cgcontext

Does someone know of a way, or has a creative idea as to how to obtain an UIImage that is rendered from a UIWebView? The catch is, that is must be on a background thread. I'll elaborate: I'm trying to obtain the image from multiple UIWebViews every second+-, and display it on screen (iPhone's of course). Because rendering a layer to a CGContext is a CPU consuming job, I wouldn't like to use the main thread, so not to hang the UI. My attempts so far were: I tried to use renderInContext on the webView's layer to the UIGraphicalContext , but the _WebTryThreadLock error crashed the webviews. I

So I have a spritesheet in png format, and have already worked out the coordinates for what I want to display. I'm trying to create a method that will return a UIImage when passed the location information on the spritesheet. I'm just not sure how to use the CGContext stuff along with the the coordinates to return an UIImage. I was looking to CGContextClipToRect because I think that is the way to do it, but I just can't seem to get it to work. Something like this CGSize size = CGSizeMake(xSize, ySize); UIGraphicsBeginImageContext(size); //CGContextClipToRect(spriteSheet.size, imageRect);

Not a graphics programmer here, so I'm trying to stumble through this. I'm trying to draw 9 filled circles, each a different color, each with a white border. The UIView's frame is CGRectMake (0,0,60,60). See attached image. The problem is I'm getting "flat spots" on the borders on each side. Following is my code (from the UIView subclass): - (void)drawRect:(CGRect)rect { CGRect borderRect = CGRectMake(0.0, 0.0, 60.0, 60.0); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0); CGContextSetRGBFillColor(context, colorRed, colorGreen,

I am working on a drawing app, where user can draw/write with his finger or stylus. For this I have referred code from https://github.com/yusenhan/Smooth-Line-View , in my application. The problem which I am facing is that, the writing sometimes when you write very closely is not very smooth. So I think, I am making some mistake in getting the control point. Below is my code //Find the midpoint CGPoint midPoint(CGPoint p1, CGPoint p2) { return CGPointMake((p1.x + p2.x) * 0.5, (p1.y + p2.y) * 0.5); } #pragma mark Gesture handle -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

How can I rotate an image drawn by CGContextDrawImage() at its center? In drawRect: CGContextSaveGState(c); rect = CGRectOffset(rect, -rect.size.width / 2, -rect.size.height / 2); CGContextRotateCTM(c, angle); CGContextDrawImage(c, rect, doodad.CGImage); CGContextRotateCTM(c, -angle); CGContextTranslateCTM(c, pt.x, pt.y); prevRect = rect; CGContextRestoreGState(c); I draw the image at the origin, and rotate it at its center, then translate to where it should be drawn. Not working. The thing to remember about coordinate transformations—well, one of the things to remember—is that you are not

I'm having trouble with drawing some lines that are stroked with a color and then filling their insides (they make a polygon) with another one. UIColor *houseBorderColor = [UIColor colorWithRed:(170/255.0) green:(138/255.0) blue:(99/255.0) alpha:1]; CGContextSetStrokeColorWithColor(context, houseBorderColor.CGColor); CGContextSetLineWidth(context, 3); // Draw the polygon CGContextMoveToPoint(context, 20, viewHeight-19.5); CGContextAddLineToPoint(context, 200, viewHeight-19.5); // base CGContextAddLineToPoint(context, 300, viewHeight-119.5); // right border CGContextAddLineToPoint(context, 120,

I am trying to create a CGContext in swift. It compiles but throws an error at runtime. let colorSpace:CGColorSpace = CGColorSpaceCreateDeviceRGB() let context:CGContext = CGBitmapContextCreate(nil, 20, 20, 8, 0, colorSpace, CGBitmapInfo.AlphaInfoMask) CGColorSpaceRelease(colorSpace); .... And the error is: Error: CGBitmapContextCreate: unsupported parameter combination: 8 integer bits/component; 32 bits/pixel; 3-component color space; unrecognized; 96 bytes/row. fatal error: Can't unwrap Optional.None loopmasta Just in case somebody is running into the same problem. The snippet below finally

I am using a method to convert images taken with the camera into black and white. The problem I'm running into is that if the picture is taken in Portrait mode, it rotates and stretches in the next view. But, if is taken in landscape it is just find. I can only duplicate this bug when I convert the image to Black And White. Here is the method I am using. Im not 100% that this bug is from the conversion, but it only happens when its converted. Oh ya. This is the iOS 4. /// - (UIImage *)convertImageToGrayScale:(UIImage *)image { // Create image rectangle with current image width/height CGRect