new Paint();
mPaint.setColor(Color.TRANSPARENT);
mPaint.setAntiAlias(true);
mPaint.setShadowLayer(shadowRadius, offsetX, offsetY, shadowColor);
mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_ATOP));
}

@Override
public void setBounds(int left, int top, int right, int bottom) {
super.setBounds(left, top, right, bottom);
mRect = new RectF(left + mShadowRadius - mOffsetX, top + mShadowRadius - mOffsetY, right - mShadowRadius - mOffsetX,
bottom - mShadowRadius - mOffsetY);
}

@Override
public void draw(@NonNull Canvas canvas) {
if (mShape == SHAPE_ROUND) {
canvas.drawRoundRect(mRect, mShapeRadius, mShapeRadius, mPaint);
Paint newPaint = new Paint();

if (mBgColor != null) {
if (mBgColor.length == 1) {
newPaint.setColor(mBgColor[0]);
} else {
newPaint.setShader(new LinearGradient(mRect.left, mRect.height() / 2, mRect.right, mRect.height() / 2, mBgColor,
null, Shader.TileMode.CLAMP));
}
}
newPaint.setAntiAlias(true);
canvas.drawRoundRect(mRect, mShapeRadius, mShapeRadius, newPaint);
} else {
canvas.drawCircle(mRect.centerX(), mRect.centerY(), Math.min(mRect.width(), mRect.height())/ 2, mPaint);
}
}

@Override
public void setAlpha(int alpha) {
mPaint.setAlpha(alpha);
}

@Override
public void setColorFilter(@Nullable ColorFilter colorFilter) {
mPaint.setColorFilter(colorFilter);
}

@Override
public int getOpacity() {
return PixelFormat.TRANSLUCENT;
}
}

由于提供的属性比较多，为了便于使用，提供了Builder的链式创建方式，同时提供了常用的几个static方法，设置阴影只需一行代码即可，具体查看ShadowDrawable.java。

public static void setShadowDrawable(View view, int shapeRadius, int shadowColor, int shadowRadius, int offsetX, int offsetY) {
ShadowDrawable drawable = new ShadowDrawable.Builder()
.setShapeRadius(shapeRadius)
.setShadowColor(shadowColor)
.setShadowRadius(shadowRadius)
.setOffsetX(offsetX)
.setOffsetY(offsetY)
.builder();
view.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
ViewCompat.setBackground(view, drawable);
}