fix(browser): iframe scale

packages/browser-playwright/src/commands/index.ts

@@ -19,6 +19,7 @@ import {
 } from './trace'
 import { type } from './type'
 import { upload } from './upload'
+import { viewport } from './viewport'
 import { wheel } from './wheel'
 
 export default {
@@ -45,4 +46,5 @@ export default {
   __vitest_markTrace: markTrace as typeof markTrace,
   __vitest_groupTraceStart: groupTraceStart as typeof groupTraceStart,
   __vitest_groupTraceEnd: groupTraceEnd as typeof groupTraceEnd,
+  __vitest_viewport: viewport as typeof viewport,
 }

packages/browser-playwright/src/commands/screenshot.ts

@@ -9,6 +9,16 @@ interface ScreenshotCommandOptions extends Omit<ScreenshotOptions, 'element' | '
   element?: string
   mask?: readonly string[]
 }
+
+const SCREENSHOT_STYLES = /* css */`
+  iframe[data-vitest="true"] {
+    position: absolute !important;
+    inset: 0 !important;
+    z-index: ${Number.MAX_SAFE_INTEGER} !important;
+    transform: none !important;
+  }
+`
+
 /**
  * Takes a screenshot using the provided browser context and returns a buffer and the expected screenshot path.
  *
@@ -43,6 +53,11 @@ export async function takeScreenshot(
   }
 
   const mask = options.mask?.map(selector => getDescribedLocator(context, selector))
+  const style = context.project.config.browser.ui
+    ? options.style === undefined
+      ? SCREENSHOT_STYLES
+      : SCREENSHOT_STYLES + options.style
+    : options.style
 
   if (options.element) {
     const { element: selector, ...config } = options
@@ -51,6 +66,7 @@ export async function takeScreenshot(
       ...config,
       mask,
       path: savePath,
+      style,
     })
     return { buffer, path }
   }
@@ -59,6 +75,7 @@ export async function takeScreenshot(
     ...options,
     mask,
     path: savePath,
+    style,
   })
   return { buffer, path }
 }

packages/browser-playwright/src/commands/viewport.ts

@@ -0,0 +1,8 @@
+import type { UserEventCommand } from './utils'
+
+export const viewport: UserEventCommand<(options: {
+  width: number
+  height: number
+}) => void> = async (context, options) => {
+  await context.page.setViewportSize(options)
+}

packages/browser-webdriverio/src/commands/screenshot.ts

@@ -63,8 +63,10 @@ export async function takeScreenshot(
   const buffer = await element.saveScreenshot(
     platformNormalize(savePathWithExtension),
   )
+
   if (!options.save) {
     await rm(savePathWithExtension, { force: true })
   }
+
   return { buffer, path }
 }

packages/browser/src/client/orchestrator.ts

@@ -67,8 +67,7 @@ export class IframeOrchestrator {
     const container = await getContainer(config)
 
     if (config.browser.ui) {
-      container.className = 'absolute origin-top mt-[8px]'
-      container.parentElement!.setAttribute('data-ready', 'true')
+      container.setAttribute('data-ready', 'true')
       // in non-isolated mode this will also remove the iframe,
       // so we only do this once
       if (container.textContent) {
@@ -154,9 +153,8 @@ export class IframeOrchestrator {
 
     const config = getConfig()
     const { width, height } = config.browser.viewport
-    const iframe = this.iframes.get(ID_ALL)!
 
-    await setIframeViewport(iframe, width, height)
+    await setIframeViewport(width, height)
     debug('run non-isolated tests', options.files.join(', '))
     await this.sendEventToIframe({
       event: 'execute',
@@ -187,13 +185,13 @@ export class IframeOrchestrator {
       this.iframes.delete(file)
     }
 
-    const iframe = await this.prepareIframe(
+    await this.prepareIframe(
       container,
       file,
       startTime,
       otelContext,
     )
-    await setIframeViewport(iframe, width, height)
+    await setIframeViewport(width, height)
     // running tests after the "prepare" event
     await this.sendEventToIframe({
       event: 'execute',
@@ -312,16 +310,40 @@ export class IframeOrchestrator {
   private createTestIframe(iframeId: string) {
     const iframe = document.createElement('iframe')
     const src = `/?sessionId=${getBrowserState().sessionId}&iframeId=${iframeId}`
+    const config = getConfig()
+
     iframe.setAttribute('loading', 'eager')
     iframe.setAttribute('src', src)
     iframe.setAttribute('data-vitest', 'true')
-
-    iframe.style.border = 'none'
-    iframe.style.width = '100%'
-    iframe.style.height = '100%'
     iframe.setAttribute('allowfullscreen', 'true')
     iframe.setAttribute('allow', 'clipboard-write;')
     iframe.setAttribute('name', 'vitest-iframe')
+
+    iframe.style.setProperty('border', 'none')
+    iframe.style.setProperty('background-color', '#fff')
+    iframe.style.setProperty('width', 'var(--viewport-width)')
+    iframe.style.setProperty('height', 'var(--viewport-height)')
+
+    // enable scaling only when using the UI, without UI the iframe fills the page
+    if (config.browser.ui) {
+      if (config.browser.name !== 'firefox') {
+        iframe.style.setProperty('transform', 'scale(min(1, calc(100cqw / var(--viewport-width)), calc(100cqh / var(--viewport-height))))')
+      }
+      else {
+        // Firefox cannot resolve relative units like `cqw` directly inside `atan2()`
+        // Storing it in a CSS variable first forces Firefox to resolve `100cqw` to an absolute pixel value
+        iframe.style.setProperty('--container-width', '100cqw')
+        iframe.style.setProperty('--container-height', '100cqh')
+        // Firefox does not support typed arithmetic (divisions between typed values): https://bugzilla.mozilla.org/show_bug.cgi?id=1264520
+        // `tan(atan2(a, b))` produces a unit-less `a / b` ratio:
+        //  - `atan2()` accepts two lengths and returns an `<angle>`
+        //  - `tan()` converts it back to a unit-less `<number>`
+        iframe.style.setProperty('transform', 'scale(min(1, tan(atan2(var(--container-width), var(--viewport-width))), tan(atan2(var(--container-height), var(--viewport-height)))))')
+      }
+
+      iframe.style.setProperty('transform-origin', 'top left')
+    }
+
     return iframe
   }
 
@@ -357,7 +379,7 @@ export class IframeOrchestrator {
           )
           break
         }
-        await setIframeViewport(iframe, width, height)
+        await setIframeViewport(width, height)
         channel.postMessage({ event: 'viewport:done', iframeId: id } satisfies IframeViewportDoneEvent)
         break
       }
@@ -447,38 +469,25 @@ function generateFileId(file: string) {
 }
 
 async function setIframeViewport(
-  iframe: HTMLIFrameElement,
   width: number,
   height: number,
 ) {
   const ui = getUiAPI()
+
   if (ui) {
     await ui.setIframeViewport(width, height)
   }
-  else if (getBrowserState().provider === 'webdriverio') {
-    iframe.parentElement?.setAttribute('data-scale', '1')
+  else {
+    document.body.style.setProperty('--viewport-width', `${width}px`)
+    document.body.style.setProperty('--viewport-height', `${height}px`)
+
     await client.rpc.triggerCommand(
       getBrowserState().sessionId,
       '__vitest_viewport',
       undefined,
       [{ width, height }],
     )
   }
-  else {
-    const scale = Math.min(
-      1,
-      iframe.parentElement!.parentElement!.clientWidth / width,
-      iframe.parentElement!.parentElement!.clientHeight / height,
-    )
-    iframe.parentElement!.style.cssText = `
-      width: ${width}px;
-      height: ${height}px;
-      transform: scale(${scale});
-      transform-origin: left top;
-    `
-    iframe.parentElement?.setAttribute('data-scale', String(scale))
-    await new Promise(r => requestAnimationFrame(r))
-  }
 }
 
 function debug(...args: unknown[]) {

packages/browser/src/client/tester/tester-utils.ts

@@ -224,15 +224,15 @@ export function processTimeoutOptions<T extends { timeout?: number }>(options_:
 }
 
 export function getIframeScale(): number {
-  const testerUi = window.parent.document.querySelector(`iframe[data-vitest]`)?.parentElement
-  if (!testerUi) {
-    throw new Error(`Cannot find Tester element. This is a bug in Vitest. Please, open a new issue with reproduction.`)
-  }
-  const scaleAttribute = testerUi.getAttribute('data-scale')
-  const scale = Number(scaleAttribute)
-  if (Number.isNaN(scale)) {
-    throw new TypeError(`Cannot parse scale value from Tester element (${scaleAttribute}). This is a bug in Vitest. Please, open a new issue with reproduction.`)
+  const iframe = window.frameElement
+
+  if (!iframe) {
+    throw new Error(`Cannot find iframe element. This is a bug in Vitest. Please, open a new issue with reproduction.`)
   }
+
+  // we can safely use `a` as both vertical and horizontal scale are the same
+  const scale = new DOMMatrix(getComputedStyle(iframe).transform).a
+
   return scale
 }
 

packages/ui/client/components/BrowserIframe.vue

@@ -1,7 +1,6 @@
 <script setup lang="ts">
 import type { ViewportSize } from '~/composables/browser'
-import { useWindowSize } from '@vueuse/core'
-import { computed } from 'vue'
+import { computed, onMounted, onUnmounted, ref, useTemplateRef } from 'vue'
 import { viewport } from '~/composables/browser'
 import { browserState } from '~/composables/client'
 import {
@@ -24,56 +23,42 @@ function isViewport(name: ViewportSize) {
   return viewport.value[0] === preset[0] && viewport.value[1] === preset[1]
 }
 
-const { width: windowWidth, height: windowHeight } = useWindowSize()
-
 async function changeViewport(name: ViewportSize) {
   viewport.value = sizes[name]
   if (browserState?.provider === 'webdriverio') {
     updateBrowserPanel()
   }
 }
 
-const PADDING_SIDES = 20
-const PADDING_TOP = 100
-
-const containerSize = computed(() => {
-  if (browserState?.provider === 'webdriverio') {
-    const [width, height] = viewport.value
-    return { width, height }
-  }
+const testContainer = useTemplateRef('tester-ui')
+const testContainerRect = ref<DOMRectReadOnly | null>(null)
 
-  const parentContainerWidth = windowWidth.value * (panels.details.size / 100)
-  const parentOffsetWidth = parentContainerWidth * (panels.details.browser / 100)
-  const containerWidth = parentOffsetWidth - PADDING_SIDES
-  const containerHeight = windowHeight.value - PADDING_TOP
-  return {
-    width: containerWidth,
-    height: containerHeight,
-  }
+const observer = new ResizeObserver(([entry]) => {
+  testContainerRect.value = entry.contentRect
 })
-
-const scale = computed(() => {
-  if (browserState?.provider === 'webdriverio') {
-    return 1
+onMounted(() => {
+  if (testContainer.value) {
+    observer.observe(testContainer.value)
   }
-
-  const [iframeWidth, iframeHeight] = viewport.value
-  const { width: containerWidth, height: containerHeight } = containerSize.value
-  const widthScale = containerWidth > iframeWidth ? 1 : containerWidth / iframeWidth
-  const heightScale = containerHeight > iframeHeight ? 1 : containerHeight / iframeHeight
-  return Math.min(1, widthScale, heightScale)
 })
-
-const marginLeft = computed(() => {
-  const containerWidth = containerSize.value.width
-  const iframeWidth = viewport.value[0]
-  const offset = Math.trunc((containerWidth + PADDING_SIDES - iframeWidth) / 2)
-  return `${offset}px`
+onUnmounted(() => {
+  observer.disconnect()
 })
+
+const scale = computed(() =>
+  testContainerRect.value
+    ? Math.floor(
+        Math.min(
+          testContainerRect.value.width / viewport.value[0],
+          testContainerRect.value.height / viewport.value[1],
+        ) * 100,
+      )
+    : 100,
+)
 </script>
 
 <template>
-  <div h="full" flex="~ col">
+  <div id="browser-frame" h="full" flex="~ col">
     <div p="3" h-10 flex="~ gap-2" items-center bg-header border="b base">
       <IconButton
         v-show="panels.navigation <= 15"
@@ -118,40 +103,30 @@ const marginLeft = computed(() => {
       />
       <span class="pointer-events-none" text-sm>
         {{ viewport[0] }}x{{ viewport[1] }}px
-        <span v-if="scale < 1">({{ (scale * 100).toFixed(0) }}%)</span>
+        <span v-if="scale < 100">({{ scale }}%)</span>
       </span>
     </div>
-    <div id="tester-container" relative>
-      <div
-        id="tester-ui"
-        class="flex h-full justify-center items-center font-light op70"
-        :data-scale="scale"
-        :style="{
-          '--viewport-width': `${viewport[0]}px`,
-          '--viewport-height': `${viewport[1]}px`,
-          '--tester-transform': `scale(${scale})`,
-          '--tester-margin-left': marginLeft,
-        }"
-      >
-        Select a test to run
-      </div>
+    <div id="tester-ui" ref="tester-ui">
+      Select a test to run
     </div>
   </div>
 </template>
 
 <style scoped>
-#tester-container:not([data-ready]) {
-  width: 100%;
+#tester-ui {
   height: 100%;
+  container-type: size;
+
+  margin-top: 0.5rem;
+}
+
+#tester-ui:not([data-ready]) {
   display: flex;
   align-items: center;
   justify-content: center;
-}
 
-[data-ready] #tester-ui {
-  width: var(--viewport-width);
-  height: var(--viewport-height);
-  transform: var(--tester-transform);
-  margin-left: var(--tester-margin-left);
+  opacity: 0.7;
+
+  font-weight: 300;
 }
 </style>

packages/ui/client/composables/browser.ts

@@ -1,7 +1,12 @@
-import { ref } from 'vue'
+import { ref, watch } from 'vue'
 
 export type ViewportSize
   = | 'small-mobile'
     | 'large-mobile'
     | 'tablet'
 export const viewport = ref<[number, number]>([414, 896])
+
+watch([viewport], () => {
+  document.body.style.setProperty('--viewport-width', `${viewport.value[0]}px`)
+  document.body.style.setProperty('--viewport-height', `${viewport.value[1]}px`)
+}, { immediate: true, flush: 'sync' })