javascript - HTML5 Canvas y-height not correct -

-

so i'm trying make simple animated hmtl canvas animated block moves around canvas using wasd. noticed painting rectangle on canvas of size 5,5 made looked rectangle of size 5,10. when testing redrawing function , printing console x , y location of element in canvas, noticed rectangle can go 1-300 in x direction, 1-150 in y direction. happens though canvas styled 300,300. can figure out if i've done silly?

    <!doctype html> <html> <head>     <link rel="stylesheet" type="text/css" href="style.css">     <script type="text/javascript" src="script.js" defer></script> </head> <body>     <div class="text-holder holder" id="instruction-holder">         <p class="text" id="instruction">use wasd navigate around viewer</p>     </div>     <div class="holder" id="canvas-holder">         <canvas id="canvas"></canvas>     </div> </body> </html>

and css

    #canvas {     width: 300px;     height:300px;     margin-left: auto;     margin-right: auto;     display: block;     border-style: solid;     border-color: grey;     border-radius: 1px; }  .holder {     display: block;     margin-left: auto;     margin-right: auto;     text-align: center; }

and js

var = "87", down = "83", left = "65", right = "68", x = 10, y = 5, xsize = 10, ysize = 5; var c = document.getelementbyid("canvas"); var ctx = c.getcontext("2d"); var xpos, ypos;  window.addeventlistener("load",init); document.addeventlistener('keydown',move);  function init() {     xpos = 1;     ypos = 1;     ctx.fillstyle = "black";     ctx.fillrect(xpos,ypos,xsize,ysize); }  function clear() {     ctx.clearrect(0,0,300,300); }  function redraw(delx, dely) {     console.log(ypos+dely + " " + (xpos+delx));     if (xpos+delx > 0 && xpos+delx < 300 &&          ypos+dely > 0 && ypos+dely < 150) {         clear();         ctx.fillstyle = "black";         xpos = xpos+delx;         ypos = ypos+dely;         ctx.fillrect(xpos,ypos,xsize,ysize);     } }  function move(ev) {     var delx, dely;     var key = ev.keycode;     if (key == up) {         delx = 0;         dely = -y;     } else if (key == down) {         delx = 0;         dely = y;     } else if (key == left) {         delx = -x;         dely = 0;            } else if (key == right) {         delx = x;         dely = 0;     }      if (delx != undefined && dely != undefined) {         redraw(delx, dely);     } }

you have set size of canvas explicitly or use default size of 300x150 (css scales element, not bitmap - bitmap of 300x150 stretched fit see on screen css rule, bitmap remain same size internally):

<canvas id="canvas" width=300 height=300></canvas>

then remove these:

#canvas {   /* width: 300px; */   /* height:300px; */   ...

Comments

Post a Comment

Popular posts from this blog

c++ - Delete matches in OpenCV (Keypoints and descriptors) -

-
i want check scene image against 2 train images. that, detect features , compute descriptors of both training images. before detecting, computing , matching scene image, delete matches of train1 , train2. because these matches won't facilitate matching of scene image train1 , train2. so, match train1 train2 , vector of matches trainidx , queryidx. how can delete these matches in keypoints-vector , descriptor matrix of train1 , train2? best regards, dwi i have done below: std::vector<cv::keypoint> keypoints[2]; cv::mat descriptor[2]; std::vector< cv::dmatch > matches; /* write code generate keypoints, descriptors , matches here... keypoint[0] -> train image 1 keypoints keypoint[1] -> train image 2 keypoints descriptor[0] -> train image 1 descriptors descriptor[1] -> train image 2 descriptors matches -> matched between train image 1 , 2 */ // logic keep unmatched keypoints , corresponding descriptor
Read more

java - Could not locate OpenAL library -

-
i writing game using slick2d library, uses lwjgl. lwjgl version 2.9.3. using netbeans 8. i tried adding sounds game, example music track on main menu. problem is, exception when run game, despite game still compiling , running except sound of course: sat mar 21 01:23:57 edt 2015 error:could not locate openal library. org.lwjgl.lwjglexception: not locate openal library. @ org.lwjgl.openal.al.create(al.java:156) @ org.lwjgl.openal.al.create(al.java:156) @ org.lwjgl.openal.al.create(al.java:102) @ org.lwjgl.openal.al.create(al.java:206) @ org.newdawn.slick.openal.soundstore$1.run(soundstore.java:295) @ java.security.accesscontroller.doprivileged(native method) @ org.newdawn.slick.openal.soundstore.init(soundstore.java:292) @ org.newdawn.slick.music.<init>(music.java:156) @ org.newdawn.slick.music.<init>(music.java:75) @ view.mainmenu.init(mainmenu.java:58) i didn't include rest of error states error happens in game code. the
Read more

sorting - opencl Bitonic sort with 64 bits keys -

-
i used nvidia sdk bitonic sort , works great me. 32 bits (uint) need ulong keys. have typically 2^14 keys @ time , power of 2. searched on not find kernel designed ulong. i tried modified nvidia sdk bitonic sort using ulong keys not work. kernel not crash after de call clenqueuendrangekernel got error : cl_invalid_command_queue can tell me how modify bitonic sort or radixsort, or can sort ulong keys? i running nvidia quadro 4000 opencl 1.1 cuda 6.5.20 full_profile used original nvidia sdk bitonicsort.cl i used"ulong" keys , value input , ouput instead of "uint" thanks helping i made work-around suit need. used 30 bits of key , 18 high bits of value sorting. changed comparators (2 lines): '#define mask 0xffffc000 // suit need from this: if( (*keya > *keyb) == dir ) this: if(((*keya > *keyb)||((*keya == *keyb)&&((*vala & mask)> (*valb & mask)))) == dir ) it works fine. but, still, it's work-a
Read more