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  • Can't compile code when working with CALayer

    - by Sheehan Alam
    For some reason I get linker errors when I try and use CALayer: "_OBJC_CLASS_$_CALayer", referenced from: I have imported the following headers: #import <Foundation/Foundation.h> #import <UIKit/UIKit.h> #import <QuartzCore/QuartzCore.h> Code: arrowImage = [[CALayer alloc] init];

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  • iPhone: How to Maintain Original Image Size Thoughout Image Edits

    - by maddy
    hi, I am developing an iPhone app that resizes and merges images. I want to select two photos of size 1600x1200 from photo library and then merge both into a single image and save that new image back to the photo library. However, I can't get the right size for the merged image. I take two image views of frame 320x480 and set the view's image to my imported images. After manipulating the images (zooming, cropping, rotating), I then save the image to album. When I check the image size it shows 600x800. How do I get the original size of 1600*1200? I've been stuck on this problem from two weeks! Thanks in advance.

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  • renderInContext creating memory that is not promptly released

    - by iworkinprogress
    While debugging in instruments using 'ObjectAlloc' I'm noticing 7megs of memory being allocated for the renderInContext call, but it never is released. When I comment out the renderInContext call this doesn't happen, and future renderInContext calls does not continue to increase the memory allotment. UIGraphicsBeginImageContext(contentHolder.bounds.size); [contentHolder.layer renderInContext:UIGraphicsGetCurrentContext()]; UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); Is there a way to force this memory to be released?

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  • Detecting Singularities 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 singularities. 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 singularities 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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  • Coordinates in distorted grid

    - by Carsten
    I have a grid in a 2D system like the one in the before image where all points A,B,C,D,A',B',C',D' are given (meaning I know the respective x- and y-coordinates). I need to calculate the x- and y-coordinates of A(new), B(new), C(new) and D(new) when the grid is distorted (so that A' is moved to A'(new), B' is moved to B'(new), C' is moved to C'(new) and D' is moved to D'(new)). The distortion happens in a way in which the lines of the grid are each divided into sub-lines of equal length (meaning for example that AB is divided into 5 parts of the equal length |AB|/5 and A(new)B(new) is divided into 5 parts of the equal length |A(new)B(new)|/5). The distortion is done with the DistortImage class of the Sandy 3D Flash engine. (My practical task is to distort an image using this class where the handles are not positioned at the corners of the image like in this demo but somewhere within it).

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  • How do I use texture-mapping in a simple ray tracer?

    - by fastrack20
    I am attempting to add features to a ray tracer in C++. Namely, I am trying to add texture mapping to the spheres. For simplicity, I am using an array to store the texture data. I obtained the texture data by using a hex editor and copying the correct byte values into an array in my code. This was just for my testing purposes. When the values of this array correspond to an image that is simply red, it appears to work close to what is expected except there is no shading. The bottom right of the image shows what a correct sphere should look like. This sphere's colour using one set colour, not a texture map. Another problem is that when the texture map is of something other than just one colour pixels, it turns white. My test image is a picture of water, and when it maps, it shows only one ring of bluish pixels surrounding the white colour. When this is done, it simply appears as this: Here are a few code snippets: Color getColor(const Object *object,const Ray *ray, float *t) { if (object->materialType == TEXTDIF || object->materialType == TEXTMATTE) { float distance = *t; Point pnt = ray->origin + ray->direction * distance; Point oc = object->center; Vector ve = Point(oc.x,oc.y,oc.z+1) - oc; Normalize(&ve); Vector vn = Point(oc.x,oc.y+1,oc.z) - oc; Normalize(&vn); Vector vp = pnt - oc; Normalize(&vp); double phi = acos(-vn.dot(vp)); float v = phi / M_PI; float u; float num1 = (float)acos(vp.dot(ve)); float num = (num1 /(float) sin(phi)); float theta = num /(float) (2 * M_PI); if (theta < 0 || theta == NAN) {theta = 0;} if (vn.cross(ve).dot(vp) > 0) { u = theta; } else { u = 1 - theta; } int x = (u * IMAGE_WIDTH) -1; int y = (v * IMAGE_WIDTH) -1; int p = (y * IMAGE_WIDTH + x)*3; return Color(TEXT_DATA[p+2],TEXT_DATA[p+1],TEXT_DATA[p]); } else { return object->color; } }; I call the colour code here in Trace: if (object->materialType == MATTE) return getColor(object, ray, &t); Ray shadowRay; int isInShadow = 0; shadowRay.origin.x = pHit.x + nHit.x * bias; shadowRay.origin.y = pHit.y + nHit.y * bias; shadowRay.origin.z = pHit.z + nHit.z * bias; shadowRay.direction = light->object->center - pHit; float len = shadowRay.direction.length(); Normalize(&shadowRay.direction); float LdotN = shadowRay.direction.dot(nHit); if (LdotN < 0) return 0; Color lightColor = light->object->color; for (int k = 0; k < numObjects; k++) { if (Intersect(objects[k], &shadowRay, &t) && !objects[k]->isLight) { if (objects[k]->materialType == GLASS) lightColor *= getColor(objects[k], &shadowRay, &t); // attenuate light color by glass color else isInShadow = 1; break; } } lightColor *= 1.f/(len*len); return (isInShadow) ? 0 : getColor(object, &shadowRay, &t) * lightColor * LdotN; } I left out the rest of the code as to not bog down the post, but it can be seen here. Any help is greatly appreciated. The only portion not included in the code, is where I define the texture data, which as I said, is simply taken straight from a bitmap file of the above image. Thanks.

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  • line is erasing in java

    - by Gogoo
    I make an Application in java and draw rectangle. When I search from combobox the rectangle is under the combobox and when I close combobox some parts of the rectangle which was under the combobox is deleted. How can I make rectangle to be visible after the combobox was closed.

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  • Custom UILabel does not show text.

    - by Oscar
    Hi! I've made an custom UILabel class in which i draw a red line at the bottom of the frame. The red line is showing but i cant get the text to show. #import <UIKit/UIKit.h> @interface LetterLabel : UILabel { } @end #import "LetterLabel.h" @implementation LetterLabel - (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame:frame]) { // Initialization code } return self; } - (void)drawRect:(CGRect)rect { CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 2.0); CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0); CGContextBeginPath(UIGraphicsGetCurrentContext()); CGContextMoveToPoint(UIGraphicsGetCurrentContext(), 0.0, self.frame.size.height); CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), self.frame.size.width, self.frame.size.height); CGContextStrokePath(UIGraphicsGetCurrentContext()); } - (void)dealloc { [super dealloc]; } @end #import <UIKit/UIKit.h> #import "Word.h" @interface WordView : UIView { Word *gameWord; } @property (nonatomic, retain) Word *gameWord; @end @implementation WordView @synthesize gameWord; - (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame:frame]) { self.backgroundColor = [UIColor whiteColor]; LetterLabel *label = [[LetterLabel alloc] initWithFrame:CGRectMake(0, 0, 20, 30)]; label.backgroundColor = [UIColor cyanColor]; label.textAlignment = UITextAlignmentCenter; label.textColor = [UIColor blackColor]; [label setText:@"t"]; [self addSubview:label]; } return self; } - (void)drawRect:(CGRect)rect { // Drawing code } - (void)dealloc { [gameWord release]; [super dealloc]; } @end

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  • How do I find hash value of a 3D vector ?

    - by brainydexter
    I am trying to perform broad-phase collision detection with a fixed-grid size approach. Thus, for each entity's position: (x,y,z) (each of type float), I need to find which cell does the entity lie in. I then intend to store all the cells in a hash-table and then iterate through to report (if any) collisions. So, here is what I am doing: Grid-cell's position: (int type) (Gx, Gy, Gz) = (x / M, y / M, z / M) where M is the size of the grid. Once, I have a cell, I'd like to add it to a hash-table with its key being a unique hash based on (Gx, Gy, Gz) and the value being the cell itself. Now, I cannot think of a good hash function and I need some help with that. Can someone please suggest me a good hash function? Thanks

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  • masking a UIImage

    - by iworkinprogress
    I'm working on an app that can change the borders or a rectangular UIImage. The borders will vary, but will look like the UIImage was cut out with scissors, or something to that affect. What is the best way to do this? My first thought is to prep a bunch of transparent PNGs with the correct border effect I'm looking for, and then somehow use that as a mask for my UIImage. Is this the right path? Or is there a more flexible programmatic way to do this?

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  • Matlab: Adding symbols to figure

    - by niko
    Hi, Below is the user interface I have created to simulate LDPC coding and decoding The code sequence is decoded iteratively by passing values between the left and right nodes through the connections. The first thing it would be good to add in order to improve visualization is to add arrows to the connections in the direction of passing values. The alternative is to draw a bigger arrow at the top of the connection showing the direction. Another thing I would like to do is displaying the current mathematical operation below the connection (in this example c * H'). What I don't know how to do is displaying special characters and mathematical symbols and other kinds of text such as subscript and superscript in the figure (for example sum sign and subscript "T" instead of sign ="'" to indicate transposed matrix). I would be very thankful if anyone could point to any useful resources for the questions above or show the solution. Thank you.

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  • iPhone+Quartz+OpenGL. What is the correct way for Quartz and OpenGL to play nice together regarding

    - by dugla
    So we know the CoreGraphics/Quartz imaging model is based on pre-multiplied alpha. We also know that OpenGL blending is based on un-premultiplied alpha. What is the best practice to avoid head explosion when doing blending with textures that are derived from pre-multiplied alpha imagery (PNG files generated in Photoshop with pre-multiplied alpha). Given the apples/oranges mish mash of Quartz and OpenGL, what is the correct glBlendFunc for doing the fundamental Porter/Duff "over" operation? Typical example: A simple paint program. Brush shapes are texture-map patterns created from pre-multiplied alpha rgba images. Paint color is specified via glColor4(...) with the alpha channel used to control paint transparency. GL_MODULATE is used so the brush texture multiplies the (translucent) paint color to blend the color into the canvas. Problem: The texture is premult. The color is not. What is the correct way to handle this fundamental inconsistency? Thanks, Doug

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  • Zoom image to pixel level

    - by zaf
    For an art project, one of the things I'll be doing is zooming in on an image to a particular pixel. I've been rubbing my chin and would love some advice on how to proceed. Here are the input parameters: Screen: sw - screen width sh - screen height Image: iw - image width ih - image height Pixel: px - x position of pixel in image py - y position of pixel in image Zoom: zf - zoom factor (0.0 to 1.0) Background colour: bc - background colour to use when screen and image aspect ratios are different Outputs: The zoomed image (no anti-aliasing) The screen position/dimensions of the pixel we are zooming to. When zf is 0 the image must fit the screen with correct aspect ratio. When zf is 1 the selected pixel fits the screen with correct aspect ratio. One idea I had was to use something like povray and move the camera towards a big image texture or some library (e.g. pygame) to do the zooming. Anyone think of something more clever with simple pseudo code? To keep it more simple you can make the image and screen have the same aspect ratio. I can live with that. I'll update with more info as its required.

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  • Simulating graphing paper on iPhone

    - by Rick
    I need to implement 'graphing paper' in an iPhone app. The user should be presented with a grid. They user can touch individual squares to turn them on, or if they're already on, off.The user can pinch to zoom and scroll around the paper as well.. So far I'm thinking Quartz 2D + UIScrollView is the way to do this but these are both areas of iPhone development that I'm unfamiliar with. Does this seem like a reasonable strategy?

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  • java/swing: Shape questions: serializing and combining

    - by Jason S
    I have two questions about java.awt.Shape. Suppose I have two Shapes, shape1 and shape2. How can I serialize them in some way so I can save the information to a file and later recreate it on another computer? (Shape is not Serializable but it does have the getPathIterator() method which seems like you could get the information out but it would be kind of a drag + I'm not sure how to reconstruct a Shape object afterwards.) How can I combine them into a new Shape so that they form a joint boundary? (e.g. if shape1 is a large square and shape2 is a small circle inside the square, I want the combined shape to be a large square with a small circular hole)

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  • iPhone Rendering Question

    - by slythic
    Hi all, I'm new to iPhone/Objective-C development. I "jumped the gun" and started reading and implementing some chapters from O'Reilly's iPhone Development. I was following the ebook's code exactly and my code was generating the following error: CGContextSetFillColorWithColor: invalid context CGContextFillRects: invalid context CGContextSetFillColorWithColor: invalid context CGContextGetShouldSmoothFonts: invalid context However, when I downloaded the sample code for the same chapter the code is different. Book Code: - (void) Render { CGContextRef g = UIGraphicsGetCurrentContext(); //fill background with gray CGContextSetFillColorWithColor(g, [UIColor grayColor].CGColor); CGContextFillRect(g, CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)); //draw text in black. CGContextSetFillColorWithColor(g, [UIColor blackColor].CGColor); [@"O'Reilly Rules!" drawAtPoint:CGPointMake(10.0, 20.0) withFont:[UIFont systemFontOfSize:[UIFont systemFontSize]]]; } Actual Project Code from the website (works): - (void) Render { [self setNeedsDisplay]; //this sets up a deferred call to drawRect. } - (void)drawRect:(CGRect)rect { CGContextRef g = UIGraphicsGetCurrentContext(); //fill background with gray CGContextSetFillColorWithColor(g, [UIColor grayColor].CGColor); CGContextFillRect(g, CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)); //draw text in black. CGContextSetFillColorWithColor(g, [UIColor blackColor].CGColor); [@"O'Reilly Rules!" drawAtPoint:CGPointMake(10.0, 20.0) withFont:[UIFont systemFontOfSize:[UIFont systemFontSize]]]; } What is it about these lines of code that make the app render correctly? - (void) Render { [self setNeedsDisplay]; //this sets up a deferred call to drawRect. } - (void)drawRect:(CGRect)rect { Thanks in advance for helping out a newbie!

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  • Java2d: Set gradient for a lines

    - by Algorist
    Hi, I am having multiple points in a plane and some hundreds of lines pass through those points. Some points can have more lines passing through them than other points. I want to show some kind of more gradient or brightness associated with lines crowded together. Is this possible to do in java2d. Please refer to this : http://ft.ornl.gov/doku/_media/ft/projects/paraxis.jpg Thank you.

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  • Can't block capslock with CGEventTap

    - by Thor Frølich
    I'm using Quartz CGEventTap in an attempt to globally intercept capslock presses and block them (to have them do something useful instead). I succesfully detect capslock presses but have so far been unable to block them. My code (originating from this stackoverflow answer) is something like this: eventTap = CGEventTapCreate(kCGHIDEventTap, kCGTailAppendEventTap, kCGEventTapOptionDefault, eventMask, myCGEventCallback, &oldFlags); runLoopSource = CFMachPortCreateRunLoopSource(kCFAllocatorDefault, eventTap, 0); CFRunLoopAddSource(CFRunLoopGetCurrent(), runLoopSource, kCFRunLoopCommonModes); CGEventTapEnable(eventTap, true); CGEventRef myCGEventCallback(CGEventTapProxy proxy, CGEventType type, CGEventRef theEvent, void *refcon) { CGEventFlags *oldFlags = (CGEventFlags *)refcon; switch (type) { case kCGEventFlagsChanged: { CGEventFlags newFlags = CGEventGetFlags(theEvent); CGEventFlags changedFlags = *oldFlags ^ newFlags; *oldFlags = newFlags; if (changedFlags == 65536) { NSLog(@"Capslock pressed. Let's not return the event"); return NULL; } break; } default: break; } NSLog(@"Different modifier than capslock. Returning the event"); return theEvent; } If I understand correctly returning NULL should effectively block the keypress from propagating. Indeed it also does for "normal" keyup and -down events. However capslock toggles regardless. Any ideas why that is? Am I making incorrect assumptions? And/or how can I do things differently to achieve my goal? Thanks, Thor

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  • Understanding colors

    - by Ankur Gupta
    Hello everyone, Kindly point towards theory/material to read for understanding colors and what makes a good color combinations. Mind it that I am not interested in say "Color combinations for web application" etc. More of the lines of say "Colors and humans". Material free to read is what i am looking for. Thanks

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  • X (close) shape in SVG

    - by danke
    I'm trying to make this SVG shape (ignore the color background, just the X shape) Close SVG Path but don't have Illustrator and wouldn't know how to use it. Can someone help out with the general idea, or point me to alternatives. I'm using it in flex.

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