quartz-2d

I wrote the following code in ViewDidLoad // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. -(void)viewDidLoad { [super viewDidLoad]; NSString *str = [NSString stringWithFormat:@"Veer"]; CGColorSpaceRef rgbColorspace = CGColorSpaceCreateDeviceRGB(); CGFloat values[4] = {55.0, 0.0, 0.0, 1.0}; CGColorRef glowColor = CGColorCreate(rgbColorspace, values); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetShadowWithColor( context, CGSizeMake( 5.0, 0.0 ), 20.0f, glowColor); [str drawAtPoint:CGPointMake(10.5f, 0.5f) withFont:[UIFont

I'm creating an bitmap context using CGBitmapContextCreate with the kCGImageAlphaPremultipliedFirst option. I made a 5 x 5 test image with some major colors (pure red, green, blue, white, black), some mixed colors (i.e. purple) combined with some alpha variations. Every time when the alpha component is not 255, the color value is wrong. I found that I could re-calculate the color when I do something like: almostCorrectRed = wrongRed * (255 / alphaValue); almostCorrectGreen = wrongGreen * (255 / alphaValue); almostCorrectBlue = wrongBlue * (255 / alphaValue); But the problem is, that my

I've been at this for awhile, it seems that there's many ways to go about this in quartz 2d: 1) Draw text using core graphics methods... CGContextSelectFont CGContextSetRGBFillColor CGContextShowTextAtPoint and on and on, which is horribly low level. 2) using NSString drawAtPoint (so far the method I like) NSString* text = @"Hello"; [text drawAtPoint:point withFont:font]; 3) using UILabel I've read this somewhere but not too sure if this is possible. but I'm thinking that instantiating a UILabel within drawRect would be pretty costly as drawRect probably gets called a zillion times. ?? I'm

I've been banging my head against the wall for a long while trying to figure out why this is not working. Basically, I am trying to plot a graph (chart) with CGPath and then use that to clip a gradient. The end effect should be like the Stocks app which comes with the iPhone. The gradient and the path draw fine separately as two layered (unclipped) elements. But if I comment out the CGContextDrawPath, neither the line nor the gradient draw to the screen. Here's my drawRect code: CGContextRef context = UIGraphicsGetCurrentContext(); [[UIColor whiteColor] set]; CGContextSetLineWidth(context, 2

I am trying to draw a pdf page onto a pdf context and then save it to disk. I cannot seem to figure out what is wrong. Can someone give me a few pointers. Thanks. - (void)testQuartz:(NSData *)pdfDocumentData { //Create the pdf document reference CGDataProviderRef dataProvider = CGDataProviderCreateWithCFData((CFDataRef)pdfDocumentData); CGPDFDocumentRef document = CGPDFDocumentCreateWithProvider(dataProvider); CGDataProviderRelease(dataProvider); //Release the data provider //Create the pdf context CGPDFPageRef page = CGPDFDocumentGetPage(document, 0); CGRect pageRect = CGPDFPageGetBoxRect

I am working on a drawing app, with pen touch, on iphone and ipad. Till now , I have implemented the basic drawing and tested with digital pen and it work fine, but I have one issue, while drawing on iphone/ipad, if my fingers touch the screen before I draw with pen , the pen wont work, So what I want to achieve is that, I want to able to write with pen, even if my fingers are touching the ipad screen. Regards Ranjit There is no way to differentiate between a finger and a stylus, as a stylus is supposed to emulate a touch from a finger. You will either have to make it so that all touches draw

I'm new to Quartz. I have 2 images, a background, and a mask with cutout shape that I want to lay over the background in order to cut out a section. The resulting image should be the shape of the cutout. This is my mask (the shape in the middle is 0 alpha): And this is my code: UIView *canvas = [[[sender superview] subviews] objectAtIndex:0]; UIGraphicsBeginImageContext(canvas.bounds.size); CGColorSpaceRef colourSpace = CGColorSpaceCreateDeviceRGB(); CGContextRef cgContext = CGBitmapContextCreate(NULL, canvas.bounds.size.width, canvas.bounds.size.height, 8, 0, colourSpace,