版本記錄

前言

CAShapeLayer類是我們經(jīng)常用到的類，平時(shí)也就用一下其基本用法，但是很少詳細(xì)的翻出來它的開發(fā)文檔仔細(xì)研究下，下面，我就帶領(lǐng)大家詳細(xì)的研究下這個(gè)類，詳細(xì)的看一下它的用法。

API文檔

這個(gè)類繼承自CALayer，屬于QuartzCore框架的類，下面我們就先看一下它的API。

/* CoreAnimation - CAShapeLayer.h

   Copyright (c) 2008-2017, Apple Inc.
   All rights reserved. */

#import <QuartzCore/CALayer.h>

NS_ASSUME_NONNULL_BEGIN

/* The shape layer draws a cubic Bezier spline in its coordinate space.
 *
 * The spline is described using a CGPath object and may have both fill
 * and stroke components (in which case the stroke is composited over
 * the fill). The shape as a whole is composited between the layer's
 * contents and its first sublayer.
 *
 * The path object may be animated using any of the concrete subclasses
 * of CAPropertyAnimation. Paths will interpolate as a linear blend of
 * the "on-line" points; "off-line" points may be interpolated
 * non-linearly (e.g. to preserve continuity of the curve's
 * derivative). If the two paths have a different number of control
 * points or segments the results are undefined.
 *
 * The shape will be drawn antialiased, and whenever possible it will
 * be mapped into screen space before being rasterized to preserve
 * resolution independence. (However, certain kinds of image processing
 * operations, e.g. CoreImage filters, applied to the layer or its
 * ancestors may force rasterization in a local coordinate space.)
 *
 * Note: rasterization may favor speed over accuracy, e.g. pixels with
 * multiple intersecting path segments may not give exact results. */

CA_CLASS_AVAILABLE (10.6, 3.0, 9.0, 2.0)
@interface CAShapeLayer : CALayer

/* The path defining the shape to be rendered. If the path extends
 * outside the layer bounds it will not automatically be clipped to the
 * layer, only if the normal layer masking rules cause that. Upon
 * assignment the path is copied. Defaults to null. Animatable.
 * (Note that although the path property is animatable, no implicit
 * animation will be created when the property is changed.) */

@property(nullable) CGPathRef path;

/* The color to fill the path, or nil for no fill. Defaults to opaque
 * black. Animatable. */

@property(nullable) CGColorRef fillColor;

/* The fill rule used when filling the path. Options are `non-zero' and
 * `even-odd'. Defaults to `non-zero'. */

@property(copy) NSString *fillRule;

/* The color to fill the path's stroked outline, or nil for no stroking.
 * Defaults to nil. Animatable. */

@property(nullable) CGColorRef strokeColor;

/* These values define the subregion of the path used to draw the
 * stroked outline. The values must be in the range [0,1] with zero
 * representing the start of the path and one the end. Values in
 * between zero and one are interpolated linearly along the path
 * length. strokeStart defaults to zero and strokeEnd to one. Both are
 * animatable. */

@property CGFloat strokeStart;
@property CGFloat strokeEnd;

/* The line width used when stroking the path. Defaults to one.
 * Animatable. */

@property CGFloat lineWidth;

/* The miter limit used when stroking the path. Defaults to ten.
 * Animatable. */

@property CGFloat miterLimit;

/* The cap style used when stroking the path. Options are `butt', `round'
 * and `square'. Defaults to `butt'. */

@property(copy) NSString *lineCap;

/* The join style used when stroking the path. Options are `miter', `round'
 * and `bevel'. Defaults to `miter'. */

@property(copy) NSString *lineJoin;

/* The phase of the dashing pattern applied when creating the stroke.
 * Defaults to zero. Animatable. */

@property CGFloat lineDashPhase;

/* The dash pattern (an array of NSNumbers) applied when creating the
 * stroked version of the path. Defaults to nil. */

@property(nullable, copy) NSArray<NSNumber *> *lineDashPattern;

@end

/* `fillRule' values. */

CA_EXTERN NSString *const kCAFillRuleNonZero
    CA_AVAILABLE_STARTING (10.6, 3.0, 9.0, 2.0);
CA_EXTERN NSString *const kCAFillRuleEvenOdd
    CA_AVAILABLE_STARTING (10.6, 3.0, 9.0, 2.0);

/* `lineJoin' values. */

CA_EXTERN NSString *const kCALineJoinMiter
    CA_AVAILABLE_STARTING (10.6, 3.0, 9.0, 2.0);
CA_EXTERN NSString *const kCALineJoinRound
    CA_AVAILABLE_STARTING (10.6, 3.0, 9.0, 2.0);
CA_EXTERN NSString *const kCALineJoinBevel
    CA_AVAILABLE_STARTING (10.6, 3.0, 9.0, 2.0);

/* `lineCap' values. */

CA_EXTERN NSString *const kCALineCapButt
    CA_AVAILABLE_STARTING (10.6, 3.0, 9.0, 2.0);
CA_EXTERN NSString *const kCALineCapRound
    CA_AVAILABLE_STARTING (10.6, 3.0, 9.0, 2.0);
CA_EXTERN NSString *const kCALineCapSquare
    CA_AVAILABLE_STARTING (10.6, 3.0, 9.0, 2.0);

NS_ASSUME_NONNULL_END

Overview

在其坐標(biāo)空間中繪制三次Bezier樣條曲線的圖層。

shape是在圖層內(nèi)容和第一個(gè)子圖層之間合成的。

shape將被繪制反鋸齒，并且在可能的情況下將被映射到屏幕空間，然后進(jìn)行光柵化以保持分辨率的獨(dú)立性。 但是，應(yīng)用于圖層或其父類的某些圖像處理操作（如CoreImage濾鏡）可能會(huì)強(qiáng)制在本地坐標(biāo)空間中進(jìn)行光柵化。

注意：與精度相比，Shape光柵化可能更有利于速度。 例如，具有多個(gè)相交路徑段的像素可能不會(huì)給出確切的結(jié)果。

shape layer在其坐標(biāo)空間中繪制一個(gè)三次貝塞爾樣條曲線。

樣條曲線使用CGPath對(duì)象進(jìn)行描述，并可能同時(shí)填充和描邊組件（在這種情況下描邊被合成填充）。 整個(gè)形狀是在圖層之間合成的內(nèi)容及其第一個(gè)子層。

路徑對(duì)象可以使用任何具體的CAPropertyAnimation的子類來動(dòng)畫。 路徑將作為線性混合插值"on-line"點(diǎn); 可以非線性地插入"off-line"點(diǎn)（例如保持曲線衍生物的連續(xù)性）。 如果兩個(gè)路徑有不同的控制數(shù)量點(diǎn)或段的結(jié)果是不確定的。

Topics

1. Specifying the Shape Path

• path
  • 定義要呈現(xiàn)的形狀的路徑，可動(dòng)畫。

2. Accessing Shape Style Properties

• fillColor

  • 用于填充形狀路徑的顏色，可動(dòng)畫。

• fillRule

  • 填充形狀路徑時(shí)使用的填充規(guī)則。

• lineCap

  • 指定形狀路徑的線條樣式。

• lineDashPattern

  • 描邊時(shí)，虛線圖案應(yīng)用于形狀的路徑。

• lineDashPhase

  • 描邊時(shí)，應(yīng)用于形狀的路徑描邊階段，可動(dòng)畫。

• lineJoin

  • 指定形狀路徑的線條連接樣式。

• lineWidth

  • 指定形狀路徑的線寬，可動(dòng)畫。

• miterLimit

  • 描邊形狀路徑時(shí)使用的尖角限制，可動(dòng)畫。

• strokeColor

  • 用于描繪形狀路徑的顏色，可動(dòng)畫。

• strokeStart

  • 開始描邊路徑的相對(duì)位置，可動(dòng)畫。

• strokeEnd

  • 停止描邊路徑的相對(duì)位置，可動(dòng)畫。

3. Constants

• Shape Fill Mode Values

  • 這些常量指定fillRule的可能填充模式。

• Line Join Values

  • 這些常量指定描邊路徑的連接段之間的連接點(diǎn)的形狀。 圖lineJoin. Figure 1顯示了線條連接樣式的外觀。

• Line Cap Values
  • 這些常量指定描邊時(shí)開放路徑的端點(diǎn)形狀。 圖 lineCap.Figure 1顯示了線帽樣式的外觀。

后記

下一篇將主要介紹CAShapeLayer的基本使用。