Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>You need to "step down" several times. Instead of scaling from a very large image to a very small, you need to re-scale it to intermediary sizes.</p> <p>Consider an image you want to draw at 1/6 scale. You could do this:</p> <pre><code>var w = 1280; var h = 853; ctx.drawImage(img, 0, 0, w/6, h/6); </code></pre> <p>Or you could draw it to an in-memory canvas at 1/2 scale, then 1/2 scale again, then 1/2 scale again. The result is a 1/6 scale image, but we use three steps:</p> <pre><code>var can2 = document.createElement('canvas'); can2.width = w/2; can2.height = w/2; var ctx2 = can2.getContext('2d'); ctx2.drawImage(img, 0, 0, w/2, h/2); ctx2.drawImage(can2, 0, 0, w/2, h/2, 0, 0, w/4, h/4); ctx2.drawImage(can2, 0, 0, w/4, h/4, 0, 0, w/6, h/6); </code></pre> <p>Then you can draw that back to your original context:</p> <pre><code>ctx.drawImage(can2, 0, 0, w/6, h/6, 0, 200, w/6, h/6); </code></pre> <p>You can see the difference live, here:</p> <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false"> <div class="snippet-code"> <pre class="snippet-code-js lang-js prettyprint-override"><code>var can = document.getElementById('canvas1'); var ctx = can.getContext('2d'); var img = new Image(); var w = 1280; var h = 853; img.onload = function() { // step it down only once to 1/6 size: ctx.drawImage(img, 0, 0, w/6, h/6); // Step it down several times var can2 = document.createElement('canvas'); can2.width = w/2; can2.height = w/2; var ctx2 = can2.getContext('2d'); // Draw it at 1/2 size 3 times (step down three times) ctx2.drawImage(img, 0, 0, w/2, h/2); ctx2.drawImage(can2, 0, 0, w/2, h/2, 0, 0, w/4, h/4); ctx2.drawImage(can2, 0, 0, w/4, h/4, 0, 0, w/6, h/6); ctx.drawImage(can2, 0, 0, w/6, h/6, 0, 200, w/6, h/6); } img.src = 'http://upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Equus_quagga_%28Namutoni%2C_2012%29.jpg/1280px-Equus_quagga_%28Namutoni%2C_2012%29.jpg'</code></pre> <pre class="snippet-code-css lang-css prettyprint-override"><code>canvas { border: 1px solid gray; }</code></pre> <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;canvas id="canvas1" width="400" height="400"&gt;&lt;/canvas&gt;</code></pre> </div> </div> </p> <p><a href="http://jsfiddle.net/qwDDP/" rel="noreferrer">View same snippet on jsfiddle.</a></p>
    singulars
    1. This table or related slice is empty.
    1. POHow to scale images on a html5 canvas with better interpolation?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USJaydles
    1. USSimon Sarris
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POHow to scale images on a html5 canvas with better interpolation?
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COThanks a lot for this idea! The second image looks really much better! I will try that now and look how performant it is...
      singulars
      1. PO
      1. USKumpu
    2. COwow i am really impressed. rescaling in 15 steps needs only 2ms! (ok, i have a i7 running here, but still....) thank you
      singulars
      1. PO
      1. USKumpu
    3. COYeah `drawImage()` is one of the fastest operations you can do on canvas, so don't feel bad about 8x step downs on image scales
      singulars
      1. PO
      1. USSimon Sarris
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload