iOS之CGcontext.h方法和属性简介

/* CoreGraphics - CGContext.h

 Copyright (c) 2000-2012 Apple Inc.

 All rights reserved. */

#ifndef CGCONTEXT_H_

#define CGCONTEXT_H_

#include <CoreFoundation/CFBase.h>

#include <CoreFoundation/CFAvailability.h>

#include <stdint.h>

typedef struct CF_BRIDGED_TYPE(id) CGContext *CGContextRef;

#include <CoreGraphics/CGBase.h>

#include <CoreGraphics/CGAffineTransform.h>

#include <CoreGraphics/CGColor.h>

#include <CoreGraphics/CGColorSpace.h>

#include <CoreGraphics/CGFont.h>

#include <CoreGraphics/CGGradient.h>

#include <CoreGraphics/CGImage.h>

#include <CoreGraphics/CGPath.h>

#include <CoreGraphics/CGPattern.h>

#include <CoreGraphics/CGPDFDocument.h>

#include <CoreGraphics/CGShading.h>

CF_IMPLICIT_BRIDGING_ENABLED

CF_ASSUME_NONNULL_BEGIN

/* Drawing modes for paths. */

typedef CF_ENUM (int32_t, CGPathDrawingMode) {

    kCGPathFill,        //非零规则

    kCGPathEOFill,      //奇偶规则

    kCGPathStroke,      //画线

    kCGPathFillStroke,  //表示填充 画线

    kCGPathEOFillStroke //表示描线 不是填充

};

/* Drawing modes for text. */

typedef CF_ENUM (int32_t, CGTextDrawingMode) {

    kCGTextFill,

    kCGTextStroke,

    kCGTextFillStroke,

    kCGTextInvisible,

    kCGTextFillClip,

    kCGTextStrokeClip,

    kCGTextFillStrokeClip,

    kCGTextClip

};

/* Text encodings. */

typedef CF_ENUM (int32_t, CGTextEncoding) {

    kCGEncodingFontSpecific,

    kCGEncodingMacRoman

} CG_AVAILABLE_BUT_DEPRECATED(__MAC_10_0, __MAC_10_9, __IPHONE_2_0, __IPHONE_7_0);

/* Interpolation quality. */

typedef CF_ENUM (int32_t, CGInterpolationQuality) {

    kCGInterpolationDefault = ,  /* Let the context decide. */

    kCGInterpolationNone = ,     /* Never interpolate. */

    kCGInterpolationLow = ,      /* Low quality, fast interpolation. */

    kCGInterpolationMedium = ,   /* Medium quality, slower than kCGInterpolationLow. */

    kCGInterpolationHigh =       /* Highest quality, slower than kCGInterpolationMedium. */

};

//混合模式

typedef CF_ENUM (int32_t, CGBlendMode) {

    /* Available in Mac OS X 10.4 & later. */

    kCGBlendModeNormal,     //正常

    kCGBlendModeMultiply,   //正片叠底

    kCGBlendModeScreen,     //滤色

    kCGBlendModeOverlay,    //叠加

    kCGBlendModeDarken,     //变暗

    kCGBlendModeLighten,    //变亮

    kCGBlendModeColorDodge, //颜色减淡

    kCGBlendModeColorBurn,  //颜色加深

    kCGBlendModeSoftLight,  //柔光

    kCGBlendModeHardLight,  //强光

    kCGBlendModeDifference, //差值

    kCGBlendModeExclusion,  //排除

    kCGBlendModeHue,        //色相

    kCGBlendModeSaturation, //保护度

    kCGBlendModeColor,      //颜色

    kCGBlendModeLuminosity, //明度

    /* Available in Mac OS X 10.5 & later.

     The Porter-Duff "source over" mode is called `kCGBlendModeNormal':

     R = S + D*(1 - Sa)

     Note that the Porter-Duff "XOR" mode is only titularly related to the

     classical bitmap XOR operation (which is unsupported by

     CoreGraphics). */

    kCGBlendModeClear,                  /* R = 0 *///清空（如果图标背景色为白色则为全白）

    kCGBlendModeCopy,                   /* R = S *///全色覆盖整个图片

    kCGBlendModeSourceIn,               /* R = S*Da *///线条变色

    kCGBlendModeSourceOut,              /* R = S*(1 - Da) *///背景变为目的色,线条自动变为白色

    kCGBlendModeSourceAtop,             /* R = S*Da + D*(1 - Sa) *///线条变色

    kCGBlendModeDestinationOver,        /* R = S*(1 - Da) + D *///背景色变为目的色，线条色不变

    kCGBlendModeDestinationIn,          /* R = D*Sa *///只看到线条色（本色）

    kCGBlendModeDestinationOut,         /* R = D*(1 - Sa) *///空白

    kCGBlendModeDestinationAtop,        /* R = S*(1 - Da) + D*Sa *///会把整个矩形的背景填充目的色 原色保留

    kCGBlendModeXOR,                    /* R = S*(1 - Da) + D*(1 - Sa) *///线条变白，背景色变为目的色

    kCGBlendModePlusDarker,             /* R = MAX(0, (1 - D) + (1 - S)) *///.线条变为黑色， 背景色变为目的色

    kCGBlendModePlusLighter             /* R = MIN(1, S + D) *///线条变为白色

};

//返回上下文的类型标识符

CG_EXTERN CFTypeID CGContextGetTypeID(void)

CG_AVAILABLE_STARTING(__MAC_10_2, __IPHONE_2_0);

/** Graphics state functions. **/

//压栈之后的修改不会影响之前的修改，如果撤销之后的修改，直接出栈就ok。

//压栈，保存一份当前图形上下文

CG_EXTERN void CGContextSaveGState(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//出栈，恢复一份当前图形上下文

CG_EXTERN void CGContextRestoreGState(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** Coordinate space transformations. **/

//CTM（current transformation matrix当前转换矩阵

//坐标系x和y缩放

CG_EXTERN void CGContextScaleCTM(CGContextRef cg_nullable c,

                                 CGFloat sx, CGFloat sy)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//坐标系平移，改变画布位置

CG_EXTERN void CGContextTranslateCTM(CGContextRef cg_nullable c,

                                     CGFloat tx, CGFloat ty)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//坐标系旋转

CG_EXTERN void CGContextRotateCTM(CGContextRef cg_nullable c, CGFloat angle)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//transform仿射变换矩阵进行图形状态的变换

CG_EXTERN void CGContextConcatCTM(CGContextRef cg_nullable c,

                                  CGAffineTransform transform)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//获取转换矩阵（CTM）

CG_EXTERN CGAffineTransform CGContextGetCTM(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** Drawing attribute functions. **/

//设置线宽

CG_EXTERN void CGContextSetLineWidth(CGContextRef cg_nullable c, CGFloat width)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置线冒样式 枚举

CG_EXTERN void CGContextSetLineCap(CGContextRef cg_nullable c, CGLineCap cap)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置线连接样式

CG_EXTERN void CGContextSetLineJoin(CGContextRef cg_nullable c, CGLineJoin join)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//连接线内外角距离限制

CG_EXTERN void CGContextSetMiterLimit(CGContextRef cg_nullable c, CGFloat limit)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//画虚线

CG_EXTERN void CGContextSetLineDash(CGContextRef cg_nullable c, CGFloat phase,

                                    const CGFloat * __nullable lengths, size_t count)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置渲染精度，数值越小，精度越高，越耗时

CG_EXTERN void CGContextSetFlatness(CGContextRef cg_nullable c, CGFloat flatness)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置透明度

CG_EXTERN void CGContextSetAlpha(CGContextRef cg_nullable c, CGFloat alpha)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//混合图层，后面绘制的图像会覆盖前面的,被覆盖不可见 此方法进行设置叠加状态。

CG_EXTERN void CGContextSetBlendMode(CGContextRef cg_nullable c, CGBlendMode mode)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

/** Path construction functions. **/

/* 注意上下文在任何时候都有一个路径在使用：路径不是图形状态的一部分。 */

//开始新路径，废弃旧的

CG_EXTERN void CGContextBeginPath(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//移动到指定点

CG_EXTERN void CGContextMoveToPoint(CGContextRef cg_nullable c,

                                    CGFloat x, CGFloat y)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//画线到指定点

CG_EXTERN void CGContextAddLineToPoint(CGContextRef cg_nullable c,

                                       CGFloat x, CGFloat y)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//画三次贝塞尔曲线

CG_EXTERN void CGContextAddCurveToPoint(CGContextRef cg_nullable c, CGFloat cp1x,

                                        CGFloat cp1y, CGFloat cp2x, CGFloat cp2y, CGFloat x, CGFloat y)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//绘制二次贝塞尔曲线

CG_EXTERN void CGContextAddQuadCurveToPoint(CGContextRef cg_nullable c,

                                            CGFloat cpx, CGFloat cpy, CGFloat x, CGFloat y)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//关闭路径

CG_EXTERN void CGContextClosePath(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** Path construction convenience functions. **/

//画矩形

CG_EXTERN void CGContextAddRect(CGContextRef cg_nullable c, CGRect rect)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//画矩形数组（多个矩形）

CG_EXTERN void CGContextAddRects(CGContextRef cg_nullable c,

                                 const CGRect * __nullable rects, size_t count)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//画线条数组（多个线条）

CG_EXTERN void CGContextAddLines(CGContextRef cg_nullable c,

                                 const CGPoint * __nullable points, size_t count)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//画椭圆

CG_EXTERN void CGContextAddEllipseInRect(CGContextRef cg_nullable c, CGRect rect)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

//画圆弧 圆心，半径，开始角度，结束角度，是否顺时针

CG_EXTERN void CGContextAddArc(CGContextRef cg_nullable c, CGFloat x, CGFloat y,

                               CGFloat radius, CGFloat startAngle, CGFloat endAngle, int clockwise)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//画圆弧 两点和半径

CG_EXTERN void CGContextAddArcToPoint(CGContextRef cg_nullable c,

                                      CGFloat x1, CGFloat y1, CGFloat x2, CGFloat y2, CGFloat radius)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//添加路径CGPath

CG_EXTERN void CGContextAddPath(CGContextRef cg_nullable c,

                                CGPathRef cg_nullable path)

CG_AVAILABLE_STARTING(__MAC_10_2, __IPHONE_2_0);

/** Path stroking. **/

//将参数CGContextRef的路径直接画在当前上下文上

CG_EXTERN void CGContextReplacePathWithStrokedPath(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

/** Path information functions. **/

//判断路径是否为空，目前的路径是否包含任何的子路径

CG_EXTERN bool CGContextIsPathEmpty(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//返回一个非空的路径中的当前点

CG_EXTERN CGPoint CGContextGetPathCurrentPoint(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//返回包含当前路径的最小矩形

CG_EXTERN CGRect CGContextGetPathBoundingBox(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//拷贝路径

CG_EXTERN CGPathRef __nullable CGContextCopyPath(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_2, __IPHONE_2_0);

//路径中是否包含某个点

CG_EXTERN bool CGContextPathContainsPoint(CGContextRef cg_nullable c,

                                          CGPoint point, CGPathDrawingMode mode)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

/** Path drawing functions. **/

//指定绘制的模式，枚举

CG_EXTERN void CGContextDrawPath(CGContextRef cg_nullable c,

                                 CGPathDrawingMode mode)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** Path drawing convenience functions. **/

//填充路径包围的区域

CG_EXTERN void CGContextFillPath(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//使用奇偶规则填充区域

CG_EXTERN void CGContextEOFillPath(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//绘制路径

CG_EXTERN void CGContextStrokePath(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//填充矩形区域 rect参数

CG_EXTERN void CGContextFillRect(CGContextRef cg_nullable c, CGRect rect)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//填充多个区域

CG_EXTERN void CGContextFillRects(CGContextRef cg_nullable c,

                                  const CGRect * __nullable rects, size_t count)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//绘制矩形框

CG_EXTERN void CGContextStrokeRect(CGContextRef cg_nullable c, CGRect rect)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//指定线宽绘制矩形框

CG_EXTERN void CGContextStrokeRectWithWidth(CGContextRef cg_nullable c,

                                            CGRect rect, CGFloat width)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//擦除绘制的图形

CG_EXTERN void CGContextClearRect(CGContextRef cg_nullable c, CGRect rect)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//填充矩形内切圆

CG_EXTERN void CGContextFillEllipseInRect(CGContextRef cg_nullable c,

                                          CGRect rect)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

//绘制矩形内切圆

CG_EXTERN void CGContextStrokeEllipseInRect(CGContextRef cg_nullable c,

                                            CGRect rect)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

/*绘制多条线段，2N个CGPoint数组，1，2组成线段 以此类推

 CGContextBeginPath(context);

 for (k = 0; k < count; k += 2) {

 CGContextMoveToPoint(context, s[k].x, s[k].y);

 CGContextAddLineToPoint(context, s[k+1].x, s[k+1].y);

 }

 CGContextStrokePath(context); */

CG_EXTERN void CGContextStrokeLineSegments(CGContextRef cg_nullable c,

                                           const CGPoint * __nullable points, size_t count)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

/** Clipping functions. **/

//修改当前剪切路径，使用非零规则

CG_EXTERN void CGContextClip(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//修改当前剪切路径，使用奇偶规则

CG_EXTERN void CGContextEOClip(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//默认值剪切路径

CG_EXTERN void CGContextResetClip(CGContextRef c);

//剪切遮罩处理（针对图片）

CG_EXTERN void CGContextClipToMask(CGContextRef cg_nullable c, CGRect rect,

                                   CGImageRef cg_nullable mask)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

//获取需要绘制的图形上下文位置和大小

CG_EXTERN CGRect CGContextGetClipBoundingBox(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_3, __IPHONE_2_0);

/** Clipping convenience functions. **/

//剪切指定矩形区域，将路径置空

CG_EXTERN void CGContextClipToRect(CGContextRef cg_nullable c, CGRect rect)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//剪切多个矩形区域，路径置空

CG_EXTERN void CGContextClipToRects(CGContextRef cg_nullable c,

                                    const CGRect *  rects, size_t count)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** Primitive color functions. **/

//填充指定颜色

CG_EXTERN void CGContextSetFillColorWithColor(CGContextRef cg_nullable c,

                                              CGColorRef cg_nullable color)

CG_AVAILABLE_STARTING(__MAC_10_3, __IPHONE_2_0);

//设置线条指定颜色

CG_EXTERN void CGContextSetStrokeColorWithColor(CGContextRef cg_nullable c,

                                                CGColorRef cg_nullable color)

CG_AVAILABLE_STARTING(__MAC_10_3, __IPHONE_2_0);

/** Color space functions. **/

//颜色空间填充

CG_EXTERN void CGContextSetFillColorSpace(CGContextRef cg_nullable c,

                                          CGColorSpaceRef cg_nullable space)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置线框颜色空间

CG_EXTERN void CGContextSetStrokeColorSpace(CGContextRef cg_nullable c,

                                            CGColorSpaceRef cg_nullable space)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** Color functions. **/

//设置填充颜色空间

CG_EXTERN void CGContextSetFillColor(CGContextRef cg_nullable c,

                                     const CGFloat * cg_nullable components)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置画笔颜色

CG_EXTERN void CGContextSetStrokeColor(CGContextRef cg_nullable c,

                                       const CGFloat * cg_nullable components)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** Pattern functions. **/

//设置位图填充

CG_EXTERN void CGContextSetFillPattern(CGContextRef cg_nullable c,

                                       CGPatternRef cg_nullable pattern, const CGFloat * cg_nullable components)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//位图绘制线条和边框

CG_EXTERN void CGContextSetStrokePattern(CGContextRef cg_nullable c,

                                         CGPatternRef cg_nullable pattern, const CGFloat * cg_nullable components)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置该c采用位图填充的相位

CG_EXTERN void CGContextSetPatternPhase(CGContextRef cg_nullable c, CGSize phase)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** Color convenience functions. **/

//设置c的填充颜色为灰色 灰度和透明度

CG_EXTERN void CGContextSetGrayFillColor(CGContextRef cg_nullable c,

                                         CGFloat gray, CGFloat alpha)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置c的线条颜色为灰色 灰度和透明度

CG_EXTERN void CGContextSetGrayStrokeColor(CGContextRef cg_nullable c,

                                           CGFloat gray, CGFloat alpha)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置c的填充色 使用RGB颜色模块

CG_EXTERN void CGContextSetRGBFillColor(CGContextRef cg_nullable c, CGFloat red,

                                        CGFloat green, CGFloat blue, CGFloat alpha)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置c的线条颜色 使用RGB颜色模块

CG_EXTERN void CGContextSetRGBStrokeColor(CGContextRef cg_nullable c,

                                          CGFloat red, CGFloat green, CGFloat blue, CGFloat alpha)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置c的填充颜色 使用CMYK颜色模块

CG_EXTERN void CGContextSetCMYKFillColor(CGContextRef cg_nullable c,

                                         CGFloat cyan, CGFloat magenta, CGFloat yellow, CGFloat black, CGFloat alpha)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置c的线条颜色 使用CMYK颜色模块

CG_EXTERN void CGContextSetCMYKStrokeColor(CGContextRef cg_nullable c,

                                           CGFloat cyan, CGFloat magenta, CGFloat yellow, CGFloat black, CGFloat alpha)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** Rendering intent. **/

/*设置当前图形状态的渲染意向

typedef CF_ENUM (int32_t, CGColorRenderingIntent) {

    kCGRenderingIntentDefault,

    kCGRenderingIntentAbsoluteColorimetric, //绝对色阶匹配

    kCGRenderingIntentRelativeColorimetric, //相对色阶匹配

    kCGRenderingIntentPerceptual,   //视觉匹配，不同设备视觉一致

    kCGRenderingIntentSaturation    //饱和度匹配

};*/

CG_EXTERN void CGContextSetRenderingIntent(CGContextRef cg_nullable c,

                                           CGColorRenderingIntent intent)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** Image functions. **/

//绘制图形到c

CG_EXTERN void CGContextDrawImage(CGContextRef cg_nullable c, CGRect rect,

                                  CGImageRef cg_nullable image)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//重复绘制的图形，填充当前区域

CG_EXTERN void CGContextDrawTiledImage(CGContextRef cg_nullable c, CGRect rect,

                                       CGImageRef cg_nullable image)

CG_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

//获取c在放大图片时的插值质量

CG_EXTERN CGInterpolationQuality

CGContextGetInterpolationQuality(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置c的插值质量水平

CG_EXTERN void CGContextSetInterpolationQuality(CGContextRef cg_nullable c,

                                                CGInterpolationQuality quality)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** Shadow support. **/

//设置阴影在X、Y方向上的偏移。模糊度、阴影颜色

CG_EXTERN void CGContextSetShadowWithColor(CGContextRef cg_nullable c,

                                           CGSize offset, CGFloat blur, CGColorRef __nullable color)

CG_AVAILABLE_STARTING(__MAC_10_3, __IPHONE_2_0);

//设置阴影在X、Y方向上的偏移。模糊度（数字越大越模糊）、阴影颜色默认为1/3透明黑

CG_EXTERN void CGContextSetShadow(CGContextRef cg_nullable c, CGSize offset,

                                  CGFloat blur)

CG_AVAILABLE_STARTING(__MAC_10_3, __IPHONE_2_0);

/** Gradient and shading functions. **/

//设置一个线性渐变填充 开始点和结束点

CG_EXTERN void CGContextDrawLinearGradient(CGContextRef cg_nullable c,

                                           CGGradientRef cg_nullable gradient, CGPoint startPoint, CGPoint endPoint,

                                           CGGradientDrawingOptions options)

CG_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

//设置一个圆形渐变填充 开始点和结束点

CG_EXTERN void CGContextDrawRadialGradient(CGContextRef cg_nullable c,

                                           CGGradientRef cg_nullable gradient, CGPoint startCenter, CGFloat startRadius,

                                           CGPoint endCenter, CGFloat endRadius, CGGradientDrawingOptions options)

CG_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

//填充剪切路径 用指定的阴影背景

CG_EXTERN void CGContextDrawShading(CGContextRef cg_nullable c,

                                    cg_nullable CGShadingRef shading)

CG_AVAILABLE_STARTING(__MAC_10_2, __IPHONE_2_0);

/** Text functions. **/

//设置当前字符间距

CG_EXTERN void CGContextSetCharacterSpacing(CGContextRef cg_nullable c,

                                            CGFloat spacing)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置绘制文本的位置

CG_EXTERN void CGContextSetTextPosition(CGContextRef cg_nullable c,

                                        CGFloat x, CGFloat y)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//返回正在绘制文本的位置

CG_EXTERN CGPoint CGContextGetTextPosition(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置当前文本矩阵

CG_EXTERN void CGContextSetTextMatrix(CGContextRef cg_nullable c,

                                      CGAffineTransform t)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//返回c矩阵

CG_EXTERN CGAffineTransform CGContextGetTextMatrix(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置c的绘图模式

CG_EXTERN void CGContextSetTextDrawingMode(CGContextRef cg_nullable c,

                                           CGTextDrawingMode mode)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置c的字体

CG_EXTERN void CGContextSetFont(CGContextRef cg_nullable c,

                                CGFontRef cg_nullable font)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置c的字体大小

CG_EXTERN void CGContextSetFontSize(CGContextRef cg_nullable c, CGFloat size)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//在提供的位置绘制字形

CG_EXTERN void CGContextShowGlyphsAtPositions(CGContextRef cg_nullable c,

                                              const CGGlyph * cg_nullable glyphs, const CGPoint * cg_nullable Lpositions,

                                              size_t count)

CG_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

/** PDF functions. **/

//绘制一个PDF页面

CG_EXTERN void CGContextDrawPDFPage(CGContextRef cg_nullable c,

                                    CGPDFPageRef cg_nullable page)

CG_AVAILABLE_STARTING(__MAC_10_3, __IPHONE_2_0);

/** Output page functions. **/

/* Begin a new page. */

CG_EXTERN void CGContextBeginPage(CGContextRef cg_nullable c,

                                  const CGRect * __nullable mediaBox)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/* End the current page. */

CG_EXTERN void CGContextEndPage(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** Context functions. **/

//c的引用计数+1

CG_EXTERN CGContextRef cg_nullable CGContextRetain(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//c的引用计数-1

CG_EXTERN void CGContextRelease(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//强制所有绘图操作立即渲染

CG_EXTERN void CGContextFlush(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//同步内容

CG_EXTERN void CGContextSynchronize(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** Antialiasing functions. **/

//字体平滑，反锯齿,和次像素渲染

//设置c是否抗锯齿

CG_EXTERN void CGContextSetShouldAntialias(CGContextRef cg_nullable c,

                                           bool shouldAntialias)

CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

//设置c是否允许抗锯齿

CG_EXTERN void CGContextSetAllowsAntialiasing(CGContextRef cg_nullable c,

                                              bool allowsAntialiasing)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

/** Font display functions. **/

//设置c是否光滑字体

CG_EXTERN void CGContextSetShouldSmoothFonts(CGContextRef cg_nullable c,

                                             bool shouldSmoothFonts)

CG_AVAILABLE_STARTING(__MAC_10_2, __IPHONE_2_0);

//设置c是否允许光滑字体

CG_EXTERN void CGContextSetAllowsFontSmoothing(CGContextRef cg_nullable c,

                                               bool allowsFontSmoothing)

CG_AVAILABLE_STARTING(__MAC_10_2, __IPHONE_2_0);

//设置c是否次像素渲染字体

CG_EXTERN void CGContextSetShouldSubpixelPositionFonts(

                                                       CGContextRef cg_nullable c, bool shouldSubpixelPositionFonts)

CG_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

//设置c是否次允许像素渲染字体

CG_EXTERN void CGContextSetAllowsFontSubpixelPositioning(

                                                         CGContextRef cg_nullable c, bool allowsFontSubpixelPositioning)

CG_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

//设置c是否次像素量化字体

CG_EXTERN void CGContextSetShouldSubpixelQuantizeFonts(

                                                       CGContextRef cg_nullable c, bool shouldSubpixelQuantizeFonts)

CG_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

//设置c是否允许次像素量化字体

CG_EXTERN void CGContextSetAllowsFontSubpixelQuantization(

                                                          CGContextRef cg_nullable c, bool allowsFontSubpixelQuantization)

CG_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

/* Transparency layer support.

 在透明层中绘制需要三步：

 1.  调用函数 CGContextBeginTransparencyLayer

 2.  在透明层中绘制需要组合的对象

 3.  调用函数 CGContextEndTransparencyLayer

*/

//开始一个透明层

CG_EXTERN void CGContextBeginTransparencyLayer(CGContextRef cg_nullable c,

                                               CFDictionaryRef __nullable auxiliaryInfo)

CG_AVAILABLE_STARTING(__MAC_10_3, __IPHONE_2_0);

//开始透明度层 知道矩形边界

CG_EXTERN void CGContextBeginTransparencyLayerWithRect(

                                                       CGContextRef cg_nullable c, CGRect rect, CFDictionaryRef __nullable auxInfo)

CG_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

//结束一个透明层

CG_EXTERN void CGContextEndTransparencyLayer(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_3, __IPHONE_2_0);

/** User space to device space tranformations.

 用户空间和设备空间的变换

 **/

//获取c的仿射变换

CG_EXTERN CGAffineTransform

CGContextGetUserSpaceToDeviceSpaceTransform(CGContextRef cg_nullable c)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

//将point从 用户空间 变换到 设备空间

CG_EXTERN CGPoint CGContextConvertPointToDeviceSpace(CGContextRef cg_nullable c,

                                                     CGPoint point)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

//将point从 设备空间 变换到 用户空间

CG_EXTERN CGPoint CGContextConvertPointToUserSpace(CGContextRef cg_nullable c,

                                                   CGPoint point)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

//将size从 用户空间 变换到 设备空间

CG_EXTERN CGSize CGContextConvertSizeToDeviceSpace(CGContextRef cg_nullable c,

                                                   CGSize size)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

//将size从 设备空间 变换到 用户空间

CG_EXTERN CGSize CGContextConvertSizeToUserSpace(CGContextRef cg_nullable c,

                                                 CGSize size)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

//将rect从 用户空间 变换到 设备空间

CG_EXTERN CGRect CGContextConvertRectToDeviceSpace(CGContextRef cg_nullable c,

                                                   CGRect rect)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

//将rect从 设备空间 变换到 用户空间

CG_EXTERN CGRect CGContextConvertRectToUserSpace(CGContextRef cg_nullable c,

                                                 CGRect rect)

CG_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_2_0);

/** Deprecated functions. **/

//设置c的字体和字体大小

CG_EXTERN void CGContextSelectFont(CGContextRef cg_nullable c,

                                   const char * cg_nullable name, CGFloat size, CGTextEncoding textEncoding)

CG_AVAILABLE_BUT_DEPRECATED(__MAC_10_0, __MAC_10_9,

                            __IPHONE_2_0, __IPHONE_7_0);

//由目前的文本矩阵指定的点显示一个字符数组

CG_EXTERN void CGContextShowText(CGContextRef cg_nullable c,

                                 const char * cg_nullable string, size_t length)

CG_AVAILABLE_BUT_DEPRECATED(__MAC_10_0, __MAC_10_9,

                            __IPHONE_2_0, __IPHONE_7_0);

//在指定的位置显示一个字符串

CG_EXTERN void CGContextShowTextAtPoint(CGContextRef cg_nullable c,

                                        CGFloat x, CGFloat y, const char * cg_nullable string, size_t length)

CG_AVAILABLE_BUT_DEPRECATED(__MAC_10_0, __MAC_10_9,

                            __IPHONE_2_0, __IPHONE_7_0);

//显示一个数组的字形

CG_EXTERN void CGContextShowGlyphs(CGContextRef cg_nullable c,

                                   const CGGlyph * __nullable g, size_t count)

CG_AVAILABLE_BUT_DEPRECATED(__MAC_10_0, __MAC_10_9,

                            __IPHONE_2_0, __IPHONE_7_0);

//在指定位置显示一个数组的字形

CG_EXTERN void CGContextShowGlyphsAtPoint(CGContextRef cg_nullable c, CGFloat x,

                                          CGFloat y, const CGGlyph * __nullable glyphs, size_t count)

CG_AVAILABLE_BUT_DEPRECATED(__MAC_10_0, __MAC_10_9,

                            __IPHONE_2_0, __IPHONE_7_0);

//绘制具有不同偏移量的一个数组

CG_EXTERN void CGContextShowGlyphsWithAdvances(CGContextRef cg_nullable c,

                                               const CGGlyph * __nullable glyphs, const CGSize * __nullable advances,

                                               size_t count)

CG_AVAILABLE_BUT_DEPRECATED(__MAC_10_3, __MAC_10_9,

                            __IPHONE_2_0, __IPHONE_7_0);

//使用CGPDFDocumentRef绘制PDF

CG_EXTERN void CGContextDrawPDFDocument(CGContextRef cg_nullable c, CGRect rect,

                                        CGPDFDocumentRef cg_nullable document, int page)

CG_AVAILABLE_BUT_DEPRECATED(__MAC_10_0, __MAC_10_5,

                            __IPHONE_NA, __IPHONE_NA);

CF_ASSUME_NONNULL_END

CF_IMPLICIT_BRIDGING_DISABLED

#endif /* CGCONTEXT_H_ */
巴特西

iOS之CGcontext.h方法和属性简介

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