cgcontext
How to erase part of an image as the user touches it
My big picture goal is to have a grey field over an image, and then as the user rubs on that grey field, it reveals the image underneath.Basically like a lottery scratcher card.I\'ve done a bunch开发者[详细]
2023-01-02 03:24 分类:问答Create new UIImage by adding shadow to existing UIImage
I\'ve taken a look at this question: UIImage Shadow Trouble But the ac开发者_JAVA百科cepted answer didn\'t work for me.[详细]
2023-01-01 06:53 分类:问答UIView drawRect: when you draw a line, the rect area will be clear so the previous drawing is gone
It is quite hard to tell so I upload an image to show my problem: http://i42.tinypic.com/2eezamo.jpg Basically in drawRect, I will draw the line from touchesMoved as finger touches and I will call \"[详细]
2022-12-28 08:17 分类:问答OpenGL ES; rendering texture created from CGBitmapContext
I am executing the following, which I have derived from a few different tutorials (Just a single render pass, initialisation code not shown but works fine for untextured primitives):[详细]
2022-12-28 00:11 分类:问答How to draw a sinusodial wave which varies with time on a UIView in Objective C?
I want to draw a sinusodial wave whi开发者_JS百科ch varies with time on a UIView. What are the approaches should i take ?[详细]
2022-12-26 14:30 分类:问答What way to use the CGContext to draw is suitable?
I know that the CGContext cannot call it to draw directly, and it needs to fill the drawing logic in the drawInContext, and call the CGContext to draw using \"setNeedsDisplay\", so, I designed a cmd t[详细]
2022-12-26 06:34 分类:问答Quartz Composer in iPhone UIView
I am trying to embed a Quartz Composer document in an iPho开发者_运维百科ne app. I know Quartz Composer support was added in iPhone OS 3.1 (at least, that\'s what Wikipedia says) but I can\'t find any[详细]
2022-12-26 02:10 分类:问答Core Graphics Rotating a Path
This should be a simple one, basically I have a few paths drawn with core graphics, and I want to be able to rotate them (for convenience). I\'ve tried using CGContextRotateCTM(context); but it\'s not[详细]
2022-12-26 01:22 分类:问答How to make a Drawing method in a View class work using CGContextRef?
I have these 2 methods in the View class. the drawRect method always gets called when the view is initalized. But i can\'t get the drawLine method to work. It doesn\'t do anything when it gets called.[详细]
2022-12-25 01:25 分类:问答CGContextDrawImage returning bad access
I\'ve been trying to blend two UIImage for about 2 days now and I\'ve been getting some BAD_ACCESS errors. First of all, I have two images that have the same orientation, basically I\'m using the Core[详细]
2022-12-24 09:25 分类:问答