Converting between these two types is easy. Note that this property is of type CGColor, not a UIColor. Line #4: This line sets the layer’s shadow color to midnight blue. In other words, this makes it the exact same size and shape as the layer it’s applied to. A shadow radius of 0 results in no blurring at all. A lower one makes the shadow more visible and more focused. A higher radius makes the shadow more spread out, but less visible. The shadow radius is the blur radius to apply to the shadow created by box.layer. Line #3: This line sets the layer’s shadow radius to 5. This means that the shadow should be 70% opaque. Line #2: This line sets the layer’s shadow opacity to 0.7. Passing (5, 5) as the value for layer.shadowOffset means that the layer’s shadow should be 5 points to the right and 5 points below box.layer. A CGSize is taken for layer.shadowOffset. Line #1: This line sets the layer’s shadow offset to (5, 5). Assuming you have a myView object, you can access its layer like this:īox. Let’s get to work! As I mentioned above, every view is backed by a layer, which can be accessed through the layer property of UIView. Accessing CALayerĮnough talk about why layers exist. Although it isn’t necessary to use CALayer directly in most cases, the lower level APIs provide developers with some more flexible customization, which we will explore in this article. The moral of this story is the following: CALayer exists so that iOS can quickly and easily generate bitmap information about your app’s view hierarchy, which is then handed over to Core Graphics, and eventually OpenGL, to be rendered on your device’s screen by its GPU. The disadvantage is that the higher level graphics APIs offer less functionality. The advantage of this design scheme is the fact that you can choose which level of graphics access you need in your app and use it, allowing you to pick and choose exactly how much functionality you need, which can help prevent you from writing unnecessary code. Once Apple decided that a lot of Core Animation’s more advanced functionality wasn’t always necessary in regular apps, UIKit was created, which provides the highest level access to graphics on iOS. It provides the CALayer class, and allows some basic low level access to graphics capabilities. To make working with Core Graphics even simpler, Core Animation was created. The tradeoff with Core Graphics is a slightly lower level of functionality. To help alleviate this issue, Core Graphics was created, providing slightly higher level functionality with less code. However, there is a tradeoff: OpenGL is very bare bones, and even the most simple of tasks require very large amounts of code. OpenGL provides the most low level (and the fastest) access to an iOS device’s graphics hardware. To keep the system moving at this rate, a very basic, but powerful, layer of graphics functionality was created, which runs directly on the GPU: OpenGL. On iOS, this rate is 60 frames per second. It’s crucial to maintain a consistent frame rate that users perceive as “smooth”. On devices like smartphones, users expect great speed in everything that they do.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |