Make texture domain a helper so that it can be incorporated into other effects.
R=robertphillips@google.com, jvanverth@google.com
Author: bsalomon@google.com
Review URL: https://codereview.chromium.org/98893006
git-svn-id: http://skia.googlecode.com/svn/trunk@12569 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/effects/GrTextureDomain.h b/src/gpu/effects/GrTextureDomain.h
new file mode 100644
index 0000000..f64d5c3
--- /dev/null
+++ b/src/gpu/effects/GrTextureDomain.h
@@ -0,0 +1,169 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrTextureDomainEffect_DEFINED
+#define GrTextureDomainEffect_DEFINED
+
+#include "GrSingleTextureEffect.h"
+#include "gl/GrGLEffect.h"
+
+class GrGLShaderBuilder;
+struct SkRect;
+
+/**
+ * Limits a texture's lookup coordinates to a domain. Samples outside the domain are either clamped
+ * the edge of the domain or result in a vec4 of zeros (decal mode). The domain is clipped to
+ * normalized texture coords ([0,1]x[0,1] square). Bilinear filtering can cause texels outside the
+ * domain to affect the read value unless the caller considers this when calculating the domain.
+ */
+class GrTextureDomain {
+public:
+ enum Mode {
+ kIgnore_Mode, // Ignore the texture domain rectangle.
+ kClamp_Mode, // Clamp texture coords to the domain rectangle.
+ kDecal_Mode, // Treat the area outside the domain rectangle as fully transparent.
+
+ kLastMode = kDecal_Mode
+ };
+ static const int kModeCount = kLastMode + 1;
+
+ /**
+ * @param index Pass a value >= 0 if using multiple texture domains in the same effect.
+ * It is used to keep inserted variables from causing name collisions.
+ */
+ GrTextureDomain(const SkRect& domain, Mode, int index = -1);
+
+ const SkRect& domain() const { return fDomain; }
+ Mode mode() const { return fMode; }
+
+ /* Computes a domain that bounds all the texels in texelRect. Note that with bilerp enabled
+ texels neighboring the domain may be read. */
+ static const SkRect MakeTexelDomain(const GrTexture* texture, const SkIRect& texelRect) {
+ SkScalar wInv = SK_Scalar1 / texture->width();
+ SkScalar hInv = SK_Scalar1 / texture->height();
+ SkRect result = {
+ texelRect.fLeft * wInv,
+ texelRect.fTop * hInv,
+ texelRect.fRight * wInv,
+ texelRect.fBottom * hInv
+ };
+ return result;
+ }
+
+ bool operator== (const GrTextureDomain& that) const {
+ return fMode == that.fMode && fDomain == that.fDomain;
+ }
+
+ /**
+ * A GrGLEffect subclass that corresponds to a GrEffect subclass that uses GrTextureDomain
+ * should include this helper. It generates the texture domain GLSL, produces the part of the
+ * effect key that reflects the texture domain code, and performs the uniform uploads necessary
+ * for texture domains.
+ */
+ class GLDomain {
+ public:
+ GLDomain() {
+ fPrevDomain[0] = SK_FloatNaN;
+ SkDEBUGCODE(fMode = (Mode) -1;)
+ }
+
+ /**
+ * Call this from GrGLEffect::emitCode() to sample the texture W.R.T. the domain and mode.
+ *
+ * @param outcolor name of vec4 variable to hold the sampled color.
+ * @param inCoords name of vec2 variable containing the coords to be used with the domain.
+ * It is assumed that this is a variable and not an expression.
+ * @param inModulateColor if non-NULL the sampled color will be modulated with this
+ * expression before being written to outColor.
+ */
+ void sampleTexture(GrGLShaderBuilder* builder,
+ const GrTextureDomain& textureDomain,
+ const char* outColor,
+ const SkString& inCoords,
+ const GrGLEffect::TextureSampler sampler,
+ const char* inModulateColor = NULL);
+
+ /**
+ * Call this from GrGLEffect::setData() to upload uniforms necessary for the texture domain.
+ * The rectangle is automatically adjusted to account for the texture's origin.
+ */
+ void setData(const GrGLUniformManager& uman, const GrTextureDomain& textureDomain,
+ GrSurfaceOrigin textureOrigin);
+
+ enum {
+ kDomainKeyBits = 2, // See DomainKey().
+ };
+
+ /**
+ * GrGLEffect::GenKey() must call this and include the returned value in it's computed key.
+ * The returned will be limited to the lower kDomainKeyBits bits.
+ */
+ static GrGLEffect::EffectKey DomainKey(const GrTextureDomain& domain) {
+ GR_STATIC_ASSERT(kModeCount <= 4);
+ return domain.mode();
+ }
+
+ private:
+ SkDEBUGCODE(Mode fMode;)
+ GrGLUniformManager::UniformHandle fDomainUni;
+ SkString fDomainName;
+ GrGLfloat fPrevDomain[4];
+ };
+
+protected:
+ Mode fMode;
+ SkRect fDomain;
+ int fIndex;
+
+ typedef GrSingleTextureEffect INHERITED;
+};
+
+class GrGLTextureDomainEffect;
+
+/**
+ * A basic texture effect that uses GrTextureDomain.
+ */
+class GrTextureDomainEffect : public GrSingleTextureEffect {
+
+public:
+ static GrEffectRef* Create(GrTexture*,
+ const SkMatrix&,
+ const SkRect& domain,
+ GrTextureDomain::Mode,
+ GrTextureParams::FilterMode filterMode,
+ GrCoordSet = kLocal_GrCoordSet);
+
+ virtual ~GrTextureDomainEffect();
+
+ static const char* Name() { return "TextureDomain"; }
+
+ typedef GrGLTextureDomainEffect GLEffect;
+
+ virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
+ virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
+
+ const GrTextureDomain& textureDomain() const { return fTextureDomain; }
+
+protected:
+ GrTextureDomain fTextureDomain;
+
+private:
+ GrTextureDomainEffect(GrTexture*,
+ const SkMatrix&,
+ const SkRect& domain,
+ GrTextureDomain::Mode,
+ GrTextureParams::FilterMode,
+ GrCoordSet);
+
+ virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE;
+
+ GR_DECLARE_EFFECT_TEST;
+
+ typedef GrSingleTextureEffect INHERITED;
+};
+
+#endif