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问题 I overriden Border control and in my overriden OnRender I do: protected override void OnRender(System.Windows.Media.DrawingContext dc) { this.SnapsToDevicePixels = true; this.VisualEdgeMode = EdgeMode.Aliased; var myPen = new Pen(new SolidColorBrush(Colors.LightGray), 1); dc.DrawLine(myPen, new Point(1, 1), new Point(1, RenderSize.Height - 1)); return; Which give me this result: Question: Is anybody can tell me why my code draw a line that start at (0,1) while it is suppose to start at (1, 1)

问题 How to you delete a specific line from a text file using readlines() like: f_open = open("textfile.txt", "r") lines = f_open.readlines() How do you use lines to choose a line in textfile.txt and delete it? Sorry if it doesn't make sense. 回答1: Use the fileinput module's inplace functionality. Refer Optional in-place filtering section at fileinput. The example below deletes the first line from a file: import fileinput import sys for line_number, line in enumerate(fileinput.input('myFile',

问题 I used canvas.drawLine to show a line but I want user to be able to see it being drawn from one point to another and also, if possible, control the duration of the animation. (something like progress bar but this is my custom widget) 回答1: You can use an AnimationController to control the animation duration. To draw the line "step by step" you can use a Tween (linear interpolation between a beginning and ending value). Then you just need to pass the current progress to your line painter and

问题 I want to remove a specific line in a plot of multiple lines. Bellow is a given example which is not sufficient for me because it removes only the last plotted line and not the line that I want to remove. How can I do that? How can I address a specific line(by name, by number, by reference) throughout the program and delete that line? self.axes.lines.remove(self.axes.lines[0]) 回答1: Almost all of the plotting functions return a reference to the artist object created ex: ln, = plot(x, y) # plot

问题 I have a string that contains some text followed by a blank line. What's the best way to keep the part with text, but remove the whitespace newline from the end? 回答1: Use String.trim() method to get rid of whitespaces (spaces, new lines etc.) from the beginning and end of the string. String trimmedString = myString.trim(); 回答2: String.replaceAll("[\n\r]", ""); 回答3: tl;dr String cleanString = dirtyString.strip() ; // Call new `String::string` method. String::strip… The old String::trim method

问题 How can I tell if a point belongs to a certain line? Examples are appreciated, if possible. 回答1: In the simplest form, just plug the coordinates into the line equation and check for equality. Given: Point p (X=4, Y=5) Line l (Slope=1, YIntersect=1) Plug in X and Y: Y = Slope * X + YIntersect => 5 = 1 * 4 + 1 => 5 = 5 So yes, the point is on the line. If your lines are represented in (X1,Y1),(X2,Y2) form, then you can calculate slope with: Slope = (y1 - y2) / (x1-x2) And then get the Y

问题 I'm writing a mobile web application where scrollbars are not displayed on the device's browser. Due to this, I'm trying to dynamically modify the height of the textarea to make it bigger, however I don't know of any way to actually get the line count on an html textarea. Any help would be greatly appreciated! EDIT So I realize now that it's not newlines per se, but actual line wrapping. So when one line finishes it wraps the text to the next line. It appears as if it is a new line. Any way

问题 I can't seem to be able to add text to a canvas if the text includes "\n". I mean, the line breaks do not show/work. ctxPaint.fillText("s ome \n \\n <br/> thing", x, y); The above code will draw "s ome \n <br/> thing" , on one line. Is this a limitation of fillText or am I doing it wrong? the "\n"s are there, and aren't printed, but they don't work either. 回答1: I'm afraid it is a limitation of Canvas' fillText . There is no multi-line support. Whats worse, there's no built-in way to measure

问题 I would like to make a game that is internally 320x240, but renders to the screen at whole number multiples of this (640x480, 960,720, etc). I am going for retro 2D pixel graphics. I have achieved this by setting the internal resolution via glOrtho(): glOrtho(0, 320, 240, 0, 0, 1); And then I scale up the output resolution by a factor of 3, like this: glViewport(0,0,960,720); window = SDL_CreateWindow("Title", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 960, 720, SDL_WINDOW_OPENGL); I

问题 I have two lines that intersect at a point. I know the endpoints of the two lines. How do I compute the intersection point in Python? # Given these endpoints #line 1 A = [X, Y] B = [X, Y] #line 2 C = [X, Y] D = [X, Y] # Compute this: point_of_intersection = [X, Y] 回答1: Unlike other suggestions, this is short and doesn't use external libraries like numpy . (Not that using other libraries is bad...it's nice not need to, especially for such a simple problem.) def line_intersection(line1, line2):