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  • Math for core animation?

    - by jasonbogd
    What is a good level of math required for, like, advanced core animation? Take this for example: http://cocoadex.com/2008/01/lemur-math.html And what's a good book/resource to learn it? -Jason

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  • CATiledLayer: Determining levelsOfDetail when in drawLayer

    - by Russell Quinn
    I have a CATiledLayer inside a UIScrollView and all is working fine. Now I want to add support for showing different tiles for three levels of zooming. I have set levelsOfDetail to 3 and my tile size is 300 x 300. This means I need to provide three sets of tiles (I'm supplying PNGs) to cover: 300 x 300, 600 x 600 and 1200 x 1200. My problem is that inside "(void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx" I cannot work out which levelOfDetail is currently being drawn. I can retrieve the bounds currently required by using CGContextGetClipBoundingBox and usually this requests a rect for one of the above sizes, but at layer edges the tiles are usually smaller and therefore this isn't a good method. Basically, if I have set levelsOfDetail to 3, how do I find out if drawLayer is requesting level 1, 2 or 3 when it's called? Thanks, Russell.

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  • Draw underlined / strikethrough text ( MULTILINE STRING ) ?

    - by Madhup
    Hi, I have to draw underlined-multiline text with all types of text alignment. I have searched on forums and got some results like: http://davidjhinson.wordpress.com/2009/11/26/underline-text-on-the-iphone/ http://forums.macrumors.com/showthread.php?t=561572 But all draw text for single line only. while i have multi-line text. The situation even become worse when the text alignment is centered. I searched and found that in iphone-sdk-3.2 there are some core-text attributes for underlining a text but no idea how to use that. Besides if I use these my problem would not be solved fully. As I have to draw strikethrough text also. Anybody having idea about this please help.

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  • Horizontal lines and PDF drawing on iPhone/iPad Quartz 2D

    - by aron
    I'm trying to display a PDF of music using the Quartz 2D calls: CGPDFDocumentGetPage and CGPDFPageGetDrawingTransform The problem is that some horizontal lines in the PDF get drawn thicker than others. The biggest problem is that I notice this in Preview on the Mac and on iPhone/iPad. Even when viewing this PDF in the iPhone/iPad mail, I get the same problem. Here is the example: http://aronnelson.com/problem/pdfproblem.jpg Note that the PDF on the left is preview, the PDF on the right is the same file but in Google Docs. See how clean the Google Docs version is? Is there any way to fix this problem? Would it help to draw the PDF larger and zoom down using a UIScrollView? Any help appreciated. I can't find much info re: this problem. Aron

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  • Android drawCircle's are not always 360 degrees

    - by user329999
    When I call drawCircle (ex. canvas.drawCircle(x, y, r, mPaint);) and I use Paint Style STROKE to initialize param #4 mPaint, the result doesn't quite make a full 360 degree (2*PI radian) circle in all cases. Sometimes you get a full circle (as I would expect) and sometimes only an arc. Does someone have an idea what would cause this to happen? I don't know what cases work and which don't (yet). I've noticed the ones that don't work seem to be the larger circles I'm drawing (100.0 radius). Could be size related. I am using floating point for x, y and r. I could try rounding to the nearest int when in the drawing code.

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  • CGContextDrawPDFPage taking up large amounts of memory

    - by Ed Marty
    I have a PDF file that I want to draw in outline form. I want to draw the first several pages on the document each in their own UIImage to use on a button so that when clicked, the main display will navigate to the clicked page. However, CGContextDrawPDFPage seems to be using copious amounts of memory when attempting to draw the page. Even though the image is only supposed to be around 100px tall, the application crashes while drawing one page in particular, which according to Instruments, allocates about 13 MB of memory just for the one page. Here's the code for drawing: //Note: This is always called in a background thread, but the autorelease pool is setup elsewhere + (void) drawPage:(CGPDFPageRef)m_page inRect:(CGRect)rect inContext:(CGContextRef) g { CGPDFBox box = kCGPDFMediaBox; CGAffineTransform t = CGPDFPageGetDrawingTransform(m_page, box, rect, 0,YES); CGRect pageRect = CGPDFPageGetBoxRect(m_page, box); //Start the drawing CGContextSaveGState(g); //Clip to our bounding box CGContextClipToRect(g, pageRect); //Now we have to flip the origin to top-left instead of bottom left //First: flip y-axix CGContextScaleCTM(g, 1, -1); //Second: move origin CGContextTranslateCTM(g, 0, -rect.size.height); //Now apply the transform to draw the page within the rect CGContextConcatCTM(g, t); //Finally, draw the page //The important bit. Commenting out the following line "fixes" the crashing issue. CGContextDrawPDFPage(g, m_page); CGContextRestoreGState(g); } Is there a better way to draw this image that doesn't take up huge amounts of memory?

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  • Arc text in iphone application

    - by Amit Battan
    Hi all I want to bend the text that of UILabel from corner. It just like appear as arc or as following link. http://picasaweb.google.com/lh/photo/kfBzK4R4IlvyHfVywUNd1A?feat=directlink please suggest me, from where i start. any documentation,link, sample code. thanks amit battan

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  • iPhone SDK Zoom and refresh PDF with Quartz

    - by Ben
    Looking at the QuartzDemo sample application, I love the speed of the PDF rending using quartz alone (that is, without using uiwebview). However, when I'm zooming in the PDF it doesn't seem to become more clear like it does in PDF view. Is there something that I can change to have the same effect when zooming in and out using multitouch? like manipulate the PDF transformation matrix or something? Thanks a bunch. --Ben

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  • UIView using Quartz rendering engine to display PDF has poor quality compared to original.

    - by Josh Kerr
    I'm using the quartz rendering engine to display a PDF file on the iphone using the 3.0 SDK. The result is a bit blurry compared to a PDF being shown in a UIWebView. How can I improve the quality in the UIView so that I don't need to rewrite my app to use the UIWebView. I'm using pretty much close to the example code that Apple provides. Here is some of my sample code: CGContextRef gc = UIGraphicsGetCurrentContext(); CGContextSaveGState(gc); CGContextTranslateCTM(gc, 0.0, rect.size.height); CGContextScaleCTM(gc, 1.0, -1.0); CGAffineTransform m = CGPDFPageGetDrawingTransform(page, kCGPDFCropBox, rect, 0, false); CGContextConcatCTM(gc, m); CGContextSetGrayFillColor(gc, 1.0, 1.0); CGContextFillRect(gc, rect); CGContextDrawPDFPage(gc, page); CGContextRestoreGState(gc); Apple's tutorial code actually results in a blurry PDF view as well. If you drop the same PDF into a UIWebView you'll see it is actually sharper. Anyone have any ideas? This one issue is holding a two year development project from launching. :(

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  • CGBitmapContextCreate issue while trying to resize images

    - by Jeff
    Hello! I'm running into an issue when I try to create a CGContextRef while attempting to resize some images: There are the errors Sun May 16 20:07:18 new-host.home app [7406] <Error>: Unable to create bitmap delegate device Sun May 16 20:07:18 new-host.home app [7406] <Error>: createBitmapContext: failed to create delegate. My code looks like this - (UIImage*) resizeImage:(UIImage*)originalImage withSize:(CGSize)newSize { CGSize originalSize = originalImage.size; CGFloat originalAspectRatio = originalSize.width / originalSize.height; CGImageRef cgImage = nil; int bitmapWidth = newSize.width; int bitmapHeight = newSize.height; CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB(); CGContextRef context = CGBitmapContextCreate(nil, bitmapWidth, bitmapHeight, 8, bitmapWidth * 4, colorspace, kCGImageAlphaPremultipliedLast); if (context != nil) { // Flip the coordinate system //CGContextScaleCTM(context, 1.0, -1.0); //CGContextTranslateCTM(context, 0.0, -bitmapHeight); // Black background CGRect rect = CGRectMake(0, 0, bitmapWidth, bitmapHeight); CGContextSetRGBFillColor (context, 0, 0, 0, 1); CGContextFillRect (context, rect); // Resize box to maintain aspect ratio if (originalAspectRatio < 1.0) { rect.origin.y += (rect.size.height - rect.size.width / originalAspectRatio) * 0.5; rect.size.height = rect.size.width / originalAspectRatio; } else { rect.origin.x += (rect.size.width - rect.size.height * originalAspectRatio) * 0.5; rect.size.width = rect.size.height * originalAspectRatio; } CGContextSetInterpolationQuality(context, kCGInterpolationHigh); // Draw image CGContextDrawImage (context, rect, [originalImage CGImage]); // Get image cgImage = CGBitmapContextCreateImage (context); // Release context CGContextRelease(context); } CGColorSpaceRelease(colorspace); UIImage *result = [UIImage imageWithCGImage:cgImage]; CGImageRelease (cgImage); return result; }

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  • Simple iPhone drawing app with Quartz 2D

    - by Mr guy 4
    I am making a simple iPhone drawing program as a personal side-project. I capture touches event in a subclassed UIView and render the actual stuff to a seperate CGLayer. After each render, I call [self setNeedsLayout] and in the drawRect: method I draw the CGLayer to the screen context. This all works great and performs decently for drawing rectangles. However, I just want a simple "freehand" mode like a lot of other iPhone applications have. The way I thought to do this was to create a CGMutablePath, and simply: CGMutablePathRef path; -(void)touchBegan { path = CGMutablePathCreate(); } -(void)touchMoved { CGPathMoveToPoint(path,NULL,x,y); CGPathAddLineToPoint(path,NULL,x,y); } -(void)drawRect:(CGContextRef)context { CGContextBeginPath(context); CGContextAddPath(context,path); CGContextStrokePath(context); } However, after drawing for more than 1 second, performance degrades miserably. I would just draw each line into the off-screen CGLayer, if it were not for variable opacity! The less-than-100% opacity causes dots to be left on the screen connecting the lines. I have looked at CGContextSetBlendingMode() but alas I cannot find an answer. Can anyone point me in the right direction? Other iPhone apps are able to do this with very good efficiency.

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  • CSG operations on implicit surfaces with marching cubes [SOLVED]

    - by Mads Elvheim
    I render isosurfaces with marching cubes, (or perhaps marching squares as this is 2D) and I want to do set operations like set difference, intersection and union. I thought this was easy to implement, by simply choosing between two vertex scalars from two different implicit surfaces, but it is not. For my initial testing, I tried with two spheres circles, and the set operation difference. i.e A - B. One circle is moving and the other one is stationary. Here's the approach I tried when picking vertex scalars and when classifying corner vertices as inside or outside. The code is written in C++. OpenGL is used for rendering, but that's not important. Normal rendering without any CSG operations does give the expected result. void march(const vec2& cmin, //min x and y for the grid cell const vec2& cmax, //max x and y for the grid cell std::vector<vec2>& tri, float iso, float (*cmp1)(const vec2&), //distance from stationary circle float (*cmp2)(const vec2&) //distance from moving circle ) { unsigned int squareindex = 0; float scalar[4]; vec2 verts[8]; /* initial setup of the grid cell */ verts[0] = vec2(cmax.x, cmax.y); verts[2] = vec2(cmin.x, cmax.y); verts[4] = vec2(cmin.x, cmin.y); verts[6] = vec2(cmax.x, cmin.y); float s1,s2; /********************************** ********For-loop of interest****** *******Set difference between **** *******two implicit surfaces****** **********************************/ for(int i=0,j=0; i<4; ++i, j+=2){ s1 = cmp1(verts[j]); s2 = cmp2(verts[j]); if((s1 < iso)){ //if inside circle1 if((s2 < iso)){ //if inside circle2 scalar[i] = s2; //then set the scalar to the moving circle } else { scalar[i] = s1; //only inside circle1 squareindex |= (1<<i); //mark as inside } } else { scalar[i] = s1; //inside neither circle } } if(squareindex == 0) return; /* Usual interpolation between edge points to compute the new intersection points */ verts[1] = mix(iso, verts[0], verts[2], scalar[0], scalar[1]); verts[3] = mix(iso, verts[2], verts[4], scalar[1], scalar[2]); verts[5] = mix(iso, verts[4], verts[6], scalar[2], scalar[3]); verts[7] = mix(iso, verts[6], verts[0], scalar[3], scalar[0]); for(int i=0; i<10; ++i){ //10 = maxmimum 3 triangles, + one end token int index = triTable[squareindex][i]; //look up our indices for triangulation if(index == -1) break; tri.push_back(verts[index]); } } This gives me weird jaggies: It looks like the CSG operation is done without interpolation. It just "discards" the whole triangle. Do I need to interpolate in some other way, or combine the vertex scalar values? I'd love some help with this. A full testcase can be downloaded HERE EDIT: Basically, my implementation of marching squares works fine. It is my scalar field which is broken, and I wonder what the correct way would look like. Preferably I'm looking for a general approach to implement the three set operations I discussed above, for the usual primitives (circle, rectangle/square, plane)

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  • Rotating a UIButton with a custom image (animation)

    - by Tiago
    Hi, I'm trying to rotate a button that I've connected to the controller from the Interface Builder. I've set it's image right from Interface Builder. I'm using this code on the method that runs when I click it: [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:2.0]; [UIView setAnimationRepeatCount:5]; updateButton.transform = CGAffineTransformMakeRotation( M_PI ); [UIView commitAnimations]; But this doesn't do anything. Can this be done, or should I create the button programmatically in order to get it to rotate?

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  • Load NSImage into QPixmap or QImage

    - by Thomi
    I have an NSImage pointer from a platform SDK, and I need to load it into Qt's QImage class. To make things easier, I can create a QImage from a CGImageRef by using QPixmap as an intermediate format, like this: CGImageRef myImage = // ... get a CGImageRef somehow. QImage img = QPixmap::fromMacCGImageRef(myImage).toImage(); However, I cannot find a way to convert from an NSImage to a CGImageRef. Several other people have had the same problem, but I have yet to find a solution. There is the CGImageForProposedRect method, but I can't seem to get it to work. I'm currently trying this (img is my NSImage ptr): CGImageRef ir = [img CGImageFirProposedRect:0:0:0]; Any ideas?

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  • iPhone SDK: Rendering a CGLayer into an image object

    - by codemercenary
    Hi all, I am trying to add a curved border around an image downloaded and to be displayed in a UITableViewCell. In the large view (ie one image on the screen) I have the following: productImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:product.image]]; [productImageView setAlpha:0.4]; productImageView.frame = CGRectMake(10.0, 30.0, 128.0, 128.0); CALayer *roundedlayer = [productImageView layer]; [roundedlayer setMasksToBounds:YES]; [roundedlayer setCornerRadius:7.0]; [roundedlayer setBorderWidth:2.0]; [roundedlayer setBorderColor:[[UIColor darkGrayColor] CGColor]]; [self addSubview:productImageView]; In the table view cell, to get it to scroll fast, an image needs to be drawn in the drawRect method of a UIView which is then added to a custom cell. so in drawRect - (void)drawRect:(CGRect)rect { ... point = CGPointMake(boundsX + LEFT_COLUMN_OFFSET, UPPER_ROW_TOP); //CALayer *roundedlayer = [productImageView layer]; //[roundedlayer setMasksToBounds:YES]; //[roundedlayer setCornerRadius:7.0]; //[roundedlayer setBorderWidth:2.0]; //[roundedlayer setBorderColor:[[UIColor darkGrayColor] CGColor]]; //[productImageView drawRect:CGRectMake(boundsX + LEFT_COLUMN_OFFSET, UPPER_ROW_TOP, IMAGE_WIDTH, IMAGE_HEIGHT)]; // [productImageView.image drawInRect:CGRectMake(boundsX + LEFT_COLUMN_OFFSET, UPPER_ROW_TOP, IMAGE_WIDTH, IMAGE_HEIGHT)]; So this works well, but if I remove the comment and try to show the rounded CA layer the scrolling goes really slow. To fix this I suppose I would have to render this image context into a different image object, and store this in an array, then set this image as something like: productImageView.image = (UIImage*)[imageArray objectAtIndex:indexPath.row]; My question is "How do I render this layer into an image?" TIA.

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  • How do you draw like a Crayon?

    - by Simucal
    Crayon Physics Deluxe is a commercial game that came out recently. Watch the video on the main link to get an idea of what I'm talking about. It allows you to draw shapes and have them react with proper physics. The goal is to move a ball to a star across the screen using contraptions and shapes you build. While the game is basically a wrapper for the popular Box2D Physics Engine, it does have one feature that I'm curious about how it is implemented. Its drawing looks very much like a Crayon. You can see the texture of the crayon and as it draws it varies in thickness and darkness just like an actual crayon drawing would look like. The background texture is freely available here. Close up of crayon drawing - Note the varying darkness What kind of algorithm would be used to render those lines in a way that looks like a Crayon? Is it a simple texture applied with a random thickness and darkness or is there something more going on?

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  • perl: tk: a way/widget that allows pixel level control over the output

    - by chhh
    I want something like a canvas, but where i'd be able to manipulate pixels easily in addition to all the provided geometries, that can be drawn on canvas. Is it possible to embed something like GD::Image into a canvas? So then I maybe could make the image transparent and set some pixels in it (GD::Image-setPixel()) positioning it over the canvas? ps: well, that doesn't necessarily have to be perl, as there seem to be bindings for all the libs for most scripting (and not only) languages.

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  • JOGL Double Buffering

    - by Bar
    What is eligible way to implement double buffering in JOGL (Java OpenGL)? I am trying to do that by the following code: ... /** Creating canvas. */ GLCapabilities capabilities = new GLCapabilities(); capabilities.setDoubleBuffered(true); GLCanvas canvas = new GLCanvas(capabilities); ... /** Function display(…), which draws a white Rectangle on a black background. */ public void display(GLAutoDrawable drawable) { drawable.swapBuffers(); gl = drawable.getGL(); gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT); gl.glClearColor(0.0f, 0.0f, 0.0f, 0.0f); gl.glColor3f(1.0f, 1.0f, 1.0f); gl.glBegin(GL.GL_POLYGON); gl.glVertex2f(-0.5f, -0.5f); gl.glVertex2f(-0.5f, 0.5f); gl.glVertex2f(0.5f, 0.5f); gl.glVertex2f(0.5f, -0.5f); gl.glEnd(); } ... /** Other functions are empty. */ Questions: — When I'm resizing the window, I usually get flickering. As I see it, I have a mistake in my double buffering implementation. — I have doubt, where I must place function swapBuffers — before or after (as many sources says) the drawing? As you noticed, I use function swapBuffers (drawable.swapBuffers()) before drawing a rectangle. Otherwise, I'm getting a noise after resize. So what is an appropriate way to do that? Including or omitting the line capabilities.setDoubleBuffered(true) does not make any effect.

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  • Any software transforming broken lines into curves?

    - by brilliant
    Hello, do you know of any software that would help me transform a broken line into a curved line? For example, I have an octagon or a heptagon and I want it to be transformed into something resembling a circle. if you know such software, please, let me know. Thank You! Update A: Here is an image from the tutorial given to me by Jamie Keeling (right now it's the first answer below). At least the picture there represents what I want. In that tutorial this process is called "flattening paths". I will try to put that image right here, but if it doesn't get displayed, you can find it here: http://msdn.microsoft.com/en-us/library/ms536364%28v=VS.85%29.aspx The red line in the picture is what I would want to submit, and the blue line is what I would want to get in the end:

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  • Rotating an Image in Silverlight without cropping

    - by Tim Saunders
    I am currently working on a simple Silverlight app that will allow people to upload an image, crop, resize and rotate it and then load it via a webservice to a CMS. Cropping and resizing is done, however rotation is causing some problems. The image gets cropped and is off centre after the rotation. WriteableBitmap wb = new WriteableBitmap(destWidth, destHeight); RotateTransform rt = new RotateTransform(); rt.Angle = 90; rt.CenterX = width/2; rt.CenterY = height/2; //Draw to the Writeable Bitmap Image tempImage2 = new Image(); tempImage2.Width = width; tempImage2.Height = height; tempImage2.Source = rawImage; wb.Render(tempImage2,rt); wb.Invalidate(); rawImage = wb; message.Text = "h:" + rawImage.PixelHeight.ToString(); message.Text += ":w:" + rawImage.PixelWidth.ToString(); //Finally set the Image back MyImage.Source = wb; MyImage.Width = destWidth; MyImage.Height = destHeight; The code above only needs to rotate by 90° at this time so I'm just setting destWidth and destHeight to the height and width of the original image.

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  • CGContextSetShadow() - shadow direction reversed between iOS 3.0 and 4.0?

    - by Pascal
    I've been using CGContextSetShadowWithColor() in my Quartz drawing code on the iPhone to generate the "stomped in" look for text and other things (in drawRect: and drawLayer:inContext:). Worked perfectly, but when running the exact same code against iOS 3.2 and now iOS 4.0 I noticed that the shadows are all in the opposite direction. E.g. in the following code I set a black shadow to be 1 pixel above the text, which gave it a "pressed in" look, and now this shadow is 1px below the text, giving it a standard shadow. ... CGContextSetShadowWithColor(context, CGSizeMake(0.f, 1.f), 0.5f, shadowColor); CGContextShowGlyphsAtPoint(context, origin.x, origin.y, glyphs, length); ... Now I don't know whether I am (or have been) doing something wrong or whether there has been a change to the handling of this setting. I haven't applied any transformation that would explain this to me, at least not knowingly. I've flipped the text matrix in one instance, but not in others and this behavior is consistent. Plus I wasn't able to find anything about this in the SDK Release Notes, so it looks like it's probably me. What might be the issue?

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  • Pixel Perfect Collision Detection in HTML5 Canvas

    - by Armin Ronacher
    Hi, I want to check a collision between two Sprites in HTML5 canvas. So for the sake of the discussion, let's assume that both sprites are IMG objects and a collision means that the alpha channel is not 0. Now both of these sprites can have a rotation around the object's center but no other transformation in case this makes this any easier. Now the obvious solution I came up with would be this: calculate the transformation matrix for both figure out a rough estimation of the area where the code should test (like offset of both + calculated extra space for the rotation) for all the pixels in the intersecting rectangle, transform the coordinate and test the image at the calculated position (rounded to nearest neighbor) for the alpha channel. Then abort on first hit. The problem I see with that is that a) there are no matrix classes in JavaScript which means I have to do that in JavaScript which could be quite slow, I have to test for collisions every frame which makes this pretty expensive. Furthermore I have to replicate something I already have to do on drawing (or what canvas does for me, setting up the matrices). I wonder if I'm missing anything here and if there is an easier solution for collision detection.

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  • "Beveled" Shapes in Quartz 2D

    - by Shaggy Frog
    I'm familiar with some of the basics of Quartz 2D drawing, like drawing basic shapes and gradients and so on, but I'm not sure how to draw a shape with a "beveled" look, like this: Essentially we've got a shine on one corner, and maybe some shading in the opposite corner. I think -- I didn't make this image, although I'd like to be able to approximate it. Any ideas? This is on the iPhone, and I'd like to use built-in frameworks and avoid any external libraries if at all possible.

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