UIGraphics.h

#import <Foundation/Foundation.h>
#import <CoreGraphics/CoreGraphics.h>
#import <UIKit/UIKitDefines.h>

@class UIImage;

UIKIT_EXTERN CGContextRef UIGraphicsGetCurrentContext(void);   // 获得当前的图形上下文

UIKIT_EXTERN void UIGraphicsPushContext(CGContextRef context);
UIKIT_EXTERN void UIGraphicsPopContext(void);

UIKIT_EXTERN void UIRectFillUsingBlendMode(CGRect rect, CGBlendMode blendMode);
UIKIT_EXTERN void UIRectFill(CGRect rect);

UIKIT_EXTERN void UIRectFrameUsingBlendMode(CGRect rect, CGBlendMode blendMode);
UIKIT_EXTERN void UIRectFrame(CGRect rect);

UIKIT_EXTERN void UIRectClip(CGRect rect);

#pragma - mark 这个方法生成的图片没有下面的清晰
UIKIT_EXTERN void     UIGraphicsBeginImageContext(CGSize size);
/**
 *  @param size         图片尺寸，使用像素
 *  @param opaque       不透明度，使用NO图片更清晰
 *  @param scale        伸缩尺寸 0.0则是根据屏幕尺寸进行伸缩
 */
UIKIT_EXTERN void     UIGraphicsBeginImageContextWithOptions(CGSize size, BOOL opaque, CGFloat scale) NS_AVAILABLE_IOS(4_0);
#pragma - mark 获取上下文中绘制的图片
UIKIT_EXTERN UIImage* UIGraphicsGetImageFromCurrentImageContext(void);
#pragma - mark 结束绘制图片
UIKIT_EXTERN void     UIGraphicsEndImageContext(void); 

#pragma - mark PDF
UIKIT_EXTERN BOOL UIGraphicsBeginPDFContextToFile(NSString *path, CGRect bounds, NSDictionary *documentInfo) NS_AVAILABLE_IOS(3_2);
UIKIT_EXTERN void UIGraphicsBeginPDFContextToData(NSMutableData *data, CGRect bounds, NSDictionary *documentInfo) NS_AVAILABLE_IOS(3_2);
UIKIT_EXTERN void UIGraphicsEndPDFContext(void) NS_AVAILABLE_IOS(3_2);

UIKIT_EXTERN void UIGraphicsBeginPDFPage(void) NS_AVAILABLE_IOS(3_2);
UIKIT_EXTERN void UIGraphicsBeginPDFPageWithInfo(CGRect bounds, NSDictionary *pageInfo) NS_AVAILABLE_IOS(3_2);

UIKIT_EXTERN CGRect UIGraphicsGetPDFContextBounds(void) NS_AVAILABLE_IOS(3_2);

UIKIT_EXTERN void UIGraphicsSetPDFContextURLForRect(NSURL *url, CGRect rect) NS_AVAILABLE_IOS(3_2);
UIKIT_EXTERN void UIGraphicsAddPDFContextDestinationAtPoint(NSString *name, CGPoint point) NS_AVAILABLE_IOS(3_2);
UIKIT_EXTERN void UIGraphicsSetPDFContextDestinationForRect(NSString *name, CGRect rect) NS_AVAILABLE_IOS(3_2);