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  • Generating a beveled edge for a 2D polygon

    - by Metaphile
    I'm trying to programmatically generate beveled edges for geometric polygons. For example, given an array of 4 vertices defining a square, I want to generate something like this. But computing the vertices of the inner shape is baffling me. Simply creating a copy of the original shape and then scaling it down will not produce the desired result most of the time. My algorithm so far involves analyzing adjacent edges (triples of vertices; e.g., the bottom-left, top-left, and top-right vertices of a square). From there, I need to find the angle between them, and then create a vertex somewhere along that angle, depending on how deep I want the bevel to be. And because I don't have much of a math background, that's where I'm stuck. How do I find that center angle? Or is there a much simpler way of attacking this problem?

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  • Image/"most resembling pixel" search optimization?

    - by SigTerm
    The situation: Let's say I have an image A, say, 512x512 pixels, and image B, 5x5 or 7x7 pixels. Both images are 24bit rgb, and B have 1bit alpha mask (so each pixel is either completely transparent or completely solid). I need to find within image A a pixel which (with its' neighbors) most closely resembles image B, OR the pixel that probably most closely resembles image B. Resemblance is calculated as "distance" which is sum of "distances" between non-transparent B's pixels and A's pixels divided by number of non-transparent B's pixels. Here is a sample SDL code for explanation: struct Pixel{ unsigned char b, g, r, a; }; void fillPixel(int x, int y, SDL_Surface* dst, SDL_Surface* src, int dstMaskX, int dstMaskY){ Pixel& dstPix = *((Pixel*)((char*)(dst->pixels) + sizeof(Pixel)*x + dst->pitch*y)); int xMin = x + texWidth - searchWidth; int xMax = xMin + searchWidth*2; int yMin = y + texHeight - searchHeight; int yMax = yMin + searchHeight*2; int numFilled = 0; for (int curY = yMin; curY < yMax; curY++) for (int curX = xMin; curX < xMax; curX++){ Pixel& cur = *((Pixel*)((char*)(dst->pixels) + sizeof(Pixel)*(curX & texMaskX) + dst->pitch*(curY & texMaskY))); if (cur.a != 0) numFilled++; } if (numFilled == 0){ int srcX = rand() % src->w; int srcY = rand() % src->h; dstPix = *((Pixel*)((char*)(src->pixels) + sizeof(Pixel)*srcX + src->pitch*srcY)); dstPix.a = 0xFF; return; } int storedSrcX = rand() % src->w; int storedSrcY = rand() % src->h; float lastDifference = 3.40282347e+37F; //unsigned char mask = for (int srcY = searchHeight; srcY < (src->h - searchHeight); srcY++) for (int srcX = searchWidth; srcX < (src->w - searchWidth); srcX++){ float curDifference = 0; int numPixels = 0; for (int tmpY = -searchHeight; tmpY < searchHeight; tmpY++) for(int tmpX = -searchWidth; tmpX < searchWidth; tmpX++){ Pixel& tmpSrc = *((Pixel*)((char*)(src->pixels) + sizeof(Pixel)*(srcX+tmpX) + src->pitch*(srcY+tmpY))); Pixel& tmpDst = *((Pixel*)((char*)(dst->pixels) + sizeof(Pixel)*((x + dst->w + tmpX) & dstMaskX) + dst->pitch*((y + dst->h + tmpY) & dstMaskY))); if (tmpDst.a){ numPixels++; int dr = tmpSrc.r - tmpDst.r; int dg = tmpSrc.g - tmpDst.g; int db = tmpSrc.g - tmpDst.g; curDifference += dr*dr + dg*dg + db*db; } } if (numPixels) curDifference /= (float)numPixels; if (curDifference < lastDifference){ lastDifference = curDifference; storedSrcX = srcX; storedSrcY = srcY; } } dstPix = *((Pixel*)((char*)(src->pixels) + sizeof(Pixel)*storedSrcX + src->pitch*storedSrcY)); dstPix.a = 0xFF; } This thing is supposed to be used for texture generation. Now, the question: The easiest way to do this is brute force search (which is used in example routine). But it is slow - even using GPU acceleration and dual core cpu won't make it much faster. It looks like I can't use modified binary search because of B's mask. So, how can I find desired pixel faster? Additional Info: It is allowed to use 2 cores, GPU acceleration, CUDA, and 1.5..2 gigabytes of RAM for the task. I would prefer to avoid some kind of lengthy preprocessing phase that will take 30 minutes to finish. Ideas?

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  • How to declare a variable that spans multiple lines

    - by Chris Wilson
    I'm attempting to initialise a string variable in C++, and the value is so long that it's going to exceed the 80 character per line limit I'm working to, so I'd like to split it to the next line, but I'm not sure how to do that. I know that when splitting the contents of a stream across multiple lines, the syntax goes like cout << "This is a string" << "This is another string"; Is there an equivalent for variable assignment, or do I have to declare multiple variables and concatenate them? Edit: I misspoke when I wrote the initial question. When I say 'next line', I'm just meaning the next line of the script. When it is printed upon execution, I would like it to be on the same line.

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  • CoreGraphics taking a while to show on a large view - can i get it to repeat pixels?

    - by Andrew
    This is my coregraphics code: void drawTopPaperBackground(CGContextRef context, CGRect rect) { CGRect paper3 = CGRectMake(10, 14, 300, rect.size.height - 14); CGRect paper2 = CGRectMake(13, 12, 294, rect.size.height - 12); CGRect paper1 = CGRectMake(16, 10, 288, rect.size.height - 10); //Shadow CGContextSetShadowWithColor(context, CGSizeMake(0,0), 10, [[UIColor colorWithWhite:0 alpha:0.5]CGColor]); CGPathRef path = createRoundedRectForRect(paper3, 0); CGContextSetFillColorWithColor(context, [[UIColor blackColor] CGColor]); CGContextAddPath(context, path); CGContextFillPath(context); //Layers of paper //CGContextSaveGState(context); drawPaper(context, paper3); drawPaper(context, paper2); drawPaper(context, paper1); //CGContextRestoreGState(context); } void drawPaper(CGContextRef context, CGRect rect) { //Shadow CGContextSaveGState(context); CGContextSetShadowWithColor(context, CGSizeMake(0,0), 1, [[UIColor colorWithWhite:0 alpha:0.5]CGColor]); CGPathRef path = createRoundedRectForRect(rect, 0); CGContextSetFillColorWithColor(context, [[UIColor blackColor] CGColor]); CGContextAddPath(context, path); CGContextFillPath(context); //CGContextRestoreGState(context); //Gradient //CGContextSaveGState(context); CGColorRef startColor = [UIColor colorWithWhite:0.92 alpha:1.0].CGColor; CGColorRef endColor = [UIColor colorWithWhite:0.94 alpha:1.0].CGColor; CGRect firstHalf = CGRectMake(rect.origin.x, rect.origin.y, rect.size.width / 2, rect.size.height); CGRect secondHalf = CGRectMake(rect.origin.x + (rect.size.width / 2), rect.origin.y, rect.size.width / 2, rect.size.height); drawVerticalGradient(context, firstHalf, startColor, endColor); drawVerticalGradient(context, secondHalf, endColor, startColor); //CGContextRestoreGState(context); //CGContextSaveGState(context); CGRect redRect = rectForRectWithInset(rect, -1); CGMutablePathRef redPath = createRoundedRectForRect(redRect, 0); //CGContextSaveGState(context); CGContextSetStrokeColorWithColor(context, [[UIColor blackColor] CGColor]); CGContextAddPath(context, path); CGContextClip(context); CGContextAddPath(context, redPath); CGContextSetShadowWithColor(context, CGSizeMake(0, 0), 15.0, [[UIColor colorWithWhite:0 alpha:0.1] CGColor]); CGContextStrokePath(context); CGContextRestoreGState(context); } The view is a UIScrollView, which contains a textview. Every time the user types something and goes onto a new line, I call [self setNeedsDisplay]; and it redraws the code. But when the view starts to get long - around 1000 height, it has very noticeable lag. How can i make this code more efficient? Can i take a line of pixels and make it just repeat that, or stretch it, all the way down?

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  • Cross Platform C library for GUI Apps?

    - by Moshe
    Free of charge, simple to learn/use, Cross Platform C library for GUI Apps? Am I looking for Qt? Bonus question: Can I develop with the said library/toolkit on Mac then recompile on PC/Linux? Super Bonus Question: Link to tutorial and/or download of said library. (RE)EDIT: The truth is that I'm in the process of catching up on the C family (coming from web development - XHTML/PHP/MySQL) to learn iPhone development. I do understand that C is not C++ or ObjectiveC but I want to keep the learning curve as simple as possible. Not to get too off topic, but I am also on the lookout for good starter books and websites. I've found this so far. I'm trying to kill many birds with one stone here. I don understand that there are platform specific extensions, but I will try to avoid those for porting purposes The idea is that I want to write the code on one machine and just compile thrice. (Mac/Win/Linux) If Objective C will compile on Windows and Linux as well as OS X then that's good. If I must use C++, that's also fine. EDIT: Link to QT Please...

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  • How do I fix "java.lang.OutOfMemoryError at sun.misc.Unsafe.allocateMemory(Native Method)"?

    - by Jephir
    I'm making a Java application that uses the Slick library to load images. However, on some computers, I get this error when trying to run the program: Exception in thread "main" java.lang.OutOfMemoryError at sun.misc.Unsafe.allocateMemory(Native Method) at java.nio.DirectByteBuffer.<init>(DirectByteBuffer.java:99) at java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:288) at org.lwjgl.BufferUtils.createByteBuffer(BufferUtils.java:60) at org.newdawn.slick.opengl.PNGImageData.loadImage(PNGImageData.java:692) at org.newdawn.slick.opengl.CompositeImageData.loadImage(CompositeImageData.java:62) at org.newdawn.slick.opengl.CompositeImageData.loadImage(CompositeImageData.java:43) My VM options are: -Djava.library.path=lib -Xms1024M -Xmx1024M -XX:PermSize=256M -XX:MaxPermSize=256M The program loads a few large images (1024 x 768 resolution) at the beginning. Any help to solve this problem would be greatly appreciated.

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  • jquery toggle+paginate+multiple instances

    - by mark
    Hi, I'm a jquery newbie - wanted to ask what might be the best strategy for achieving what I am after as I think it uses a mix of jquery functions : If list of items exceeds 5 items a 'more' link appears which when toggled will reveal the rest of the items. If items list is 5 or less no 'more' link is shown. Hide button also at bottom of long full revealed list. (perhaps this is toggle+pagination?) And then also that this can be used in multiple instances, as it is for multiple category menu's.(to be used in typical indexhibit websites structure like http://mikeyburton.com/) link 1 link 2 link 3 link 4 link 5 link 6 link 7 link 8 more Any help or links greatly appreciated.

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  • Get Highest Res Favicon

    - by Jeremy
    I'm making a website that needs to dynamically obtain the favicon of sites upon request. I've found a few api's that can accomplish this fairly well, and so far I'm liking http://www.fvicon.com/. The final image for my website will be 64x64px, and some websites such as Google and Wordpress have nice images of this size that are easily retrieved via this api. Though, of course, most websites only have a 16x16 favicon image and scaling that image to 64x64 has very bad quality loss. Examples: (high res) http://a.fvicon.com/wordpress.com?format=png&width=64&height=64 (low res) http://a.fvicon.com/yahoo.com?format=png&width=64&height=64 Keeping this in mind, I'm planning on somehow determining whether a high-res image is available and, if so, the website will use this image. If not, I want to use a pre-made 64x64 icon with the smaller icon layered over it. What I'm having trouble with is determining if there is a high res favicon available or not. Also, I'm curious if there's a better approach to this situation. I'd rather not use smaller images (64x64 works out really well for this project). The lowest res I'm willing to drop to is 48x48 but even then there will be a significant quality loss for scaling up 16x16 favicons. Any ideas? If you need any more information I will gladly provide it. Thank you!

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  • Which OpenGL functions are not GPU-accelerated?

    - by Xavier Ho
    I was shocked when I read this (from the OpenGL wiki): glTranslate, glRotate, glScale Are these hardware accelerated? No, there are no known GPUs that execute this. The driver computes the matrix on the CPU and uploads it to the GPU. All the other matrix operations are done on the CPU as well : glPushMatrix, glPopMatrix, glLoadIdentity, glFrustum, glOrtho. This is the reason why these functions are considered deprecated in GL 3.0. You should have your own math library, build your own matrix, upload your matrix to the shader. For a very, very long time I thought most of the OpenGL functions use the GPU to do computation. I'm not sure if this is a common misconception, but after a while of thinking, this makes sense. Old OpenGL functions (2.x and older) are really not suitable for real-world applications, due to too many state switches. This makes me realise that, possibly, many OpenGL functions do not use the GPU at all. So, the question is: Which OpenGL function calls don't use the GPU? I believe knowing the answer to the above question would help me become a better programmer with OpenGL. Please do share some of your insights.

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  • Is it possible to achieve MAX(As,Ad) openGL blending?

    - by Jeff B
    I am working on a game where I want to create shadows under a series of sprites on a grid. The shadows are larger than the sprites themselves and the sprites are animated (i.e. move and rotate). I cannot simply render them into the sprite png, or the shadows will overlap adjacent sprites. I also cannot simply put shadows on a lower layer by themselves, because when they overlap, they will create dark bands at their intersection. These sprites are animated, so it is not feasible to render these en masse. Basically, I want the sprites' shadows to blend together such that they max out at a set opacity. Example: I believe this is equivalent to an openGL blending of (Rs,Gs,Bs,Max(As,Ds)), where I don't really care about R,G, and B, as it will always be the same color in src and dst. However, this is not a valid openGL blending mode. Is there an easy way to accomplish this, especially in cocos2d-iphone? I would be able to approximate this by making the shadow sprites opaque, then applying them both to a parent sprite, and making the parent sprite 40% opacity. However, the way cocos2d works, this only sets the opacity of each child to 40%, rather than the combined sprite image, which results in the same stripe.

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  • Pretty Pixel-level Picture Painting, Programatically

    - by dreeves
    My mac laptop has 1,024,000 pixels. What's the simplest way to turn my display completely black and go nuts with writing little programs to twiddle pixels to my heart's delight? To make it more concrete, say I wanted to implement the Chaos Game to draw a Sierpinski triangle, at the pixel level, with nothing else on the screen. What are ways to do that?

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  • Repeating animations using the Stop Selector

    - by Tiago
    I'm trying to repeat an animation until a certain condition is met. Something like this: - (void) animateUpdate { if (inUpdate) { [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:2.0]; [UIView setAnimationDelegate: self]; [UIView setAnimationDidStopSelector: @selector(animateUpdate)]; button.transform = CGAffineTransformMakeRotation( M_PI ); [UIView commitAnimations]; } } This will run the first time, but it won't repeat. The selector will just be called until the application crashes. How should I do this? Thanks.

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  • Strange iPhone application icon view in the iTunes's Applications section

    - by Spiel
    When I drag 'My iPhone App' application's file into iTunes it has proper view. Rounded corners and transparent background. Then I close iTunes and open it again. Corners are still rounded but... What has happened with the background? http://www.freeimagehosting.net/uploads/15fee337bc.png Icon is a project's resource file named 'iTunesArtwork' with dimension 512x512, PNG format.

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  • Best Practices for Working with Multiple Monitors in Visual Studio 2010

    - by Clever Human
    Now that Visual Studio 2010 has support for multiple monitors, I am curious how other people have their environments arranged. I have yet to come up with an arrangement that I am really satisfied with. The current best I have come up with for my 2 monitor system is to have all code windows detached. Then, on my primary monitor, I am able to have two code windows side by side (using the Windows 7 keyboard shortcuts WinKey+LeftArrow and WinKey+RightArrow.) On my secondary monitor I put the rest of the IDE with all of the tool windows that are normally on the bottom (errors list, find window, call stack, etc...) docked where the code windows normally go. I've also tried having all those things detached and having almost nothing in the IDE proper. The problems with this layout are: Newly opened code windows always open in the IDE, not on top of one of the detached windows. Detached code windows do not remember their exact placement from session to session (they are slightly off, having me to use the winkey + arrow key shortcut again and again for each window. There seems to be no way to have the code panes aware that they are on top of one another (IE -- multiple tabs.) The CTRL+TAB shortcut always displays on top of the IDE proper. The Code Panes are always "on top" of (children of) the IDE. So clicking on any code pane brings the IDE to the foreground, even when I care only about that code pane, and not the IDE. Other more minor issues... What would go a long way to making this better is having the code panes detach such that they are tab strips that can have other code panes docked within them. The new multi-monitor support in VS2010 is good, but it still seems really lacking. Can these issues be solved with an add-in? If so, is anyone aware of one? Is there a better way to work with the IDE on multiple monitors than what I am doing? NOTE: While this question is subjective (there is certainly no "this is the best way and that's final" answer) I'd really like to know possibly better methods of working with the IDE than what I have come up with. The intent is not to start a "mine's best" flame war.

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  • Drawing using Dynamic Array and Buffer Object

    - by user1905910
    I have a problem when creating the vertex array and the indices array. I don't know what really is the problem with the code, but I guess is something with the type of the arrays, can someone please give me a light on this? #define GL_GLEXT_PROTOTYPES #include<GL/glut.h> #include<iostream> using namespace std; #define BUFFER_OFFSET(offset) ((GLfloat*) NULL + offset) const GLuint numDiv = 2; const GLuint numVerts = 9; GLuint VAO; void display(void) { enum vertex {VERTICES, INDICES, NUM_BUFFERS}; GLuint * buffers = new GLuint[NUM_BUFFERS]; GLfloat (*squareVerts)[2] = new GLfloat[numVerts][2]; GLubyte * indices = new GLubyte[numDiv*numDiv*4]; GLuint delta = 80/numDiv; for(GLuint i = 0; i < numVerts; i++) { squareVerts[i][1] = (i/(numDiv+1))*delta; squareVerts[i][0] = (i%(numDiv+1))*delta; } for(GLuint i=0; i < numDiv; i++){ for(GLuint j=0; j < numDiv; j++){ //cada iteracao gera 4 pontos #define NUM_VERT(ii,jj) ((ii)*(numDiv+1)+(jj)) #define INDICE(ii,jj) (4*((ii)*numDiv+(jj))) indices[INDICE(i,j)] = NUM_VERT(i,j); indices[INDICE(i,j)+1] = NUM_VERT(i,j+1); indices[INDICE(i,j)+2] = NUM_VERT(i+1,j+1); indices[INDICE(i,j)+3] = NUM_VERT(i+1,j); } } glGenVertexArrays(1, &VAO); glBindVertexArray(VAO); glGenBuffers(NUM_BUFFERS, buffers); glBindBuffer(GL_ARRAY_BUFFER, buffers[VERTICES]); glBufferData(GL_ARRAY_BUFFER, sizeof(squareVerts), squareVerts, GL_STATIC_DRAW); glVertexPointer(2, GL_FLOAT, 0, BUFFER_OFFSET(0)); glEnableClientState(GL_VERTEX_ARRAY); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, buffers[INDICES]); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW); glClear(GL_COLOR_BUFFER_BIT); glColor3f(1.0,1.0,1.0); glDrawElements(GL_POINTS, 16, GL_UNSIGNED_BYTE, BUFFER_OFFSET(0)); glutSwapBuffers(); } void init() { glClearColor(0.0, 0.0, 0.0, 0.0); gluOrtho2D((GLdouble) -1.0, (GLdouble) 90.0, (GLdouble) -1.0, (GLdouble) 90.0); } int main(int argv, char** argc) { glutInit(&argv, argc); glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE); glutInitWindowSize(500,500); glutInitWindowPosition(100,100); glutCreateWindow("myCode.cpp"); init(); glutDisplayFunc(display); glutMainLoop(); return 0; } Edit: The problem here is that drawing don't work at all. But I don't get any error, this just don't display what I want to display. Even if I put the code that make the vertices and put them in the buffers in a diferent function, this don't work. I just tried to do this: void display(void) { glBindVertexArray(VAO); glClear(GL_COLOR_BUFFER_BIT); glColor3f(1.0,1.0,1.0); glDrawElements(GL_POINTS, 16, GL_UNSIGNED_BYTE, BUFFER_OFFSET(0)); glutSwapBuffers(); } and I placed the rest of the code in display in another function that is called on the start of the program. But the problem still

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  • Can XCode draw the call graph of a program?

    - by Werner
    Hi, I am new to Mac OSX, and I wonder if Xcode can generate , for a given C++ source code, the call graph of the program in a visual way. I also wonder if for each function, and after a run, whether it can also print the %time spent on the function If so, I would thank really some links with tutorials or info, after googling I did not find anything relevant Thanks

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  • Python OpenGL Can't Redraw Scene

    - by RobbR
    I'm getting started with OpenGL and shaders using GLUT and PyOpenGL. I can draw a basic scene but for some reason I can't get it to update. E.g. any changes I make during idle(), display(), or reshape() are not reflected. Here are the methods: def display(self): glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ) glMatrixMode(GL_MODELVIEW) glLoadIdentity() glUseProgram(self.shader_program) self.m_vbo.bind() glEnableClientState( GL_VERTEX_ARRAY ) glVertexPointerf(self.m_vbo) glDrawArrays(GL_TRIANGLES, 0, len(self.m_vbo)) glutSwapBuffers() glutReportErrors() def idle(self): test_change += .1 self.m_vbo = vbo.VBO( array([ [ test_change, 1, 0 ], # triangle [ -1,-1, 0 ], [ 1,-1, 0 ], [ 2,-1, 0 ], # square [ 4,-1, 0 ], [ 4, 1, 0 ], [ 2,-1, 0 ], [ 4, 1, 0 ], [ 2, 1, 0 ], ],'f') ) glutPostRedisplay() def begin(self): glutInit() glutInitWindowSize(400, 400) glutCreateWindow("Simple OpenGL") glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB) glutDisplayFunc(self.display) glutReshapeFunc(self.reshape) glutMouseFunc(self.mouse) glutMotionFunc(self.motion) glutIdleFunc(self.idle) self.define_shaders() glutMainLoop() I'd like to implement a time step in idle() but even basic changes to the vertices or tranlastions and rotations on the MODELVIEW matrix don't display. It just puts up the initial state and does not update. Am I missing something?

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  • Handling multiple accounts in Android app

    - by bebeTech
    I would like to build an application that caters for multiple accounts (eg. home, work) and account types (e.g. ISP, VoIP, Mobile). Essentially, I would like to get the user to create the accounts they want and then have all the accounts listed on the start page grouped by type. For example: ISP: - Home - Work Mobile: - Mum - Dad When you click on the account, it would take you to another screen where I do a bunch of calcs and display the results. I currently do this via multiple apps but am looking at consolidating into the one app. I am just not sure where to start or how I go about achieving this? The way the Contacts app works is a good example of what I am wanting to do.

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