Source code
Revision control
Copy as Markdown
Other Tools
Test Info:
- Manifest: layout/reftests/scrolling/reftest.list
<!DOCTYPE html>
<head>
<meta charset="utf-8">
<title>Testcase for %-height potentially-overflowing images</title>
<!-- This test exercises a series of scenarios where the presence of
scrollbars affects the layout in a way that may make those scrollbars
unnecessary. Specifically, we have a series of examples here
with a scrollable div, where...
- The child's width depends on its container's height, via
its aspect ratio and via having a percent-height.
- *Without* scrollbars, the child is too wide and causes horizontal
overflow.
- If we *add* a horizontal scrollbar (which occupies vertical space),
the child's height is reduced (on platforms where scrollbars take up
space) and so its width is reduced as well, and it might not
cause horizontal overflow beyond its parent's border-box anymore.
This creates a bit of a paradox. We resolve it by opting to show
scrollbars, to be on the safe side & to make sure that we don't
have any unreachable content.
-->
<style>
.container {
overflow: auto;
height: 80px;
border: 2px solid purple;
margin: 1px;
display: inline-block;
}
.percent-size {
display: block;
height: 100%;
border: 2px solid black;
box-sizing: border-box;
}
</style>
</head>
<body>
<!-- Here, the div is extremely skinny; there'll definitely be horizontal
overflow (but not vertical), so we should just show the horizontal
scrollbar: -->
<div class="container" style="width: 50px; height: 120px">
<img class="percent-size" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAYAAABytg0kAAAADklEQVQImWP4DwUMMAAAa6YH+b3nj3MAAAAASUVORK5CYII=">
</div>
<div class="container" style="width: 60px; height: 120px">
<img class="percent-size" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAYAAABytg0kAAAADklEQVQImWP4DwUMMAAAa6YH+b3nj3MAAAAASUVORK5CYII=">
</div>
<br>
<!-- Here, the div is nearly wide enough to avoid overflow, but not quite. On
platforms where scrollbars occupy layout-space, the presence of any
horizontal scrollbar here will reduce the height of the child, and (via
the child's aspect ratio) reduce the width of the child, such that the
child ends up skinnier than the parent's width and won't overflow the
parent's border-box anymore. We resolve this by just throwing up our
hands and showing *both* scrollbars (horizontal and vertical). -->
<div class="container" style="width: 78px">
<img class="percent-size" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAYAAABytg0kAAAADklEQVQImWP4DwUMMAAAa6YH+b3nj3MAAAAASUVORK5CYII=">
</div>
<div class="container" style="width: 79px">
<img class="percent-size" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAYAAABytg0kAAAADklEQVQImWP4DwUMMAAAa6YH+b3nj3MAAAAASUVORK5CYII=">
</div>
<br>
<!-- Here, the div is wide enough so that no scrollbars are needed. -->
<div class="container" style="width: 80px">
<img class="percent-size" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAYAAABytg0kAAAADklEQVQImWP4DwUMMAAAa6YH+b3nj3MAAAAASUVORK5CYII=">
</div>
<div class="container" style="width: 90px">
<img class="percent-size" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAYAAABytg0kAAAADklEQVQImWP4DwUMMAAAa6YH+b3nj3MAAAAASUVORK5CYII=">
</div>
</body>