Cómo capturar UIView a UIImage sin pérdida de calidad en la pantalla retina
Mi código funciona bien para dispositivos normales, pero crea imágenes borrosas en dispositivos retina.
¿alguien sabe una solución para mi problema?
+ (UIImage *) imageWithView:(UIView *)view
{
UIGraphicsBeginImageContext(view.bounds.size);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
15 answers
Cambiar del uso de UIGraphicsBeginImageContext
a UIGraphicsBeginImageContextWithOptions
(como se documenta en esta página). Pase 0.0 para scale (el tercer argumento) y obtendrá un contexto con un factor de escala igual al de la pantalla.
UIGraphicsBeginImageContext
utiliza un factor de escala fijo de 1.0, por lo que en realidad está obteniendo exactamente la misma imagen en un iPhone 4 que en los otros iPhones. Apuesto a que el iPhone 4 está aplicando un filtro cuando lo escalas implícitamente o simplemente tu cerebro está captando que es menos nítido que todo lo que lo rodea se.
Así que, supongo:
#import <QuartzCore/QuartzCore.h>
+ (UIImage *)imageWithView:(UIView *)view
{
UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.opaque, 0.0);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
Y en swift 4:
func image(with view: UIView) -> UIImage? {
UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.isOpaque, 0.0)
defer { UIGraphicsEndImageContext() }
if let context = UIGraphicsGetCurrentContext() {
view.layer.render(in: context)
let image = UIGraphicsGetImageFromCurrentImageContext()
return image
}
return nil
}
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2018-03-10 11:08:16
La respuesta aceptada actual está desactualizada, al menos si es compatible con iOS 7.
Esto es lo que debe usar si solo admite iOS7+:
+ (UIImage *) imageWithView:(UIView *)view
{
UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.opaque, 0.0f);
[view drawViewHierarchyInRect:view.bounds afterScreenUpdates:NO];
UIImage * snapshotImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return snapshotImage;
}
Swift 4:
func imageWithView(view: UIView) -> UIImage? {
UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.isOpaque, 0.0)
view.drawHierarchy(in: view.bounds, afterScreenUpdates: true)
let snapshotImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return snapshotImage
}
Según este artículo, puede ver que el nuevo método iOS7 drawViewHierarchyInRect:afterScreenUpdates:
es muchas veces más rápido que renderInContext:
.
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2018-09-04 17:06:16
He creado una extensión Swift basada en la solución @Dima:
extension UIImage {
class func imageWithView(view: UIView) -> UIImage {
UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.opaque, 0.0)
view.drawViewHierarchyInRect(view.bounds, afterScreenUpdates: true)
let img = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return img
}
}
EDIT: Swift 4 versión mejorada
extension UIImage {
class func imageWithView(_ view: UIView) -> UIImage {
UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.isOpaque, 0)
defer { UIGraphicsEndImageContext() }
view.drawHierarchy(in: view.bounds, afterScreenUpdates: true)
return UIGraphicsGetImageFromCurrentImageContext() ?? UIImage()
}
}
Uso:
let view = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
let image = UIImage.imageWithView(view)
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2018-03-08 16:45:51
Para mejorar las respuestas de @Tommy y @Dima, utilice la siguiente categoría para renderizar UIView en UIImage con fondo transparente y sin pérdida de calidad. Trabajando en iOS7. (O simplemente reutilice ese método en la implementación, reemplazando self
referencia con su imagen)
UIView+RenderViewToImage.h
#import <UIKit/UIKit.h>
@interface UIView (RenderToImage)
- (UIImage *)imageByRenderingView;
@end
UIView+RenderViewToImage.m
#import "UIView+RenderViewToImage.h"
@implementation UIView (RenderViewToImage)
- (UIImage *)imageByRenderingView
{
UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, 0.0);
[self drawViewHierarchyInRect:self.bounds afterScreenUpdates:YES];
UIImage * snapshotImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return snapshotImage;
}
@end
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2015-06-21 19:12:31
Usando el moderno UIGraphicsImageRenderer
public extension UIView {
@available(iOS 10.0, *)
public func renderToImage(afterScreenUpdates: Bool = false) -> UIImage {
let rendererFormat = UIGraphicsImageRendererFormat.default()
rendererFormat.opaque = isOpaque
let renderer = UIGraphicsImageRenderer(size: bounds.size, format: rendererFormat)
let snapshotImage = renderer.image { _ in
drawHierarchy(in: bounds, afterScreenUpdates: afterScreenUpdates)
}
return snapshotImage
}
}
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2016-12-03 08:17:33
Swift 3
La solución Swift 3 (basada en la respuesta de Dima ) con extensión UIView debería ser así:
extension UIView {
public func getSnapshotImage() -> UIImage {
UIGraphicsBeginImageContextWithOptions(self.bounds.size, self.isOpaque, 0)
self.drawHierarchy(in: self.bounds, afterScreenUpdates: false)
let snapshotImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return snapshotImage
}
}
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2017-05-23 12:02:56
Swift 2.0:
Usando el método de extensión:
extension UIImage{
class func renderUIViewToImage(viewToBeRendered:UIView?) -> UIImage
{
UIGraphicsBeginImageContextWithOptions((viewToBeRendered?.bounds.size)!, false, 0.0)
viewToBeRendered!.drawViewHierarchyInRect(viewToBeRendered!.bounds, afterScreenUpdates: true)
viewToBeRendered!.layer.renderInContext(UIGraphicsGetCurrentContext()!)
let finalImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return finalImage
}
}
Uso:
override func viewDidLoad() {
super.viewDidLoad()
//Sample View To Self.view
let sampleView = UIView(frame: CGRectMake(100,100,200,200))
sampleView.backgroundColor = UIColor(patternImage: UIImage(named: "ic_120x120")!)
self.view.addSubview(sampleView)
//ImageView With Image
let sampleImageView = UIImageView(frame: CGRectMake(100,400,200,200))
//sampleView is rendered to sampleImage
var sampleImage = UIImage.renderUIViewToImage(sampleView)
sampleImageView.image = sampleImage
self.view.addSubview(sampleImageView)
}
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2016-04-30 05:34:22
Extensión Swift 3.0 que admite la nueva API de iOS 10.0 y el método anterior.
Nota:
- Comprobación de la versión de iOS
- Tenga en cuenta el uso de defer para simplificar la limpieza de contexto.
- también aplicará la opacidad y la escala actual de la vista.
- No se abre nada usando
!
que podría causar un bloqueo.
extension UIView
{
public func renderToImage(afterScreenUpdates: Bool = false) -> UIImage?
{
if #available(iOS 10.0, *)
{
let rendererFormat = UIGraphicsImageRendererFormat.default()
rendererFormat.scale = self.layer.contentsScale
rendererFormat.opaque = self.isOpaque
let renderer = UIGraphicsImageRenderer(size: self.bounds.size, format: rendererFormat)
return
renderer.image
{
_ in
self.drawHierarchy(in: self.bounds, afterScreenUpdates: afterScreenUpdates)
}
}
else
{
UIGraphicsBeginImageContextWithOptions(self.bounds.size, self.isOpaque, self.layer.contentsScale)
defer
{
UIGraphicsEndImageContext()
}
self.drawHierarchy(in: self.bounds, afterScreenUpdates: afterScreenUpdates)
return UIGraphicsGetImageFromCurrentImageContext()
}
}
}
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2017-05-26 07:16:35
Implementación de Swift 3.0
extension UIView {
func getSnapshotImage() -> UIImage {
UIGraphicsBeginImageContextWithOptions(bounds.size, isOpaque, 0)
drawHierarchy(in: bounds, afterScreenUpdates: false)
let snapshotImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return snapshotImage
}
}
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2016-10-07 21:38:48
Todas las respuestas de Swift 3 no funcionaron para mí, así que he traducido la respuesta más aceptada:
extension UIImage {
class func imageWithView(view: UIView) -> UIImage {
UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.isOpaque, 0.0)
view.layer.render(in: UIGraphicsGetCurrentContext()!)
let img: UIImage? = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return img!
}
}
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2017-05-09 12:06:24
Algunas veces el método drawRect hace un problema, así que obtuve estas respuestas más apropiadas. Tú también puedes echarle un vistazo. Captura UIImage de UIView atascado en el método drawRect
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2017-05-23 12:26:27
- (UIImage*)screenshotForView:(UIView *)view
{
UIGraphicsBeginImageContext(view.bounds.size);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// hack, helps w/ our colors when blurring
NSData *imageData = UIImageJPEGRepresentation(image, 1); // convert to jpeg
image = [UIImage imageWithData:imageData];
return image;
}
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2016-03-01 06:05:46
Aquí hay una extensión Swift 4 UIView basada en la respuesta de @Dima.
extension UIView {
func image () -> UIImage?
{
UIGraphicsBeginImageContextWithOptions(bounds.size, isOpaque, 0)
drawHierarchy(in: bounds, afterScreenUpdates: false)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
}
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2018-06-06 20:02:12
En este método simplemente pase un objeto view y devolverá un objeto UIImage.
-(UIImage*)getUIImageFromView:(UIView*)yourView
{
UIGraphicsBeginImageContext(yourView.bounds.size);
[yourView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
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2016-04-12 12:29:51
Agregue esto al método a la categoría UIView
- (UIImage*) capture {
UIGraphicsBeginImageContext(self.bounds.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[self.layer renderInContext:context];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
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2013-01-30 06:44:01