drawing

问题 I am drawing annotations on a view. The approach i am using to draw star is below. -(void)drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetLineWidth(context, 2.0); CGFloat xCenter = rect.size.width / 2; CGFloat yCenter = rect.size.height / 2; float width; if(rect.size.width > rect.size.height) { width = rect.size.height; } else { width = rect.size.width; } double r = width / 2.0; float flip = -1.0; double theta = 2.0 * M_PI * (2.0 / 5.0); // 144

问题 I'm writing a PyGtk paint program based on the basic tutorial found here. Is there any way to add an image to the drawing area so that you can still draw over the image? Like a stamp, or an imported photo for example. I've tried adding a gtk.Image() but gtk.DrawingArea object has no attribute add . self.window = gtk.Window((gtk.WINDOW_TOPLEVEL)) self.window.set_title ("Canvas") self.window.set_position(gtk.WIN_POS_CENTER) hbox = gtk.HBox(False, 0) self.window.add(hbox) self.window.set

问题 I want to give a blur effect to my DrawingVisual . I can do this using BitmapEffect properties like: DrawingVisual drawingVisual = new DrawingVisual(); DrawingContext drawingContext = drawingVisual.RenderOpen(); var effect = new System.Windows.Media.Effects.BlurBitmapEffect(); effect.Radius = 10; drawingVisual.BitmapEffect = effect; But the compiler give me a warning that Bitmap effect properties is obsolete. What other alternative I can use to achive the effect on DrawingVisual ? 回答1: Effect

问题 I know how to draw lines and shapes with CGPath s . But I couldn't figure out how to draw this symbol for a circuit diagram What code should I write to get that half circle shape? This is what I have so far: - (void)drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetLineWidth(context, 5.0); CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor); CGContextMoveToPoint(context, 60, 80); CGContextAddLineToPoint(context, 120, 80);

问题 I am trying to do custom drawing of an image(with alpha) and eventually going to apply different color tints to it. Right now I am just trying to draw it correctly. This might be simple problem but the result is the ALPHA on my image is black. Image is .png created from photoshop with correct alpha. - (void) drawRect:(CGRect)area { [imgView.image drawInRect: area blendMode:blendMode alpha:alpha]; // draw image } blendMode is normal and alpha is 1.0. The image is good except alpha being black.

问题 I'm current drawing some tile (small square images) for a mapping app. I'm using WPF to draw shapes on to these tiles. I have a list of geospatial coordinates that make up polygons that are drawn. The geospatial coordinates that make up these polygons are converted in to pixel coordinates. The tiles are created at various set levels of detail. At most of these levels of detail the drawing is fine; but at certain levels a visual artifact appears in the form of a spike or a line. Here's an

问题 I have been tasked with turning this rough idea into a live page. While I have a basic structure established, I am wondering the best way to go about creating the curved lines that connect the months. Should I just create images and over lay them? Is there a way to draw them with some kind of scripting/coding? Canvas? I don't know the best way to do this. 回答1: I just put this together to show you that it is very possible and there are probably other ways to do it. #upper-line { border: solid

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed last year . I am wondering if anyone here can help me with some pseudocode or at least point me in the right direction on how to draw a circle segment without anti-aliasing. 回答1: The formula for points on a circle are: x = xcenter + radius * sin(theta) y = ycenter + radius * cos(theta) where

问题 I am trying to create a white picture (greyscale format). So here is the code I use: Bitmap bmp = new Bitmap(1, 1, System.Drawing.Imaging.PixelFormat.Format16bppGrayScale); bmp.SetPixel(0, 0, Color.FromArgb(255, 255, 255)); bmp = new Bitmap(bmp, i.Width, i.Height); "I" is an existing Bitmap image. I am playing with its channels. The principle is to create a 1 pixel image in greyscale, give this pixel the white color and then enlarge it to the good size. But I have this as a result: "An

问题 I have it so that you can draw under the image, but you must start drawing outside of the image border and move under the image. So you can't start right on the image. How do I fix this? My html is just: <canvas id="canvas"></canvas> <img id="html5" src="http://i.imgur.com/Wpx3Vum.png" style="position:absolute;left:100px;top:15px;" /> 回答1: You can use two canvas elements instead: Put two canvas elements on top of each other Draw the image you want to superimpose on the top canvas Add mouse