45 lines
1.8 KiB
Markdown
45 lines
1.8 KiB
Markdown
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# Spec Delta
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## Purpose
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Keeps the application rendering crisp on displays with integer or fractional scaling by converting between logical and physical coordinates.
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## ADDED Requirements
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### Requirement: Fractional scale is applied when available
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The system SHALL use the compositor-provided fractional preferred scale for rendering when the fractional scale protocol is available.
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#### Scenario: Fractional display
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- **WHEN** the compositor sends a preferred scale of 1.5
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- **THEN** the render buffer is created at 1.5 times the logical size
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- **AND** the buffer is displayed at the logical size
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### Requirement: Integer scale is used as fallback
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The system SHALL use the output's integer scale when fractional scale is unavailable.
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#### Scenario: No fractional protocol
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- **WHEN** the compositor does not support fractional scaling
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- **THEN** the render buffer uses the output integer scale
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- **AND** the buffer is displayed at the logical size
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### Requirement: Input coordinates remain logical
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The system SHALL report mouse positions and grid cells in logical coordinates regardless of the active scale.
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#### Scenario: Scaled click
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- **WHEN** the user clicks on a scaled display
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- **THEN** the selected grid cell matches the visual location of the cursor
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### Requirement: Rendering uses physical resolution
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The system SHALL render all content at physical resolution so that lines and cells stay sharp at the active scale.
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#### Scenario: Sharp cells
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- **WHEN** the application runs on a 2x scaled display
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- **THEN** cells are drawn with 2 physical pixels per logical pixel
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### Requirement: Scale changes trigger re-render
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The system SHALL recreate buffers and re-render when the active scale changes.
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#### Scenario: Scale change
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- **WHEN** the compositor changes the preferred scale
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- **THEN** the application updates its buffers
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- **AND** subsequent frames use the new scale
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