Quartz 2D 简单应用【打水印】&&【图片裁剪】&&【屏幕截图】

打水印

一、代码实现

    UIImage *bgImage = [UIImage imageNamed:@"scene"];    // 上小文 : 基于位图(bitmap) ,  所有的东西需要绘制到一张新的图片上去    // 1.创建一个基于位图的上下文(开启一个基于位图的上下文)    // size : 新图片的尺寸    // opaque : YES : 不透明,  NO : 透明    // 这行代码过后.就相当于常见一张新的bitmap,也就是新的UIImage对象    UIGraphicsBeginImageContextWithOptions(bgImage.size, NO, 0.0);    // 2.画背景    [bgImage drawInRect:CGRectMake(0, 0, bgImage.size.width, bgImage.size.height)];    // 3.画右下角的水印    UIImage *waterImage = [UIImage imageNamed:@"logo"];    CGFloat scale = 0.2;    CGFloat margin = 5;    CGFloat waterW = waterImage.size.width * scale;    CGFloat waterH = waterImage.size.height * scale;    CGFloat waterX = bgImage.size.width - waterW - margin;    CGFloat waterY = bgImage.size.height - waterH - margin;    [waterImage drawInRect:CGRectMake(waterX, waterY, waterW, waterH)];    // 4.从上下文中取得制作完毕的UIImage对象    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    // 5.结束上下文    UIGraphicsEndImageContext();    // 6.显示到UIImageView    self.iconView.image = newImage;    // 7.将image对象压缩为PNG格式的二进制数据    NSData *data = UIImagePNGRepresentation(newImage);    //    UIImageJPEGRepresentation(<#UIImage *image#>, <#CGFloat compressionQuality#>)    // 8.写入文件    NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"new.png"];    [data writeToFile:path atomically:YES];

二、创建一个分类

我们可以创建一个分类把上面的代码封装起来，以后的项目中如果用到打水印的功能可以直接拿过来用

//  UIImage+WaterImage.h#import <UIKit/UIKit.h>@interface UIImage (WaterImage)/** *  打水印 * *  @param bg   背景图片 *  @param logo 右下角的水印图片 */+ (instancetype)waterImageWithBg:(NSString *)bg logo:(NSString *)logo;@end

//  UIImage+WaterImage.m#import "UIImage+WaterImage.h"@implementation UIImage (WaterImage)+ (instancetype)waterImageWithBg:(NSString *)bg logo:(NSString *)logo{    UIImage *bgImage = [UIImage imageNamed:bg];    // 1.创建一个基于位图的上下文(开启一个基于位图的上下文)    UIGraphicsBeginImageContextWithOptions(bgImage.size, NO, 0.0);    // 2.画背景    [bgImage drawInRect:CGRectMake(0, 0, bgImage.size.width, bgImage.size.height)];    // 3.画右下角的水印    UIImage *waterImage = [UIImage imageNamed:logo];    CGFloat scale = 0.2;    CGFloat margin = 5;    CGFloat waterW = waterImage.size.width * scale;    CGFloat waterH = waterImage.size.height * scale;    CGFloat waterX = bgImage.size.width - waterW - margin;    CGFloat waterY = bgImage.size.height - waterH - margin;    [waterImage drawInRect:CGRectMake(waterX, waterY, waterW, waterH)];    // 4.从上下文中取得制作完毕的UIImage对象    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    // 5.结束上下文    UIGraphicsEndImageContext();    return newImage;}@end

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图片裁剪

一、代码实现

直接裁剪

    // 1.加载原图    UIImage *oldImage = [UIImage imageNamed:@"XXX"];    // 2.开启上下文    UIGraphicsBeginImageContextWithOptions(oldImage.size, NO, 0.0);    // 3.取得当前的上下文    CGContextRef ctx = UIGraphicsGetCurrentContext();    // 4.画圆    CGRect circleRect = CGRectMake(0, 0, oldImage.size.width, oldImage.size.height);    CGContextAddEllipseInRect(ctx, circleRect);    // 5.按照当前的路径形状(圆形)裁剪, 超出这个形状以外的内容都不显示    CGContextClip(ctx);    // 6.画图    [oldImage drawInRect:circleRect];    // 7.取图    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    // 8.结束    UIGraphicsEndImageContext();    // 9.写出文件    NSData *data = UIImagePNGRepresentation(newImage);    NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"new.png"];    [data writeToFile:path atomically:YES];    // 10.显示图片    self.iconView.image = newImage;

裁剪完的图片上加一个小圆环

// 1.加载原图    UIImage *oldImage = [UIImage imageNamed:@"XXX"];    // 2.开启上下文    CGFloat borderW = 2; // 圆环的宽度    CGFloat imageW = oldImage.size.width + 2 * borderW;    CGFloat imageH = oldImage.size.height + 2 * borderW;    CGSize imageSize = CGSizeMake(imageW, imageH);    UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);    // 3.取得当前的上下文    CGContextRef ctx = UIGraphicsGetCurrentContext();    // 4.画边框(大圆)    [[UIColor whiteColor] set];    CGFloat bigRadius = imageW * 0.5; // 大圆半径    CGFloat centerX = bigRadius; // 圆心    CGFloat centerY = bigRadius;    CGContextAddArc(ctx, centerX, centerY, bigRadius, 0, M_PI * 2, 0);    CGContextFillPath(ctx); // 画圆    // 5.小圆    CGFloat smallRadius = bigRadius - borderW;    CGContextAddArc(ctx, centerX, centerY, smallRadius, 0, M_PI * 2, 0);    // 裁剪(后面画的东西才会受裁剪的影响)    CGContextClip(ctx);    // 6.画图    [oldImage drawInRect:CGRectMake(borderW, borderW, oldImage.size.width, oldImage.size.height)];    // 7.取图    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    // 8.结束上下文    UIGraphicsEndImageContext();    // 9.显示图片    self.iconView.image = newImage;    // 10.写出文件    NSData *data = UIImagePNGRepresentation(newImage);    NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"new.png"];    [data writeToFile:path atomically:YES];

二、创建一个分类

创建一个UIImage+ClipCircleImage的分类，把上面的代码封装起来，方便以后调用

//  UIImage+ClipCircleImage.h#import <UIKit/UIKit.h>@interface UIImage (ClipCircleImage)+ (instancetype)circleImageWithName:(NSString *)name borderWidth:(CGFloat)borderWidth borderColor:(UIColor *)borderColor;@end

//  UIImage+ClipCircleImage.m#import "UIImage+ClipCircleImage.h"@implementation UIImage (ClipCircleImage)+ (instancetype)circleImageWithName:(NSString *)name borderWidth:(CGFloat)borderWidth borderColor:(UIColor *)borderColor{    // 1.加载原图    UIImage *oldImage = [UIImage imageNamed:name];    // 2.开启上下文    CGFloat imageW = oldImage.size.width + 2 * borderWidth;    CGFloat imageH = oldImage.size.height + 2 * borderWidth;    CGSize imageSize = CGSizeMake(imageW, imageH);    UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);    // 3.取得当前的上下文    CGContextRef ctx = UIGraphicsGetCurrentContext();    // 4.画边框(大圆)    [borderColor set];    CGFloat bigRadius = imageW * 0.5; // 大圆半径    CGFloat centerX = bigRadius; // 圆心    CGFloat centerY = bigRadius;    CGContextAddArc(ctx, centerX, centerY, bigRadius, 0, M_PI * 2, 0);    CGContextFillPath(ctx); // 画圆    // 5.小圆    CGFloat smallRadius = bigRadius - borderWidth;    CGContextAddArc(ctx, centerX, centerY, smallRadius, 0, M_PI * 2, 0);    // 裁剪(后面画的东西才会受裁剪的影响)    CGContextClip(ctx);    // 6.画图    [oldImage drawInRect:CGRectMake(borderWidth, borderWidth, oldImage.size.width, oldImage.size.height)];    // 7.取图    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    // 8.结束上下文    UIGraphicsEndImageContext();    return newImage;}@end

屏幕截图

一、代码实现

    // 1.开启上下文    UIGraphicsBeginImageContextWithOptions(view.frame.size, NO, 0.0);    // 2.将view的layer渲染到上下文    [view.layer renderInContext:UIGraphicsGetCurrentContext()];    // 3.取出图片    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    // 4.结束上下文    UIGraphicsEndImageContext();    // 5.写文件    NSData *data = UIImagePNGRepresentation(newImage);    NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"new.png"];    [data writeToFile:path atomically:YES];

二、创建一个分类

//  UIImage+Capture.h#import <UIKit/UIKit.h>@interface UIImage (Capture)+ (instancetype)captureWithView:(UIView *)view;@end

//  UIImage+Capture.m#import "UIImage+Capture.h"@implementation UIImage (Capture)+ (instancetype)captureWithView:(UIView *)view{    // 1.开启上下文    UIGraphicsBeginImageContextWithOptions(view.frame.size, NO, 0.0);    // 2.将view的layer渲染到上下文    [view.layer renderInContext:UIGraphicsGetCurrentContext()];    // 3.取出图片    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    // 4.结束上下文    UIGraphicsEndImageContext();    return newImage;}@end