paint: Use viewport meta tag's `min-scale` and `max-scale` to clamp pinch zoom by shubhamg13 · Pull Request #40098 · servo/servo

shubhamg13 · 2025-10-23T08:58:28Z

Note: Targeting Mobile devices only.

Clamp Pinch Zoom factor using viewport' scale range parsed from <meta> tag.

Behavior in Servo with this PR

Zoom Type	Device Type	Meta Supported	Range
Pinch Zoom	Mobile	Yes	Parsed from
Pinch Zoom	Desktop	No	Default

Observed behavior in Chrome:

Device Type	Viewport Meta Support (pref)	Pinch Zoom (No Reflow)	Zoom (using keyboard)
Mobile (Android)	Yes	Clamped within Viewport Meta Range	Applied to Pinch Zoom*
Desktop (Touch Screen)	No	Clamped within Default Range	Same as Zoom (using menu)

References from Chromium:

Defination of page_scale_delta;
WebViewImpl::ApplyViewportChanges -> SetPageScaleFactorAndLocation -> SetScaleAndLocation -> DidSetScaleOrLocation -> ClampToConstraints

Testing: New WPT Test Added: wpt/visual-viewport/viewport-scale-clamped.html

Fixes: #40390 (Observed Inconsistent behavior with Chrome Android)

shubhamg13 · 2025-10-23T09:01:50Z

#39868 (comment) @mrobinson

In addition, stop clamping the pinch zoom by the page zoom clamp values.
They aren't meant for that. Instead set up some reasonable clamping
values for pinch zoom in the compositor.

I compared the behavior on Android and OHOS device, they use viewport values and restrict the pinch zoom accordingly.

cc: @xiaochengh

mrobinson

This just needs a bit of justification:

mrobinson · 2025-10-23T09:12:34Z

+        if let Some(viewport) = self.viewport_description.as_ref() {
+            requested_pinch_zoom = viewport.clamp_page_zoom(requested_pinch_zoom);
+        }

-        let old_zoom =
-            std::mem::replace(&mut self.pinch_zoom, PinchZoomFactor::new(new_pinch_zoom));
+        let old_zoom = std::mem::replace(
+            &mut self.pinch_zoom,
+            PinchZoomFactor::new(requested_pinch_zoom),
+        );


What happens when you combine pinch zoom and page zoom on these devices? Where in the specification does it mention that this should the non-layout viewport? Failing that, can you somehow explain the reasoning used by the other browsers and what their general strategy is with clamping values from the viewport metatag (an internal bug report or link to the code would suffice to)?

Splitting the scenarios observed on Chrome:

Mobile Devices: Supports Viewport Meta via pref, and when pinch zoom it is clamped as per meta viewport. When page zoomed using zoom option aka desktop zoom, it has range from 50% to 300% using slider.

Desktop Devices: Doesn't support Viewport Meta via pref, no pinch zoom only desktop zoom using preset values range from 25% to 500%.

Desktop Devices (with touch screen): Doesn't support Viewport Meta via pref, when pinch zoom, since no viewport meta parsed it gets clamped in default range and when desktop style zoom applied, it uses preset value range from 25% to 500%.

@mrobinson I have added the table for more clarity. Tell me know if you have any other concerns.

@shubhamg13 Some clarification:

When I ask how pinch zoom / page zoom interact here. I mean to ask whether or not combining pinch zoom and page zoom affect the clamping. For instance if page zoom is 2x, does that mean that we should clamp pinch zoom to [min_zoom / 2, max_zoom / 2]? If you first apply a page zoom, does it change the range of available pinch zoom values?

In addition, I'm looking for some justification to explain why this change is necessary. FWIW, I believe you that it is, but it just needs to reasoned so that it does not regress again. For example, the viewport meta tag was changed to only affect the page zoom viewport in #40055 and this change undoes some of that work. You also proposed a related change, so I'm pretty confused. We just need to be clear on what viewport it should affect. It seems quite odd that parts of the meta tag affect the layout viewport and others the visual viewport.

So we either need:

Specification text that describes how this is supposed to work.

In the case that this is underspecified either:

A link to a bug from another browser where the implementation and what viewport it affects is discussed.

A link to the code which shows how this works in other browsers.

When I ask how pinch zoom / page zoom interact here. I mean to ask whether or not combining pinch zoom and page zoom affect the clamping. For instance if page zoom is 2x, does that mean that we should clamp pinch zoom to [min_zoom / 2, max_zoom / 2]? If you first apply a page zoom, does it change the range of available pinch zoom values?

No they aren't combined. They are applied irrespective of each other having their separate clamping range.

And this change is required due to inconsistency observed as compared to Chrome.

P.S: I'll try to find some reference.

2. A link to the code which shows how this works in other browsers.

Here, In chromium PinchZoom is applied by first fetching the current page_scale, and applying magnify_delta over that.

Inside, it is clamped here.

And I further backtracked, its range comes from viewport_description

What you call "Desktop Zoom" in the table above is typically called "page zoom" and that's what we call it in Servo. I'm not sure how you were able to test this in the mobile version of Chrome as it no longer seems to be enabled in the Chrome browser. What did you do to test this? I am skeptical that it would be adjust the pinch zoom as these are very different concepts. Maybe whatever you were doing to test was adjusting the pinch zoom?

Safari for iOS does support reflowing style page zoom. I can try to see what its behavior is.

I'm not sure how you were able to test this in the mobile version of Chrome as it no longer seems to be enabled in the Chrome browser. What did you do to test this?

Updated table headings, PTAL.

Zoom (using menu): Click on More Menu (⋮) -> Zoom

Zoom (using keyboard) on Mobile: Connect Bluetooth Keyboard

Let me know what scenarios steps you are suspicious about.

Safari for iOS does support reflowing style page zoom. I can try to see what its behavior is.

Safari and Chrome on iOS uses WebKit.

On the other hand Chrome Desktop and Chrome Android use Blink.

IMHO our comparison should be with Blink Engine, right?

@mrobinson Chrome even provides an override switch to zoom where websites prevent zoom.

Reference 1

To zoom in on pages that prevent zoom, turn on Force enable zoom.

See 3 of Set default Page Zoom for all web pages

Reference 2

Websites can only control via <viewport> meta

They control pinch-zoom via this toogle switch.

When user enabled force enable zoom, we should always allow pinch-zoom [1]

shubhamg13 · 2026-01-29T15:33:28Z

Please help to review

mrobinson · 2026-01-30T07:37:34Z


    /// Constrains a zoom value within the allowed scale range
-    pub fn clamp_page_zoom(&self, zoom: f32) -> f32 {
+    pub fn clamp_zoom(&self, zoom: f32) -> f32 {


Please name this to be explicit ie clamp_pinch_zoom.

I am using it for both the zooms now.

Where in the specification does it say that it should be used to clamp both values? Everything that I have read suggests that it should be used to clamp the visual viewport (pinch zoom / page scale). If you clamp both values separately, I do not think this will have the correct behavior when both a page zoom and pinch zoom are applied -- which was my original question.

I just use the fallback behavior for clamping by using DEFAULT. Yes they should be different indeed.

In Chrome they have page Zoom Range of 0.25 to 50.0. But In Servo our Range was 0.1 and 10.0 as you didn't agree for this here.

If they should be separate, let's separate these concepts fully. If we still need to clamp the page zoom range via a hardcoded set of values create two new constants:

MINIMUM_PAGE_ZOOM

MAXIMUM_PAGE_ZOOM

in the code unit that needs to clamp page zoom. Then we can stop clamping page zoom at all using the ViewportDescription.

Sure will do, What range do you suggest for this...

I think we should just maintain the current behavior for page zooms.

Sure. Reverting changes for I made with page zoom.

Everything that I have read suggests that it should be used to clamp the visual viewport (pinch zoom / page scale).

With this conclusion of yours and coming to sole and primary goal of this PR. Please take a look and review

P.S: Sorry for lot of back and forth changes. I removed all the unrelated changes.

mrobinson · 2026-01-30T07:39:21Z

+        let new_page_zoom = self
+            .viewport_description
+            .unwrap_or_default()
+            .clamp_zoom(new_page_zoom);


Why are you clamping page zoom here as this change is about making the viewport metatag clamp pinch zoom. Why would it clamp both values? If page zoom needs to be clamped it should certain be a separate set of values as these concepts are distinct aren't they?

Basically it does same thing,

For Desktop (Meta not Parsed):, use Defualt Values

For Mobile (Meta Parsed): use Meta Values

Same as Chrome and ChromeAndroid

I'm pretty unconvinced by this, but I would change my mind if you could justify this choice by helping my understand how the specification says we should do this.

Please take a look over the table for observed behavior in Chrome (Firefox also has same behavior)

There seems no explicit specs for this, I found inconsistent behavior with chrome that's it.

If there is no specification, let's keep this simple. Can we only use the <meta viewport> tag to clamp pinch zoom and nothing else?

Yes, that's the goal.

mrobinson · 2026-01-30T07:40:21Z

+                    let new_factor = self
+                        .viewport_description
+                        .unwrap_or_default()
+                        .clamp_zoom(factor * new_pinch_zoom.zoom_factor().get());


You are clamping each individual pinch zoom delta here rather than the final value. This will lead to incorrect results. You need to figure out what the final value will be and clamp that.

I am clamping delta*existing_zoom_factor

I see. I think you were on the right track before clamping inside of PinchZoom. Theoretically there could be some other caller to PinchZoom::zoom() and the behavior should be consistent.

servo-wpt-sync · 2026-03-27T09:03:32Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58805).

shubhamg13 · 2026-03-27T09:17:04Z

#40098 (comment)

Everything that I have read suggests that it should be used to clamp the visual viewport (pinch zoom / page scale).

#40098 (comment)

Can we only use the tag to clamp pinch zoom and nothing else?

@mrobinson
Summing up to your prior achieved conclusion, I'm resolving all the irrelevant comments.

And coming to sole and only purpose of this PR. Please take a look and review.

P.S: Sorry for lot of back and forth changes. I removed all the unrelated changes.

servo-wpt-sync · 2026-03-27T09:29:53Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58805).

servo-wpt-sync · 2026-03-27T09:31:09Z

✍ Updated existing upstream WPT pull request (web-platform-tests/wpt#58805) title and body.

servo-wpt-sync · 2026-03-27T09:48:44Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58805).

servo-wpt-sync · 2026-03-27T10:06:29Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58805).

servo-wpt-sync · 2026-03-27T10:27:26Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58805).

servo-wpt-sync · 2026-03-27T11:22:14Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58805).

mrobinson · 2026-04-01T16:17:54Z

+  <script> promise_test(async () => {
+      const x = 200, y = 200;
+      const initialScale = window.visualViewport.scale;
+      // Perform pinch zoom


Are there other tests that perform a pinch zoom like this? If so this is probably fine, but otherwise this should likely be a Servo-only test.

I took reference from existing WPT : https://github.com/servo/servo/blob/main/tests/wpt/tests/touch-events/pinch-zoom-change.html

servo-wpt-sync · 2026-04-02T01:40:52Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58805).

servo-wpt-sync · 2026-04-02T07:27:35Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58805).

servo-wpt-sync · 2026-04-02T07:28:52Z

✍ Updated existing upstream WPT pull request (web-platform-tests/wpt#58805) title and body.

servo-wpt-sync · 2026-04-02T16:03:17Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58805).

shubhamg13

Can we Please add it to MQ again. I detected one false positive.

shubhamg13 · 2026-04-02T16:01:05Z

@@ -1,3 +1,7 @@
 [pointerevent_touch-action_two-finger_interaction.html]
+  expected: TIMEOUT


IMO this was false positive as Servo doesn't support touch-action due to which this was removed from MQ.

Any idea why the test starts to fail now though? It doesn't seem to be using the viewport metatag, so it seems that this change if modifying the behavior of Servo even when the viewport metatag isn't used -- which seems wrong.

With this PR the clamp range is 0.1 to 10.0 so this is affecting the test. Adding the workaround back.

We should not allow pinch zooming to values below 1 by default.

Yeah, when I enable it in here #43688. I will add a check for same.

Signed-off-by: Shubham Gupta <[email protected]>

servo-wpt-sync · 2026-04-03T06:01:46Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58805).

github-actions · 2026-04-03T06:21:47Z

🔨 Triggering try run (#23936449766) for Linux (WPT)

github-actions · 2026-04-03T06:50:51Z

Test results for linux-wpt from try job (#23936449766):

Flaky unexpected result (29)

OK /FileAPI/url/url-with-fetch.any.html (#21517)
- FAIL [expected PASS] subtest: Revoke blob URL after calling fetch, fetch should succeed
```
promise_test: Unhandled rejection with value: object "TypeError: Network error: Blob URL store error: InvalidFileID"
```

OK /IndexedDB/idbtransaction-oncomplete.any.worker.html (#42804)

FAIL [expected PASS] subtest: IDBTransaction - complete event

assert_array_equals: lengths differ, expected array ["upgradeneeded", "complete", "success", "opencursor"] length 4, got ["upgradeneeded", "complete", "success"] length 3

OK /_mozilla/css/offset_properties_inline.html (#40543)

FAIL [expected PASS] subtest: offsetTop

assert_equals: offsetTop of #inline-1 should be 0. expected 0 but got -1

FAIL [expected PASS] subtest: offsetLeft

assert_equals: offsetLeft of #inline-2 should be 40. expected 40 but got 25

CRASH [expected ERROR] /_webgl/conformance2/misc/uninitialized-test-2.html (#41656)
FAIL [expected PASS] /css/css-backgrounds/background-size-042.html
OK /css/css-cascade/layer-font-face-override.html (#35935)
- PASS [expected FAIL] subtest: @font-face override update with appended sheet 1
- PASS [expected FAIL] subtest: @font-face override update with appended sheet 2
FAIL [expected PASS] /css/css-ui/appearance-menulist-button-001.html
OK /fetch/metadata/generated/css-font-face.sub.tentative.html (#34624)
- PASS [expected FAIL] subtest: sec-fetch-storage-access - Not sent to non-trustworthy same-site destination
OK /fetch/metadata/window-open.https.sub.html (#40339)
- FAIL [expected PASS] subtest: Cross-site window, forced, reloaded
```
The operation is insecure.
```
OK /html/browsers/browsing-the-web/navigating-across-documents/initial-empty-document/load-pageshow-events-window-open.html (#28691)
- FAIL [expected PASS] subtest: load event does not fire on window.open('about:blank')
```
assert_unreached: load should not be fired Reached unreachable code
```
CRASH [expected TIMEOUT] /html/browsers/browsing-the-web/navigating-across-documents/javascript-url-no-beforeunload.window.html
OK /html/browsers/history/the-history-interface/traverse_the_history_5.html (#21383)
- PASS [expected FAIL] subtest: Multiple history traversals, last would be aborted
OK /html/semantics/document-metadata/the-meta-element/pragma-directives/attr-meta-http-equiv-refresh/allow-scripts-flag-changing-1.html (#39694)
- PASS [expected FAIL] subtest: Meta refresh is blocked by the allow-scripts sandbox flag at its creation time, not when refresh comes due
OK /html/semantics/document-metadata/the-meta-element/pragma-directives/attr-meta-http-equiv-refresh/allow-scripts-flag-changing-2.html (#39703)
- FAIL [expected PASS] subtest: Meta refresh of the original iframe is not blocked if moved into a sandboxed iframe
```
uncaught exception: Error: assert_unreached: The iframe into which the meta was moved must not refresh Reached unreachable code
```
TIMEOUT [expected OK] /html/semantics/embedded-content/the-iframe-element/iframe_sandbox_navigate_other_frame_popup.sub.html (#39702)
- TIMEOUT [expected FAIL] subtest: Sandboxed iframe can not navigate other frame's popup
```
Test timed out
```
OK /html/semantics/forms/form-submission-0/jsurl-form-submit.tentative.html (#36489)
- PASS [expected FAIL] subtest: Verifies that form submissions scheduled inside javascript: urls take precedence over the javascript: url's return value.
OK /html/semantics/scripting-1/the-script-element/module/dynamic-import/blob-url.any.worker-module.html (#43510)
- FAIL [expected PASS] subtest: Revoking a blob URL immediately after calling import will not fail
```
promise_test: Unhandled rejection with value: object "TypeError: Module fetching failed"
```
TIMEOUT [expected OK] /html/user-activation/navigation-state-reset-sameorigin.html
- TIMEOUT [expected PASS] subtest: Post-navigation state reset.
```
Test timed out
```
OK /html/webappapis/dynamic-markup-insertion/document-write/module-tla-import.html (#42419)
- FAIL [expected PASS] subtest: document.write in an imported module
```
assert_true: onload must be called expected true got false
```
OK /mixed-content/tentative/autoupgrades/video-upgrade.https.sub.html (#41135)
- FAIL [expected PASS] subtest: Video autoupgraded
```
assert_equals: Length. expected 1 but got Infinity
```
TIMEOUT [expected OK] /preload/modulepreload-sri-importmap.html (#43354)
- TIMEOUT [expected PASS] subtest: Script should not be loaded if modulepreload's integrity is invalid
```
Test timed out
```
ERROR [expected OK] /resource-timing/cors-preflight.any.html (#28694)
OK /resource-timing/test_resource_timing.https.html (#25216)
- PASS [expected FAIL] subtest: PerformanceEntry has correct name, initiatorType, startTime, and duration (link)
OK [expected TIMEOUT] /trusted-types/trusted-types-navigation.html?01-05 (#38975)
- PASS [expected TIMEOUT] subtest: Navigate a window via anchor with javascript:-urls in report-only mode.
- PASS [expected NOTRUN] subtest: Navigate a window via anchor with javascript:-urls w/ default policy in report-only mode.
- PASS [expected NOTRUN] subtest: Navigate a frame via anchor with javascript:-urls in enforcing mode.
TIMEOUT /trusted-types/trusted-types-navigation.html?26-30 (#38807)
- PASS [expected TIMEOUT] subtest: Navigate a window via form-submission with javascript:-urls in report-only mode.
- PASS [expected NOTRUN] subtest: Navigate a window via form-submission with javascript:-urls w/ default policy in report-only mode.
- PASS [expected NOTRUN] subtest: Navigate a frame via form-submission with javascript:-urls in enforcing mode.
- TIMEOUT [expected NOTRUN] subtest: Navigate a frame via form-submission with javascript:-urls w/ default policy in enforcing mode.
```
Test timed out
```
CRASH [expected OK] /webaudio/the-audio-api/the-mediastreamaudiodestinationnode-interface/closed-audiocontext-construction.html
OK [expected TIMEOUT] /webstorage/localstorage-about-blank-3P-iframe-opens-3P-window.partitioned.html (#29053)
- PASS [expected TIMEOUT] subtest: StorageKey: test 3P about:blank window opened from a 3P iframe
OK [expected ERROR] /webxr/render_state_update.https.html (#27535)
OK /webxr/xrSession_features_deviceSupport.https.html (#24357)
- FAIL [expected PASS] subtest: Immersive XRSession requests with no supported device should reject
```
assert_unreached: Should have rejected: undefined Reached unreachable code
```

Stable unexpected results that are known to be intermittent (19)

FAIL [expected PASS] /_mozilla/mozilla/sslfail.html (#10760)
TIMEOUT [expected OK] /_mozilla/mozilla/window_resize_event.html (#36741)
- TIMEOUT [expected PASS] subtest: Popup onresize event fires after resizeTo
```
Test timed out
```
CRASH [expected PASS] /_mozilla/shadow-dom/move-element-with-ua-shadow-tree-crash.html (#39473)

OK /_webgl/conformance/textures/misc/texture-upload-size.html (#21770)

FAIL [expected PASS] subtest: WebGL test #45

assert_true: Texture was smaller than the expected size 2x2 expected true got false

FAIL [expected PASS] subtest: WebGL test #47

assert_true: getError expected: INVALID_VALUE. Was NO_ERROR : when calling texSubImage2D with the same texture upload with offset 1, 1 expected true got false

FAIL [expected PASS] subtest: WebGL test #49

assert_true: Texture was smaller than the expected size 2x2 expected true got false

FAIL [expected PASS] subtest: WebGL test #51

assert_true: getError expected: INVALID_VALUE. Was NO_ERROR : when calling texSubImage2D with the same texture upload with offset 1, 1 expected true got false

PASS [expected FAIL] subtest: WebGL test #53
PASS [expected FAIL] subtest: WebGL test #55
PASS [expected FAIL] subtest: WebGL test #57
PASS [expected FAIL] subtest: WebGL test #59

FAIL [expected PASS] subtest: WebGL test #61

assert_true: Texture was smaller than the expected size 2x2 expected true got false

FAIL [expected PASS] subtest: WebGL test #63

assert_true: getError expected: INVALID_VALUE. Was NO_ERROR : when calling texSubImage2D with the same texture upload with offset 1, 1 expected true got false

And 14 more unexpected results...

CRASH [expected OK] /content-security-policy/meta/sandbox-iframe.html (#43478)
OK /css/css-fonts/generic-family-keywords-001.html (#37467)
- PASS [expected FAIL] subtest: @font-face matching for quoted and unquoted generic(fangsong)
- PASS [expected FAIL] subtest: @font-face matching for quoted and unquoted generic(kai)
OK /css/css-fonts/generic-family-keywords-003.html (#38994)
- FAIL [expected PASS] subtest: @font-face matching for quoted and unquoted cursive (drawing text in a canvas)
```
assert_equals: quoted cursive matches  @font-face rule expected 125 but got 40
```
- FAIL [expected PASS] subtest: @font-face matching for quoted and unquoted fantasy (drawing text in a canvas)
```
assert_equals: quoted fantasy matches  @font-face rule expected 125 but got 40
```
- FAIL [expected PASS] subtest: @font-face matching for quoted and unquoted generic(kai) (drawing text in a canvas)
```
assert_equals: unquoted generic(kai) does not match @font-face rule expected 40 but got 125
```
- FAIL [expected PASS] subtest: @font-face matching for quoted and unquoted generic(khmer-mul) (drawing text in a canvas)
```
assert_equals: quoted generic(khmer-mul) matches  @font-face rule expected 125 but got 40
```
- FAIL [expected PASS] subtest: @font-face matching for quoted and unquoted generic(nastaliq) (drawing text in a canvas)
```
assert_equals: quoted generic(nastaliq) matches  @font-face rule expected 125 but got 40
```
OK /dom/nodes/moveBefore/iframe-document-preserve.window.html (#43152)
- FAIL [expected PASS] subtest: moveBefore(): cross-origin iframe is preserved: remove self via innerHTML
```
assert_equals: iframe does not fire a second load event expected 1 but got 0
```
OK [expected ERROR] /fetch/fetch-later/quota/same-origin-iframe/multiple-iframes.https.window.html (#35176)
OK /fetch/metadata/generated/css-font-face.https.sub.tentative.html (#32732)
- PASS [expected FAIL] subtest: sec-fetch-mode
- PASS [expected FAIL] subtest: sec-fetch-user
ERROR [expected OK] /focus/focus-event-after-switching-iframes.sub.html (#40368)
OK /html/browsers/browsing-the-web/navigating-across-documents/005.html (#27062)
- FAIL [expected PASS] subtest: Link with onclick navigation and href navigation
```
assert_equals: expected "href" but got "click"
```
OK [expected TIMEOUT] /html/infrastructure/urls/base-url/document-base-url-window-initiator-is-not-opener.https.window.html (#30970)
TIMEOUT /html/interaction/focus/the-autofocus-attribute/supported-elements.html (#24145)
- PASS [expected TIMEOUT] subtest: Non-HTMLElement should not support autofocus
- FAIL [expected NOTRUN] subtest: Host element with delegatesFocus should support autofocus
```
promise_test: Unhandled rejection with value: object "TypeError: can't access property "appendChild", w.document.body is null"
```
- TIMEOUT [expected NOTRUN] subtest: Host element with delegatesFocus including no focusable descendants should be skipped
```
Test timed out
```
OK /html/semantics/scripting-1/the-script-element/module/dynamic-import/blob-url.any.worker.html (#33909)
- FAIL [expected PASS] subtest: Revoking a blob URL immediately after calling import will not fail
```
promise_test: Unhandled rejection with value: object "TypeError: Module fetching failed"
```
OK [expected TIMEOUT] /infrastructure/testdriver/click_nested.html (#43887)
- FAIL [expected NOTRUN] subtest: TestDriver click method with multiple windows and nested iframe
```
can't access property "document", child.frames[2] is undefined
```
OK /mixed-content/tentative/autoupgrades/mixed-content-cors.https.sub.html (#41123)
- PASS [expected FAIL] subtest: Cross-Origin video should get upgraded even if CORS is set
OK /resource-timing/test_resource_timing.html (#25720)
- PASS [expected FAIL] subtest: PerformanceEntry has correct name, initiatorType, startTime, and duration (iframe)
OK /trusted-types/trusted-types-reporting.html (#43737)
- PASS [expected FAIL] subtest: Trusted Type violation report: creating a forbidden-but-not-reported policy.
- PASS [expected FAIL] subtest: Trusted Type violation report: sample for SVGScriptElement href assignment by setAttribute
- PASS [expected FAIL] subtest: Trusted Type violation report: sample for eval
- PASS [expected FAIL] subtest: Trusted Type violation report: sample for custom element assignment
- PASS [expected FAIL] subtest: Trusted Type violation report: Worker constructor

github-actions · 2026-04-03T06:50:58Z

✨ Try run (#23936449766) succeeded.

servo-wpt-sync · 2026-04-03T09:13:34Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58805).

Signed-off-by: Shubham Gupta <[email protected]>

servo-wpt-sync · 2026-04-03T09:19:44Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58805).

mrobinson · 2026-04-03T10:28:15Z

+        if new_factor <= 1.0 {
+            self.zoom_factor = 1.0; // Update the zoom factor to 1.0 to avoid precision issues when zooming back in after zooming out fully.
            self.transform = Transform2D::identity();
            return;


This does seem like it will cause an issue in the case that the ViewportDescription does say that we should be able to pinch zoom to values below 1.0. Would it make sense to change the default minimum zoom in ViewportDescription to be 1.0?

There are some websites that have initial-scale as 0.5. We should support entire range from 0.1 to 10.0, but selectively modify depending on platforms.

In those cases it seems that the ViewportDescription will no longer be the default one and so when you call clamp on the new value it will be clamped properly to [0.5, ...].

Yes, that's what exactly I am doing ( in PR where I support for scale less than 1, yet to push or I can add separate PR if you say)

Please a take a look here #43905

shubhamg13 requested a review from mrobinson as a code owner October 23, 2025 08:58

servo-highfive added the S-awaiting-review There is new code that needs to be reviewed. label Oct 23, 2025

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servo-highfive added S-needs-code-changes Changes have not yet been made that were requested by a reviewer. S-needs-rebase There are merge conflict errors. and removed S-awaiting-review There is new code that needs to be reviewed. labels Oct 23, 2025

shubhamg13 force-pushed the clamp_pinch_zoom branch from bfb13e7 to bf203f5 Compare October 24, 2025 06:56

servo-highfive added S-awaiting-review There is new code that needs to be reviewed. and removed S-needs-code-changes Changes have not yet been made that were requested by a reviewer. S-needs-rebase There are merge conflict errors. labels Oct 24, 2025

shubhamg13 requested a review from mrobinson October 24, 2025 07:27

shubhamg13 force-pushed the clamp_pinch_zoom branch 3 times, most recently from bfc53e1 to c36a956 Compare October 31, 2025 06:41

This was referenced Nov 4, 2025

clamp pinch zoom factor if any viewport description. #40394

Closed

Incorrect deletion logic; it should be restricted using self.viewport_description. #40390

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shubhamg13 force-pushed the clamp_pinch_zoom branch from c36a956 to 95a2320 Compare January 9, 2026 09:08

shubhamg13 mentioned this pull request Jan 19, 2026

Feature: <meta name="viewport"> #36159

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shubhamg13 force-pushed the clamp_pinch_zoom branch 2 times, most recently from ddb132d to 398c14e Compare January 29, 2026 06:31

mrobinson reviewed Jan 29, 2026

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Comment thread components/paint/pinch_zoom.rs Outdated

Comment thread components/paint/pinch_zoom.rs Outdated

Comment thread components/paint/pinch_zoom.rs Outdated

shubhamg13 marked this pull request as draft January 30, 2026 04:39

shubhamg13 force-pushed the clamp_pinch_zoom branch 2 times, most recently from a303c1a to bf8e887 Compare January 30, 2026 07:19

shubhamg13 requested a review from mrobinson January 30, 2026 07:21

shubhamg13 marked this pull request as ready for review January 30, 2026 07:21

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servo-highfive removed the S-awaiting-review There is new code that needs to be reviewed. label Jan 30, 2026

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mrobinson approved these changes Apr 2, 2026

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shubhamg13 commented Apr 2, 2026

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Clamp Pinch Zoom using Viewport Meta Range.

bd23241

Signed-off-by: Shubham Gupta <[email protected]>

shubhamg13 added 2 commits April 3, 2026 17:15

Add Test to verify Viewport Scale is clamped and can not pinch zoomed

da03d90

Signed-off-by: Shubham Gupta <[email protected]>

Add a workaround.

e9ff926

Signed-off-by: Shubham Gupta <[email protected]>

mrobinson reviewed Apr 3, 2026

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shubhamg13 mentioned this pull request Apr 3, 2026

paint: Anchor the minimum value of clamp to the initial scale #43905

Closed

shubhamg13 mentioned this pull request May 4, 2026

paint: Support pinch-zoom for factors less than 1. #43688

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servo-wpt-sync mentioned this pull request May 19, 2026

paint: Support pinch-zoom for factors less than 1. web-platform-tests/wpt#59660

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shubhamg13 mentioned this pull request May 26, 2026

paint: Support pinch-zoom for factors less than 1 #45150

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servo-wpt-sync mentioned this pull request May 26, 2026

paint: Support pinch-zoom for factors less than 1 web-platform-tests/wpt#60170

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		@@ -1,3 +1,7 @@
		[pointerevent_touch-action_two-finger_interaction.html]
		expected: TIMEOUT

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Behavior in Servo with this PR

Observed behavior in Chrome:

References from Chromium:

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shubhamg13 commented Oct 23, 2025

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