IOS Drawing Tutorial 2

1. Image Watermark

The layer context can only be displayed in DrawRect.

When the context is turned on, drawing can be done in viewdidload

Context of the bitmap

Uigraphicsbeginimagecontext () for non-retina screens only

Open Bitmap Context

Size: Dimensions of the bitmap

Opaque: Opaque is yes, transparency is no

Scale: Whether the context is scaled

Uigraphicsbeginimagecontextwithoptions (image.size, NO, 0);

Draw the original picture

[Image Drawatpoint:cgpointzero];

[Image drawinrect:cgrectmake (0, 0, Image.size.width, image.size.height)];

First Kind

NSString * info = @ "@ Big Huan";

Nsdictionary * dict = @{nsforegroundcolorattributename:[uicolor Whitecolor],

Nsfontattributename:[uifont systemfontofsize:30]};

[Info Drawatpoint:cgpointmake (+) withattributes:dict];

The second Kind

Uibezierpath * Path = [Uibezierpath bezierpathwithrect:cgrectmake (100, 100, 100, 100)];

[[Uicolor Redcolor] set];

[Path fill];

Third Kind

Cgcontextref CTX = Uigraphicsgetcurrentcontext ();

Cgcontextmovetopoint (CTX, 20, 20);

Cgcontextaddlinetopoint (CTX, 40, 40);

Cgcontextstrokepath (CTX);

Generate a new picture, obtained from the bitmap context

UIImage * newimage = Uigraphicsgetimagefromcurrentimagecontext ();

Close Picture Context

Uigraphicsendimagecontext ();

Self.imageView.image = NewImage;

2, picture and other proportion of the reduction

Action write before getting a picture through context

UIImage * image = [UIImage imagenamed:@ "huoyanshan.jpg"];

CGFloat NEWIMAGEWH = image.size.height;

Open Bitmap Context

Uigraphicsbeginimagecontextwithoptions (Cgsizemake (NEWIMAGEWH, NEWIMAGEWH), NO, 0);

Uibezierpath * Path = [Uibezierpath bezierpathwithovalinrect:cgrectmake (0, 0, NEWIMAGEWH, NEWIMAGEWH)];

Add cut

[Path Addclip];

Drawing

[Image Drawatpoint:cgpointzero];

Get a picture by context

UIImage * newimage = Uigraphicsgetimagefromcurrentimagecontext ();

Close context

Uigraphicsendimagecontext ();

Self.imageView.image = NewImage;

3. Draw the Line

The first method of pure code execution

-(Instancetype) initWithFrame: (CGRect) frame

{

self = [super Initwithframe:frame];

if (self) {

[Self setUp];

}

return self;

}

The first method of storyboard execution

-(void) awakefromnib {

[Self setUp];

}

4. Albums

Save to Phone album

Uiimagewritetosavedphotosalbum (image, Self, @selector (image:didFinishSavingWithError:contextInfo:), nil);

Create albums

Uiimagepickercontroller * Imagepicker = [[Uiimagepickercontroller alloc] init];

<uinavigationcontrollerdelegate, Uiimagepickercontrollerdelegate>, write two protocols.

Imagepicker.delegate = self;

Uiimagepickercontrollersourcetypephotolibrary albums

//uiimagepickercontrollersourcetypecamera Camera

Imagepicker.sourcetype = uiimagepickercontrollersourcetypephotolibrary;

Allow Editing

imagepicker.allowsediting = YES;

[Self Presentviewcontroller:imagepicker animated:yes completion:nil];

}

How to choose a photo album

-(void) Imagepickercontroller: (Uiimagepickercontroller *) Picker Didfinishpickingmediawithinfo: (NSDictionary< NSString *,id> *) Info {

Edit picture if allowsediting has no value for No,image

_drawview.image = Info[uiimagepickercontrollereditedimage];

Original picture

_drawview.image = Info[uiimagepickercontrolleroriginalimage];

[Picker Dismissviewcontrolleranimated:yes Completion:nil];

}

Cancel Selection

-(void) Imagepickercontrollerdidcancel: (Uiimagepickercontroller *) Picker {

NSLog (@ "Cancel selection");

[Picker Dismissviewcontrolleranimated:yes Completion:nil];

}

IOS Drawing Tutorial 2