Core Animation指南：Mac与iPhone开发的强大工具详解

需积分: 10 59 浏览量更新于2024-07-24 收藏 2.8MB PDF 举报

《Core.Animation: Mac and iPhone Development》是一本专为Mac OS X、iPhone和iPod touch开发者设计的全面指南，由 Marcus Zarra 和 Matt Long 联合撰写。本书针对有经验的OS X和iPhone开发者，旨在帮助他们充分利用苹果强大的Core Animation框架，以更轻松、代码量更少的方式创建出视觉效果丰富的应用程序。该书首先介绍了Core Animation的基本概念和功能边界，明确其能做什么以及如何最有效地运用，同时强调避免误用的重要性。作者基于Objective-C、Cocoa和Xcode的基础知识，深入讲解了核心动画编程的各个方面，包括关键帧技术、动画控制、Core Image在动画中的过滤能力、使用QTMovieLayer播放QuickTime电影、OpenGL层对电影播放的控制、Quartz Composer的集成以及如何利用helper layers进行渐变绘制、形状组合和子层复制等高级技术。书中特别关注了Mac和iPhone上Core Animation的异同，以便开发者能够编写可以跨平台使用的代码。对于初学者和高级开发者，书中都提供了大量的实用信息和技术提示，涵盖了从基础到进阶的动画设计和优化策略。此外，书中的"Advanced Material"部分确保了这本书在帮助开发者掌握基础知识后仍能保持其价值，因为它将持续提供有关复杂动画、交互式用户界面设计等方面的深入指导。本书受到业界专业人士的好评，认为它不仅适合入门者，也适合寻求进一步提升动画技巧和设计风格的专业人士。无论是为了迎接Mac和iPhone未来界面开发的挑战，还是为了提升个人项目的技术深度，这都是一本不可或缺的参考资源。通过阅读和实践书中的内容，读者将能够熟练掌握Core Animation，并将其应用到实际项目中，从而创造出令人惊叹的视觉体验。

ptg5994185

IN THIS CHAPTER

. Animation and the Cartesian

Plane

. Your Free Lunch

. What Is a Layer?

. Animation and Layers

. Math? I Was Told There Would

Be No Math

. Core Animation and the

iPhone

. Notes on Sample Projects

CHAPTER 1

What Is Core

Animation?

Core Animation enables you to develop complex anima-

tions for many different types of applications. You can

simply animate your views within a window, or you can

create a thousand sprites represented by layers on the

screen for that next killer game. In this chapter, we intro-

duce you to the basic concepts behind Core Animation.

We take a look at views and layers to ensure you under-

stand what you can do with animation in each. We start

with a discussion about animation and the coordinate

plane and then move on to getting well acquainted with

the Core Animation base class,

CALayer, and its related

protocols.

Animation and the Cartesian

Plane

When you have become familiar with Core Animation and

start using it in your applications, you will see that anima-

tion is easy on both Mac OS X and the iPhone. The fact is,

though, that animation has not always been easy. Prior to

Core Animation, you needed to understand some fairly

complex subjects such as double buffering and more

complicated mathematics such as plane geometry—espe-

cially if you wanted to give your animations any sense of

depth. Core Animation abstracts all of that away. If you

wanted to move a sprite across the screen doing it the old

way, you needed to create an off-screen graphics context,

draw your sprite to that context, swap out that context

ptg5994185

with one currently on the screen, move the sprite position, and then draw to the swapped

out off-screen graphics context. Lather, rinse, repeat.

Although this process isn’t terribly difficult, it can present some challenges to the

developer that Core Animation completely eliminates. The Core Animation way to do

the exact same thing is to create a layer that contains your sprite and simply call

–setPosition. As you learn in chapters to come, the position of a layer is represented by

a single point on the screen. By default, a layer’s position is the center point of the layer

within its parent’s coordinate space. So what does that mean?

Core Animation uses the standard Cartesian coordinate system you remember from geom-

etry and trigonometry. The values for x are on the horizontal axis, and the values for y are

on vertical axis. When naming a point, the x is always the first value, so a value of 25,35

means x = 25 and y = 35. Different from a standard Cartesian coordinate plane, however,

is that you are only ever using the upper-right portion of the plane where the numbers

are all positive. This means that the bottom-left corner of the screen is at point

0,0. The

upper-right portion of the screen then is the width (x) and height (y) depending on the

resolution of the screen you use. On a 15-inch MacBook Pro, this value is

1440,900. For

example, if you created a sprite on a layer and wanted to animate it from coordinate

0,0

on this MacBook Pro, you could set the position of the sprite to 0,0 when it is created

and then call

–setPosition(CGPointMake(1440,900)) and the sprite layer would animate

to the upper-right corner of the screen. Of course, this assumes that the sprite is in a view

that covers the entire screen, as layers cannot display without being backed by a view.

CHAPTER 1 What Is Core Animation?

Differing Coordinate Systems

One thing you should keep in mind when determining where to position your layers on a view

is that the coordinate system might work differently from one system to another. If you have

experience drawing in a coordinate system on other platforms such as Windows, the coordi-

nate system might feel upside down. On Windows, the origin point

0,0 is located at the

upper-left corner of the screen instead of the bottom-left corner.

Fortunately, if you are used to using a coordinate system that works this way, Cocoa views

provide a simple way to help you feel right at home. You can create your own NSView derived

view and override the method called

–isFlipped. In this method, simply return YES (a true

value) and Quartz (the 2D drawing system) assumes you want to draw everything with your

coordinate origin in the upper-left corner.

Interestingly, this coordinate system—with the origin in the upper-left corner—is the default

for drawing behavior in a

UIView on the iPhone, so keep that in mind if you need to duplicate

drawing functionality between OS X and the iPhone. You want to override

NSView and have

–isFlipped return YES for OS X so that you don’t need to rewrite your code for the iPhone.

ptg5994185

Your Free Lunch

They say that there is no such thing as a free lunch, but when it comes to animating

with Core Animation, you don’t just get lunch, you get a drink and desert as well. For

example, all the drawing going on is happening behind the scenes using OpenGL. Yet,

you don’t need to know anything about OpenGL to take advantage of the hardware accel-

eration offered by your video card. This is fully abstracted by Core Animation. If you do

want to get to the more nuts-and-bolts level of OpenGL, though, you can do so by using

the

CAOpenGLLayer on OS X. As of this writing, things aren’t quite as easy on the iPhone

for OpenGL, but they are not too far off. The layers and layer-backed views on the iPhone

also give you great performance benefits.

Another freebie in Core Animation is that all the animation happens on a background

thread. This means that the user interface isn’t blocked when the animation runs. And

you don’t need to be a multithreading

expert to take advantage of it! In fact, if

you’ve never worked with multiple

threads, you won’t notice a thing. Just

set the

animatable property on your

layer or view and watch the action

happen.

What Is a Layer?

The layer, represented by the CALayer class and its derivatives, is the most basic funda-

mental building block you will use for your all your Core Animation-based applications.

All Core Animation layers provide a lightweight layer within a view that enables you to

display visual content. Here is how Apple describes a

CALayer in the API documentation:

CALayer is the model class for layer-tree objects. It encapsulates the position, size,

and transform of a layer, which defines its coordinate system. It also encapsulates

the duration and pacing of a layer and its animations by adopting the

CAMediaTiming protocol, which defines a layer’s time space.

Notice how it says that it is the “model class.” This might be confusing if you are familiar

with the Model-View-Controller (MVC) design pattern, as you might more naturally think

that because Core Animation is of a visual nature, the View part of MVC might make

more sense. Ultimately, it is the

NSView on the OS X side and the UIView on the iPhone

side in which the layer is stored that does the drawing. The

CALayer simply contains the

data (model) that is relevant to all the layer’s attributes such as background color, border

width, position, size, transform, and such.

What Is a Layer?

NOTE

To learn more about how to use Core

Animation in your iPhone apps, see Chapter

13, “Core Animation on the iPhone.”

From p. 7 of Apple’s CALayer Class Reference: http://developer.apple.com/mac/library/

documentation/GraphicsImaging/Reference/CALayer_class/CALayer_class.pdf.

ptg5994185

. CATextLayer

This layer provides a convenient way to display a string in your layer tree. You

specify all the layout information as with any other layer, but you can also specify

the text, font, font size, and foreground color that the layer uses for the text

provided. If you specify an

NSAttributedString, these other fields with be ignored.

This layer is only available on OS X.

CAScrollLayer

This layer enables you to scroll content that is larger than the viewport of the

containing view.

CATiledLayer

This layer enables zooming and panning of content that is larger than the viewport

of the containing view.

CAOpenGLLayer

This layer provides a convenient way to do OpenGL rendering in your application.

We cover this layer is greater depth in Chapter 8, “OpenGL Layer.” This layer is only

available on OS X.

CAEAGLLayer

This layer provides a way to perform OpenGL rendering on the iPhone. This layer is

only available on the iPhone.

QTMovieLayer

This layer enables you to simply play back QuickTime movies in your Core

Animation-based application. Because it is a Core Animation layer, you can add

additional layers to its

sublayers property and composite other visuals on top of a

playing movie. We cover this layer in greater depth in Chapter 7, “QuickTime

Layers.” This layer is only available on OS X.

QTCaptureLayer

This layer takes advantage of a camera connected to your computer for the purpose

of video capture and real-time playback. You can use your iSight camera or a muxed

device such as a DV camera to capture video. The actual capturing is done via other

QuickTime classes available, but the

QTCaptureLayer enables you to see current

frames from your connected camera in real time. We cover this layer in greater

depth in Chapter 7. This layer is only available on OS X.

QCCompositionLayer

This layer enables you to play back a Quartz composition as part of your Core

Animation-based application. It also enables you to control the Quartz composition

using key-value coding. We cover this layer in greater depth in Chapter, 9 “Quartz

Composer Layer.” This layer is only available on OS X.

What Is a Layer?

剩余263页未读，继续阅读

insect27

粉丝: 12
资源: 50

Core Animation指南：Mac与iPhone开发的强大工具详解

iOS-CoreAnimation.pdf

iPhone_Development.pdf

CoreAnimation(iOS源代码)

iPhone.SDK.Development：Building.iPhone.Applications(Pragmatic.2009-09).pdf

Core Animation : Iphone and Mac OS X Development

Mac与iPhone开发动画秘籍：《Core.Animation简化教程》

CoreAnimation实战：Mac与iPhone开发简化动画技术

Core Animation入门：Mac和iPhone开发的简化动画技术

Learn Xcode Tools for Mac OS X and iPhone Development.pdf

Wrox.Professional.iPhone.and.iPad.Application.Development.Nov.2010

最新资源