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  • How do I translate a point from one rect to a point in a scaled rect?

    - by Bill
    I have an image (i) that's been scaled from its original size (rectLarge) to fit a smaller rectangle (rectSmall). Given a point p in rectSmall, how can I translate this to a point in rectLarge. To make this concrete, suppose I have a 20x20 image that's been scaled to a 10x10 rect. The point (1, 1) in the smaller rect should be scaled up to a point in the larger rect (i.e. (2,2)). I'm trying to achieve this with: result.x = point.x * (destRect.size.width / srcRect.size.width ); result.y = point.y * (destRect.size.height / srcRect.size.height); However, the points generated by this code are not correct - they do not map to the appropriate point in the original image. What am I doing wrong?

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  • How do bezier handles work?

    - by user146780
    On Wikipedia I found information about bezier curves and made a function to generate the inbetween points for a bezier polygon. I noticed that Expression Design uses bezier handles. This allows a circle to be made with 4 points each with a bezier handle. I'm just not sure mathematically how this works in relation with the formula for bezier point at time T. How do these handle vectors work to modify the shape? Basically what's there relation to the bezier formula? Thanks

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  • iPhone image distortion

    - by Corey Floyd
    Are there any reasons why the simulator will display UIImageViews properly, but incorrectly on the iPhone? My Process: An image in a PNG file Start a UIGraphicsBeginImageContext() Draw the PNG in a CGrect Draw text in the CGRect Create an UIImage from the context Set the image of a UIImaveView to the UIImage Set the frame of the UIImageView to the size of the PNG Add as a subview Outcome: The image does not display correctly. The rightmost 1-3 pixels of the image is just a vertical white line. This occurs only on the device and not on the simulator. I can fix the problem, but only by increasing the size of the UIImageView. If I increase the size.height of the UIImageView by 1 pixel, it displays the UIImage correctly. Of course, these leaves the iPhone to scale my image before drawing it on screen which is not desirable. Any ideas why this occurs or any fixes for it? (I will post my code if needed)

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  • Odd values/movement with UITouch and CGPoint.

    - by Joshua
    I'm getting odd numbers from UITouch and CGPoint and one is different, I also think this maybe causing a flickering affect in my app when I try to move something by following a touch. This is the code I'm using: - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { NSLog(@"touchDown"); UITouch *touch = [touches anyObject]; firstTouch = [touch locationInView:self.view]; if (CGRectContainsPoint(but.frame, firstTouch)) { butContains = YES; NSLog(@"butContains = %d", butContains); } } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; currentTouch = [touch locationInView:self.view]; NSInteger x = currentTouch.x; NSInteger y = currentTouch.y; CGFloat CGX = (CGFloat)x; CGFloat CGY = (CGFloat)y; if (butContains == YES) { NSLog(@"touch in subView/contentView"); sub.frame = CGRectMake(CGX, CGY, 130.0, 21.0); } NSLog(@"touch moved"); } - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; currentTouch = [touch locationInView:self.view]; NSLog(@"User tapped at %@", NSStringFromCGPoint(currentTouch)); NSLog(@"Point %a, %a", currentTouch.x, currentTouch.y); NSInteger x = currentTouch.x; NSInteger y = currentTouch.y; NSLog(@"Point %a, %a", y, x); CGFloat CGX = (CGFloat)x; CGFloat CGY = (CGFloat)y; NSLog(@"Point %g, %g", CGX, CGY); if (butContains == YES) { NSLog(@"touch in subView/contentView"); sub.frame = CGRectMake(CGX, CGY, 130.0, 21.0); } butContains = NO; NSLog(@"touch ended"); } - (IBAction)add:(id)sender{ InSightViewController *contentView = [[InSightViewController alloc] initWithNibName:@"SubView" bundle:[NSBundle mainBundle]]; [contentView loadView]; [self.view insertSubview:contentView.view atIndex:0]; } This is what I get from the touchesEnded method in the Debugger. 2010-04-20 20:06:13.045 InSight[25042:207] User tapped at {50, 78} 2010-04-20 20:06:13.047 InSight[25042:207] Point 0x1.9p+5, 0x1.38p+6 2010-04-20 20:06:13.048 InSight[25042:207] Point 0x1.900000027p-1037, 0x1.38p+6 2010-04-20 20:06:13.048 InSight[25042:207] Point 50, 78 And this is what's happening in the Simulator. fwdr.org/file:y8bd As this is a complicated problem this is the source code of my XCode Project aswell. http://cl.ly/Qjj

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  • How to read and modify the colorspace of an image in c#

    - by Matthias
    I'm loading a Bitmap from a jpg file. If the image is not 24bit RGB, I'd like to convert it. The conversion should be fairly fast. The images I'm loading are up to huge (9000*9000 pixel with a compressed size of 40-50MB). How can this be done? Btw: I don't want to use any external libraries if possible. But if you know of an open source utility class performing the most common imaging tasks, I'd be happy to hear about it. Thanks in advance.

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  • Nonblocking texture upload on iPhone and other OpenGL ES platforms

    - by spurserh
    Hello, I am doing some work which involves drawing video frames in real time in OpenGL ES. Right now I am using glTexImage2D to transfer the data, in the absence of Pixel Buffer Objects and the like. A below answer suggests that glTexImage2D is always blocking, even if texture object referenced does is not used for any drawing. Is there a way to do a nonblocking texture upload with OpenGL ES (any version)? Thank you very much, Sean

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  • Visual Python - Visualize graphs relating to a movement

    - by Francisco P.
    Hello, everyone! I'm working with visual python on a project where I need to simulate a physical movement. I'd like to present, in a different window than the one the actual, 3D sim is running, two graphs, both related to the movement: How the velocity and angular velocity progress over time. How the movement and rotation progress over time. All these vars are refreshed once per cycle (inside a while(true)) How can I accomplish this? Thank you for your time!

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  • Video Synthesis - Making waves, patterns, gradients...

    - by Nathan
    I'm writing a program to generate some wild visuals. So far I can paint each pixel with a random blue value: for (y = 0; y < YMAX; y++) { for (x = 0; x < XMAX; x++) { b = rand() % 255; setPixelColor(x,y,r,g,b); } } I'd like to do more than just make blue noise, but I'm not sure where to start (Google isn't helping me much today), so it would be great if you could share anything you know on the subject or some links to related resources.

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  • Detecting Asymptotes in a Graph

    - by nasufara
    I am creating a graphing calculator in Java as a project for my programming class. There are two main components to this calculator: the graph itself, which draws the line(s), and the equation evaluator, which takes in an equation as a String and... well, evaluates it. To create the line, I create a Path2D.Double instance, and loop through the points on the line. To do this, I calculate as many points as the graph is wide (e.g. if the graph itself is 500px wide, I calculate 500 points), and then scale it to the window of the graph. Now, this works perfectly for most any line. However, it does not when dealing with asymptotes. If, when calculating points, the graph encounters a domain error (such as 1/0), the graph closes the shape in the Path2D.Double instance and starts a new line, so that the line looks mathematically correct. Example: However, because of the way it scales, sometimes it is rendered correctly, sometimes it isn't. When it isn't, the actual asymptotic line is shown, because within those 500 points, it skipped over x = 2.0 in the equation 1 / (x-2), and only did x = 1.98 and x = 2.04, which are perfectly valid in that equation. Example: In that case, I increased the window on the left and right one unit each. My question is: Is there a way to deal with asymptotes using this method of scaling so that the resulting line looks mathematically correct? I myself have thought of implementing a binary search-esque method, where, if it finds that it calculates one point, and then the next point is wildly far away from the last point, it searches in between those points for a domain error. I had trouble figuring out how to make it work in practice, however. Thank you for any help you may give!

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  • iPhone app crashes on start-up, in stack-trace only messages from built-in frameworks

    - by Aleksejs
    My app some times crashes at start-up. In stack-trace only messages from built-in frameworks. An excerpt from a crash log: OS Version: iPhone OS 3.1.3 (7E18) Report Version: 104 Exception Type: EXC_BAD_ACCESS (SIGBUS) Exception Codes: KERN_PROTECTION_FAILURE at 0x000e6000 Crashed Thread: 0 Thread 0 Crashed: 0 CoreGraphics 0x339305d8 argb32_image_mark_RGB32 + 704 1 CoreGraphics 0x338dbcd4 argb32_image + 1640 2 libRIP.A.dylib 0x320d99f0 ripl_Mark 3 libRIP.A.dylib 0x320db3ac ripl_BltImage 4 libRIP.A.dylib 0x320cc2a0 ripc_RenderImage 5 libRIP.A.dylib 0x320d5238 ripc_DrawImage 6 CoreGraphics 0x338d7da4 CGContextDelegateDrawImage + 80 7 CoreGraphics 0x338d7d14 CGContextDrawImage + 364 8 UIKit 0x324ee68c compositeCGImageRefInRect 9 UIKit 0x324ee564 -[UIImage(UIImageDeprecated) compositeToRect:fromRect:operation:fraction:] 10 UIKit 0x32556f44 -[UINavigationBar drawBackButtonBackgroundInRect:withStyle:pressed:] 11 UIKit 0x32556b00 -[UINavigationItemButtonView drawRect:] 12 UIKit 0x324ecbc4 -[UIView(CALayerDelegate) drawLayer:inContext:] 13 QuartzCore 0x311cacfc -[CALayer drawInContext:] 14 QuartzCore 0x311cab00 backing_callback 15 QuartzCore 0x311ca388 CABackingStoreUpdate 16 QuartzCore 0x311c978c -[CALayer _display] 17 QuartzCore 0x311c941c -[CALayer display] 18 QuartzCore 0x311c9368 CALayerDisplayIfNeeded 19 QuartzCore 0x311c8848 CA::Context::commit_transaction(CA::Transaction*) 20 QuartzCore 0x311c846c CA::Transaction::commit() 21 QuartzCore 0x311c8318 +[CATransaction flush] 22 UIKit 0x324f5e94 -[UIApplication _reportAppLaunchFinished] 23 UIKit 0x324a7a80 -[UIApplication _runWithURL:sourceBundleID:] 24 UIKit 0x324f8df8 -[UIApplication handleEvent:withNewEvent:] 25 UIKit 0x324f8634 -[UIApplication sendEvent:] 26 UIKit 0x324f808c _UIApplicationHandleEvent 27 GraphicsServices 0x335067dc PurpleEventCallback 28 CoreFoundation 0x323f5524 CFRunLoopRunSpecific 29 CoreFoundation 0x323f4c18 CFRunLoopRunInMode 30 UIKit 0x324a6c00 -[UIApplication _run] 31 UIKit 0x324a5228 UIApplicationMain 32 Journaler 0x000029ac main (main.m:14) 33 Journaler 0x00002948 start + 44 File main.m is simple as possible: #import <UIKit/UIKit.h> int main(int argc, char *argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; int retVal = UIApplicationMain(argc, argv, nil, nil); // line 14 [pool release]; return retVal; } What my cause the app to crash?

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  • Can a GeneralPath be modified?

    - by Dov
    java2d is fairly expressive, but requires constructing lots of objects. In contrast, the older API would let you call methods to draw various shapes, but lacks all the new features like transparency, stroke, etc. Java has fairly high costs associated with object creation. For speed, I would like to create a GeneralPath whose structure does not change, but go in and change the x,y points inside. path = new GeneralPath(GeneralPath.WIND_EVEN_ODD, 10); path.moveTo(x,y); path.lineTo(x2, y2); double len = Math.sqrt((x2-x)*(x2-x) + (y2-y)*(y2-y)); double dx = (x-x2) * headLen / len; double dy = (y-y2) * headLen / len; double dx2 = -dy * (headWidth/headLen); double dy2 = dx * (headWidth/headLen); path.lineTo(x2 + dx + dx2, y2 + dy + dy2); path.moveTo(x2 + dx - dx2, y2 + dy - dy2); path.lineTo(x2,y2); This one isn't even that long. Imagine a much longer sequence of commands, and only the ones on the end are changing. I just want to be able to overwrite commands, to have an iterator effectively. Does that exist?

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  • Drawing triangle/arrow on a line with CGContext

    - by Pete
    Hi, I am using the framework of route-me for working with locations. In this code the path between two markers(points) will be drawn as a line. My Question: "What code should I add if I want to add an arrow in the middle(or top) of the line, so that it points the direction" Thanks - (void)drawInContext:(CGContextRef)theContext { renderedScale = [contents metersPerPixel]; float scale = 1.0f / [contents metersPerPixel]; float scaledLineWidth = lineWidth; if(!scaleLineWidth) { scaledLineWidth *= renderedScale; } //NSLog(@"line width = %f, content scale = %f", scaledLineWidth, renderedScale); CGContextScaleCTM(theContext, scale, scale); CGContextBeginPath(theContext); CGContextAddPath(theContext, path); CGContextSetLineWidth(theContext, scaledLineWidth); CGContextSetStrokeColorWithColor(theContext, [lineColor CGColor]); CGContextSetFillColorWithColor(theContext, [fillColor CGColor]); // according to Apple's documentation, DrawPath closes the path if it's a filled style, so a call to ClosePath isn't necessary CGContextDrawPath(theContext, drawingMode); }

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  • Image animation over CGContextDrawPDFPage

    - by BittenApple
    I'm modifying the QuartzDemo sample app from Apple. In QuartzViewController.m I have modifications (by DyingCactus) which replac the back button and add a method to handle the back button press as follows: -(void)viewDidLoad { // Add the QuartzView [scrollView addSubview:self.quartzView]; //add custom back button if this is the PDF view... if ([self.quartzView isKindOfClass:[QuartzPDFView class]]) { self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"QuartzDemo" style:UIBarButtonItemStyleBordered target:self action:@selector(myBackButtonHandler:)]; } } - (void)myBackButtonHandler:(id)sender { [self.quartzView setFrame:CGRectMake(150, -200, 100, 200)]; [UIView beginAnimations:nil context:nil]; [UIView setAnimationDelegate:self]; [UIView setAnimationDidStopSelector:@selector(animationDidStop:finished:context:)]; [UIView setAnimationDuration:1.0]; [self.quartzView setFrame:CGRectMake(150, 0, 100, 200)]; [UIView commitAnimations]; } - (void)animationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context { [self.navigationController popViewControllerAnimated:YES]; } I have a PNG image in resources folder called "bookmark.png" and would like to have that image animate as in animation in the example above. The image can be loaded in an UImageview or something and lets say that I have one called bookmark. How do I call that instead of self.quartzview in this part of code: [self.quartzView setFrame:CGRectMake(150, -200, 100, 200)]; [UIView beginAnimations:nil context:nil]; [UIView setAnimationDelegate:self]; [UIView setAnimationDidStopSelector:@selector(animationDidStop:finished:context:)]; [UIView setAnimationDuration:1.0]; [self.quartzView setFrame:CGRectMake(150, 0, 100, 200)]; [UIView commitAnimations];

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  • Image animation over CGContextDrawPDFPage

    - by BittenApple
    I have a pdf page displayed with CGContextDrawPDFPage in QuartzDemo sample application. I want to keep this page shown and have an image slide in from top over this page, just as it can be seen in the iBooks application. It's a book, the sliding image is a bookmark that slides in when you are about to close the book. I added this code by DyingCactus (hint: im a newbie to obj c and iphone dev) as follows: In QuartzViewController.m, the animation starts to show but the view slides away before the animation is finished, in fact I think the animation goes on while the view is sliding away. -(void)viewWillDisappear:(BOOL)animated { [self.quartzView setFrame:CGRectMake(150, -200, 100, 200)]; [UIView beginAnimations:nil context:nil]; [UIView setAnimationDuration:1.0]; [self.quartzView setFrame:CGRectMake(150, 0, 100, 200)]; [UIView commitAnimations]; } How can I keep the view visible and finish the animation before view disappears?

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  • iphone: how to do Page turning

    - by srnm12
    hi frnds, I am facing the problem from a month and didn't find anything from google.. I am using UIView for pdf display. there is no problem with pdf but problem is with transition. I have to turn each page of pdf with realistic page turn exp. I search, dig a lot about that but i didn't get anything that how to do that. I don't want to use any API'S like codeflake or any other. all i want to do this by my own programming. First i read that this can be done using cocos2d or CAAnimation but i want to know how? b'coz realistic page i think so is completely 3d concept. Let me know guys how to do thay?? here's the example video: http://www.youtube.com/watch?v=oknMWvRO2XE I want animation just like in video....

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  • Algorithm for Text Wrapping Within a Shape

    - by devongovett
    I am looking for an algorithm to wrap text within a non-rectangular shape, preferably based on the Knuth and Plass algorithm. The hardest part of this is that the lines may have different heights due to differing font sizes in the text. The image below is an example of what the algorithm should be able to generate. Thanks for any help!

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  • How to create a "Clustergram" plot ? (in R)

    - by Tal Galili
    Hi all, I came across this interesting website, with an idea of a way to visualize a clustering algorithm called "Clustergram": I am not sure how useful this really is, but in order to play with it I would like to reproduce it with R, but am not sure how to go about doing it. How would you create a line for each item so it would stay consistent throughout the different number of clusters? Here is an example code/data to play with for potential answer: hc <- hclust(dist(USArrests), "ave") plot(hc)

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  • SVG to Android Shape

    - by Buggieboy
    I have started learning about vector drawing in Android with the Shape class. Since Shape is a Drawable, and Drawables are usually defined as XML, it sounds a lot like the vector drawing commands in SVG. My question is this: Has anybody created an XSLT transformation, or other mechanism, for converting an SVG drawing description into Android Shapes?

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  • trying to draw scaled UIImage in custom view, but nothing's rendering

    - by Ben Collins
    I've created a custom view class and right now just want to draw an image scaled to fit the view, given a UIImage. I tried just drawing the UIImage.CGImage, but as others have attested to on this site (and in the docs), that renders the image upside down. So, at the suggestion of an answer I found to another question, I'm trying to draw it directly, but nothing is rendering in the view and I'm not sure why. Here's my drawing code: - (void)drawRect:(CGRect)rect { // Drawing code [super drawRect:rect]; if (self.originalImage) { [self drawImage]; } } - (void) drawImage { if (CGSizeEqualToSize(originalImage.size, self.frame.size) == NO) { CGFloat scaleFactor = 1.0; CGFloat scaledWidth = 0.0; CGFloat scaledHeight = 0.0; CGPoint thumbPoint = CGPointMake(0.0, 0.0); CGFloat widthFactor = self.frame.size.width / originalImage.size.width; CGFloat heightFactor = self.frame.size.height / originalImage.size.height; if (widthFactor < heightFactor) { scaleFactor = widthFactor; } else { scaleFactor = heightFactor; } scaledWidth = originalImage.size.width * scaleFactor; scaledHeight = originalImage.size.height * scaleFactor; if (widthFactor < heightFactor) { thumbPoint.y = (self.frame.size.height - scaledHeight) * 0.5; } else if (widthFactor > heightFactor) { thumbPoint.x = (self.frame.size.width - scaledWidth) * 0.5; } UIGraphicsBeginImageContext(self.frame.size); CGRect thumbRect = CGRectZero; thumbRect.origin = thumbPoint; thumbRect.size.width = scaledWidth; thumbRect.size.height = scaledHeight; [originalImage drawInRect:thumbRect]; self.scaledImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); } else { self.scaledImage = originalImage; } } My understanding (after studying this a bit) is that the UIGraphicsBeginImageContext function creates an offscreen for me to draw into, so now how do I render that context on top of the original one?

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  • Millions of 3D points: How to find the 10 of them closest to a given point?

    - by Kazoom
    A point in 3-d is defined by (x,y,z). Distance d between any two points (X,Y,Z) and (x,y,z) is d= Sqrt[(X-x)^2 + (Y-y)^2 + (Z-z)^2]. Now there are a million entries in a file, each entry is some point in space, in no specific order. Given any point (a,b,c) find the nearest 10 points to it. How would you store the million points and how would you retrieve those 10 points from that data structure.

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  • efficient algorithm for drawing circle arcs?

    - by banister
    I am using the mid-point circle algorithm (bresenham circle) to efficiently draw whole circles. Is there something similar to draw circle arcs? I would like to specify a start angle and end angle and have only that portion of the circle drawn. Thanks in advance! EDIT: I would like to draw filled circle arcs too, i.e pie-slices. :)

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  • Quartz 2D: draw from a CGContext to another CGContext

    - by alexey
    I have a CGBitmapContext (bitmapContext) and I would like to draw some rectangle part (rect) of it to the current CGContext (context). Right now I do that way: CGContextRef context = UIGraphicsGetCurrentContext(); CGImageRef cgImage = CGBitmapContextCreateImage(bitmapContext); CGContextClipToRect(context, rect); CGContextDrawImage(context, CGRectMake(0, 0, width, height), cgImage); CGImageRelease(cgImage); Is it optimal? What is the best way to do it?

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  • Encode complex number as RGB pixel

    - by Vi
    How is it better to encode a complex number into RGB pixel and vice versa? Probably (logarithm of) an absolute value goes to brightness and an argument goes to hue. Desaturated pixes should receive randomized argument in reverse transformation. Something like: 0 - (0,0,0) 1 - (255,0,0) -1 - (0,255,255) 0.5 - (128,0,0) i - (255,255,0) -i - (255,0,255) (0,0,0) - 0 (255,255,255) - e^(i * random) (128,128,128) - 0.5 * e^(i *random) (0,128,128) - -0.5 Are there ready-made formulas for that?

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  • millions of 3d points how to 10 closest to origin

    - by Kazoom
    A point in 3-d is defined by (x,y,z). Distance d between any two points (X,Y,Z) and (x,y,z) is d= Sqrt[(X-x)^2 + (Y-y)^2 + (Z-z)^2]. Now there are a million entries in a file, each entry is some point in space, in no specific order. Given any point (a,b,c) find the nearest 10 points to it. How would you store the million points and how would you retrieve those 10 points from that data structure.

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