在 layer-list 中的自定义 shape设定的大小无效
最近在做自定义 shape 效果时发现,自定义shape的大小在layer-list中无效了，较小的shape被拉伸至最大shape的大小了。(API23+没有此问题)
把自定义的 shape 单独拿出来用却没有问题,唯独放在 LayerDrawable 出现问题.
code
原本想实现一个圆环中包含一个实心圆的 drawable, 写出来类似下面的代码,在 IDE 预览时也没啥问题,到了真机就有问题了.
shape_layer.xml
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:gravity="center">
<shape
android:innerRadius="15px"
android:shape="ring"
android:thickness="10px"
android:useLevel="false">
<size
android:width="50px"
android:height="50px" />
<solid android:color="@color/colorAccent" />
</shape>
</item>
<item android:gravity="center">
<shape android:shape="oval">
<size
android:width="20px"
android:height="20px" />
<solid android:color="@color/colorPrimary" />
</shape>
</item>
</layer-list>
shape_layer_fixed. xml
后面将这2层的顺序换了下,但是实心和环之间的空白还是没有,所以给设置了位置来限定大小.
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:gravity="center">
<shape
android:innerRadius="15px"
android:shape="ring"
android:thickness="10px"
android:useLevel="false">
<size
android:width="50px"
android:height="50px" />
<solid android:color="@color/colorAccent" />
</shape>
</item>
// 这里通过计算设置了其4个方向的 inset 值来保证不会覆盖上层的环
<item
android:bottom="20px"
android:gravity="center"
android:left="20px"
android:right="20px"
android:top="20px">
<shape android:shape="oval">
<size
android:width="20px"
android:height="20px" />
<solid android:color="@color/colorPrimary" />
</shape>
</item>
</layer-list>
Anroid L MR1 以前
预览布局效果
问题跟踪：
LayerDrawable#onBoundsChange
// API22以前 在Bound更新时直接把所有的子Drawable的bound设置成LayerDrawable的bound了
@Override
protected void onBoundsChange(Rect bounds) {
int padL = 0;
int padT = 0;
int padR = 0;
int padB = 0;
final boolean nest = mLayerState.mPaddingMode == PADDING_MODE_NEST;
final ChildDrawable[] array = mLayerState.mChildren;
final int N = mLayerState.mNum;
for (int i = 0; i < N; i++) {
final ChildDrawable r = array[i];
r.mDrawable.setBounds(bounds.left + r.mInsetL + padL, bounds.top + r.mInsetT + padT,
bounds.right - r.mInsetR - padR, bounds.bottom - r.mInsetB - padB);
if (nest) {
padL += mPaddingL[i];
padR += mPaddingR[i];
padT += mPaddingT[i];
padB += mPaddingB[i];
}
}
}
LayerDrawable#onBoundsChange
// API 23+ 不会直接使用容器的bound，而是通过相对位置得到
private void updateLayerBoundsInternal(Rect bounds) {
int paddingL = 0;
int paddingT = 0;
int paddingR = 0;
int paddingB = 0;
final Rect outRect = mTmpOutRect;
final int layoutDirection = getLayoutDirection();
final boolean isLayoutRtl = layoutDirection == LayoutDirection.RTL;
final boolean isPaddingNested = mLayerState.mPaddingMode == PADDING_MODE_NEST;
final ChildDrawable[] array = mLayerState.mChildren;
for (int i = 0, count = mLayerState.mNum; i < count; i++) {
final ChildDrawable r = array[i];
final Drawable d = r.mDrawable;
if (d == null) {
continue;
}
final int insetT = r.mInsetT;
final int insetB = r.mInsetB;
// Resolve insets for RTL. Relative insets override absolute
// insets.
final int insetRtlL = isLayoutRtl ? r.mInsetE : r.mInsetS;
final int insetRtlR = isLayoutRtl ? r.mInsetS : r.mInsetE;
final int insetL = insetRtlL == INSET_UNDEFINED ? r.mInsetL : insetRtlL;
final int insetR = insetRtlR == INSET_UNDEFINED ? r.mInsetR : insetRtlR;
// Establish containing region based on aggregate padding and
// requested insets for the current layer.
final Rect container = mTmpContainer;
container.set(bounds.left + insetL + paddingL, bounds.top + insetT + paddingT,
bounds.right - insetR - paddingR, bounds.bottom - insetB - paddingB);
// Compute a reasonable default gravity based on the intrinsic and
// explicit dimensions, if specified.
final int intrinsicW = d.getIntrinsicWidth();
final int intrinsicH = d.getIntrinsicHeight();
final int layerW = r.mWidth;
final int layerH = r.mHeight;
final int gravity = resolveGravity(r.mGravity, layerW, layerH, intrinsicW, intrinsicH);
// Explicit dimensions override intrinsic dimensions.
final int resolvedW = layerW < 0 ? intrinsicW : layerW;
final int resolvedH = layerH < 0 ? intrinsicH : layerH;
Gravity.apply(gravity, resolvedW, resolvedH, container, outRect, layoutDirection);
d.setBounds(outRect);
if (isPaddingNested) {
paddingL += mPaddingL[i];
paddingR += mPaddingR[i];
paddingT += mPaddingT[i];
paddingB += mPaddingB[i];
}
}
}
解决方案：
旧版本不支持gravity 属性
可以设置inset left,top,right,bottom 来指定偏移位置，从而得到层叠效果的Drawable
