public class ShadowLayout extends FrameLayout {
private int mShadowColor;
private float mShadowRadius;
private float mCornerRadius;
private float mDx;
private float mDy;
private boolean mInvalidateShadowOnSizeChanged = true;
private boolean mForceInvalidateShadow = false;
public ShadowLayout(Context context) {
super(context);
initView(context, null);
}
public ShadowLayout(Context context, AttributeSet attrs) {
super(context, attrs);
initView(context, attrs);
}
public ShadowLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initView(context, attrs);
}
@Override
protected int getSuggestedMinimumWidth() {
return 0;
}
@Override
protected int getSuggestedMinimumHeight() {
return 0;
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
if(w > 0 && h > 0 && (getBackground() == null || mInvalidateShadowOnSizeChanged || mForceInvalidateShadow)) {
mForceInvalidateShadow = false;
setBackgroundCompat(w, h);
}
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
if (mForceInvalidateShadow) {
mForceInvalidateShadow = false;
setBackgroundCompat(right - left, bottom - top);
}
}
public void setInvalidateShadowOnSizeChanged(boolean invalidateShadowOnSizeChanged) {
mInvalidateShadowOnSizeChanged = invalidateShadowOnSizeChanged;
}
public void invalidateShadow() {
mForceInvalidateShadow = true;
requestLayout();
invalidate();
}
private void initView(Context context, AttributeSet attrs) {
initAttributes(context, attrs);
int xPadding = (int) (mShadowRadius + Math.abs(mDx));
int yPadding = (int) (mShadowRadius + Math.abs(mDy));
setPadding(xPadding, yPadding, xPadding, yPadding);
}
@SuppressWarnings("deprecation")
private void setBackgroundCompat(int w, int h) {
Bitmap bitmap = createShadowBitmap(w, h, mCornerRadius, mShadowRadius, mDx, mDy, mShadowColor, Color.TRANSPARENT);
BitmapDrawable drawable = new BitmapDrawable(getResources(), bitmap);
if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.JELLY_BEAN) {
setBackgroundDrawable(drawable);
} else {
setBackground(drawable);
}
}
private void initAttributes(Context context, AttributeSet attrs) {
TypedArray attr = getTypedArray(context, attrs, R.styleable.ShadowLayout);
if (attr == null) {
return;
}
try {
mCornerRadius = attr.getDimension(R.styleable.ShadowLayout_sl_cornerRadius, getResources().getDimension(R.dimen.default_corner_radius));
mShadowRadius = attr.getDimension(R.styleable.ShadowLayout_sl_shadowRadius, getResources().getDimension(R.dimen.default_shadow_radius));
mDx = attr.getDimension(R.styleable.ShadowLayout_sl_dx, 0);
mDy = attr.getDimension(R.styleable.ShadowLayout_sl_dy, 0);
mShadowColor = attr.getColor(R.styleable.ShadowLayout_sl_shadowColor, getResources().getColor(R.color.default_shadow_color));
} finally {
attr.recycle();
}
}
private TypedArray getTypedArray(Context context, AttributeSet attributeSet, int[] attr) {
return context.obtainStyledAttributes(attributeSet, attr, 0, 0);
}
private Bitmap createShadowBitmap(int shadowWidth, int shadowHeight, float cornerRadius, float shadowRadius,
float dx, float dy, int shadowColor, int fillColor) {
Bitmap output = Bitmap.createBitmap(shadowWidth, shadowHeight, Bitmap.Config.ALPHA_8);
Canvas canvas = new Canvas(output);
RectF shadowRect = new RectF(
shadowRadius,
shadowRadius,
shadowWidth - shadowRadius,
shadowHeight - shadowRadius);
if (dy > 0) {
shadowRect.top += dy;
shadowRect.bottom -= dy;
} else if (dy < 0) {
shadowRect.top += Math.abs(dy);
shadowRect.bottom -= Math.abs(dy);
}
if (dx > 0) {
shadowRect.left += dx;
shadowRect.right -= dx;
} else if (dx < 0) {
shadowRect.left += Math.abs(dx);
shadowRect.right -= Math.abs(dx);
}
Paint shadowPaint = new Paint();
shadowPaint.setAntiAlias(true);
shadowPaint.setColor(fillColor);
shadowPaint.setStyle(Paint.Style.FILL);
if (!isInEditMode()) {
shadowPaint.setShadowLayer(shadowRadius, mDx, mDy, shadowColor);
}
canvas.drawRoundRect(shadowRect, cornerRadius, cornerRadius, shadowPaint);
return output;
}
<declare-styleable name="ShadowLayout">
<attr name="sl_cornerRadius" format="dimension"/>
<attr name="sl_shadowRadius" format="dimension"/>//阴影宽度
<attr name="sl_shadowColor" format="color"/>//阴影颜色
<attr name="sl_dx" format="dimension"/>//偏移
<attr name="sl_dy" format="dimension"/>
</declare-styleable>
用例:
<com.ShadowLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/gf_tree_gif"
android:layout_marginLeft="6dp"
android:layout_marginRight="6dp"
android:layout_marginTop="-40dp"
app:sl_dx="2dp"
app:sl_dy="2dp"
app:sl_shadowColor="#1Aefefef"
app:sl_shadowRadius="8dp"
>
<任意布局>
</ShadowLayout>