pixel | 易学教程

How to display pixels on screen directly from a raw array of RGB values faster than SetPixel()?

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I enjoy making "animations" in c++ such as a MandelBrot Set zoomer, Game of Life simulator etc. by setting pixels directly to the screen frame-by-frame. The SetPixel() command makes this incredibly easy, although unfortunately it's also painfully slow. Here is the sort of set-up I use for each frame, if I wanted to paint the entire screen with the contents of the array R: #include <windows.h> using namespace std; int main() { int xres = 1366; int yres = 768; char *R = new char [xres*yres*3]; /* R is a char array containing the RGB value of each pixel sequentially Arithmetic operations done to

sass和stylus1px解决方案

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1.sass 1 @charset "utf-8"; 2 /** 3 * @module 背景与边框 4 * @description 为元素添加边框（包括1px边框） 5 * @method border 6 * @version 2.0.0 7 * @param {String} $border-width 指定边框厚度（单位为px），默认值：1px，取值与`border-width`属性一致，不同方向代表边框位置 <2.0.0> 8 * @param {String} $border-color 指定边框颜色 <2.0.0> 9 * @param {String} $border-style 指定边框样式 <2.0.0> 10 * @param {String} $radius 指定边框圆角半径，默认值：null <2.0.0> 11 */ 12 @mixin border($border-width: 1px, $border-color: map-get($base, border-color), $border-style: solid, $radius: null) { 13 // 为边框位置提供定位参考 14 position: relative; 15 @if $border-width == null { 16 $border-width: 0; 17 } 18

Java: Get the RGBA from a Buffered Image as an Array of Integer

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问题 Given an image file, say of PNG format, how to I get an array of int [r,g,b,a] representing the pixel located at row i, column j? So far I am starting here: private static int[][][] getPixels(BufferedImage image) { final byte[] pixels = ((DataBufferByte) image.getRaster().getDataBuffer()).getData(); final int width = image.getWidth(); final int height = image.getHeight(); int[][][] result = new int[height][width][4]; // SOLUTION GOES HERE.... } Thanks in advance! 回答1: You need to get the

python — measuring pixel brightness

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How can I get a measure for a pixels brightness for a specific pixel in an image? I'm looking for an absolute scale for comparing different pixels' brightness. Thanks Saulpila To get the pixel's RGB value you can use PIL : from PIL import Image from math import sqrt imag = Image.open("yourimage.yourextension") #Convert the image te RGB if it is a .gif for example imag = imag.convert ('RGB') #coordinates of the pixel X,Y = 0,0 #Get RGB pixelRGB = imag.getpixel((X,Y)) R,G,B = pixelRGB Then, brightness is simply a scale from black to white, witch can be extracted if you average the three RGB

OpenGL ES: Undo in a Pixel Painting App

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问题 I'm currently working on an app that allows the user to draw pixelated images using OpenGL ES, but I don't know how to implement an undo function. How could I do it? I thought of using an image for every pixel and adding it to an array. Basically, how can I store the rectangles I use as pixels? 回答1: you can try : NSData *data = [NSData dataWithBytes:vertexBuffer length:vertexCount * sizeof(GL_FLOAT) * 2] ; if (self.vertexBuffers == nil) self.vertexBuffers = [[NSMutableArray alloc] init];

Why use ems for padding & margins with browsers now scaling correctly? [closed]

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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 5 years ago . I've been wondering about this questions for some time and created a pixel version and and em version to compare the differences when zoomed in - there were none. Most of what I've read states something like "you need to make them ems for scalability" but I think it's a moot point

Drawing multiple pixels/rectangles

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问题 I'm trying to make a java sand game and can't get past one bit. i've made my method that draws a rectangle at mouseX and mouseY, and i have set it up so it updates every frame so it constantly follows the mouse. what i assume is that i would use an array to create each rectangle, and from there would use a pre-defined algorithm to float to the ground, I'm all good with that, i just don't understand how to 'hook my method' up to an array. This is the method i am using to draw the rectangle (in

How to create and implement a pixel tracking code

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OK, here's a goal I've been looking for a while. As it's known, most advertising and analytics companies use a so called "pixel" code in order to track websites views, transactions, conversion etc. I do have a general idea on how it works, the problem is how to implement it. The tracking codes consist from few parts. The tracking code itself. This is the code that the users inserts on his webpage in the <head> section. The main goal of this code is to set some customer specific variables and to call the *.js file. *.js file. This file holds all the magic of CRUD (create/read/update/delete)

How does invisible pixel conversion tracking work?

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I'm trying to track clicks from our site to an external website. On the external website, I'd like to place some code on their checkout thank-you page, that tells our server that a particular click has resulted in a sale. How does this tracking code work? Does it need to be a pixel? Do we need to drop a cookie before we send the user to the external website? Thanks. jonaz Pixel-based conversion tracking is pretty straightforward. You set up a basic web server to accept HTTP GET requests and write logs for those requests. On the merchant's confirmation page you put an image where the src

Python: how do you create an array with information about each pixel from an image?

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问题 For example, a 3 pixel by 3 pixel jpeg image of a checkerboard should be something like [[#000000, #FFFFFF, #000000], [#FFFFFF, #000000, #FFFFFF], [#000000, #FFFFFF, #000000]] I feel like I may need to download PIL, but I cannot tell what the module does from their website. I also need to be able to generate images from these types of arrays. Thank you! 回答1: Use the Image.getdata method. The method returns a generator that you can iterate over: from PIL import Image img = Image.open("a.png")