本文共 3527 字，大约阅读时间需要 11 分钟。
绘制图片和文字不需要手动获取图形上下文,只要开启图形上下文就获取了.
图片和文字可以直接绘制到图形上下文中,
如果图形上下文中绘制了路径并执行了裁剪,那么只有路径区域会显示图片;
图片的显示形状与路径的形状有关.执行裁剪实际上就是把图形上下文裁剪成了路径的形状.
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//1.加载要裁剪的图片
UIImage * image = [UIImageimageNamed:@"dst2"];
//2.开启一个图形上下文 (bitmap 大小和要裁剪的图片大小一样)
UIGraphicsBeginImageContextWithOptions(image.size,NO,0.0);//参数:上下文区域大小,是否透明,缩放率
//3.获取图形上下文
CGContextRef ctx =UIGraphicsGetCurrentContext();
//4.创建路径
//设置圆心
CGPoint centerP = CGPointMake(image.size.width/2, image.size.height/2);
//设置半径
CGFloat radius = MIN(image.size.width, image.size.height)/2;
UIBezierPath * path = [UIBezierPathbezierPathWithArcCenter:centerPradius:radiusstartAngle:0endAngle:2 *M_PI clockwise:YES];
//5.把路径添加到图形上下文中
CGContextAddPath(ctx, path.CGPath);
//6.执行裁剪
CGContextClip(ctx);
//7.绘制图片
[image drawAtPoint:CGPointZero];
//8.获取图片
UIImage * getImage =UIGraphicsGetImageFromCurrentImageContext();
//8.1 结束图形上下文
UIGraphicsEndImageContext();
//
// //8.2 裁剪图片
//
// CGFloat x = 0;
// CGFloat y = (image.size.height - 2 * radius)/2;
//
// CGFloat w = 2 * radius;
// CGFloat h = w;
//
// //获取屏幕的缩放比
// CGFloat scale = [UIScreen mainScreen].scale;
// x *= scale;
// y *= scale;
//
// w *= scale;
// h *= scale;
//
// CGImageRef imageRef = CGImageCreateWithImageInRect(getImage.CGImage, CGRectMake(x, y, w, h));
//
获取裁剪后的图片
// getImage = [UIImage imageWithCGImage:imageRef];
//
self.imageView.image = getImage;
//9.保存
//9.1 保存相册
UIImageWriteToSavedPhotosAlbum(getImage, self, @selector(image:didFinishSavingWithError:contextInfo:),@"hello word");
//9.2 保存沙盒
NSString * documents = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES)lastObject];
//拼接文件名
NSString * fileName = [documents stringByAppendingPathComponent:@"001.png"];
//把UIimage--->NSData
NSData * imageData = UIImagePNGRepresentation(getImage);
[imageData writeToFile:fileName atomically:YES];
NSLog(@"%@",fileName);
}
//保存相册方法
- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
NSLog(@"保存完毕 %@",contextInfo);
}
//1.加载要添加水印图片
UIImage * image = [UIImageimageNamed:@"img05"];
//2.开启和图片大小相同的图形上下文(bitmap)
UIGraphicsBeginImageContextWithOptions(image.size,NO,0.0);
//3.把图片绘制到刚刚开启的图形上下文中
[image drawInRect:CGRectMake(0,0, image.size.width, image.size.height)];
//4.添加文字水印
NSString * text =@"美人你一直是我的春天,你是我的世外桃源";
NSDictionary * attrs =@{ NSForegroundColorAttributeName:[UIColorredColor],
NSFontAttributeName:[UIFontsystemFontOfSize:20.f]
};
[text drawInRect:CGRectMake(200,500,300,200)withAttributes:attrs];
//4.1 添加图片水印
//加载水印图片
UIImage * logoImage = [UIImageimageNamed:@"logo"];
[logoImage drawInRect:CGRectMake(300,700,100,38)];
//5.从图形上下文中获取图片
UIImage * getImage =UIGraphicsGetImageFromCurrentImageContext();
//5.1 结束上下文
UIGraphicsEndImageContext();
//6.保存图片到相册
UIImageWriteToSavedPhotosAlbum(getImage,nil,nil,nil);
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截屏
//1.开启一个图形上下文
UIGraphicsBeginImageContextWithOptions(self.view.frame.size,NO,0.0);
//2.获取图形上下文对象
CGContextRef ctx =UIGraphicsGetCurrentContext();
//3.调用view属性layer的方法 renderIncontex 把内容绘制到图形上下文中
[self.view.layerrenderInContext:ctx];
//4.获取图片
UIImage * getImage =UIGraphicsGetImageFromCurrentImageContext();
//5.结束图形上下文
UIGraphicsEndImageContext();
//6.保存图片
UIImageWriteToSavedPhotosAlbum(getImage,nil,nil, nil);
截屏方法二(只能在设备上运行,模拟器会报错):
CGImageRef UIGetScreenImage();
CGImageRef img = UIGetScreenImage();
UIImage* scImage=[UIImage imageWithCGImage:img];
UIImageWriteToSavedPhotosAlbum(scImage, nil, nil, nil);
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