Add LCD support for distance field text.
LCD support is handled by shifting the uv coordinate by 1/3 of a pixel (transformed by the inverse CTM) to the left and right of the original texture coordinate, and using left, center, and right lookups to set the RGB values. This supports both RGB and BGR subpixel order. BUG=skia:2173 R=robertphillips@google.com, egdaniel@google.com, bungeman@google.com Author: jvanverth@google.com Review URL: https://codereview.chromium.org/219243012 git-svn-id: http://skia.googlecode.com/svn/trunk@14049 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
commit-bot@chromium.org
parent
b6779439c4
commit
609ced42e7
@ -84,13 +84,18 @@ void GrDistanceFieldTextContext::flushGlyphs() {
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SkASSERT(fCurrTexture);
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GrTextureParams params(SkShader::kRepeat_TileMode, GrTextureParams::kBilerp_FilterMode);
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// This effect could be stored with one of the cache objects (atlas?)
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drawState->addCoverageEffect(
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GrDistanceFieldTextureEffect::Create(fCurrTexture, params,
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fContext->getMatrix().isSimilarity()),
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kGlyphCoordsAttributeIndex)->unref();
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// Effects could be stored with one of the cache objects (atlas?)
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if (fUseLCDText) {
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bool useBGR = SkDeviceProperties::Geometry::kBGR_Layout ==
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fDeviceProperties.fGeometry.getLayout();
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drawState->addCoverageEffect(GrDistanceFieldLCDTextureEffect::Create(
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fCurrTexture,
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params,
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fContext->getMatrix().rectStaysRect() &&
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fContext->getMatrix().isSimilarity(),
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useBGR),
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kGlyphCoordsAttributeIndex)->unref();
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if (!GrPixelConfigIsAlphaOnly(fCurrTexture->config())) {
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if (kOne_GrBlendCoeff != fPaint.getSrcBlendCoeff() ||
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kISA_GrBlendCoeff != fPaint.getDstBlendCoeff() ||
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fPaint.numColorStages()) {
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@ -107,6 +112,10 @@ void GrDistanceFieldTextContext::flushGlyphs() {
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drawState->setBlendConstant(skcolor_to_grcolor_nopremultiply(fSkPaint.getColor()));
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drawState->setBlendFunc(kConstC_GrBlendCoeff, kISC_GrBlendCoeff);
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} else {
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drawState->addCoverageEffect(GrDistanceFieldTextureEffect::Create(fCurrTexture, params,
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fContext->getMatrix().isSimilarity()),
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kGlyphCoordsAttributeIndex)->unref();
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// set back to normal in case we took LCD path previously.
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drawState->setBlendFunc(fPaint.getSrcBlendCoeff(), fPaint.getDstBlendCoeff());
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drawState->setColor(fPaint.getColor());
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@ -318,6 +327,8 @@ inline void GrDistanceFieldTextContext::init(const GrPaint& paint, const SkPaint
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fSkPaint.setTextSize(SkIntToScalar(kLargeDFFontSize));
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}
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fUseLCDText = fSkPaint.isLCDRenderText();
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fSkPaint.setLCDRenderText(false);
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fSkPaint.setAutohinted(false);
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fSkPaint.setSubpixelText(true);
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@ -32,6 +32,7 @@ public:
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private:
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GrTextStrike* fStrike;
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SkScalar fTextRatio;
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bool fUseLCDText;
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void init(const GrPaint&, const SkPaint&);
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void drawPackedGlyph(GrGlyph::PackedID, SkFixed left, SkFixed top, GrFontScaler*);
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@ -66,7 +66,7 @@ public:
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builder->fsCodeAppendf("\tvec2 uv = %s;\n", fsCoordName.c_str());
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builder->fsCodeAppendf("\tvec2 st = uv*%s;\n", textureSizeUniName);
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builder->fsCodeAppend("\tfloat afwidth;\n");
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if (dfTexEffect.isUniformScale()) {
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if (dfTexEffect.isSimilarity()) {
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// this gives us a smooth step across approximately one fragment
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// (assuming a radius of the diagonal of the fragment, hence a factor of sqrt(2)/2)
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builder->fsCodeAppend("\tafwidth = 0.7071*dFdx(st.x);\n");
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@ -118,7 +118,7 @@ public:
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const GrDistanceFieldTextureEffect& dfTexEffect =
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drawEffect.castEffect<GrDistanceFieldTextureEffect>();
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return dfTexEffect.isUniformScale() ? 0x1 : 0x0;
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return dfTexEffect.isSimilarity() ? 0x1 : 0x0;
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}
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private:
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@ -132,9 +132,9 @@ private:
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GrDistanceFieldTextureEffect::GrDistanceFieldTextureEffect(GrTexture* texture,
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const GrTextureParams& params,
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bool uniformScale)
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bool similarity)
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: fTextureAccess(texture, params)
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, fUniformScale(uniformScale) {
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, fIsSimilarity(similarity) {
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this->addTextureAccess(&fTextureAccess);
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this->addVertexAttrib(kVec2f_GrSLType);
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}
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@ -180,5 +180,210 @@ GrEffectRef* GrDistanceFieldTextureEffect::TestCreate(SkRandom* random,
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GrTextureParams params(tileModes, random->nextBool() ? GrTextureParams::kBilerp_FilterMode :
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GrTextureParams::kNone_FilterMode);
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return GrDistanceFieldTextureEffect::Create(textures[texIdx], params, random->nextBool());
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return GrDistanceFieldTextureEffect::Create(textures[texIdx], params,
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random->nextBool());
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}
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///////////////////////////////////////////////////////////////////////////////
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class GrGLDistanceFieldLCDTextureEffect : public GrGLVertexEffect {
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public:
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GrGLDistanceFieldLCDTextureEffect(const GrBackendEffectFactory& factory,
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const GrDrawEffect& drawEffect)
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: INHERITED (factory)
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, fTextureSize(SkISize::Make(-1,-1)) {}
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virtual void emitCode(GrGLFullShaderBuilder* builder,
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const GrDrawEffect& drawEffect,
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EffectKey key,
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const char* outputColor,
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const char* inputColor,
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const TransformedCoordsArray&,
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const TextureSamplerArray& samplers) SK_OVERRIDE {
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SkASSERT(1 == drawEffect.castEffect<GrDistanceFieldLCDTextureEffect>().numVertexAttribs());
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SkAssertResult(builder->enableFeature(GrGLShaderBuilder::kStandardDerivatives_GLSLFeature));
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const GrDistanceFieldLCDTextureEffect& dfTexEffect =
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drawEffect.castEffect<GrDistanceFieldLCDTextureEffect>();
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SkString fsCoordName;
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const char* vsCoordName;
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const char* fsCoordNamePtr;
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builder->addVarying(kVec2f_GrSLType, "textureCoords", &vsCoordName, &fsCoordNamePtr);
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fsCoordName = fsCoordNamePtr;
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const char* attrName0 =
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builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[0])->c_str();
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builder->vsCodeAppendf("\t%s = %s;\n", vsCoordName, attrName0);
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const char* textureSizeUniName = NULL;
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// width, height, 1/(3*width)
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fTextureSizeUni = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
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kVec3f_GrSLType, "TextureSize",
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&textureSizeUniName);
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// create LCD offset adjusted by inverse of transform
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builder->fsCodeAppendf("\tvec2 uv = %s;\n", fsCoordName.c_str());
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builder->fsCodeAppendf("\tvec2 st = uv*%s.xy;\n", textureSizeUniName);
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if (dfTexEffect.isUniformScale()) {
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builder->fsCodeAppend("\tfloat dx = dFdx(st.x);\n");
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builder->fsCodeAppendf("\tvec2 offset = vec2(dx*%s.z, 0.0);\n", textureSizeUniName);
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} else {
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builder->fsCodeAppend("\tvec2 Jdx = dFdx(st);\n");
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builder->fsCodeAppend("\tvec2 Jdy = dFdy(st);\n");
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builder->fsCodeAppendf("\tvec2 offset = %s.z*Jdx;\n", textureSizeUniName);
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}
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// green is distance to uv center
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builder->fsCodeAppend("\tvec4 texColor = ");
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builder->fsAppendTextureLookup(samplers[0], "uv", kVec2f_GrSLType);
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builder->fsCodeAppend(";\n");
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builder->fsCodeAppend("\tvec3 distance;\n");
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builder->fsCodeAppend("\tdistance.y = " MULTIPLIER "*(texColor.r - " THRESHOLD ");\n");
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// red is distance to left offset
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builder->fsCodeAppend("\tvec2 uv_adjusted = uv - offset;\n");
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builder->fsCodeAppend("\ttexColor = ");
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builder->fsAppendTextureLookup(samplers[0], "uv_adjusted", kVec2f_GrSLType);
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builder->fsCodeAppend(";\n");
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builder->fsCodeAppend("\tdistance.x = " MULTIPLIER "*(texColor.r - " THRESHOLD ");\n");
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// blue is distance to right offset
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builder->fsCodeAppend("\tuv_adjusted = uv + offset;\n");
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builder->fsCodeAppend("\ttexColor = ");
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builder->fsAppendTextureLookup(samplers[0], "uv_adjusted", kVec2f_GrSLType);
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builder->fsCodeAppend(";\n");
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builder->fsCodeAppend("\tdistance.z = " MULTIPLIER "*(texColor.r - " THRESHOLD ");\n");
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// we adjust for the effect of the transformation on the distance by using
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// the length of the gradient of the texture coordinates. We use st coordinates
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// to ensure we're mapping 1:1 from texel space to pixel space.
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// To be strictly correct, we should compute the anti-aliasing factor separately
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// for each color component. However, this is only important when using perspective
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// transformations, and even then using a single factor seems like a reasonable
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// trade-off between quality and speed.
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builder->fsCodeAppend("\tfloat afwidth;\n");
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if (dfTexEffect.isUniformScale()) {
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// this gives us a smooth step across approximately one fragment
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// (assuming a radius of the diagonal of the fragment, hence a factor of sqrt(2)/2)
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builder->fsCodeAppend("\tafwidth = 0.7071*dx;\n");
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} else {
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builder->fsCodeAppend("\tvec2 uv_grad;\n");
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if (builder->ctxInfo().caps()->dropsTileOnZeroDivide()) {
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// this is to compensate for the Adreno, which likes to drop tiles on division by 0
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builder->fsCodeAppend("\tfloat uv_len2 = dot(uv, uv);\n");
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builder->fsCodeAppend("\tif (uv_len2 < 0.0001) {\n");
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builder->fsCodeAppend("\t\tuv_grad = vec2(0.7071, 0.7071);\n");
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builder->fsCodeAppend("\t} else {\n");
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builder->fsCodeAppend("\t\tuv_grad = uv*inversesqrt(uv_len2);\n");
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builder->fsCodeAppend("\t}\n");
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} else {
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builder->fsCodeAppend("\tuv_grad = normalize(uv);\n");
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}
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builder->fsCodeAppend("\tvec2 grad = vec2(uv_grad.x*Jdx.x + uv_grad.y*Jdy.x,\n");
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builder->fsCodeAppend("\t uv_grad.x*Jdx.y + uv_grad.y*Jdy.y);\n");
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// this gives us a smooth step across approximately one fragment
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// (assuming a radius of the diagonal of the fragment, hence a factor of sqrt(2)/2)
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builder->fsCodeAppend("\tafwidth = 0.7071*length(grad);\n");
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}
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builder->fsCodeAppend("\tvec4 val = vec4(smoothstep(vec3(-afwidth), vec3(afwidth), distance), 1.0);\n");
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builder->fsCodeAppendf("\t%s = %s;\n", outputColor,
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(GrGLSLExpr4(inputColor) * GrGLSLExpr4("val")).c_str());
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}
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virtual void setData(const GrGLUniformManager& uman,
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const GrDrawEffect& drawEffect) SK_OVERRIDE {
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SkASSERT(fTextureSizeUni.isValid());
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GrTexture* texture = drawEffect.effect()->get()->texture(0);
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if (texture->width() != fTextureSize.width() ||
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texture->height() != fTextureSize.height()) {
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const GrDistanceFieldLCDTextureEffect& dfTexEffect =
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drawEffect.castEffect<GrDistanceFieldLCDTextureEffect>();
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fTextureSize = SkISize::Make(texture->width(), texture->height());
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float delta = 1.0f/(3.0f*texture->width());
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if (dfTexEffect.useBGR()) {
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delta = -delta;
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}
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uman.set3f(fTextureSizeUni,
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SkIntToScalar(fTextureSize.width()),
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SkIntToScalar(fTextureSize.height()),
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delta);
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}
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}
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static inline EffectKey GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
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const GrDistanceFieldLCDTextureEffect& dfTexEffect =
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drawEffect.castEffect<GrDistanceFieldLCDTextureEffect>();
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int uniformScale = dfTexEffect.isUniformScale() ? 0x01 : 0x00;
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int useBGR = dfTexEffect.useBGR() ? 0x10 : 0x00;
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return uniformScale | useBGR;
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}
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private:
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GrGLUniformManager::UniformHandle fTextureSizeUni;
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SkISize fTextureSize;
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typedef GrGLVertexEffect INHERITED;
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};
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///////////////////////////////////////////////////////////////////////////////
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GrDistanceFieldLCDTextureEffect::GrDistanceFieldLCDTextureEffect(GrTexture* texture,
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const GrTextureParams& params,
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bool uniformScale,
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bool useBGR)
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: fTextureAccess(texture, params)
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, fUniformScale(uniformScale)
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, fUseBGR(useBGR) {
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this->addTextureAccess(&fTextureAccess);
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this->addVertexAttrib(kVec2f_GrSLType);
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}
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bool GrDistanceFieldLCDTextureEffect::onIsEqual(const GrEffect& other) const {
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const GrDistanceFieldLCDTextureEffect& cte = CastEffect<GrDistanceFieldLCDTextureEffect>(other);
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return fTextureAccess == cte.fTextureAccess;
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}
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void GrDistanceFieldLCDTextureEffect::getConstantColorComponents(GrColor* color,
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uint32_t* validFlags) const {
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if ((*validFlags & kA_GrColorComponentFlag) && 0xFF == GrColorUnpackA(*color) &&
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GrPixelConfigIsOpaque(this->texture(0)->config())) {
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*validFlags = kA_GrColorComponentFlag;
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} else {
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*validFlags = 0;
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}
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}
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const GrBackendEffectFactory& GrDistanceFieldLCDTextureEffect::getFactory() const {
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return GrTBackendEffectFactory<GrDistanceFieldLCDTextureEffect>::getInstance();
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}
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///////////////////////////////////////////////////////////////////////////////
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GR_DEFINE_EFFECT_TEST(GrDistanceFieldLCDTextureEffect);
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GrEffectRef* GrDistanceFieldLCDTextureEffect::TestCreate(SkRandom* random,
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GrContext*,
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const GrDrawTargetCaps&,
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GrTexture* textures[]) {
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int texIdx = random->nextBool() ? GrEffectUnitTest::kSkiaPMTextureIdx :
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GrEffectUnitTest::kAlphaTextureIdx;
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static const SkShader::TileMode kTileModes[] = {
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SkShader::kClamp_TileMode,
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SkShader::kRepeat_TileMode,
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SkShader::kMirror_TileMode,
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};
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SkShader::TileMode tileModes[] = {
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kTileModes[random->nextULessThan(SK_ARRAY_COUNT(kTileModes))],
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kTileModes[random->nextULessThan(SK_ARRAY_COUNT(kTileModes))],
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};
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GrTextureParams params(tileModes, random->nextBool() ? GrTextureParams::kBilerp_FilterMode :
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GrTextureParams::kNone_FilterMode);
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return GrDistanceFieldLCDTextureEffect::Create(textures[texIdx], params,
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random->nextBool(), random->nextBool());
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}
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@ -12,6 +12,7 @@
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#include "GrVertexEffect.h"
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class GrGLDistanceFieldTextureEffect;
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class GrGLDistanceFieldLCDTextureEffect;
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/**
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* The output color of this effect is a modulation of the input color and a sample from a
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@ -21,8 +22,8 @@ class GrGLDistanceFieldTextureEffect;
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*/
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class GrDistanceFieldTextureEffect : public GrVertexEffect {
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public:
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static GrEffectRef* Create(GrTexture* tex, const GrTextureParams& para, bool uniformScale) {
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AutoEffectUnref effect(SkNEW_ARGS(GrDistanceFieldTextureEffect, (tex, para, uniformScale)));
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static GrEffectRef* Create(GrTexture* tex, const GrTextureParams& params, bool similarity) {
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AutoEffectUnref effect(SkNEW_ARGS(GrDistanceFieldTextureEffect, (tex, params, similarity)));
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return CreateEffectRef(effect);
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}
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@ -31,7 +32,7 @@ public:
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static const char* Name() { return "DistanceFieldTexture"; }
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virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
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bool isUniformScale() const { return fUniformScale; }
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bool isSimilarity() const { return fIsSimilarity; }
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typedef GrGLDistanceFieldTextureEffect GLEffect;
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@ -44,11 +45,54 @@ private:
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virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE;
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GrTextureAccess fTextureAccess;
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bool fUniformScale;
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bool fIsSimilarity;
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GR_DECLARE_EFFECT_TEST;
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typedef GrVertexEffect INHERITED;
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};
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/**
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* The output color of this effect is a modulation of the input color and samples from a
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* distance field texture (using a smoothed step function near 0.5), adjusted for LCD displays.
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* It allows explicit specification of the filtering and wrap modes (GrTextureParams). The input
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* coords are a custom attribute.
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*/
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class GrDistanceFieldLCDTextureEffect : public GrVertexEffect {
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public:
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static GrEffectRef* Create(GrTexture* tex, const GrTextureParams& params,
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bool uniformScale, bool useBGR) {
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AutoEffectUnref effect(SkNEW_ARGS(GrDistanceFieldLCDTextureEffect,
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(tex, params, uniformScale, useBGR)));
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return CreateEffectRef(effect);
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}
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virtual ~GrDistanceFieldLCDTextureEffect() {}
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static const char* Name() { return "DistanceFieldLCDTexture"; }
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virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
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bool isUniformScale() const { return fUniformScale; }
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bool useBGR() const { return fUseBGR; }
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typedef GrGLDistanceFieldLCDTextureEffect GLEffect;
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virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
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private:
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GrDistanceFieldLCDTextureEffect(GrTexture* texture, const GrTextureParams& params,
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bool uniformScale, bool useBGR);
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virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE;
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GrTextureAccess fTextureAccess;
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bool fUniformScale;
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bool fUseBGR;
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GR_DECLARE_EFFECT_TEST;
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typedef GrVertexEffect INHERITED;
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};
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#endif
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