Alter coordinates system by flipping X axis (start at top right corner)

Question

I'm looking for a simple way to make the coordinate system in a given svg element start from the top right corner, instead of the top left. This means the X axis is flipped, thus increasing the x attribute of an element renders it further to the left, and increasing the y attribute renders it further to the bottom as usual.

I've played around with scale and viewBox, however:

• scale almost solves the problem, but it doesn't really work for my use case because it also flips the text I've got rendered
• viewBox doesn't seem work with height="100%" and width="100%". For my use case I don't think I can hard code the height and width of the SVG because I need it to be usable across many different resolutions and screen sizes.

This question says it solves the same problem for the Y axis with a matrix transformation. I looked around and tried to calculate the equivalent for the X axis, but with no success.

Here is an example of what I'm trying to achieve:

<svg style="border: 1px black solid;" height="100%" width="100%">
  <g>
    <g>
      <rect fill="#F0BC40" width="70" height="12" x="0" y="30"></rect>
      <text fill="black" font-size="10px" text-anchor="middle" x="35" y="29">7</text>
    </g>
    <g>
      <rect fill="orange" width="50" height="12" x="72" y="30"></rect>
      <text fill="black" font-size="10px" text-anchor="middle" x="97" y="29">5</text>
    </g>
    <g>
      <rect fill="orange" width="40" height="12" x="124" y="30"></rect>
      <text fill="black" font-size="10px" text-anchor="middle" x="144" y="29">4</text>
    </g>
    <g>
      <rect fill="red" width="50" height="12" x="166" y="30"></rect>
      <text fill="black" font-size="10px" text-anchor="middle" x="191" y="29">5</text>
    </g>
      <rect fill="#52575E" width="2" height="16" x="70" y="28"></rect>
      <rect fill="#52575E" width="2" height="16" x="122" y="28"></rect>
      <rect fill="#52575E" width="2" height="16" x="164" y="28"></rect>
    </g>
  </svg>

As you can see I'd like this stacked bar to be rendered from the right, with the red bar being the furthest to the left (so essentially the stacked bar would be flipped)

Also I'm doing this in Elm, so I can't access the DOM to check widths, heights or coordinates of elements (I'm calculating everything in a functional way).

If anyone could help me achieve this I'd be greatly thankful.

Answer 1

The way I would think about this is drawing your bars from x="0" to the left, and then setting the viewBox with a negative x value and a width that lets it end at x="0".

For the text elements, add a negative sign to the x value. For the rects, set the x value as x -> -x - width.

Define a viewBox such that the lowest x value is still inside, or whatever is appropriate.

<svg style="border: 1px black solid;" height="100%" width="100%" viewBox="-500 0 500 100">
  <g>
    <g>
      <rect fill="#F0BC40" width="70" height="12" x="-70" y="30"></rect>
      <text fill="black" font-size="10px" text-anchor="middle" x="-35" y="29">7</text>
    </g>
    <g>
      <rect fill="orange" width="50" height="12" x="-122" y="30"></rect>
      <text fill="black" font-size="10px" text-anchor="middle" x="-97" y="29">5</text>
    </g>
    <g>
      <rect fill="orange" width="40" height="12" x="-164" y="30"></rect>
      <text fill="black" font-size="10px" text-anchor="middle" x="-144" y="29">4</text>
    </g>
    <g>
      <rect fill="red" width="50" height="12" x="-216" y="30"></rect>
      <text fill="black" font-size="10px" text-anchor="middle" x="-191" y="29">5</text>
    </g>
    <rect fill="#52575E" width="2" height="16" x="-72" y="28"></rect>
    <rect fill="#52575E" width="2" height="16" x="-124" y="28"></rect>
    <rect fill="#52575E" width="2" height="16" x="-166" y="28"></rect>
  </g>
</svg>

This will scale the text and the bars; if you need to avoid that, there is a trick. You can surround the content with two <svg> elements and use the inner one to move everything 100% to the right. overflow="visible" (or style="overflow:visible") makes sure the content is visible although it is formally outside the viewport of the inner <svg>.

<svg style="border: 1px black solid;" height="100%" width="100%">
  <svg x="100%" overflow="visible">
    <g>
      <g>
        <rect fill="#F0BC40" width="70" height="12" x="-70" y="30"></rect>
        <text fill="black" font-size="10px" text-anchor="middle" x="-35" y="29">7</text>
      </g>
      <g>
        <rect fill="orange" width="50" height="12" x="-122" y="30"></rect>
        <text fill="black" font-size="10px" text-anchor="middle" x="-97" y="29">5</text>
      </g>
      <g>
        <rect fill="orange" width="40" height="12" x="-164" y="30"></rect>
        <text fill="black" font-size="10px" text-anchor="middle" x="-144" y="29">4</text>
      </g>
      <g>
        <rect fill="red" width="50" height="12" x="-216" y="30"></rect>
        <text fill="black" font-size="10px" text-anchor="middle" x="-191" y="29">5</text>
      </g>
      <rect fill="#52575E" width="2" height="16" x="-72" y="28"></rect>
      <rect fill="#52575E" width="2" height="16" x="-124" y="28"></rect>
      <rect fill="#52575E" width="2" height="16" x="-166" y="28"></rect>
    </g>
  </svg>
</svg>