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- (void)viewDidLoad
{
[super viewDidLoad];
// 1.返回水印图片
UIImage *newImage = [UIImage waterImageWithBg:@"scene" logo:@"logo"];
// 2.显示图片
self.iconView.image = newImage;
}
- (void)testWater
{
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];
}
给image添加一类目
/**
* 打水印
*返回带有水印的图片
* @param bg 背景图片
* @param logo 右下角的水印图片
*/
+ (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;
}
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原文地址：http://www.cnblogs.com/xiaoyuaixiami/p/5211018.html
