iOS开发CGImage.h简介

1、前因

　　由于剪切图片用到下面方法，此方法属于CGImage.h中，通过创建CGImageRef像素位图，可以通过操作存储的像素位来编辑图片。

/* Create an image using the data contained within the subrectangle `rect'
 of `image'.
 截取图像的一个区域重绘图像*/
CG_EXTERN CGImageRef __nullable CGImageCreateWithImageInRect(
                                                             CGImageRef cg_nullable image, CGRect rect)

　　效果图展示：

　　代码展示：

    UIImage *bgImage =[UIImage imageNamed:@"1111"];

    // 上半部
    UIImageView *topImgView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 140, CScreenWidth, (CScreenHeight-140) * 0.5)];
    topImgView.image = [self clipImage:bgImage withRect:CGRectMake(0, 0, imageW, imageH)];
    
    // 下半部
    UIImageView *bottomImgView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 140+(CScreenHeight-140) * 0.5, CScreenWidth, (CScreenHeight-140) * 0.5)];
    bottomImgView.image = [self clipImage:bgImage withRect:CGRectMake(0, imageH, imageW, imageH)];
    [self.view addSubview:topImgView];
    [self.view addSubview:bottomImgView];

    CGAffineTransform transform = CGAffineTransformIdentity;
    transform =CGAffineTransformScale(transform, .5, .5);
    [UIView animateWithDuration:2.0f animations:^{
        CGRect topRect = topImgView.frame;
        topRect.origin.x -= CScreenWidth;
        topImgView.frame = topRect;
        topImgView.transform = transform;
        
        CGRect bottomRect = bottomImgView.frame;
        bottomRect.origin.x += CScreenWidth;
        bottomImgView.frame = bottomRect;
        bottomImgView.transform = transform;
    } completion:^(BOOL finished) {
        [topImgView removeFromSuperview];
        [bottomImgView removeFromSuperview];
    }];

- (UIImage *)clipImage:(UIImage *)image withRect:(CGRect)rect {
    CGRect clipFrame = rect;
    CGImageRef refImage = CGImageCreateWithImageInRect(image.CGImage, clipFrame);
    UIImage *newImage = [UIImage imageWithCGImage:refImage];
    CGImageRelease(refImage);
    return newImage;
}

2、CGImage.h文件方法简介

typedef CF_ENUM(uint32_t, CGImageAlphaInfo) {
    kCGImageAlphaNone,               /* For example, RGB. */
    kCGImageAlphaPremultipliedLast,  /* For example, premultiplied RGBA */
    kCGImageAlphaPremultipliedFirst, /* For example, premultiplied ARGB */
    kCGImageAlphaLast,               /* For example, non-premultiplied RGBA */
    kCGImageAlphaFirst,              /* For example, non-premultiplied ARGB */
    kCGImageAlphaNoneSkipLast,       /* For example, RBGX. */
    kCGImageAlphaNoneSkipFirst,      /* For example, XRGB. */
    kCGImageAlphaOnly                /* No color data, alpha data only */
};

typedef CF_ENUM(uint32_t, CGImageByteOrderInfo) {
    kCGImageByteOrderMask     = 0x7000,
    kCGImageByteOrderDefault  = (0 << 12),
    kCGImageByteOrder16Little = (1 << 12),
    kCGImageByteOrder32Little = (2 << 12),
    kCGImageByteOrder16Big    = (3 << 12),
    kCGImageByteOrder32Big    = (4 << 12)
} CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

typedef CF_OPTIONS(uint32_t, CGBitmapInfo) {
    kCGBitmapAlphaInfoMask = 0x1F,
    
    kCGBitmapFloatInfoMask = 0xF00,
    kCGBitmapFloatComponents = (1 << 8),
    
    kCGBitmapByteOrderMask     = kCGImageByteOrderMask,
    kCGBitmapByteOrderDefault  = kCGImageByteOrderDefault,
    kCGBitmapByteOrder16Little = kCGImageByteOrder16Little,
    kCGBitmapByteOrder32Little = kCGImageByteOrder32Little,
    kCGBitmapByteOrder16Big    = kCGImageByteOrder16Big,
    kCGBitmapByteOrder32Big    = kCGImageByteOrder32Big
} CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

#ifdef __BIG_ENDIAN__
# define kCGBitmapByteOrder16Host kCGBitmapByteOrder16Big
# define kCGBitmapByteOrder32Host kCGBitmapByteOrder32Big
#else    /* Little endian. */
# define kCGBitmapByteOrder16Host kCGBitmapByteOrder16Little
# define kCGBitmapByteOrder32Host kCGBitmapByteOrder32Little
#endif

/* Return the CFTypeID for CGImageRefs. */
CG_EXTERN CFTypeID CGImageGetTypeID(void)

/* Create an image.
 width：图片宽度像素
 height：图片高度像素
 bitsPerComponent：每个颜色的比特数，例如在rgba-32模式下为8
 bitsPerPixel：每个像素的总比特数
 bytesPerRow：每一行占用的字节数，注意这里的单位是字节
 space：颜色空间模式，例如const CFStringRef kCGColorSpaceGenericRGB 这个函数可以返回一个颜色空间对象。
 bitmapInfo：位图像素布局
 provider：数据源提供者
 decode[]：解码渲染数组
 shouldInterpolate：是否抗锯齿
 intent：图片相关参数*/
CG_EXTERN CGImageRef __nullable CGImageCreate(size_t width, size_t height,
                                              size_t bitsPerComponent, size_t bitsPerPixel, size_t bytesPerRow,
                                              CGColorSpaceRef cg_nullable space, CGBitmapInfo bitmapInfo,
                                              CGDataProviderRef cg_nullable provider,
                                              const CGFloat * __nullable decode, bool shouldInterpolate,
                                              CGColorRenderingIntent intent)

/* Create an image mask.
 创建mask图片图层，可以设置其显示部分与不显示部分达到特殊的效果*/
CG_EXTERN CGImageRef __nullable CGImageMaskCreate(size_t width, size_t height,
                                                  size_t bitsPerComponent, size_t bitsPerPixel, size_t bytesPerRow,
                                                  CGDataProviderRef cg_nullable provider, const CGFloat * __nullable decode,
                                                  bool shouldInterpolate)

/* Return a copy of `image'. Only the image structure itself is copied; the
 underlying data is not.
 复制一个CGImageRef对象*/
CG_EXTERN CGImageRef __nullable CGImageCreateCopy(CGImageRef cg_nullable image)

/* Create an image from `source', a data provider of JPEG-encoded data.
通过JPEG数据源获取图像 */
CG_EXTERN CGImageRef __nullable CGImageCreateWithJPEGDataProvider(
                                                                  CGDataProviderRef cg_nullable source, const CGFloat * __nullable decode,
                                                                  bool shouldInterpolate,
                                                                  CGColorRenderingIntent intent)

/* Create an image using `source', a data provider for PNG-encoded data.
通过PNG数据源获取图像 */
CG_EXTERN CGImageRef __nullable CGImageCreateWithPNGDataProvider(
                                                                 CGDataProviderRef cg_nullable source, const CGFloat * __nullable decode,
                                                                 bool shouldInterpolate,
                                                                 CGColorRenderingIntent intent)

/* Create an image using the data contained within the subrectangle `rect'
 of `image'.
 截取图像的一个区域重绘图像*/
CG_EXTERN CGImageRef __nullable CGImageCreateWithImageInRect(
                                                             CGImageRef cg_nullable image, CGRect rect)

/* Create a new image from `image' masked by `mask', which may be an image
 mask or an image.
截取mask图像的某个区域重绘图像 */
CG_EXTERN CGImageRef __nullable CGImageCreateWithMask(
                                                      CGImageRef cg_nullable image, CGImageRef cg_nullable mask)

/* Create a new image from `image' masked by `components'
 通过颜色分量数组创建位图*/
CG_EXTERN CGImageRef __nullable CGImageCreateWithMaskingColors(
                                                               CGImageRef cg_nullable image, const CGFloat * cg_nullable components)

/* Create a copy of `image', replacing the image's color space with `space'.
 Returns NULL if `image' is an image mask, or if the number of components
 of `space' isn't the same as the number of components of the color space
 of `image'.
 通过颜色空间模式复制位图*/
CG_EXTERN CGImageRef __nullable CGImageCreateCopyWithColorSpace(
                                                                CGImageRef cg_nullable image, CGColorSpaceRef cg_nullable space)

/* Equivalent to `CFRetain(image)'.
 引用计数+1*/
CG_EXTERN CGImageRef cg_nullable CGImageRetain(CGImageRef cg_nullable image)

/* Equivalent to `CFRelease(image)'.
 引用计数-1*/
CG_EXTERN void CGImageRelease(CGImageRef cg_nullable image)

/* Return true if `image' is an image mask, false otherwise.
是否是mask图层 */
CG_EXTERN bool CGImageIsMask(CGImageRef cg_nullable image)

/* Return the width of `image'.
 获取图像宽度像素*/
CG_EXTERN size_t CGImageGetWidth(CGImageRef cg_nullable image)

/* Return the height of `image'.
 获取图像的高度像素*/
CG_EXTERN size_t CGImageGetHeight(CGImageRef cg_nullable image)

//获取图像相应属性
/* Return the number of bits/component of `image'. */
CG_EXTERN size_t CGImageGetBitsPerComponent(CGImageRef cg_nullable image)
/* Return the number of bits/pixel of `image'. */
CG_EXTERN size_t CGImageGetBitsPerPixel(CGImageRef cg_nullable image)
/* Return the number of bytes/row of `image'. */
CG_EXTERN size_t CGImageGetBytesPerRow(CGImageRef cg_nullable image)
/* Return the color space of `image', or NULL if `image' is an image
 mask. */
CG_EXTERN CGColorSpaceRef __nullable CGImageGetColorSpace(CGImageRef cg_nullable image)
/* Return the alpha info of `image'. */
CG_EXTERN CGImageAlphaInfo CGImageGetAlphaInfo(CGImageRef cg_nullable image)
/* Return the data provider of `image'. */
CG_EXTERN CGDataProviderRef __nullable CGImageGetDataProvider(CGImageRef cg_nullable image)
/* Return the decode array of `image'. */
CG_EXTERN const CGFloat * __nullable CGImageGetDecode(CGImageRef cg_nullable image)
/* Return the interpolation parameter of `image'. */
CG_EXTERN bool CGImageGetShouldInterpolate(CGImageRef cg_nullable image)
/* Return the rendering intent of `image'. */
CG_EXTERN CGColorRenderingIntent CGImageGetRenderingIntent(cg_nullable CGImageRef image)
/* Return the bitmap info of `image'. */
CG_EXTERN CGBitmapInfo CGImageGetBitmapInfo(CGImageRef cg_nullable image)
/* Return the UTType of `image'. */
CG_EXTERN CFStringRef  __nullable CGImageGetUTType(cg_nullable CGImageRef image)