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skia2/samplecode/SampleAndroidShadows.cpp
jvanverth c20c0c0925 Switch default for SkGaussianBlurShader radius size. 
One step towards removing the 6.2 radius entirely.
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2333403002
TBR=bsalomon@google.com

Review-Url: https://codereview.chromium.org/2333403002
2016-09-14 07:04:49 -07:00

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/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SampleCode.h"
#include "SkBlurMask.h"
#include "SkBlurMaskFilter.h"
#include "SkCanvas.h"
#include "SkGaussianEdgeShader.h"
#include "SkPath.h"
#include "SkPoint3.h"
#include "SkUtils.h"
#include "SkView.h"
#include "sk_tool_utils.h"
////////////////////////////////////////////////////////////////////////////
class ShadowsView : public SampleView {
SkPath fRectPath;
SkPath fRRPath;
SkPath fCirclePath;
SkPoint3 fLightPos;
bool fShowAmbient;
bool fShowSpot;
bool fUseAlt;
bool fShowObject;
public:
ShadowsView()
: fShowAmbient(true)
, fShowSpot(true)
, fUseAlt(true)
, fShowObject(true) {}
protected:
void onOnceBeforeDraw() override {
fCirclePath.addCircle(0, 0, 50);
fRectPath.addRect(SkRect::MakeXYWH(-100, -50, 200, 100));
fRRPath.addRRect(SkRRect::MakeRectXY(SkRect::MakeXYWH(-100, -50, 200, 100), 4, 4));
fLightPos = SkPoint3::Make(-700, -700, 2800);
}
// overrides from SkEventSink
bool onQuery(SkEvent* evt) override {
if (SampleCode::TitleQ(*evt)) {
SampleCode::TitleR(evt, "AndroidShadows");
return true;
}
SkUnichar uni;
if (SampleCode::CharQ(*evt, &uni)) {
switch (uni) {
case 'B':
fShowAmbient = !fShowAmbient;
break;
case 'S':
fShowSpot = !fShowSpot;
break;
case 'T':
fUseAlt = !fUseAlt;
break;
case 'O':
fShowObject = !fShowObject;
break;
case '>':
fLightPos.fZ += 10;
break;
case '<':
fLightPos.fZ -= 10;
break;
default:
break;
}
this->inval(nullptr);
}
return this->INHERITED::onQuery(evt);
}
void drawBG(SkCanvas* canvas) {
canvas->drawColor(0xFFDDDDDD);
}
static void GetOcclRect(const SkPath& path, SkRect* occlRect) {
SkRect pathRect;
SkRRect pathRRect;
if (path.isOval(&pathRect)) {
*occlRect = sk_tool_utils::compute_central_occluder(SkRRect::MakeOval(pathRect));
} else if (path.isRRect(&pathRRect)) {
*occlRect = sk_tool_utils::compute_central_occluder(pathRRect);
} else if (path.isRect(occlRect)) {
// the inverse transform for the spot shadow occluder doesn't always get us
// back to exactly the same position, so deducting a little slop
occlRect->inset(1, 1);
} else {
*occlRect = SkRect::MakeEmpty();
}
}
void drawAmbientShadow(SkCanvas* canvas, const SkPath& path, SkScalar zValue,
SkScalar ambientAlpha) {
if (ambientAlpha <= 0) {
return;
}
const SkScalar kHeightFactor = 1.f / 128.f;
const SkScalar kGeomFactor = 64;
SkScalar umbraAlpha = 1 / (1 + SkMaxScalar(zValue*kHeightFactor, 0));
SkScalar radius = zValue*kHeightFactor*kGeomFactor;
// occlude blur
SkRect occlRect;
GetOcclRect(path, &occlRect);
sk_sp<SkMaskFilter> mf = SkBlurMaskFilter::Make(kNormal_SkBlurStyle,
SkBlurMask::ConvertRadiusToSigma(radius),
occlRect,
SkBlurMaskFilter::kNone_BlurFlag);
SkPaint paint;
paint.setAntiAlias(true);
paint.setMaskFilter(std::move(mf));
paint.setColor(SkColorSetARGB((unsigned char)(ambientAlpha*umbraAlpha*255.999f), 0, 0, 0));
canvas->drawPath(path, paint);
// draw occlusion rect
#if DRAW_OCCL_RECT
SkPaint stroke;
stroke.setStyle(SkPaint::kStroke_Style);
stroke.setColor(SK_ColorBLUE);
canvas->drawRect(occlRect, stroke);
#endif
}
void drawAmbientShadowAlt(SkCanvas* canvas, const SkPath& path, SkScalar zValue,
SkScalar ambientAlpha) {
if (ambientAlpha <= 0) {
return;
}
const SkScalar kHeightFactor = 1.f / 128.f;
const SkScalar kGeomFactor = 64;
SkScalar umbraAlpha = 1 / (1 + SkMaxScalar(zValue*kHeightFactor, 0));
SkScalar radius = zValue*kHeightFactor*kGeomFactor;
// distance to outer of edge of geometry from original shape edge
SkScalar offset = radius*umbraAlpha;
SkRect pathRect;
SkRRect pathRRect;
SkScalar scaleFactors[2];
if (!canvas->getTotalMatrix().getMinMaxScales(scaleFactors)) {
return;
}
if (scaleFactors[0] != scaleFactors[1] || radius*scaleFactors[0] >= 64 ||
!((path.isOval(&pathRect) && pathRect.width() == pathRect.height()) ||
(path.isRRect(&pathRRect) && pathRRect.allCornersCircular()) ||
path.isRect(&pathRect))) {
this->drawAmbientShadow(canvas, path, zValue, ambientAlpha);
return;
}
// For all of these, we inset the offset rect by half the radius to get our stroke shape.
SkScalar strokeOutset = offset - SK_ScalarHalf*radius;
// Make sure we'll have a radius of at least 0.5 after xform
if (strokeOutset*scaleFactors[0] < 0.5f) {
strokeOutset = 0.5f / scaleFactors[0];
}
if (path.isOval(nullptr)) {
pathRect.outset(strokeOutset, strokeOutset);
pathRRect = SkRRect::MakeOval(pathRect);
} else if (path.isRect(nullptr)) {
pathRect.outset(strokeOutset, strokeOutset);
pathRRect = SkRRect::MakeRectXY(pathRect, strokeOutset, strokeOutset);
} else {
pathRRect.outset(strokeOutset, strokeOutset);
}
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
// we outset the stroke a little to cover up AA on the interior edge
SkScalar pad = 0.5f;
paint.setStrokeWidth(radius + 2*pad);
// handle scale of radius and pad due to CTM
radius *= scaleFactors[0];
pad *= scaleFactors[0];
SkASSERT(radius < 16384);
SkASSERT(pad < 64);
// Convert radius to 14.2 fixed point and place in the R & G components.
// Convert pad to 6.2 fixed point and place in the B component.
uint16_t iRadius = (uint16_t)(radius*4.0f);
unsigned char alpha = (unsigned char)(ambientAlpha*255.999f);
paint.setColor(SkColorSetARGB(alpha, iRadius >> 8, iRadius & 0xff,
(unsigned char)(4.0f*pad)));
paint.setShader(SkGaussianEdgeShader::Make());
canvas->drawRRect(pathRRect, paint);
}
void drawSpotShadow(SkCanvas* canvas, const SkPath& path, SkScalar zValue,
SkPoint3 lightPos, SkScalar lightWidth, SkScalar spotAlpha) {
if (spotAlpha <= 0) {
return;
}
SkScalar zRatio = zValue / (lightPos.fZ - zValue);
if (zRatio < 0.0f) {
zRatio = 0.0f;
} else if (zRatio > 0.95f) {
zRatio = 0.95f;
}
SkScalar blurRadius = lightWidth*zRatio;
// compute the transformation params
SkPoint center = SkPoint::Make(path.getBounds().centerX(), path.getBounds().centerY());
SkMatrix ctmInverse;
if (!canvas->getTotalMatrix().invert(&ctmInverse)) {
return;
}
SkPoint lightPos2D = SkPoint::Make(lightPos.fX, lightPos.fY);
ctmInverse.mapPoints(&lightPos2D, 1);
SkPoint offset = SkPoint::Make(zRatio*(center.fX - lightPos2D.fX),
zRatio*(center.fY - lightPos2D.fY));
SkScalar scale = lightPos.fZ / (lightPos.fZ - zValue);
SkAutoCanvasRestore acr(canvas, true);
sk_sp<SkMaskFilter> mf = SkBlurMaskFilter::Make(kNormal_SkBlurStyle,
SkBlurMask::ConvertRadiusToSigma(blurRadius),
SkBlurMaskFilter::kNone_BlurFlag);
SkPaint paint;
paint.setAntiAlias(true);
paint.setMaskFilter(std::move(mf));
paint.setColor(SkColorSetARGB((unsigned char)(spotAlpha*255.999f), 0, 0, 0));
// apply transformation to shadow
canvas->scale(scale, scale);
canvas->translate(offset.fX, offset.fY);
canvas->drawPath(path, paint);
}
void drawSpotShadowAlt(SkCanvas* canvas, const SkPath& path, SkScalar zValue,
SkPoint3 lightPos, SkScalar lightWidth, SkScalar spotAlpha) {
if (spotAlpha <= 0) {
return;
}
SkScalar zRatio = zValue / (lightPos.fZ - zValue);
if (zRatio < 0.0f) {
zRatio = 0.0f;
} else if (zRatio > 0.95f) {
zRatio = 0.95f;
}
SkScalar radius = 2.0f*lightWidth*zRatio;
SkRect pathRect;
SkRRect pathRRect;
SkScalar scaleFactors[2];
if (!canvas->getTotalMatrix().getMinMaxScales(scaleFactors)) {
return;
}
if (scaleFactors[0] != scaleFactors[1] || radius*scaleFactors[0] >= 16384 ||
!((path.isOval(&pathRect) && pathRect.width() == pathRect.height()) ||
(path.isRRect(&pathRRect) && pathRRect.allCornersCircular()) ||
path.isRect(&pathRect))) {
this->drawSpotShadow(canvas, path, zValue, lightPos, lightWidth, spotAlpha);
return;
}
// For all of these, we need to ensure we have a rrect with radius >= 0.5f in device space
SkScalar minRadius = SK_ScalarHalf/scaleFactors[0];
if (path.isOval(nullptr)) {
pathRRect = SkRRect::MakeOval(pathRect);
} else if (path.isRect(nullptr)) {
pathRRect = SkRRect::MakeRectXY(pathRect, minRadius, minRadius);
} else {
if (pathRRect.getSimpleRadii().fX < minRadius) {
pathRRect.setRectXY(pathRRect.rect(), minRadius, minRadius);
}
}
// compute the scale and translation for the shadow
SkScalar scale = lightPos.fZ / (lightPos.fZ - zValue);
SkRRect shadowRRect;
pathRRect.transform(SkMatrix::MakeScale(scale, scale), &shadowRRect);
SkPoint center = SkPoint::Make(shadowRRect.rect().centerX(), shadowRRect.rect().centerY());
SkMatrix ctmInverse;
if (!canvas->getTotalMatrix().invert(&ctmInverse)) {
return;
}
SkPoint lightPos2D = SkPoint::Make(lightPos.fX, lightPos.fY);
ctmInverse.mapPoints(&lightPos2D, 1);
SkPoint offset = SkPoint::Make(zRatio*(center.fX - lightPos2D.fX),
zRatio*(center.fY - lightPos2D.fY));
SkAutoCanvasRestore acr(canvas, true);
SkPaint paint;
paint.setAntiAlias(true);
// We outset the stroke by the length of the translation so the shadow extends to
// the edge of the shape. We also add 1/2 to cover up AA on the interior edge.
SkScalar pad = offset.length() + 0.5f;
// compute area
SkScalar strokeWidth = radius + 2.0f*pad/scaleFactors[0];
SkScalar strokedArea = 2.0f*strokeWidth*(shadowRRect.width() + shadowRRect.height());
SkScalar filledArea = (shadowRRect.height() + radius)*(shadowRRect.width() + radius);
// If the area of the stroked geometry is larger than the fill geometry, or
// if our pad is too big to convert to 6.2 fixed point, just fill it.
if (strokedArea > filledArea || pad >= 64) {
pad = 0;
paint.setStyle(SkPaint::kStrokeAndFill_Style);
paint.setStrokeWidth(radius);
} else {
paint.setStyle(SkPaint::kStroke_Style);
paint.setStrokeWidth(strokeWidth);
}
paint.setShader(SkGaussianEdgeShader::Make());
// handle scale of radius due to CTM
radius *= scaleFactors[0];
// don't need to scale pad as it was computed from the transformed offset
SkASSERT(radius < 16384);
SkASSERT(pad < 64);
// Convert radius to 14.2 fixed point and place in the R & G components.
// Convert pad to 6.2 fixed point and place in the B component.
uint16_t iRadius = (uint16_t)(radius*4.0f);
unsigned char alpha = (unsigned char)(spotAlpha*255.999f);
paint.setColor(SkColorSetARGB(alpha, iRadius >> 8, iRadius & 0xff,
(unsigned char)(4.0f*pad)));
// apply transformation to shadow
canvas->translate(offset.fX, offset.fY);
canvas->drawRRect(shadowRRect, paint);
}
void drawShadowedPath(SkCanvas* canvas, const SkPath& path, SkScalar zValue,
const SkPaint& paint, SkScalar ambientAlpha,
const SkPoint3& lightPos, SkScalar lightWidth, SkScalar spotAlpha) {
if (fShowAmbient) {
if (fUseAlt) {
this->drawAmbientShadowAlt(canvas, path, zValue, ambientAlpha);
} else {
this->drawAmbientShadow(canvas, path, zValue, ambientAlpha);
}
}
if (fShowSpot) {
if (fUseAlt) {
this->drawSpotShadowAlt(canvas, path, zValue, lightPos, lightWidth, spotAlpha);
} else {
this->drawSpotShadow(canvas, path, zValue, lightPos, lightWidth, spotAlpha);
}
}
if (fShowObject) {
canvas->drawPath(path, paint);
}
}
void onDrawContent(SkCanvas* canvas) override {
this->drawBG(canvas);
const SkScalar kLightWidth = 2800;
const SkScalar kAmbientAlpha = 0.25f;
const SkScalar kSpotAlpha = 0.25f;
SkPaint paint;
paint.setAntiAlias(true);
SkPoint3 lightPos = fLightPos;
paint.setColor(SK_ColorWHITE);
canvas->translate(200, 90);
lightPos.fX += 200;
lightPos.fY += 90;
this->drawShadowedPath(canvas, fRectPath, 2, paint, kAmbientAlpha,
lightPos, kLightWidth, kSpotAlpha);
paint.setColor(SK_ColorRED);
canvas->translate(250, 0);
lightPos.fX += 250;
this->drawShadowedPath(canvas, fRRPath, 4, paint, kAmbientAlpha,
lightPos, kLightWidth, kSpotAlpha);
paint.setColor(SK_ColorBLUE);
canvas->translate(-250, 110);
lightPos.fX -= 250;
lightPos.fY += 110;
this->drawShadowedPath(canvas, fCirclePath, 8, paint, 0.0f,
lightPos, kLightWidth, 0.5f);
paint.setColor(SK_ColorGREEN);
canvas->translate(250, 0);
lightPos.fX += 250;
this->drawShadowedPath(canvas, fRRPath, 64, paint, kAmbientAlpha,
lightPos, kLightWidth, kSpotAlpha);
}
protected:
SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned modi) override {
return new SkView::Click(this);
}
bool onClick(Click *click) override {
SkScalar x = click->fCurr.fX;
SkScalar y = click->fCurr.fY;
SkScalar dx = x - click->fPrev.fX;
SkScalar dy = y - click->fPrev.fY;
if (dx != 0 || dy != 0) {
fLightPos.fX += dx;
fLightPos.fY += dy;
this->inval(nullptr);
}
return true;
}
private:
typedef SkView INHERITED;
};
//////////////////////////////////////////////////////////////////////////////
static SkView* MyFactory() { return new ShadowsView; }
static SkViewRegister reg(MyFactory);
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