Gamma correction for distance field text.
Handles both non-LCD and LCD text. Uses a texture to look up the gamma correction values for a given text color or luminance.
BUG=skia:
Committed: https://skia.googlesource.com/skia/+/4d517fdbb145cb95e5e935470df331e1b6667cfc
R=reed@google.com, bungeman@google.com, robertphillips@google.com, bsalomon@google.com
Author: jvanverth@google.com
Review URL: https://codereview.chromium.org/258883002
diff --git a/src/gpu/effects/GrDistanceFieldTextureEffect.cpp b/src/gpu/effects/GrDistanceFieldTextureEffect.cpp
index 6196cce..29f0985 100755
--- a/src/gpu/effects/GrDistanceFieldTextureEffect.cpp
+++ b/src/gpu/effects/GrDistanceFieldTextureEffect.cpp
@@ -15,6 +15,19 @@
#include "SkDistanceFieldGen.h"
+// To get optical sizes people don't complain about when we blit correctly,
+// we need to slightly bold each glyph. On the Mac, we need a larger bold value.
+#if defined(SK_BUILD_FOR_MAC)
+#define SK_DistanceFieldLCDFactor "0.33"
+#define SK_DistanceFieldNonLCDFactor "0.25"
+#else
+#define SK_DistanceFieldLCDFactor "0.05"
+#define SK_DistanceFieldNonLCDFactor "0.05"
+#endif
+
+// Assuming a radius of the diagonal of the fragment, hence a factor of sqrt(2)/2
+#define SK_DistanceFieldAAFactor "0.7071"
+
class GrGLDistanceFieldTextureEffect : public GrGLVertexEffect {
public:
GrGLDistanceFieldTextureEffect(const GrBackendEffectFactory& factory,
@@ -56,7 +69,8 @@
kVec2f_GrSLType);
builder->fsCodeAppend(";\n");
builder->fsCodeAppend("\tfloat distance = "
- SK_DistanceFieldMultiplier "*(texColor.r - " SK_DistanceFieldThreshold ");\n");
+ SK_DistanceFieldMultiplier "*(texColor.r - " SK_DistanceFieldThreshold ")"
+ "+ " SK_DistanceFieldNonLCDFactor ";\n");
// we adjust for the effect of the transformation on the distance by using
// the length of the gradient of the texture coordinates. We use st coordinates
@@ -66,8 +80,7 @@
builder->fsCodeAppend("\tfloat afwidth;\n");
if (dfTexEffect.isSimilarity()) {
// this gives us a smooth step across approximately one fragment
- // (assuming a radius of the diagonal of the fragment, hence a factor of sqrt(2)/2)
- builder->fsCodeAppend("\tafwidth = 0.7071*dFdx(st.x);\n");
+ builder->fsCodeAppend("\tafwidth = " SK_DistanceFieldAAFactor "*dFdx(st.x);\n");
} else {
builder->fsCodeAppend("\tvec2 Jdx = dFdx(st);\n");
builder->fsCodeAppend("\tvec2 Jdy = dFdy(st);\n");
@@ -88,12 +101,25 @@
builder->fsCodeAppend("\t uv_grad.x*Jdx.y + uv_grad.y*Jdy.y);\n");
// this gives us a smooth step across approximately one fragment
- // (assuming a radius of the diagonal of the fragment, hence a factor of sqrt(2)/2)
- builder->fsCodeAppend("\tafwidth = 0.7071*length(grad);\n");
+ builder->fsCodeAppend("\tafwidth = " SK_DistanceFieldAAFactor "*length(grad);\n");
}
-
builder->fsCodeAppend("\tfloat val = smoothstep(-afwidth, afwidth, distance);\n");
+#ifdef SK_GAMMA_APPLY_TO_A8
+ // adjust based on gamma
+ const char* luminanceUniName = NULL;
+ // width, height, 1/(3*width)
+ fLuminanceUni = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
+ kFloat_GrSLType, "Luminance",
+ &luminanceUniName);
+
+ builder->fsCodeAppendf("\tuv = vec2(val, %s);\n", luminanceUniName);
+ builder->fsCodeAppend("\tvec4 gammaColor = ");
+ builder->fsAppendTextureLookup(samplers[1], "uv", kVec2f_GrSLType);
+ builder->fsCodeAppend(";\n");
+ builder->fsCodeAppend("\tval = gammaColor.r;\n");
+#endif
+
builder->fsCodeAppendf("\t%s = %s;\n", outputColor,
(GrGLSLExpr4(inputColor) * GrGLSLExpr1("val")).c_str());
}
@@ -110,6 +136,15 @@
SkIntToScalar(fTextureSize.width()),
SkIntToScalar(fTextureSize.height()));
}
+#ifdef SK_GAMMA_APPLY_TO_A8
+ const GrDistanceFieldTextureEffect& dfTexEffect =
+ drawEffect.castEffect<GrDistanceFieldTextureEffect>();
+ float luminance = dfTexEffect.getLuminance();
+ if (luminance != fLuminance) {
+ uman.set1f(fLuminanceUni, luminance);
+ fLuminance = luminance;
+ }
+#endif
}
static inline EffectKey GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
@@ -122,6 +157,8 @@
private:
GrGLUniformManager::UniformHandle fTextureSizeUni;
SkISize fTextureSize;
+ GrGLUniformManager::UniformHandle fLuminanceUni;
+ float fLuminance;
typedef GrGLVertexEffect INHERITED;
};
@@ -130,10 +167,22 @@
GrDistanceFieldTextureEffect::GrDistanceFieldTextureEffect(GrTexture* texture,
const GrTextureParams& params,
+#ifdef SK_GAMMA_APPLY_TO_A8
+ GrTexture* gamma,
+ const GrTextureParams& gammaParams,
+ float luminance,
+#endif
bool similarity)
: fTextureAccess(texture, params)
+#ifdef SK_GAMMA_APPLY_TO_A8
+ , fGammaTextureAccess(gamma, gammaParams)
+ , fLuminance(luminance)
+#endif
, fIsSimilarity(similarity) {
this->addTextureAccess(&fTextureAccess);
+#ifdef SK_GAMMA_APPLY_TO_A8
+ this->addTextureAccess(&fGammaTextureAccess);
+#endif
this->addVertexAttrib(kVec2f_GrSLType);
}
@@ -166,6 +215,10 @@
GrTexture* textures[]) {
int texIdx = random->nextBool() ? GrEffectUnitTest::kSkiaPMTextureIdx :
GrEffectUnitTest::kAlphaTextureIdx;
+#ifdef SK_GAMMA_APPLY_TO_A8
+ int texIdx2 = random->nextBool() ? GrEffectUnitTest::kSkiaPMTextureIdx :
+ GrEffectUnitTest::kAlphaTextureIdx;
+#endif
static const SkShader::TileMode kTileModes[] = {
SkShader::kClamp_TileMode,
SkShader::kRepeat_TileMode,
@@ -177,8 +230,16 @@
};
GrTextureParams params(tileModes, random->nextBool() ? GrTextureParams::kBilerp_FilterMode :
GrTextureParams::kNone_FilterMode);
+#ifdef SK_GAMMA_APPLY_TO_A8
+ GrTextureParams params2(tileModes, random->nextBool() ? GrTextureParams::kBilerp_FilterMode :
+ GrTextureParams::kNone_FilterMode);
+#endif
return GrDistanceFieldTextureEffect::Create(textures[texIdx], params,
+#ifdef SK_GAMMA_APPLY_TO_A8
+ textures[texIdx2], params2,
+ random->nextF(),
+#endif
random->nextBool());
}
@@ -211,7 +272,7 @@
fsCoordName = fsCoordNamePtr;
const char* attrName0 =
- builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[0])->c_str();
+ builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[0])->c_str();
builder->vsCodeAppendf("\t%s = %s;\n", vsCoordName, attrName0);
const char* textureSizeUniName = NULL;
@@ -237,22 +298,24 @@
builder->fsAppendTextureLookup(samplers[0], "uv", kVec2f_GrSLType);
builder->fsCodeAppend(";\n");
builder->fsCodeAppend("\tvec3 distance;\n");
- builder->fsCodeAppend("\tdistance.y = "
- SK_DistanceFieldMultiplier "*(texColor.r - " SK_DistanceFieldThreshold ");\n");
+ builder->fsCodeAppend("\tdistance.y = texColor.r;\n");
// red is distance to left offset
builder->fsCodeAppend("\tvec2 uv_adjusted = uv - offset;\n");
builder->fsCodeAppend("\ttexColor = ");
builder->fsAppendTextureLookup(samplers[0], "uv_adjusted", kVec2f_GrSLType);
builder->fsCodeAppend(";\n");
- builder->fsCodeAppend("\tdistance.x = "
- SK_DistanceFieldMultiplier "*(texColor.r - " SK_DistanceFieldThreshold ");\n");
+ builder->fsCodeAppend("\tdistance.x = texColor.r;\n");
// blue is distance to right offset
builder->fsCodeAppend("\tuv_adjusted = uv + offset;\n");
builder->fsCodeAppend("\ttexColor = ");
builder->fsAppendTextureLookup(samplers[0], "uv_adjusted", kVec2f_GrSLType);
builder->fsCodeAppend(";\n");
- builder->fsCodeAppend("\tdistance.z = "
- SK_DistanceFieldMultiplier "*(texColor.r - " SK_DistanceFieldThreshold ");\n");
+ builder->fsCodeAppend("\tdistance.z = texColor.r;\n");
+
+ builder->fsCodeAppend("\tdistance = "
+ "vec3(" SK_DistanceFieldMultiplier ")*(distance - vec3(" SK_DistanceFieldThreshold"))"
+ "+ vec3(" SK_DistanceFieldLCDFactor ");\n");
+
// we adjust for the effect of the transformation on the distance by using
// the length of the gradient of the texture coordinates. We use st coordinates
// to ensure we're mapping 1:1 from texel space to pixel space.
@@ -264,8 +327,7 @@
builder->fsCodeAppend("\tfloat afwidth;\n");
if (dfTexEffect.isUniformScale()) {
// this gives us a smooth step across approximately one fragment
- // (assuming a radius of the diagonal of the fragment, hence a factor of sqrt(2)/2)
- builder->fsCodeAppend("\tafwidth = 0.7071*dx;\n");
+ builder->fsCodeAppend("\tafwidth = " SK_DistanceFieldAAFactor "*dx;\n");
} else {
builder->fsCodeAppend("\tvec2 uv_grad;\n");
if (builder->ctxInfo().caps()->dropsTileOnZeroDivide()) {
@@ -283,12 +345,36 @@
builder->fsCodeAppend("\t uv_grad.x*Jdx.y + uv_grad.y*Jdy.y);\n");
// this gives us a smooth step across approximately one fragment
- // (assuming a radius of the diagonal of the fragment, hence a factor of sqrt(2)/2)
- builder->fsCodeAppend("\tafwidth = 0.7071*length(grad);\n");
+ builder->fsCodeAppend("\tafwidth = " SK_DistanceFieldAAFactor "*length(grad);\n");
}
builder->fsCodeAppend("\tvec4 val = vec4(smoothstep(vec3(-afwidth), vec3(afwidth), distance), 1.0);\n");
+ // adjust based on gamma
+ const char* textColorUniName = NULL;
+ // width, height, 1/(3*width)
+ fTextColorUni = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
+ kVec3f_GrSLType, "TextColor",
+ &textColorUniName);
+
+ builder->fsCodeAppendf("\tuv = vec2(val.x, %s.x);\n", textColorUniName);
+ builder->fsCodeAppend("\tvec4 gammaColor = ");
+ builder->fsAppendTextureLookup(samplers[1], "uv", kVec2f_GrSLType);
+ builder->fsCodeAppend(";\n");
+ builder->fsCodeAppend("\tval.x = gammaColor.r;\n");
+
+ builder->fsCodeAppendf("\tuv = vec2(val.y, %s.y);\n", textColorUniName);
+ builder->fsCodeAppend("\tgammaColor = ");
+ builder->fsAppendTextureLookup(samplers[1], "uv", kVec2f_GrSLType);
+ builder->fsCodeAppend(";\n");
+ builder->fsCodeAppend("\tval.y = gammaColor.r;\n");
+
+ builder->fsCodeAppendf("\tuv = vec2(val.z, %s.z);\n", textColorUniName);
+ builder->fsCodeAppend("\tgammaColor = ");
+ builder->fsAppendTextureLookup(samplers[1], "uv", kVec2f_GrSLType);
+ builder->fsCodeAppend(";\n");
+ builder->fsCodeAppend("\tval.z = gammaColor.r;\n");
+
builder->fsCodeAppendf("\t%s = %s;\n", outputColor,
(GrGLSLExpr4(inputColor) * GrGLSLExpr4("val")).c_str());
}
@@ -296,12 +382,13 @@
virtual void setData(const GrGLUniformManager& uman,
const GrDrawEffect& drawEffect) SK_OVERRIDE {
SkASSERT(fTextureSizeUni.isValid());
+ SkASSERT(fTextColorUni.isValid());
+ const GrDistanceFieldLCDTextureEffect& dfTexEffect =
+ drawEffect.castEffect<GrDistanceFieldLCDTextureEffect>();
GrTexture* texture = drawEffect.effect()->get()->texture(0);
if (texture->width() != fTextureSize.width() ||
texture->height() != fTextureSize.height()) {
- const GrDistanceFieldLCDTextureEffect& dfTexEffect =
- drawEffect.castEffect<GrDistanceFieldLCDTextureEffect>();
fTextureSize = SkISize::Make(texture->width(), texture->height());
float delta = 1.0f/(3.0f*texture->width());
if (dfTexEffect.useBGR()) {
@@ -312,40 +399,55 @@
SkIntToScalar(fTextureSize.height()),
delta);
}
+
+ GrColor textColor = dfTexEffect.getTextColor();
+ if (textColor != fTextColor) {
+ static const float ONE_OVER_255 = 1.f / 255.f;
+ uman.set3f(fTextColorUni,
+ GrColorUnpackR(textColor) * ONE_OVER_255,
+ GrColorUnpackG(textColor) * ONE_OVER_255,
+ GrColorUnpackB(textColor) * ONE_OVER_255);
+ fTextColor = textColor;
+ }
}
static inline EffectKey GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
const GrDistanceFieldLCDTextureEffect& dfTexEffect =
drawEffect.castEffect<GrDistanceFieldLCDTextureEffect>();
- int uniformScale = dfTexEffect.isUniformScale() ? 0x01 : 0x00;
- int useBGR = dfTexEffect.useBGR() ? 0x10 : 0x00;
- return uniformScale | useBGR;
+ return dfTexEffect.isUniformScale() ? 0x01 : 0x00;;
}
private:
GrGLUniformManager::UniformHandle fTextureSizeUni;
SkISize fTextureSize;
+ GrGLUniformManager::UniformHandle fTextColorUni;
+ SkColor fTextColor;
typedef GrGLVertexEffect INHERITED;
};
///////////////////////////////////////////////////////////////////////////////
-GrDistanceFieldLCDTextureEffect::GrDistanceFieldLCDTextureEffect(GrTexture* texture,
- const GrTextureParams& params,
- bool uniformScale,
- bool useBGR)
+GrDistanceFieldLCDTextureEffect::GrDistanceFieldLCDTextureEffect(
+ GrTexture* texture, const GrTextureParams& params,
+ GrTexture* gamma, const GrTextureParams& gParams,
+ SkColor textColor,
+ bool uniformScale, bool useBGR)
: fTextureAccess(texture, params)
+ , fGammaTextureAccess(gamma, gParams)
+ , fTextColor(textColor)
, fUniformScale(uniformScale)
, fUseBGR(useBGR) {
this->addTextureAccess(&fTextureAccess);
+ this->addTextureAccess(&fGammaTextureAccess);
this->addVertexAttrib(kVec2f_GrSLType);
}
bool GrDistanceFieldLCDTextureEffect::onIsEqual(const GrEffect& other) const {
- const GrDistanceFieldLCDTextureEffect& cte = CastEffect<GrDistanceFieldLCDTextureEffect>(other);
- return fTextureAccess == cte.fTextureAccess;
+ const GrDistanceFieldLCDTextureEffect& cte =
+ CastEffect<GrDistanceFieldLCDTextureEffect>(other);
+ return (fTextureAccess == cte.fTextureAccess && fGammaTextureAccess == cte.fGammaTextureAccess);
}
void GrDistanceFieldLCDTextureEffect::getConstantColorComponents(GrColor* color,
@@ -371,7 +473,9 @@
const GrDrawTargetCaps&,
GrTexture* textures[]) {
int texIdx = random->nextBool() ? GrEffectUnitTest::kSkiaPMTextureIdx :
- GrEffectUnitTest::kAlphaTextureIdx;
+ GrEffectUnitTest::kAlphaTextureIdx;
+ int texIdx2 = random->nextBool() ? GrEffectUnitTest::kSkiaPMTextureIdx :
+ GrEffectUnitTest::kAlphaTextureIdx;
static const SkShader::TileMode kTileModes[] = {
SkShader::kClamp_TileMode,
SkShader::kRepeat_TileMode,
@@ -383,7 +487,14 @@
};
GrTextureParams params(tileModes, random->nextBool() ? GrTextureParams::kBilerp_FilterMode :
GrTextureParams::kNone_FilterMode);
-
+ GrTextureParams params2(tileModes, random->nextBool() ? GrTextureParams::kBilerp_FilterMode :
+ GrTextureParams::kNone_FilterMode);
+ GrColor textColor = GrColorPackRGBA(random->nextULessThan(256),
+ random->nextULessThan(256),
+ random->nextULessThan(256),
+ random->nextULessThan(256));
return GrDistanceFieldLCDTextureEffect::Create(textures[texIdx], params,
+ textures[texIdx2], params2,
+ textColor,
random->nextBool(), random->nextBool());
}