[Webkit-unassigned] [Bug 160804] New: ctx.drawImage fails silently if arguments are non-integers

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Fri Aug 12 08:49:46 PDT 2016


            Bug ID: 160804
           Summary: ctx.drawImage fails silently if arguments are
    Classification: Unclassified
           Product: WebKit
           Version: Safari Technology Preview
          Hardware: Macintosh
                OS: OS X 10.11
            Status: NEW
          Severity: Major
          Priority: P2
         Component: Canvas
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: richard.a.harris at gmail.com
                CC: dino at apple.com


Using ctx.drawImage(image, sx, sy, swidth, sheight, dx, dy, dwidth, dheight), where ctx is a CanvasRenderingContext2D, fails if any of sx, sy, swidth or sheight are non-integers. No error is given.

Steps to Reproduce:

Create an HTML page with the following code, and open it in Safari or Safari Technology Preview:

<canvas id='target' width='100' height='100'/>

  image = new Image();

  image.onload = function () {
    // Changing 0.1 to 0 will cause the image to appear
    target.getContext( '2d' ).drawImage( image, 0.1, 0, 100, 100, 0, 0, 100, 100 );

  image.src = 'http://placehold.it/100x100';

Actual Results:

The canvas remains blank.

Expected Results:

The image is drawn to the canvas (albeit possibly with some sampling artifacts).

Build Date & Platform: Date and platform of the build in which you first encountered the bug.

Safari Version 9.1.2 (11601.7.7) on Mac OS 10.

Additional Information:

This works as expected in all other browsers. The dx, dy, dwidth and dheight arguments work whether or not they are integers.

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