SkRegion::Spanerator Class Reference

#include <SkRegion.h>

Public Member Functions
	Spanerator (const SkRegion &region, int y, int left, int right)
bool	next (int *left, int *right)

Detailed Description

Returns the line segment ends within SkRegion that intersect a horizontal line.

Definition at line 563 of file SkRegion.h.

Constructor & Destructor Documentation

Spanerator()

SkRegion::Spanerator::Spanerator	(	const SkRegion &	region,
		int	y,
		int	left,
		int	right
	)

Sets SkRegion::Spanerator to return line segments in SkRegion on scan line.

Parameters

region	SkRegion to iterate
y	horizontal line to intersect
left	bounds of iteration
right	bounds of iteration

Returns

SkRegion iterator

example: https://fiddle.skia.org/c/@Region_Spanerator_const_SkRegion_int_int_int

Definition at line 1466 of file SkRegion.cpp.

                                            {
    SkDEBUGCODE(SkRegionPriv::Validate(rgn));
 
    const SkIRect& r = rgn.getBounds();
 
    fDone = true;
    if (!rgn.isEmpty() && y >= r.fTop && y < r.fBottom &&
            right > r.fLeft && left < r.fRight) {
        if (rgn.isRect()) {
            if (left < r.fLeft) {
                left = r.fLeft;
            }
            if (right > r.fRight) {
                right = r.fRight;
            }
            fLeft = left;
            fRight = right;
            fRuns = nullptr;    // means we're a rect, not a rgn
            fDone = false;
        } else {
            const SkRegion::RunType* runs = rgn.fRunHead->findScanline(y);
            runs += 2;  // skip Bottom and IntervalCount
            for (;;) {
                // runs[0..1] is to the right of the span, so we're done
                if (runs[0] >= right) {
                    break;
                }
                // runs[0..1] is to the left of the span, so continue
                if (runs[1] <= left) {
                    runs += 2;
                    continue;
                }
                // runs[0..1] intersects the span
                fRuns = runs;
                fLeft = left;
                fRight = right;
                fDone = false;
                break;
            }
        }
    }
}

Member Function Documentation

next()

bool SkRegion::Spanerator::next	(	int *	left,
		int *	right
	)

Advances iterator to next span intersecting SkRegion within line segment provided in constructor. Returns true if interval was found.

Parameters

left	pointer to span start; may be nullptr
right	pointer to span end; may be nullptr

Returns

true if interval was found

example: https://fiddle.skia.org/c/@Region_Spanerator_next

Definition at line 1510 of file SkRegion.cpp.

                                                   {
    if (fDone) {
        return false;
    }
 
    if (fRuns == nullptr) {   // we're a rect
        fDone = true;   // ok, now we're done
        if (left) {
            *left = fLeft;
        }
        if (right) {
            *right = fRight;
        }
        return true;    // this interval is legal
    }
 
    const SkRegion::RunType* runs = fRuns;
 
    if (runs[0] >= fRight) {
        fDone = true;
        return false;
    }
 
    SkASSERT(runs[1] > fLeft);
 
    if (left) {
        *left = std::max(fLeft, runs[0]);
    }
    if (right) {
        *right = std::min(fRight, runs[1]);
    }
    fRuns = runs + 2;
    return true;
}

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

• third_party/skia/include/core/SkRegion.h
• third_party/skia/src/core/SkRegion.cpp