一. 关于监听手机截图
1. 背景: 发现商品的售价页总是被人转发截图,为了方便用户添加截图分享的小功能
首先要注册用户截屏操作的通知
- (void)viewDidLoad {
[super viewDidLoad];
//注册用户的截屏操作通知
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(userDidTakeScreenshot:)
name:UIApplicationUserDidTakeScreenshotNotification object:nil];
}之后人为截图
// 截屏响应
- (void)userDidTakeScreenshot:(NSNotification *)notification
{
//人为截屏, 模拟用户截屏行为, 获取所截图片
_screenshotImg = [UIutils imageWithScreenshot]; // 这里封装了一下 获得图片就可以取分享啦
DhshareActionSheetScreenshot *shareAlert = [[DhshareActionSheetScreenshot alloc] init];
[shareAlert showWithImg:_screenshotImg];
}人为截图,在这里可以对图片进行一些操作,比如添加自己的APP二维码啥的类似微博
/**
* 截取当前屏幕 并修改
*/
+ (UIImage *)imageWithScreenshot
{
CGSize imageSize = CGSizeZero;
UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation;
if (UIInterfaceOrientationIsPortrait(orientation))
imageSize = [UIScreen mainScreen].bounds.size;
else
imageSize = CGSizeMake([UIScreen mainScreen].bounds.size.height, [UIScreen mainScreen].bounds.size.width);
UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
for (UIWindow *window in [[UIApplication sharedApplication] windows])
{
CGContextSaveGState(context);
CGContextTranslateCTM(context, window.center.x, window.center.y);
CGContextConcatCTM(context, window.transform);
CGContextTranslateCTM(context, -window.bounds.size.width * window.layer.anchorPoint.x, -window.bounds.size.height * window.layer.anchorPoint.y);
if (orientation == UIInterfaceOrientationLandscapeLeft)
{
CGContextRotateCTM(context, M_PI_2);
CGContextTranslateCTM(context, 0, -imageSize.width);
}else if (orientation == UIInterfaceOrientationLandscapeRight)
{
CGContextRotateCTM(context, -M_PI_2);
CGContextTranslateCTM(context, -imageSize.height, 0);
} else if (orientation == UIInterfaceOrientationPortraitUpsideDown) {
CGContextRotateCTM(context, M_PI);
CGContextTranslateCTM(context, -imageSize.width, -imageSize.height);
}
if ([window respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)])
{
[window drawViewHierarchyInRect:window.bounds afterScreenUpdates:YES];
}
else
{
[window.layer renderInContext:context];
}
CGContextRestoreGState(context);
}
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}当然最后不要忘记注销通知,这里要注意,根据需求来,如果商品详情页又可以跳转到别的商品详情页最好这样注销,
避免跳到别的商品详情页多次截图
- (void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationUserDidTakeScreenshotNotification object:nil];
}二. UIView生成UIImag
UIView生成UIImage 时可以转一下jpg格式,这样图片不会太大具体参数可以百度,屏幕密度我一般采用0.7;
// UIView生成图片
+(UIImage*)convertViewToImage:(UIView*)v{
CGSize s = v.bounds.size;
// 下面方法，第一个参数表示区域大小。第二个参数表示是否是非透明的。如果需要显示半透明效果，需要传NO，否则传YES。第三个参数就是屏幕密度了
// NSLog(@"[UIScreen mainScreen].scale-%f",[UIScreen mainScreen].scale);
// 3.0 高清图 分享不了 用2.0即可 或者分享的时候压缩图片
UIGraphicsBeginImageContextWithOptions(s, YES, [UIScreen mainScreen].scale);
[v.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage*image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSData * data = UIImageJPEGRepresentation(image, 0.7);
UIImage* imagelast = [UIImage imageWithData:data];
return imagelast;
}三. UIImage的裁剪
// 图片裁剪
+ (UIImage *)ct_imageFromImage:(UIImage *)image inRect:(CGRect)rect{
//把像 素rect 转化为 点rect（如无转化则按原图像素取部分图片）
CGFloat scale = [UIScreen mainScreen].scale;
CGFloat x= rect.origin.x*scale,y=rect.origin.y*scale,w=rect.size.width*scale,h=rect.size.height*scale;
CGRect dianRect = CGRectMake(x, y, w, h);
//截取部分图片并生成新图片
CGImageRef sourceImageRef = [image CGImage];
CGImageRef newImageRef = CGImageCreateWithImageInRect(sourceImageRef, dianRect);
UIImage *newImage = [UIImage imageWithCGImage:newImageRef scale:[UIScreen mainScreen].scale orientation:UIImageOrientationUp];
NSData * data = UIImageJPEGRepresentation(newImage, 0.7);
UIImage* imagelast = [UIImage imageWithData:data];
return imagelast;
}四. UIImage的压缩
分享图片时根据分享的应用不同对图片大小是有限制的,微信是10M,但是qq小一些,
另外小程序分享的话也是有限制的128Kb,当截图裁剪后无法满足时就需要压缩一下
先是密度压缩然后大小压缩,一般都可以解决的
// 图片压缩
+ (UIImage *)compressImage:(UIImage *)image toByte:(NSUInteger)maxLength {
// Compress by quality
CGFloat compression = 0.7;
//UIImage转换为NSData
NSData *data = UIImageJPEGRepresentation(image, compression);
if (data.length < maxLength){
return image;
}
CGFloat max = 1;
CGFloat min = 0;
for (int i = 0; i < 6; ++i) {
compression = (max + min) / 2;
data = UIImageJPEGRepresentation(image, compression);
if (data.length < maxLength * 0.9) {
min = compression;
} else if (data.length > maxLength) {
max = compression;
} else {
break;
}
}
UIImage *resultImage = [UIImage imageWithData:data];
if (data.length < maxLength){
return resultImage;
}
// Compress by size
NSUInteger lastDataLength = 0;
while (data.length > maxLength && data.length != lastDataLength) {
lastDataLength = data.length;
CGFloat ratio = (CGFloat)maxLength / data.length;
CGSize size = CGSizeMake((NSUInteger)(resultImage.size.width * sqrtf(ratio)),
(NSUInteger)(resultImage.size.height * sqrtf(ratio))); // Use NSUInteger to prevent white blank
UIGraphicsBeginImageContext(size);
[resultImage drawInRect:CGRectMake(0, 0, size.width, size.height)];
resultImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
data = UIImageJPEGRepresentation(resultImage, compression);
}
return resultImage;
}这些是最近APP的截图分享,小程序分享的关于图片的总结.希望帮助到需要的人.