Basic ios image rendering based on bitmap

The content includes image watermark, image cropping, screen, and background tile.

1. Image Watermark Function

# Import "UIImage + MJ. h "@ implementation UIImage (MJ) + (instancetype) waterImageWithBg :( NSString *) bg logo :( NSString *) logo {UIImage * bgImage = [UIImage imageNamed: bg]; // 1. create a bitmap-based context (enable a bitmap-based context) uigraphicsbeginimagecontextwitexceptions (bgImage. size, NO, 0.0); // 2. image background [bgImage drawInRect: CGRectMake (0, 0, bgImage. size. width, bgImage. size. height)]; // 3. UIImage * waterImage = [UIImage imageNamed: logo]; CGFloat scale = 0.2; CGFloat margin = 5; CGFloat waterW = waterImage. size. width * scale; CGFloat waterH = waterImage. size. height * scale; CGFloat waterX = bgImage. size. width-waterW-margin; CGFloat waterY = bgImage. size. height-waterH-margin; [waterImage drawInRect: CGRectMake (waterX, waterY, waterW, waterH)]; // 4. obtain the created UIImage object UIImage * newImage = UIGraphicsGetImageFromCurrentImageContext () from the context; // 5. end context UIGraphicsEndImageContext (); return newImage ;}@ end

Call

// 1. return the watermark image UIImage * newImage = [UIImage waterImageWithBg: @ "scene" logo: @ "logo"]; // 2. show image self. iconView. image = newImage;

2. Image Cropping

# Import "UIImage + MJ. h "@ implementation UIImage (MJ) + (instancetype) circleImageWithName :( NSString *) name borderWidth :( CGFloat) borderWidth borderColor :( UIColor *) borderColor {// 1. load the source image UIImage * oldImage = [UIImage imageNamed: name]; // 2. enable the context CGFloat imageW = oldImage. size. width + 2 * borderWidth; CGFloat imageH = oldImage. size. height + 2 * borderWidth; CGSize imageSize = CGSizeMake (imageW, imageH); uigraphicsbeginimagecontextwitexceptions (imageSize, NO, 0.0); // 3. obtain the current context CGContextRef ctx = UIGraphicsGetCurrentContext (); // 4. border (large circle) [borderColor set]; CGFloat bigRadius = imageW * 0.5; // large circle radius CGFloat centerX = bigRadius; // center CGFloat centerY = bigRadius; CGContextAddArc (ctx, centerX, centerY, bigRadius, 0, M_PI * 2, 0); CGContextFillPath (ctx); // circle // 5. small Round CGFloat smallRadius = bigRadius-borderWidth; CGContextAddArc (ctx, centerX, centerY, smallRadius, 0, M_PI * 2, 0 ); // crop (the things drawn after the cropping will be affected) CGContextClip (ctx); // 6. drawing [oldImage drawInRect: CGRectMake (borderWidth, borderWidth, oldImage. size. width, oldImage. size. height)]; // 7. figure UIImage * newImage = UIGraphicsGetImageFromCurrentImageContext (); // 8. end context UIGraphicsEndImageContext (); return newImage ;}@ End

Call

- (void)viewDidLoad{    [super viewDidLoad];        UIImage *newImage = [UIImage circleImageWithName:@"me" borderWidth:3 borderColor:[UIColor whiteColor]];    self.iconView.image = newImage;        NSData *data = UIImagePNGRepresentation(newImage);    NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"new.png"];    [data writeToFile:path atomically:YES];}

3. Screen

# Import "UIImage + MJ. h "@ implementation UIImage (MJ) + (instancetype) captureWithView :( UIView *) view {// 1. enable context uigraphicsbeginimagecontextwitexceptions (view. frame. size, NO, 0.0); // 2. render the layer of the controller view to the context [view. layer renderInContext: UIGraphicsGetCurrentContext ()]; // 3. retrieve image UIImage * newImage = UIGraphicsGetImageFromCurrentImageContext (); // 4. end context UIGraphicsEndImageContext (); return newImage ;}@ end

Call

-(IBAction) clip {dispatch_after (dispatch_time (DISPATCH_TIME_NOW, (int64_t) (1.0 * NSEC_PER_SEC), dispatch_get_main_queue (), ^ {/1. capture UIImage * newImage = [UIImage captureWithView: self. view]; // 2. write File NSData * data = UIImagePNGRepresentation (newImage); NSString * path = [using (NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent: @ "new.png"]; [data writeToFile: path atomically: YES];});}

4. Stretch the background

- (void)imageBg{    UIImage *oldImage = [UIImage imageNamed:@"me"];        UIGraphicsBeginImageContextWithOptions(self.view.frame.size, NO, 0.0);    [oldImage drawInRect:self.view.bounds];    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();        self.view.backgroundColor = [UIColor colorWithPatternImage:newImage];}

5. tiled background

-(Void) viewDidLoad {[super viewDidLoad]; // self. view. backgroundColor = [UIColor redColor]; // 1. create a row of background image CGFloat rowW = self. view. frame. size. width; // CGFloat rowH = 40; CGFloat rowH = 30; then (CGSizeMake (rowW, rowH), NO, 0.0); CGContextRef ctx = UIGraphicsGetCurrentContext (); // draw a rectangle box [[UIColor redColor] set]; CGContextAddRect (ctx, CGRectMake (0, 0, rowW, rowH); CGContextFillPath (ctx); // 2. draw line [[UIColor greenColor] set]; CGFloat lineWidth = 2; CGContextSetLineWidth (ctx, lineWidth); CGFloat dividerX = 0; CGFloat dividerY = rowH-lineWidth; struct (ctx, dividerX, dividerY); CGContextAddLineToPoint (ctx, rowW-dividerX, dividerY); CGContextStrokePath (ctx); // 3. figure UIImage * newImage = UIGraphicsGetImageFromCurrentImageContext (); // 4. end context UIGraphicsEndImageContext (); // 5. set as background self. textView. backgroundColor = [UIColor colorWithPatternImage: newImage];}