Image processing code snippets to process code snippets

Image processing code snippets to process code snippets
1. image Scaling: code-(UIImage *) resizeImage :( UIImage *) image toWidth :( NSInteger) width height :( NSInteger) height {// Create a graphics context with the target size // On iOS 4 and later, use uigraphicsbeginimagecontextwittions to take the scale into consideration // On iOS prior to 4, fall back to use UIGraphicsBeginImageContext CGSize size = CGSizeMake (width, height); if (NULL! = Optional) uigraphicsbeginimagecontextwitexceptions (size, NO, 0); else UIGraphicsBeginImageContext (size); CGContextRef context = UIGraphicsGetCurrentContext (); // Flip the context because UIKit coordinate system is upside down to Quartz coordinate system CGContextTranslateCTM (context, 0.0, height); CGContextScaleCTM (context, 1.0,-1.0 ); // Draw the original image to Context CGContextSetBlendMode (context, kCGBlendModeCopy); CGContextDrawImage (context, CGRectMake (0.0, 0.0, width, height), image. CGImage); // Retrieve the UIImage from the current context UIImage * imageOut = UIGraphicsGetImageFromCurrentImageContext (); UIGraphicsEndImageContext (); return imageOut;} 2. UIView rotation: code-(void) rotateView :( UIView *) view toAngle :( float) angle {[UIView beginAnimations: nil co Ntext: nil]; [view setTransform: CGAffineTransformMakeRotation (angle)]; [UIView commitAnimations];} 3. color processing function: Code # pragma mark Color convert-(UIColor *) str2Color :( NSString *) str {SEL blackSel = NSSelectorFromString (str); // NSSelectorFromString (@ "blackColor "); UIColor * tColor = nil; if ([UIColor respondsToSelector: blackSel]) tColor = [UIColor performSelector: blackSel]; return tColor;}-(UIColor *) HexStr2Color :( NSString *) hexStr {NSString * cString = [hexStr stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet] uppercaseString]; // String shoshould be 6 or 8 characters if ([cString length] <6) return [UIColor blackColor]; // strip 0X if it appears if ([cString hasPrefix: @ "0X"]) cString = [cString substringFromIndex: 2]; if ([cString length]! = 6) return [UIColor blackColor]; // Separate into r, g, B substrings nsange range; range. location = 0; range. length = 2; NSString * rString = [cString substringWithRange: range]; range. location = 2; NSString * gString = [cString substringWithRange: range]; range. location = 4; NSString * bString = [cString substringWithRange: range]; // Scan values unsigned int r, g, B; [[ns1_scannerwithstring: rSt Ring] scanHexInt: & r]; [[ns1_scannerwithstring: gString] scanHexInt: & g]; [ns1_scannerwithstring: bString] scanHexInt: & B]; return [UIColor colorWithRed :( (float) r/255.0f) green :( (float) g/255.0f) blue :( (float) B/255.0f) alpha: 1.0f];} -(NSString *) color2str :( UIColor *) color {CGColorRef c = color. CGColor; const CGFloat * components = CGColorGetComponents (c); size_t numberOfComponent S = CGColorGetNumberOfComponents (c); NSMutableString * s = [[NSMutableString alloc] init] autorelease]; [s appendString: @ "{"]; for (size_t I = 0; I <numberOfComponents; ++ I) {if (I> 0) {[s appendString: @ ","];} [s appendString: [NSString stringWithFormat: @ "% d", (int) (components [I] * 255)];} [s appendString: @ "}"]; return s ;}- (NSString *) color2str1 :( UIColor *) color {const CGFloat * components = CGColorGetComponents (color. CGColor); NSString * colorAsString = [NSString stringWithFormat: @ "% 1f, % 1f, % 1f, % 1f", components [0] * 255, components [1] * 255, components [2] * 255, components [3];} 4. the angle corresponding to the intermediate point of the Three-Point coordinate, and determine whether the code is clockwise-(BOOL) chkClockWise :( CGPoint) a B :( CGPoint) B C :( CGPoint) c {double ax =. x-B. x; double ay =-. y + B. y; double cx = c. x-B. x; double cy =-c. y + B. y; NSLog (@ "result: % d", (cy * ax) <= (Y * cx); NSLog (@ "(x1, y1) = (% 1f, % 1f)", ax, ay); NSLog (@ "(x2, y2) = (% 1f, % 1f) \ r \ n ", cx, cy); return (cy * ax) <= (ay * cx ));} 5. after the coordinates are rotated, the new coordinates are obtained: code-(CGPoint) getNewPoint: (CGPoint) old rotate :( double) rotate {// The actual coordinates are converted to the origin coordinate old. x = (old. x-center.x); old. y = (center. y-old.y); // calculate the new coordinate after selection double x = old. x * cos (rotate)-old. y * sin (rotate); double y = old. y * cos (rotate) + old. x * sin (rotate); // The origin coordinate is converted to the actual coordinate x = center. x + x; Y = center. y-y; return CGPointMake (x, y);} 6. capture the color of any point in UIView: code-(UIColor *) getPixelColorAtLocation :( CGPoint) point {UIGraphicsBeginImageContext (self. bounds. size); [self. layer renderInContext: UIGraphicsGetCurrentContext ()]; UIImage * viewImage = UIGraphicsGetImageFromCurrentImageContext (); UIGraphicsEndImageContext (); CGImageRef inImage = viewImage. CGImage; UIColor * color = nil; // Create off Screen bitmap context to draw the image. format ARGB is 4 bytes for each pixel: Alpa, Red, Green, Blue CGContextRef cgctx = [self createARGBBitmapContextFromImage: inImage]; if (cgctx = NULL) {return nil; /* error */} size_t w = CGImageGetWidth (inImage); size_t h = CGImageGetHeight (inImage); CGRect rect = {0, 0}, {w, h }}; // Draw the image to the bitmap context. once we draw, the memory // al Located for the context for rendering will then contain the // raw image data in the specified color space. CGContextDrawImage (cgctx, rect, inImage); // Now we can get a pointer to the image data associated with the bitmap // context. unsigned char * data = CGBitmapContextGetData (cgctx); if (data! = NULL) {// offset locates the pixel in the data from x, y. // 4 for 4 bytes of data per pixel, w is width of one row of data. int offset = 4 * (w * round (point. y) + round (point. x); int alpha = data [offset]; int red = data [offset + 1]; int green = data [offset + 2]; int blue = data [offset + 3]; NSLog (@ "offset: % I colors: rgb a % I", offset, red, green, blue, alpha); color = [UIColor colorWithRed :( red/255.0f) Green :( green/255.0f) blue :( blue/255.0f) alpha :( alpha/255.0f)];} // When finished, release the context CGContextRelease (cgctx ); // Free image data memory for the context if (data) {free (data);} return color;}-(CGContextRef) createARGBBitmapContextFromImage :( CGImageRef) inImage {CGContextRef context = NULL; CGColorSpaceRef colorSpace; void * bitmapData; int bitmapByteCount; int bitmapBytesPe RRow; // Get image width, height. we'll use the entire image. size_t pixelsWide = CGImageGetWidth (inImage); size_t pixelsHigh = CGImageGetHeight (inImage); // Declare the number of bytes per row. each pixel in the bitmap in this // example is represented by 4 bytes; 8 bits each of red, green, blue, and // alpha. bitmapBytesPerRow = (pixelsWide * 4); bitmapByteCount = (bitmapBytesPerRow * pixelsHigh ); // Use the generic RGB color space. colorSpace = CGColorSpaceCreateDeviceRGB (); if (colorSpace = NULL) {fprintf (stderr, "Error allocating color space \ n"); return NULL;} // Allocate memory for image data. this is the destination in memory // where any drawing to the bitmap context will be rendered. bitmapData = malloc (bitmapByteCount); if (bitmapData = NULL) {fprintf (stderr, "Memory not Allocated! "); CGColorSpaceRelease (colorSpace); return NULL;} // Create the bitmap context. we want pre-multiplied ARGB, 8-bits // per component. regardless of what the source image format is // (CMYK, Grayscale, and so on) it will be converted over to the format // specified here by CGBitmapContextCreate. context = CGBitmapContextCreate (bitmapData, pixelsWide, pixelsHigh, 8, // bits per component bitmapB YtesPerRow, colorSpace, kCGImageAlphaPremultipliedFirst); if (context = NULL) {free (bitmapData); fprintf (stderr, "Context not created! ");} // Make sure and release colorspace before returning CGColorSpaceRelease (colorSpace); return context;} 7. one method to implement screenshot capture in the iphone program: // import the header file # import <QuartzCore/QuartzCore. h> // set the entire self. create an image imageUIGraphicsBeginImageContext (self. view. bounds. size); [self. view. layer renderInContext: UIGraphicsGetCurrentContext ()]; UIImage * image = encrypt (); UIGraphicsEndImageContext (); // Save the image to the image UIImageWriteToSavedPhotosAlbum (image, self, nil, nil); 8. draw a dot image:-(UIImage *) createImage {CGSize size = [[UIScreen mainScreen] bounds]. size; CGRect rect = CGRectMake (size. width/2, size. height/2, 5, 5); UIGraphicsBeginImageContext (size); CGContextRef context = UIGraphicsGetCurrentContext (); unsigned int red, green, blue; // Fill color. CGContextSetRGBFillColor (context, 0, 0.7, 0.7, 1.0); // Your drawing code. CGContextFillEllipseInRect (context, rect); // Get the image and return. UIImage * image = UIGraphicsGetImageFromCurrentImageContext (); UIGraphicsEndImageContext (); return image ;}