quartz-2d

I have read what I believe to be the relevant parts of the Quartz 2D Programming Guide, but cannot find an answer to the following (they don't seem to talk a lot about iOS in the document): My application displays a drawing in a UIView . Every now and then I have to update the drawing in some way, e.g. change the fill colour of one of the shapes (I keep CGPathRefs to the important shapes to be able to redraw them with a different fill colour later). As described in the Section "Drawing With a CGLayer" on page 169 of the aforementioned document, I was thinking of drawing the entire drawing into

I've been trying to display text using a Quartz context, but no matter what I've tried I simply haven't had luck getting the text to display (I'm able to display all sorts of other Quartz objects though). Anybody knows what I might be doing wrong? example: -(void)drawRect:(CGRect)rect { // Drawing code CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSelectFont(context, "Arial", 24, kCGEncodingFontSpecific); CGContextSetTextPosition(context,80,80); CGContextShowText(context, "hello", 6); //not even this works CGContextShowTextAtPoint(context, 1,1, "hello", 6); } Darron Here is a

So far I have looked at using CGContextDrawLinearGradient() and CGContextDrawRadialGradient(), however, with the former I can't figure out how to make the gradient look like a sphere, and with the latter, I can't figure out how to make the gradient into the shape of a sphere, because every time I try, it turns out in the shape of the full cylinder instead of only a sphere. The code I am using to current draw a 2D circle is shown below. I would like to use a gradient or any other method possible using only Core Graphics and/or Quartz 2D to fill the circle in a manner that makes it look like a

I am using quartz 2d to draw a pie chart. I use layer to draw a reflection of the pie chart on the bottom. I would like to add a transparent alpha gradient to the reflection to make the it more and more transparent until it gets invisible. Someone has an idea ? @EDIT : more details My pie chart is in a CGLayerRef. I first draw this layer to the CGContextRef. Then I do a CGContextTranslateCTM(context, 0, rect.size.height); CGContextScaleCTM(context, 1.0, -1.0); To be upside down. Then i draw my layer a new time Thanks in advance, Loic You need to use an image mask. You can make the mask by

I'm having a hard time deciding whether to go with Quartz2D or OpenGL for an iPad game. It will be 2D mostly, but effect-intense (simultaneous lighting effects for 10-30 objects, 10-20 simultaneous animations on the screen). So far, assuming i'm equally dumb in both technologies and have to learn them from the ground, i came to this list. (I've read several topics here, on SO, with names like "Quartz or OpenGL", but i'm still left with some questions) Quartz : Better time-to-market, because of ready to use absractions like UIView, UIImageView, CoreAnimation abstractions Open GL ES Closer to