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/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkDrawShadowInfo.h"
#include "SkMatrix.h"
#include "SkPath.h"
#include "SkRect.h"
namespace SkDrawShadowMetrics {
static SkScalar compute_z(SkScalar x, SkScalar y, const SkPoint3& params) {
return x*params.fX + y*params.fY + params.fZ;
}
void GetLocalBounds(const SkPath& path, const SkDrawShadowRec& rec, const SkMatrix& ctm,
SkRect* bounds) {
SkRect ambientBounds = path.getBounds();
SkScalar occluderZ;
if (SkScalarNearlyZero(rec.fZPlaneParams.fX) && SkScalarNearlyZero(rec.fZPlaneParams.fY)) {
occluderZ = rec.fZPlaneParams.fZ;
} else {
occluderZ = compute_z(ambientBounds.fLeft, ambientBounds.fTop, rec.fZPlaneParams);
occluderZ = SkTMax(occluderZ, compute_z(ambientBounds.fRight, ambientBounds.fTop,
rec.fZPlaneParams));
occluderZ = SkTMax(occluderZ, compute_z(ambientBounds.fLeft, ambientBounds.fBottom,
rec.fZPlaneParams));
occluderZ = SkTMax(occluderZ, compute_z(ambientBounds.fRight, ambientBounds.fBottom,
rec.fZPlaneParams));
}
SkScalar ambientBlur;
SkScalar spotBlur;
SkScalar spotScale;
SkPoint spotOffset;
if (ctm.hasPerspective()) {
// transform ambient and spot bounds into device space
ctm.mapRect(&ambientBounds);
// get ambient blur (in device space)
ambientBlur = SkDrawShadowMetrics::AmbientBlurRadius(occluderZ);
// get spot params (in device space)
SkPoint devLightPos = SkPoint::Make(rec.fLightPos.fX, rec.fLightPos.fY);
ctm.mapPoints(&devLightPos, 1);
SkDrawShadowMetrics::GetSpotParams(occluderZ, devLightPos.fX, devLightPos.fY,
rec.fLightPos.fZ, rec.fLightRadius,
&spotBlur, &spotScale, &spotOffset);
} else {
SkScalar devToSrcScale = SkScalarInvert(ctm.getMinScale());
// get ambient blur (in local space)
SkScalar devSpaceAmbientBlur = SkDrawShadowMetrics::AmbientBlurRadius(occluderZ);
ambientBlur = devSpaceAmbientBlur*devToSrcScale;
// get spot params (in local space)
SkDrawShadowMetrics::GetSpotParams(occluderZ, rec.fLightPos.fX, rec.fLightPos.fY,
rec.fLightPos.fZ, rec.fLightRadius,
&spotBlur, &spotScale, &spotOffset);
// convert spot blur to local space
spotBlur *= devToSrcScale;
}
// in both cases, adjust ambient and spot bounds
SkRect spotBounds = ambientBounds;
ambientBounds.outset(ambientBlur, ambientBlur);
spotBounds.fLeft *= spotScale;
spotBounds.fTop *= spotScale;
spotBounds.fRight *= spotScale;
spotBounds.fBottom *= spotScale;
spotBounds.offset(spotOffset.fX, spotOffset.fY);
spotBounds.outset(spotBlur, spotBlur);
// merge bounds
*bounds = ambientBounds;
bounds->join(spotBounds);
// outset a bit to account for floating point error
bounds->outset(1, 1);
// if perspective, transform back to src space
if (ctm.hasPerspective()) {
// TODO: create tighter mapping from dev rect back to src rect
SkMatrix inverse;
if (ctm.invert(&inverse)) {
inverse.mapRect(bounds);
}
}
}
}
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