drag_to_offset_delta()

MAYAFLUX_API glm::vec2 MayaFlux::Kinesis::drag_to_offset_delta ( glm::vec2  pixel_delta, glm::vec2  visible_extent, glm::vec2  viewport_size_pixels  )

noexcept

Convert a pixel-space drag delta into a content-space delta.

Scales the fraction of the viewport a pointer moved by the content extent currently visible, so drag speed stays proportionate to scale: more content in view moves the result further per pixel than less. No sign convention is imposed; a caller applies whatever sign its own semantics need (a grabbed canvas moves opposite the drag, a dragged scrollbar thumb moves with it).

Shared by PanZoom2DState::apply_pan_zoom_pan and any CPU-side drag scroll: both are "drag the content by moving the viewport's frame over it," differing only in what consumes the result (a GPU ViewTransform versus a CPU layout offset).

Parameters

pixel_delta	Pixel-space delta.
visible_extent	Currently visible content extent (width, height), same units as the return value.
viewport_size_pixels	Viewport size in pixels the delta was measured against.

Definition at line 5 of file ScrollState.cpp.

{
    return (pixel_delta / viewport_size_pixels) * visible_extent;
}

Referenced by apply_pan_zoom_pan().

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