From bdb7cd6a21e41bfcfd58393cc63cbb647973cbbe Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pedro=20Louren=C3=A7o?= <pedro.lourenco@outsystems.com>
Date: Tue, 22 Oct 2024 16:03:11 +0100
Subject: [PATCH] fix(modal): fix enter animation when the initial breakpoint
 value is less than the backdrop breakpoint (#29955)

Issue number: internal

---------

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## What is the current behavior?
This PR aims to fix an issue introduced in
https://github.com/ionic-team/ionic-framework/pull/29932 where the enter
animation for ionic theme was in a broken state when the modal's initial
breakpoint value was lesser than the specified backdrop breakpoint.

## What is the new behavior?
- The erroneous behaviour happened because the shouldShowBackdrop
constant had a false value which was being taken into consideration when
computing the backdrop opacity for the ionic theme. This PR fixes this
by always transitioning the backdrop opacity from 0 to 0.7 once the
modal appears, independently of the initial, current or activation
breakpoint.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

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screenshots of how the component looks before and after the change. -->
---
 core/src/components/modal/animations/sheet.ts | 9 ++++++---
 core/src/components/modal/modal.tsx           | 2 ++
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/core/src/components/modal/animations/sheet.ts b/core/src/components/modal/animations/sheet.ts
index 8224effb9f..a786f5dbf9 100644
--- a/core/src/components/modal/animations/sheet.ts
+++ b/core/src/components/modal/animations/sheet.ts
@@ -12,9 +12,12 @@ export const createSheetEnterAnimation = (opts: ModalAnimationOptions) => {
    * current breakpoint, then the backdrop should be fading in.
    */
   const shouldShowBackdrop = backdropBreakpoint === undefined || backdropBreakpoint < currentBreakpoint!;
-  const initialBackdrop = shouldShowBackdrop
-    ? `calc(var(--backdrop-opacity) * ${staticBackdropOpacity ? 1 : currentBreakpoint!})`
-    : '0';
+  let initialBackdrop = '0';
+  if (staticBackdropOpacity) {
+    initialBackdrop = 'calc(var(--backdrop-opacity)';
+  } else if (shouldShowBackdrop) {
+    initialBackdrop = `calc(var(--backdrop-opacity) * ${currentBreakpoint!})`;
+  }
 
   const backdropAnimation = createAnimation('backdropAnimation').fromTo('opacity', 0, initialBackdrop);
 
diff --git a/core/src/components/modal/modal.tsx b/core/src/components/modal/modal.tsx
index f9b161da6d..5dc1f2e069 100644
--- a/core/src/components/modal/modal.tsx
+++ b/core/src/components/modal/modal.tsx
@@ -1049,6 +1049,8 @@ interface ModalOverlayOptions {
   /**
    * The point after which the backdrop will begin
    * to fade in when using a sheet modal.
+   * This option is ignored for the ionic theme
+   * due to the option below.
    */
   backdropBreakpoint: number;
   /**