fix(PdfReader): prevent render twice when url is null

[ArgoZhang]

Link issues

fixes #894

Summary By Copilot

Regression?

• Yes
• No

Risk

• High
• Medium
• Low

Verification

• Manual (required)
• Automated

Packaging changes reviewed?

• Yes
• No
• N/A

☑️ Self Check before Merge

⚠️ Please check all items below before review. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• Merge the latest code from the main branch

Summary by Sourcery

Bug Fixes:

• Avoid triggering a second render pass by exiting early after applying initial toolbar and layout state when no URL is provided.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Ensures PdfReader's OnAfterRenderAsync exits early after initializing internal state on first render to prevent duplicate rendering when Url is null, and includes a no-op touch to the project file.

Sequence diagram for PdfReader OnAfterRenderAsync first render behavior

sequenceDiagram
    actor User
    participant Browser
    participant BlazorRenderer
    participant PdfReader

    User->>Browser: Navigate to page with PdfReader
    Browser->>BlazorRenderer: Initial render
    BlazorRenderer->>PdfReader: OnAfterRenderAsync(firstRender=true)
    PdfReader->>PdfReader: Initialize _showToolbar, _enableThumbnails, _fitMode
    PdfReader-->>BlazorRenderer: return (early exit, no URL handling)

    note over User,Browser: Later, application sets PdfReader.Url
    User->>Browser: Trigger state change (e.g., set Url)
    Browser->>BlazorRenderer: Re-render PdfReader
    BlazorRenderer->>PdfReader: OnAfterRenderAsync(firstRender=false)
    PdfReader->>PdfReader: Compare _url and Url
    PdfReader->>PdfReader: Perform URL-related render logic once
    PdfReader-->>BlazorRenderer: return

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Flow diagram for PdfReader OnAfterRenderAsync control logic

flowchart TD
    A[OnAfterRenderAsync invoked] --> B{firstRender}
    B -- yes --> C[Set _showToolbar from ShowToolbar]
    C --> D[Set _enableThumbnails from EnableThumbnails]
    D --> E[Set _fitMode from FitMode]
    E --> F[Return immediately]

    B -- no --> G{_url != Url}
    G -- yes --> H[Update _url]
    H --> I[Execute URL-related render logic]
    I --> J[Return]
    G -- no --> J[Return]

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File-Level Changes

Change	Details	Files
Add an early return on first render in PdfReader to avoid duplicate render logic execution when Url is null or unchanged.	Update OnAfterRenderAsync to return immediately after syncing internal fields with component parameters on firstRender Keep subsequent Url change check logic only for non-first renders	src/components/BootstrapBlazor.PdfReader/PdfReader.razor.cs

Assessment against linked issues

Issue	Objective	Addressed	Explanation
#894	Fix the PdfReader bug that causes pages to be duplicated / rendered twice after upgrading to version 10.0.24 (likely due to OnAfterRenderAsync running logic twice when Url is null or unchanged).	✅

Possibly linked issues

• bug(PdfReader): duplicates pages issue #894: The PR short‑circuits OnAfterRenderAsync on first render, preventing double rendering that caused duplicated pages.

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[sourcery-ai]

Hey - I've left some high level feedback:

• The early return in OnAfterRenderAsync now skips the subsequent _url != Url logic on every first render, not just when Url is null; consider guarding the early exit with a string.IsNullOrEmpty(Url) (or similar) check so valid URLs still trigger the expected initialization path.
• It may be clearer to explicitly separate the Url-is-null/empty branch from the normal initialization path (e.g., with an early guard at the top of OnAfterRenderAsync), so the control flow reflects the intent of avoiding double render only when there is no URL.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- The early `return` in `OnAfterRenderAsync` now skips the subsequent `_url != Url` logic on every first render, not just when `Url` is null; consider guarding the early exit with a `string.IsNullOrEmpty(Url)` (or similar) check so valid URLs still trigger the expected initialization path.
- It may be clearer to explicitly separate the `Url`-is-null/empty branch from the normal initialization path (e.g., with an early guard at the top of `OnAfterRenderAsync`), so the control flow reflects the intent of avoiding double render only when there is no URL.

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[Copilot]

Pull request overview

This PR fixes a bug in the PdfReader component where rendering would occur twice when the Url parameter is null, by adding an early return statement after initializing state variables on the first render.

Changes:

• Added early return in OnAfterRenderAsync after first render initialization to prevent subsequent execution
• Bumped component version from 10.0.25 to 10.0.26

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/components/BootstrapBlazor.PdfReader/PdfReader.razor.cs	Added return statement after first render initialization to prevent double rendering when Url is null
src/components/BootstrapBlazor.PdfReader/BootstrapBlazor.PdfReader.csproj	Version bump to 10.0.26 to reflect the bug fix

Comments suppressed due to low confidence (1)

src/components/BootstrapBlazor.PdfReader/PdfReader.razor.cs:231

• Equality checks on floating point values can yield unexpected results.

        if (_currentRotation != CurrentRotation)

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[Copilot]

This bug fix prevents double rendering when Url is null, but there are no automated tests to verify this behavior. Consider adding unit tests for the PdfReader component to ensure this issue doesn't regress in the future, especially for the OnAfterRenderAsync lifecycle method with various Url states.