<!DOCTYPE HTML> <html> <head> <title>Test that pixel lengths don't change based on DPI</title> <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script> <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" /> </head> <body> <div id="display"> <div id="pt" style="width:90pt; height:90pt; background:lime;">pt</div> <div id="pc" style="width:5pc; height:5pc; background:yellow;">pc</div> <div id="mm" style="width:25.4mm; height:25.4mm; background:orange;">mm</div> <div id="cm" style="width:2.54cm; height:2.54cm; background:purple;">cm</div> <div id="in" style="width:1in; height:1in; background:magenta;">in</div> <div id="q" style="width:101.6q; height:101.6q; background:blue;">q</div> <div id="mozmm" style="width:25.4mozmm; height:25.4mozmm; background:cyan;">mozmm</div> </div> <pre id="test"> <script class="testbody" type="text/javascript"> var oldDPI = SpecialPowers.getIntPref("layout.css.dpi"); var dpi = oldDPI; function check(id, val) { var e = document.getElementById(id); is(Math.round(e.getBoundingClientRect().width), Math.round(val), "Checking width in " + id + " at " + dpi + " DPI"); is(Math.round(e.getBoundingClientRect().height), Math.round(val), "Checking height in " + id + " at " + dpi + " DPI"); } function checkPixelRelativeUnits() { check("pt", 120); check("pc", 80); check("mm", 96); check("cm", 96); check("in", 96); check("q", 96); } checkPixelRelativeUnits(); SimpleTest.waitForExplicitFinish(); SpecialPowers.pushPrefEnv({'set': [['layout.css.dpi', dpi=96]]}, test1); var mozmmSize; function test1() { var mozmm = document.getElementById("mozmm"); mozmmSize = mozmm.getBoundingClientRect().width; is(Math.round(mozmmSize), Math.round(mozmm.getBoundingClientRect().height), "mozmm div should be square"); checkPixelRelativeUnits(); SpecialPowers.pushPrefEnv({'set': [['layout.css.dpi', dpi=192]]}, test2); } function test2() { // At 192 dpi, a one-inch box should be twice the number of device pixels, // and since we haven't changed the device-pixels-per-CSS-pixel ratio, the // mozmm box should be twice the size in CSS pixels. check("mozmm", mozmmSize*2); checkPixelRelativeUnits(); SimpleTest.finish(); } </script> </pre> </body> </html>