截取UIImage指定大小区域
UIImage扩展
我的解决方案是对UIImage进行扩展。通过CGImageRef和CGImage完成截取，调用的方法是：CGImageCreateWithImageInRect。扩展类叫UIImage+Crop，具体代码如下：
UIImage+Crop.h
#import <UIKit/UIKit.h>
typedef NS_ENUM(NSInteger, XYCropImageStyle){
XYCropImageStyleRight =0, // 右半部分
XYCropImageStyleCenter =1, // 中间部分
XYCropImageStyleLeft =2, // 左半部分
XYCropImageStyleRightOneOfThird =3, // 右侧三分之一部分
XYCropImageStyleCenterOneOfThird =4, // 中间三分之一部分
XYCropImageStyleLeftOneOfThird =5, // 左侧三分之一部分
XYCropImageStyleRightQuarter =6, // 右侧四分之一部分
XYCropImageStyleCenterRightQuarter =7, // 中间右侧四分之一部分
XYCropImageStyleCenterLeftQuarter =8, // 中间左侧四分之一部分
XYCropImageStyleLeftQuarter =9, // 左侧四分之一部分
};
@interface UIImage (Crop)
- (UIImage *)imageByCroppingWithStyle:(XYCropImageStyle)style;
@end
UIImage+Crop.m
#import "UIImage+Crop.h"
@implementation UIImage (Crop)
- (UIImage *)imageByCroppingWithStyle:(XYCropImageStyle)style
{
CGRect rect;
switch (style) {
case XYCropImageStyleLeft:
rect = CGRectMake(0, 0, self.size.width/2, self.size.height);
break;
case XYCropImageStyleCenter:
rect = CGRectMake(self.size.width/4, 0, self.size.width/2, self.size.height);
break;
case XYCropImageStyleRight:
rect = CGRectMake(self.size.width/2, 0, self.size.width/2, self.size.height);
break;
case XYCropImageStyleLeftOneOfThird:
rect = CGRectMake(0, 0, self.size.width/3, self.size.height);
break;
case XYCropImageStyleCenterOneOfThird:
rect = CGRectMake(self.size.width/3, 0, self.size.width/3, self.size.height);
break;
case XYCropImageStyleRightOneOfThird:
rect = CGRectMake(self.size.width/3*2, 0, self.size.width/3, self.size.height);
break;
case XYCropImageStyleLeftQuarter:
rect = CGRectMake(0, 0, self.size.width/4, self.size.height);
break;
case XYCropImageStyleCenterLeftQuarter:
rect = CGRectMake(self.size.width/4, 0, self.size.width/4, self.size.height);
break;
case XYCropImageStyleCenterRightQuarter:
rect = CGRectMake(self.size.width/4*2, 0, self.size.width/4, self.size.height);
break;
case XYCropImageStyleRightQuarter:
rect = CGRectMake(self.size.width/4*3, 0, self.size.width/4, self.size.height);
break;
default:
break;
}
CGImageRef imageRef = self.CGImage;
CGImageRef imagePartRef = CGImageCreateWithImageInRect(imageRef, rect);
UIImage *cropImage = [UIImage imageWithCGImage:imagePartRef];
CGImageRelease(imagePartRef);
return cropImage;
}
实际运用
简单测试一下，看看有没有实现我们想要的效果。首先，先加载一个完整的UIImageView。这个应该不难。代码如下：
UIImageView *imgView = [[UIImageView alloc] init];
imgView.frame = CGRectMake((SCREEN.width - 226) / 2, 100, 226, 106);
UIImage *image = [UIImage imageNamed:@"ganggang"];
imgView.image = image;
[self.view addSubview:imgView];
运行一下：
要对UIImage进行裁剪，首先导入头文件：
#import "UIImage+Crop.h"
在上面UIImage *image = [UIImage imageNamed:@"ganggang"];这段代码之后加上下面这句：
image = [image imageByCroppingWithStyle:XYCropImageStyleLeft];
XYCropImageStyleLeft是截取照片的左半部分。效果如下：
截取成功，还可以截取其他区域的，只需要传入不同的XYCropImageStyle即可实现。以上代码依然在iOSStrongDemo里。