From c2e3971013b49c68bfa590b3b491d606b4f3adfb Mon Sep 17 00:00:00 2001
From: Jamie Pate <jpate@fortinet.com>
Date: Mon, 15 Aug 2022 21:12:19 -0700
Subject: Improve performance of screen_get_dpi() in Javascript
Replace a bisect with a single multiplication when calling
screen_get_dpi() in Javascript
Tested the value of
window.matchMedia(`(resolution:${(window.devicePixelRatio*96).toFixed(100)}dpi)`).matches
which is true except for values that cause a lot of rounding errors
(e.g. dpr : 0.3 => resolution: 28.799999999999997dpi)
Even in these cases the value matches the result of the previous
`findDPI()` method.
See also:
https://github.com/godotengine/godot/commit/6cff589b5bd483b563fe465bde74ca94902aab41#r81273660
---
.../javascript/js/libs/library_godot_display.js | 28 ++++++----------------
1 file changed, 7 insertions(+), 21 deletions(-)
(limited to 'platform/javascript/js/libs')
diff --git a/platform/javascript/js/libs/library_godot_display.js b/platform/javascript/js/libs/library_godot_display.js
index c7729a8c5b..768eaf9e1d 100644
--- a/platform/javascript/js/libs/library_godot_display.js
+++ b/platform/javascript/js/libs/library_godot_display.js
@@ -336,26 +336,12 @@ const GodotDisplay = {
$GodotDisplay__deps: ['$GodotConfig', '$GodotRuntime', '$GodotDisplayCursor', '$GodotEventListeners', '$GodotDisplayScreen', '$GodotDisplayVK'],
$GodotDisplay: {
window_icon: '',
- findDPI: function () {
- function testDPI(dpi) {
- return window.matchMedia(`(max-resolution: ${dpi}dpi)`).matches;
- }
- function bisect(low, high, func) {
- const mid = parseInt(((high - low) / 2) + low, 10);
- if (high - low <= 1) {
- return func(high) ? high : low;
- }
- if (func(mid)) {
- return bisect(low, mid, func);
- }
- return bisect(mid, high, func);
- }
- try {
- const dpi = bisect(0, 800, testDPI);
- return dpi >= 96 ? dpi : 96;
- } catch (e) {
- return 96;
- }
+ getDPI: function () {
+ // devicePixelRatio is given in dppx
+ // https://drafts.csswg.org/css-values/#resolution
+ // > due to the 1:96 fixed ratio of CSS *in* to CSS *px*, 1dppx is equivalent to 96dpi.
+ const dpi = Math.round(window.devicePixelRatio * 96);
+ return dpi >= 96 ? dpi : 96;
},
},
@@ -461,7 +447,7 @@ const GodotDisplay = {
godot_js_display_screen_dpi_get__sig: 'i',
godot_js_display_screen_dpi_get: function () {
- return GodotDisplay.findDPI();
+ return GodotDisplay.getDPI();
},
godot_js_display_pixel_ratio_get__sig: 'f',
--
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