Added UI Scaling support

[JohnGreenFC]

Added UI Scaling from 1x-3x
Tested scaling on custom UI
Saving scaling settings into the IMGui Config

[Copilot]

🟡 Changes recommended

Critical font-resource and settings-handler issues, plus unresolved scaling and input-handling issues, block approval.

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Pull request overview

This PR adds configurable 1x–3x Dear ImGui UI scaling with runtime controls, monitor-based defaults, and persistent settings.

Changes:

• Adds centralized scaling constants and scaled UI dimensions.
• Rebuilds fonts and styles when scaling changes.
• Persists UI scale through ImGui configuration.

File summaries

File	Summary
src/viewer/rendering/ui/uiSettings.h	Adds settings API declarations.
src/viewer/rendering/ui/uiSettings.cpp	Adds configuration persistence. Critical (3 votes): initialize settings callbacks and user data. Moderate (1 vote): reject non-finite scale values.
src/viewer/rendering/ui/uiRenderer.h	Declares scaling support.
src/viewer/rendering/ui/uiRenderer.cpp	Applies font/style scaling. Critical (3 votes): synchronize font resource replacement across frames. Moderate (1 vote): scale fixed table dimensions.
src/viewer/rendering/ui/uiMenubar.h	Adds slider state.
src/viewer/rendering/ui/uiMenubar.cpp	Adds scale controls. Moderate (1 vote): handle slider deactivation when the menu closes.
src/viewer/rendering/ui/uiGeneralWindow.cpp	Uses scaled button dimensions.
src/viewer/rendering/ui/uiDetailWindow.cpp	Uses scaled spacing and table heights. Moderate (1 vote): scale fixed table column widths.
src/viewer/rendering/ui/uiCustomWidgets.h	Adds scaled widget defaults.
src/viewer/rendering/ui/uiCustomWidgets.cpp	Applies scaled widget geometry.
src/viewer/rendering/ui/uiConsts.h	Defines scaling constants and accessors.
src/viewer/rendering/ui/uiConsts.cpp	Stores runtime scale state.
src/viewer/rendering/ui/uiAnimationPlayback.cpp	Scales playback controls.
src/viewer/appState.h	Adds UI scale state.
src/viewer/appState.cpp	Dispatches scale callbacks.
src/viewer/application.cpp	Initializes monitor-based scaling and saves settings. Moderate (2 votes): use logical window or viewport dimensions for UI layout.

Review details

Suppressed comments (4)

src/viewer/rendering/ui/uiDetailWindow.cpp:1221

• The new scaled height still uses fixed indexColumnWidth/columnWidth values (60/80px) for both tables below. At 2x/3x the text font and row heights grow but these columns do not, so vertex indices and coordinates can be clipped. Scale those base widths through UiConsts::Scaled before passing them to TableSetupColumn.

		const float tableHeight = std::min( (float)vertexCount * ImGui::GetTextLineHeightWithSpacing() + ImGui::GetTextLineHeightWithSpacing(), UiConsts::Scaled( 200.0f ) );

src/viewer/rendering/ui/uiMenubar.cpp:141

• If the slider is dragged and the mouse is released outside the open menu, the slider is not submitted on that frame, so IsItemDeactivatedAfterEdit() is never observed. m_uiScaleSliderActive then remains true and the pending value is never copied to appState.uiScale; reopening the menu also skips the synchronization at lines 135-138. Handle deactivation/menu closure outside BeginMenu and explicitly commit or discard the pending value.

		m_uiScaleSliderActive = ImGui::IsItemActive();

src/viewer/rendering/ui/uiRenderer.cpp:163

• ScaleAllSizes only scales values stored in ImGuiStyle; it does not affect explicit pixel dimensions elsewhere. For example, uiDetailWindow.cpp still passes fixed 48px/72px/80px table widths, so at 3x the text and padding grow while those columns remain 1x and can clip their headers and content. Route all fixed UI dimensions through the scaled accessors as well.

	// ScaleAllSizes is cumulative, so always start from a fresh style
	ImGuiStyle& style = ImGui::GetStyle();
	style = ImGuiStyle();
	ImGui::StyleColorsDark( &style );
	style.ScaleAllSizes( scale );

src/viewer/rendering/ui/uiSettings.cpp:101

• strtof accepts nan, and the end check succeeds for it; std::clamp does not sanitize a NaN. A malformed UiScale=nan therefore propagates into ApplyUiScale, SizePixels, and ScaleAllSizes, which can break font construction/rendering. Reject non-finite values (and ideally trailing junk) before storing the clamped scale.

		const float uiScale = std::strtof( line + keyLength, &end );
		if( end != line + keyLength )
		{
			GetAppState( handler ).uiScale.SetValueNoCallback( std::clamp( uiScale, UiConsts::MIN_UI_SCALE, UiConsts::MAX_UI_SCALE ) );

• Files reviewed: 16/16 changed files
• Comments generated: 3
• Review effort level: Lite

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