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[操作系统]App开发流程之图像处理工具类


先罗列一下工具类中提供的方法:

/** * 根据原始view和毛玻璃样式,获取模糊视图,并自动作为原view的subview(如果不需要作为子视图,自行调用removeFromSuperview) */+ (UIView *)getBlurEffectViewWithOriginalView:(UIView *)originalView style:(ImageHelperBlurEffectStyle)style;/** * 根据原始图像和毛玻璃样式,获取新图像 */+ (UIImage *)getBlurEffectImageWithOriginalImage:(UIImage *)originalImage style:(ImageHelperBlurEffectStyle)style;/** * 根据原始图像,等比缩放系数,得到新图像 */+ (UIImage *)getImageWithOriginalImage:(UIImage *)originalImage scale:(CGFloat)scale;/** * 根据原始图像,等比缩放最大尺寸,得到新图像 */+ (UIImage *)getImageWithOriginalImage:(UIImage *)originalImage scaleMaxSize:(CGSize)scaleMaxSize;/** * 根据原始图像,等比缩放最大尺寸,得到新尺寸 */+ (CGSize)getImageSizeWithOriginalImage:(UIImage *)originalImage scaleMaxSize:(CGSize)scaleMaxSize;/** * 根据原始图像,完全填充尺寸,得到新图像 */+ (UIImage *)getImageWithOriginalImage:(UIImage *)originalImage fillSize:(CGSize)fillSize;/** * 根据原始图像,裁剪区域,得到新图像 */+ (UIImage *)getImageWithOriginalImage:(UIImage *)originalImage cutFrame:(CGRect)cutFrame;/** * 根据颜色,得到单位尺寸的纯色新图像 */+ (UIImage *)getImageWithColor:(UIColor *)color;/** * 根据view,得到快照 */+ (UIImage *)getSnapshotWithView:(UIView *)view;/** * 全屏截图,但不包括状态栏 */+ (UIImage *)getFullScreenSnapshot;

说明:

1.获取毛玻璃效果(高斯模糊)图像

在iOS8以后,提供了类UIBlurEffect、UIVisualEffectView,可以方便的生成高斯模糊的视图,然后只需要作为目标视图的subview即可看到效果。在iOS7上需要自行实现,不过苹果在WWDC 2013上提供了一个UIImage+ImageEffects的分类,可以生成高斯模糊的图像。将分类加入项目Categories目录后,在ImageHelper中引用。因为UIBlurEffectStyle是在iOS8以后出现的,所以自定义了一个与其对应的枚举类型ImageHelperBlurEffectStyle,以便在iOS7中也可以正常使用。实现代码如下:

+ (UIView *)getBlurEffectViewWithOriginalView:(UIView *)originalView style:(ImageHelperBlurEffectStyle)style{  if (DeviceIOSVersionAbove(8)) {    UIBlurEffectStyle blurStyle;        switch (style) {      case ImageHelperBlurEffectStyleExtraLight: {        blurStyle = UIBlurEffectStyleExtraLight;        break;      }      case ImageHelperBlurEffectStyleLight: {        blurStyle = UIBlurEffectStyleLight;        break;      }      case ImageHelperBlurEffectStyleDark: {        blurStyle = UIBlurEffectStyleDark;        break;      }    }        UIBlurEffect *effect = [UIBlurEffect effectWithStyle:blurStyle];    UIVisualEffectView *effectView = [[UIVisualEffectView alloc] initWithEffect:effect];    effectView.frame = originalView.bounds;    [originalView addSubview:effectView];    return effectView;  } else {    UIImage *originalImage = [self getSnapshotWithView:originalView];    UIImage *blurImage = [self getBlurEffectImageWithOriginalImage:originalImage style:style];        UIImageView *effectView = [[UIImageView alloc] initWithFrame:originalView.bounds];    [effectView setImage:blurImage];        [originalView addSubview:effectView];        return effectView;  }}+ (UIImage *)getBlurEffectImageWithOriginalImage:(UIImage *)originalImage style:(ImageHelperBlurEffectStyle)style{  UIImage *newImage;    switch (style) {    case ImageHelperBlurEffectStyleExtraLight: {      newImage = [originalImage applyExtraLightEffect];      break;    }    case ImageHelperBlurEffectStyleLight: {      newImage = [originalImage applyLightEffect];      break;    }    case ImageHelperBlurEffectStyleDark: {      newImage = [originalImage applyDarkEffect];      break;    }  }    return newImage;}

 

2.提供了将图像等比例缩放的系列方法,以及裁剪的方法。基本思路就是在当前图像上下文中,指定绘制尺寸(即位图的尺寸),然后将相应图像绘制到指定位置,然后生成最终图像。例如裁剪图像示例代码:

+ (UIImage *)getImageWithOriginalImage:(UIImage *)originalImage cutFrame:(CGRect)cutFrame{  CGSize newSize = cutFrame.size;    UIGraphicsBeginImageContext(newSize);  [originalImage drawInRect:CGRectMake(-cutFrame.origin.x, -cutFrame.origin.y, cutFrame.size.width, cutFrame.size.height)];  UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();  UIGraphicsEndImageContext();    return newImage;}

 

3.截屏方法

需要用到方法:

UIGraphicsBeginImageContextWithOptions(CGSize size, BOOL opaque, CGFloat scale)。第一个参数仍然是指定图像上下文绘制尺寸;第二个参数指定是否不透明;第三个为等比例缩放系数,如果为0.0,表示与设备主屏幕的系数一致。

CALayer的renderInContext:(CGContextRef)ctx方法,将图层全部渲染到某个上下文中,建议为当前图像上下文。最后得到图像。

+ (UIImage *)getSnapshotWithView:(UIView *)view{  UIGraphicsBeginImageContextWithOptions(view.bounds.size, YES, 0.0);  [view.layer renderInContext:UIGraphicsGetCurrentContext()];  UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();  UIGraphicsEndImageContext();    return newImage;}+ (UIImage *)getFullScreenSnapshot{  return [self getSnapshotWithView:[UIApplication sharedApplication].keyWindow];}

全屏截图时候,不包括状态栏,因为状态栏不在应用的window上,无法直接获取。但是可以通过私有Api拿到系统截屏图像,在此不展开探究。

 

测试内容

  UIImage *icon = LOADIMAGE(AppIcon);    UIImage *testImg;  testImg = [ImageHelper getImageWithOriginalImage:icon scale:2];  LOG(@"%@", testImg);  testImg = [ImageHelper getImageWithOriginalImage:icon scaleMaxSize:CGSizeMake(100, 90)];  LOG(@"%@", testImg);  testImg = [ImageHelper getImageWithOriginalImage:icon fillSize:CGSizeMake(100, 90)];  LOG(@"%@", testImg);  testImg = [ImageHelper getImageWithOriginalImage:icon cutFrame:CGRectMake(10, 10, 50, 50)];  LOG(@"%@", testImg);  testImg = [ImageHelper getImageWithColor:COLOR(255, 120, 100)];  LOG(@"%@", testImg);  testImg = [ImageHelper getSnapshotWithView:self.view];  LOG(@"%@", testImg);  testImg = [ImageHelper getFullScreenSnapShot];  LOG(@"%@", testImg);  testImg = [ImageHelper getBlurEffectImageWithOriginalImage:testImg style:ImageHelperBlurEffectStyleDark];  LOG(@"%@", testImg);    UIView *coverView = [ImageHelper getBlurEffectViewWithOriginalView:[UIApplication sharedApplication].keyWindow style:ImageHelperBlurEffectStyleDark];

2016-09-13 19:05:11.995 base[33087:2301853] <UIImage: 0x7ffaf97e8d00>, {120, 120}2016-09-13 19:05:11.997 base[33087:2301853] <UIImage: 0x7ffaf97e9610>, {90, 90}2016-09-13 19:05:11.999 base[33087:2301853] <UIImage: 0x7ffaf950a330>, {100, 90}2016-09-13 19:05:12.001 base[33087:2301853] <UIImage: 0x7ffaf9463630>, {50, 50}2016-09-13 19:05:12.002 base[33087:2301853] <UIImage: 0x7ffaf950a330>, {1, 1}2016-09-13 19:05:12.007 base[33087:2301853] <UIImage: 0x7ffaf96004b0>, {375, 667}2016-09-13 19:05:12.013 base[33087:2301853] <UIImage: 0x7ffaf950a330>, {375, 667}2016-09-13 19:05:12.040 base[33087:2301853] <UIImage: 0x7ffaf9506f30>, {375, 667}

 

1.可以单步调试代码,查看testImg图像内容:

 

2.[ImageHelper getSnapshotWithView:self.view];这行代码中的self.view生成快照后,尺寸为{375, 667},但如果在viewDidLoad方法中加入代码:

self.edgesForExtendedLayout = UIRectEdgeNone;

重新输出的尺寸为{375, 603},因为edgesForExtendedLayout属性默认为UIRectEdgeAll,这在处理UI布局时候需要注意。后续记录的UIViewContoller父类也会提到。

 

base项目已更新:git@github.com:ALongWay/base.git