iOS compositing pictures

The way iOS is synthesized, I know two other kinds:

1: Direct synthesis using uiimage

Method: The picture is drawn to the context by the context to which it will be synthesized, and then the resultant picture

-(uiimage*) Ntesatcoverlaywith: (uiimage*) overlayimage{

Uigraphicsbeginimagecontext (self.size);

[Self Drawatpoint:cgpointzero];

[OverlayImage drawinrect:cgrectmake (0, 0, self.size.width, self.size.height) Blendmode:kcgblendmodenormal alpha:0. 9999999];

UIImage *combinedimage = Uigraphicsgetimagefromcurrentimagecontext ();

Uigraphicsendimagecontext ();

return combinedimage;

}

2: Through the UIView

Method: Load the picture onto a uiview and then generate the picture through UIView.

-(UIImage *) Imagefromview: (UIView *) View {

We need to size the graphics context according to the device scale

CGFloat scale = [[UIScreen mainscreen] scale];

Cgsize pageSize = view.frame.size;

Cgcolorspaceref colorspace = Cgcolorspacecreatedevicergb ();

Cgcontextref context = Cgbitmapcontextcreate (NULL,

Pagesize.width*scale,

Pagesize.height*scale,

8,/* bits per component*/

Pagesize.width*scale * 4,/* bytes per row */

ColorSpace,

Kcgimagealphapremultipliedfirst | Kcgbitmapbyteorderdefault);

Cgcolorspacerelease (ColorSpace);

Cgcontextcliptorect (context, CGRectMake (0, 0, Pagesize.width*scale, Pagesize.height*scale));

CGCONTEXTSCALECTM (context, scale, scale);

[View.layer Renderincontext:context];

Cgimageref image = Cgbitmapcontextcreateimage (context);

Cgcontextrelease (context);

UIImage *destimaage = [UIImage imagewithcgimage:image scale:1 Orientation:uiimageorientationdown | Uiimageorientationdownmirrored];

Cgimagerelease (image);

return destimaage;

}

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