ReUseX::vision::osd::LabelLayoutSolver Class Reference

Greedy iterative label placement solver. More...

#include <labelLayoutSolver.hpp>

Classes
struct	Candidate
	Internal representation of a single placement candidate for a label. More...

Public Member Functions
template<typename Func>
	LabelLayoutSolver (int w, int h, Func &&func, const LayoutConfig &cfg=LayoutConfig())
	Construct a solver for a canvas of the given dimensions.
void	setConfig (const LayoutConfig &cfg)
	Update the layout configuration.
void	setCanvasSize (int w, int h)
	Change the canvas dimensions (e.g. after a resize).
void	clear ()
	Remove all items from the solver (allows reuse across frames).
void	add (float l, float t, float r, float b, const std::string &text, int baseFontSize)
	Register a new label to be placed.
void	solve ()
	Run the iterative placement optimisation.
std::vector< LayoutResult >	getResults () const
	Retrieve the placement result for each label in insertion order.

Detailed Description

Greedy iterative label placement solver.

Given a set of object bounding boxes and their text labels, LabelLayoutSolver finds a non-overlapping placement for each label by minimising a cost function that penalises:

• departure from the preferred anchor position (top of the object),
• overlap with other object boxes, and
• overlap with other already-placed labels.

The solver generates a set of discrete placement candidates for each label (four anchor positions × several font-scale tiers + sliding variants) and then iteratively re-assigns labels to reduce total cost.

Usage example:

LabelLayoutSolver solver(imgW, imgH, [&](const std::string &t, int sz) {
    int w, h, base;
    renderer.getTextSize(t, sz, &w, &h, &base);
    return TextSize{w, h, base};
});
solver.add(box.left, box.top, box.right, box.bottom, label, fontSize);
solver.solve();
for (const auto &res : solver.getResults()) { /* draw */ }

Definition at line 214 of file labelLayoutSolver.hpp.

Constructor & Destructor Documentation

LabelLayoutSolver()

template<typename Func>

ReUseX::vision::osd::LabelLayoutSolver::LabelLayoutSolver ( int w, int h, Func && func, const LayoutConfig & cfg = LayoutConfig() )

inline

Construct a solver for a canvas of the given dimensions.

Parameters

w	Canvas width in pixels.
h	Canvas height in pixels.
func	Callable that measures a text string at a given font size and returns a TextSize. Signature: TextSize(const std::string &text, int fontSize).
cfg	Optional tuning parameters.

Definition at line 262 of file labelLayoutSolver.hpp.

Member Function Documentation

add()

void ReUseX::vision::osd::LabelLayoutSolver::add ( float l, float t, float r, float b, const std::string & text, int baseFontSize )

inline

Register a new label to be placed.

Parameters

l	Left edge of the associated object box.
t	Top edge.
r	Right edge.
b	Bottom edge.
text	Label string (UTF-8).
baseFontSize	Initial (maximum) font size in pixels.

Definition at line 294 of file labelLayoutSolver.hpp.

References ReUseX::vision::osd::LabelLayoutSolver::Candidate::area, ReUseX::vision::osd::LabelLayoutSolver::Candidate::box, ReUseX::vision::osd::LabelLayoutSolver::Candidate::fontSize, ReUseX::vision::osd::LabelLayoutSolver::Candidate::geometricCost, ReUseX::vision::osd::LabelLayoutSolver::Candidate::invArea, ReUseX::vision::osd::LabelLayoutSolver::Candidate::staticCost, and ReUseX::vision::osd::LabelLayoutSolver::Candidate::textAscent.

clear()

void ReUseX::vision::osd::LabelLayoutSolver::clear ( )

inline

Remove all items from the solver (allows reuse across frames).

Definition at line 281 of file labelLayoutSolver.hpp.

getResults()

std::vector< LayoutResult > ReUseX::vision::osd::LabelLayoutSolver::getResults ( ) const

inline

Retrieve the placement result for each label in insertion order.

Returns

Vector of LayoutResult, one per call to add().

Definition at line 483 of file labelLayoutSolver.hpp.

setCanvasSize()

void ReUseX::vision::osd::LabelLayoutSolver::setCanvasSize ( int w, int h )

inline

Change the canvas dimensions (e.g. after a resize).

Definition at line 275 of file labelLayoutSolver.hpp.

setConfig()

void ReUseX::vision::osd::LabelLayoutSolver::setConfig ( const LayoutConfig & cfg )

inline

Update the layout configuration.

Definition at line 272 of file labelLayoutSolver.hpp.

solve()

void ReUseX::vision::osd::LabelLayoutSolver::solve ( )

inline

Run the iterative placement optimisation.

Call this after adding all items and before calling getResults().

Definition at line 342 of file labelLayoutSolver.hpp.

References ReUseX::vision::osd::LabelLayoutSolver::Candidate::box, ReUseX::vision::osd::LabelLayoutSolver::Candidate::geometricCost, ReUseX::vision::osd::LayoutBox::intersectArea(), ReUseX::vision::osd::LayoutBox::intersects(), ReUseX::vision::osd::LabelLayoutSolver::Candidate::invArea, and ReUseX::vision::osd::LabelLayoutSolver::Candidate::staticCost.

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The documentation for this class was generated from the following file:

• libs/reusex/include/ReUseX/vision/osd/labelLayoutSolver.hpp