UIGraphicsBeginImageContext con parametri

Question

Sto scattando uno screenshot nella mia applicazione. Sono in grado di prendere lo screenshot.

Ora voglio prendere lo screenshot specificando il X e Y coordinate. È possibile?

UIGraphicsBeginImageContext(self.view.bounds.size); 
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()]; 
UIImage* aImage = UIGraphicsGetImageFromCurrentImageContext(); 

Answer 1

UIGraphicsBeginImageContext(self.view.bounds.size); 
CGContextRef c = UIGraphicsGetCurrentContext(); 
CGContextTranslateCTM(c, 0, -40); // <-- shift everything up by 40px when drawing. 
[self.view.layer renderInContext:c]; 
UIImage* viewImage = UIGraphicsGetImageFromCurrentImageContext(); 
UIGraphicsEndImageContext(); 

Answer 2

Se si utilizza un dispositivo di display retina più recente, il codice dovrebbe fattore nella risoluzione utilizzando UIGraphicsBeginImageContextWithOptions invece di UIGraphicsBeginImageContext:

UIGraphicsBeginImageContextWithOptions(self.view.bounds.size,YES,2.0); 
CGContextRef c = UIGraphicsGetCurrentContext(); 
CGContextTranslateCTM(c, 0, -40); // <-- shift everything up by 40px when drawing. 
[self.view.layer renderInContext:c]; 
UIImage* viewImage = UIGraphicsGetImageFromCurrentImageContext(); 
UIGraphicsEndImageContext(); 

Questo renderà il contesto dell'immagine display retina .

Answer 3

Basta fare una cosa del genere, così facile che tutti quei calcoli complessi

+ (UIImage *)imageWithView:(UIView *)view { 
    UIGraphicsBeginImageContextWithOptions([view bounds].size, NO, [[UIScreen mainScreen] scale]); 

    [[view layer] renderInContext:UIGraphicsGetCurrentContext()]; 

    UIImage *result = UIGraphicsGetImageFromCurrentImageContext(); 

    UIGraphicsEndImageContext(); 

    return result; 
} 

Answer 4

Ecco versione Swift versione

//Capture Screen 
func capture()->UIImage { 

    UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, false, UIScreen.mainScreen().scale) 
    self.view.layer.renderInContext(UIGraphicsGetCurrentContext()!) 
    let image = UIGraphicsGetImageFromCurrentImageContext() 
    UIGraphicsEndImageContext() 
    return image 

} 

Answer 5

rapida

UIGraphicsBeginImageContext(self.view.bounds.size) 
    let image: CGContextRef = UIGraphicsGetCurrentContext()! 
    CGContextTranslateCTM(image, 0, -40) 
    // <-- shift everything up by 40px when drawing. 
    self.view.layer.renderInContext(image) 
    let viewImage: UIImage = UIGraphicsGetImageFromCurrentImageContext() 
    UIGraphicsEndImageContext() 
    UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil)