这是我所使用的视图的样式
backCover: {
position: 'absolute',
marginTop: 20,
top: 0,
bottom: 0,
left: 0,
right: 0,
}
目前它的背景是白色的。我可以改变我想要的backgroundColor，如“#343434”，但它只接受最大6十六进制的颜色，所以我不能给不透明度，如“#00ffffff”。我试着像这样使用不透明度
backCover: {
position: 'absolute',
marginTop: 20,
top: 0,
bottom: 0,
left: 0,
right: 0,
opacity: 0.5,
}
但是它降低了视图内容的可见性。 有答案吗?
当前回答
为backgroundColor使用rgba值。
例如,
backgroundColor: 'rgba(52, 52, 52, 0.8)'
这将它设置为不透明度为80%的灰色，这是由不透明度小数0.8派生出来的。这个值可以是0.0到1.0之间的任何值。
其他回答
为backgroundColor使用rgba值。
例如,
backgroundColor: 'rgba(52, 52, 52, 0.8)'
这将它设置为不透明度为80%的灰色，这是由不透明度小数0.8派生出来的。这个值可以是0.0到1.0之间的任何值。
使用background的最好方法是十六进制代码#rrggbbaa，但它应该是十六进制。 例如:50%的不透明度意味着256/2 =128，然后将该值(128)在HEX中转换为80，在这里使用#00000080 80表示50%透明。
以下工作很好:
backgroundColor: 'rgba(52, 52, 52, alpha)'
你也可以试试:
backgroundColor: 'transparent'
试试这个backgroundColor: '#00000000' 它将设置背景颜色为透明，它遵循#rrggbbaa十六进制代码
你应该意识到当前存在的与iOS和RGBA背景的冲突。
Summary: public React Native currently exposes the iOS layer shadow properties more-or-less directly, however there are a number of problems with this: 1) Performance when using these properties is poor by default. That's because iOS calculates the shadow by getting the exact pixel mask of the view, including any tranlucent content, and all of its subviews, which is very CPU and GPU-intensive. 2) The iOS shadow properties do not match the syntax or semantics of the CSS box-shadow standard, and are unlikely to be possible to implement on Android. 3) We don't expose the layer.shadowPath property, which is crucial to getting good performance out of layer shadows. This diff solves problem number 1) by implementing a default shadowPath that matches the view border for views with an opaque background. This improves the performance of shadows by optimizing for the common usage case. I've also reinstated background color propagation for views which have shadow props - this should help ensure that this best-case scenario occurs more often. For views with an explicit transparent background, the shadow will continue to work as it did before ( shadowPath will be left unset, and the shadow will be derived exactly from the pixels of the view and its subviews). This is the worst-case path for performance, however, so you should avoid it unless absolutely necessary. Support for this may be disabled by default in future, or dropped altogether. For translucent images, it is suggested that you bake the shadow into the image itself, or use another mechanism to pre-generate the shadow. For text shadows, you should use the textShadow properties, which work cross-platform and have much better performance. Problem number 2) will be solved in a future diff, possibly by renaming the iOS shadowXXX properties to boxShadowXXX, and changing the syntax and semantics to match the CSS standards. Problem number 3) is now mostly moot, since we generate the shadowPath automatically. In future, we may provide an iOS-specific prop to set the path explicitly if there's a demand for more precise control of the shadow. Reviewed By: weicool
提交:https://github.com/facebook/react-native/commit/e4c53c28aea7e067e48f5c8c0100c7cafc031b06
