javascript - Using CSS and HTML5 to create navigation buttons using trapezoids

Question

I'm trying to make a navigation-div with 4 buttons, one to go left, one to go right, another one to go down and yet another one to go up. Plus there needs to be an OK-button in the middle.

The buttons need to be positions that they form any (the size is not set) rectangle, inside the buttons are positions on the very right, left, top and bottom, and each of them are trapezoids, leaving a square in the middle for the OK-Button.

Just like that:

What I've done is, that I created a trapezoid parent, with position relative shape using css:

.trapezoid_parent {
    position: relative;
}

And a trapezoid to use, which is absolute.

.trapezoid {
    position: absolute;
    border-bottom: 50px solid #f98d12;
    border-left: 80px solid transparent;
    border-right: 80px solid transparent;
    width: 100%; 
    height: 0; 
    z-index: 2;
    border-top: 1px solid #000000;
}

to make the top one, I flip the normal one and position it at the top:

.trapezoid.top {
    transform: rotate(180deg);
    top: 0;
}

the bottom trapezoid just has to be position on the bottom:

.trapezoid.bottom {
    bottom: 0;
}

Next up we need the left button

.left_button {
    height: 100%; 
    position: absolute; 
    width: 40%; 
    left:0; 
    z-index: 1;
    border-right: 1px solid #000000;
}

the one one the right

.right_button {
    height: 100%; 
    position: absolute; 
    width: 40%; 
    right:0; 
    z-index: 1;
    border-left: 1px solid #000000;
}

and last but not least the one in the center:

.center_button {
    height: 100%; position: absolute; width: 100%; right:0; z-index: 0;
}

Then, to put it all together I used the following html:

<div class="trapezoid_parent" style="width:200px; height:125px">
        <button class="left_button function"><i class='fa fa-arrow-left'></i></button>
        <button class="trapezoid top function"><i class='fa fa-arrow-down'></i></button>
        <button class="trapezoid bottom function"><i class='fa fa-arrow-down'></i></button>
        <button class="right_button function"><i class='fa fa-arrow-right'></i></button>
        <button class="center_button">OK</button>
</div>

To make the whole thing responsive I made jQuery plugin which changes the sizes accordingly. It does that, by changing the border-bottom, border-left and border-right properties according to the size of the parent:

var internal_square_size = ((1.0 / 2) - plugin.settings.square_size);

var tpw = $element.width();
var tph = $element.height();
$(".trapezoid", $element)
.css("border-left-width", "" + (tpw * internal_square_size) + "px")
.css("border-right-width", "" + (tpw * internal_square_size) + "px")
.css("border-bottom-width","" + (tph * internal_square_size) + "px");

$(".left_button, .right_button", $element).css("width", "" + internal_square_size*100 + "%");

The result looks like this:

You can view the whole thing here: full jsfiddle example

There are still a few problems and I've spend all my magic already, but maybe someone else has a few ideas how to get the last few pieces.

The diagonal borders can not be displayed using the method presented, which is something I cannot live with. Has anyone an idea?

Second of all: It would be very nice, if the buttons could actually end with the diagonal, because touching a button which is to small is always tough. Am I missing something? Is HTML5 not equipped to do the thing I ask of it?

Answer 1

As I mentioned in the comments, I think I would be using an SVG here.

A brief example of the proposed structure.

svg {
  display: block;
  width: 200px;
  height: 200px;
  margin: 25px auto;
  border: 1px solid grey;
  stroke: #006600;
}
#buttons polygon:hover {
  fill: orange;
}
#buttons rect:hover {
  fill: blue
}
#center {
  fill: #00cc00;
}
#top {
  fill: #cc3333;
}
#right {
  fill: #663399;
}
#left {
  fill: #bada55;
}

<svg viewbox="0 0 100 100">
  <g id="buttons">
    <rect id="center" x="25" y="25" height="50" width="50" />
    <polygon id="top" points="0,0 100,0 75,25 25,25" />
    <polygon id="right" points="100,0 75,25 75,75 100,100" />
    <polygon id="bottom" points="0,100 25,75 75,75 100,100" />
    <polygon id="left" points="0,0 25,25 25,75 0,100" />
  </g>
</svg>