29751 2016-07-22 22:47:52 +0000 7.2 equivalent transform of an SVG viewport is mathematically wrong 2016-07-23 00:58:23 +0000 1 1 1 Unclassified SVG Coordinate Systems SVG 2.0 PC Linux NEW P2 normal Test Suite 1 ccprog schepers amelia.bellamy.royds www-svg oldest_to_newest 127043 0 ccprog 2016-07-22 22:47:52 +0000 I've tried to implement the algorithm described in section "7.2 Computing the equivalent transform of an SVG viewport" and found it to be wrong. > 9. Initialize translate-x to vb-x - e-x. > 10. Initialize translate-y to vb-y - e-y. The purpose of this is to move the viewport origin to the left/top coordinates of the viewBox. I. e. when the viewBox is to the right of the initial origin (vb-x > e-x), the origin needs to be moved to the right: x values get thus smaller (tx < 0). In addition, the last sentence implies that translation is applied after scaling. In this case the translation values also need to be multiplied by the scaling values. Therefore these steps must be > 9. Initialize translate-x to (e-x - vb-x) * scale-x. > 10. Initialize translate-y to (e-y - vb-y) * scale-y. Here are a few test cases to illustrate: x="0" y="0" width="21" height="10" viewBox="11 13 3 2" preserveAspectRatio="none" is equivalent to transform="translate(-77 -65) scale(7 5)" x="0" y="0" width="21" height="10" viewBox="11 13 3 2" preserveAspectRatio="xMinYMin meet" is equivalent to transform="translate(-55 -65) scale(5 5)" x="0" y="0" width="21" height="10" viewBox="11 13 3 2" preserveAspectRatio="xMidYMid meet" is equivalent to transform="translate(-52 -65) scale(5 5)" x="0" y="0" width="21" height="10" viewBox="11 13 3 2" preserveAspectRatio="xMaxYMax meet" is equivalent to transform="translate(-49 -65) scale(5 5)" x="0" y="0" width="21" height="10" viewBox="11 13 3 2" preserveAspectRatio="xMinYMin slice" is equivalent to transform="translate(-77 -91) scale(7 7)" x="0" y="0" width="21" height="10" viewBox="11 13 3 2" preserveAspectRatio="xMidYMid slice" is equivalent to transform="translate(-77 -93) scale(7 7)" x="0" y="0" width="21" height="10" viewBox="11 13 3 2" preserveAspectRatio="xMinYMin slice" is equivalent to transform="translate(-77 -95) scale(7 7)" 127044 1 amelia.bellamy.royds 2016-07-22 23:00:41 +0000 We're now using GitHub issues to track SVG spec bugs, I've created a copy of this issue here: https://github.com/w3c/svgwg/issues/215 127045 2 ccprog 2016-07-23 00:58:23 +0000 I got directed here from https://www.w3.org/Graphics/SVG/feedback.html, maybe you should update that page.