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      1 /*
      2  * Copyright 2012 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef GrTextureDomainEffect_DEFINED
      9 #define GrTextureDomainEffect_DEFINED
     10 
     11 #include "GrSingleTextureEffect.h"
     12 #include "gl/GrGLEffect.h"
     13 
     14 class GrGLShaderBuilder;
     15 struct SkRect;
     16 
     17 /**
     18  * Limits a texture's lookup coordinates to a domain. Samples outside the domain are either clamped
     19  * the edge of the domain or result in a vec4 of zeros (decal mode). The domain is clipped to
     20  * normalized texture coords ([0,1]x[0,1] square). Bilinear filtering can cause texels outside the
     21  * domain to affect the read value unless the caller considers this when calculating the domain.
     22  */
     23 class GrTextureDomain {
     24 public:
     25     enum Mode {
     26         kIgnore_Mode,  // Ignore the texture domain rectangle.
     27         kClamp_Mode,   // Clamp texture coords to the domain rectangle.
     28         kDecal_Mode,   // Treat the area outside the domain rectangle as fully transparent.
     29 
     30         kLastMode = kDecal_Mode
     31     };
     32     static const int kModeCount = kLastMode + 1;
     33 
     34     /**
     35      * @param index     Pass a value >= 0 if using multiple texture domains in the same effect.
     36      *                  It is used to keep inserted variables from causing name collisions.
     37      */
     38     GrTextureDomain(const SkRect& domain, Mode, int index = -1);
     39 
     40     const SkRect& domain() const { return fDomain; }
     41     Mode mode() const { return fMode; }
     42 
     43     /* Computes a domain that bounds all the texels in texelRect. Note that with bilerp enabled
     44        texels neighboring the domain may be read. */
     45     static const SkRect MakeTexelDomain(const GrTexture* texture, const SkIRect& texelRect) {
     46         SkScalar wInv = SK_Scalar1 / texture->width();
     47         SkScalar hInv = SK_Scalar1 / texture->height();
     48         SkRect result = {
     49             texelRect.fLeft * wInv,
     50             texelRect.fTop * hInv,
     51             texelRect.fRight * wInv,
     52             texelRect.fBottom * hInv
     53         };
     54         return result;
     55     }
     56 
     57     bool operator== (const GrTextureDomain& that) const {
     58         return fMode == that.fMode && fDomain == that.fDomain;
     59     }
     60 
     61     /**
     62      * A GrGLEffect subclass that corresponds to a GrEffect subclass that uses GrTextureDomain
     63      * should include this helper. It generates the texture domain GLSL, produces the part of the
     64      * effect key that reflects the texture domain code, and performs the uniform uploads necessary
     65      * for texture domains.
     66      */
     67     class GLDomain {
     68     public:
     69         GLDomain() {
     70             fPrevDomain[0] = SK_FloatNaN;
     71             SkDEBUGCODE(fMode = (Mode) -1;)
     72         }
     73 
     74         /**
     75          * Call this from GrGLEffect::emitCode() to sample the texture W.R.T. the domain and mode.
     76          *
     77          * @param outcolor  name of vec4 variable to hold the sampled color.
     78          * @param inCoords  name of vec2 variable containing the coords to be used with the domain.
     79          *                  It is assumed that this is a variable and not an expression.
     80          * @param inModulateColor   if non-NULL the sampled color will be modulated with this
     81          *                          expression before being written to outColor.
     82          */
     83         void sampleTexture(GrGLShaderBuilder* builder,
     84                            const GrTextureDomain& textureDomain,
     85                            const char* outColor,
     86                            const SkString& inCoords,
     87                            const GrGLEffect::TextureSampler sampler,
     88                            const char* inModulateColor = NULL);
     89 
     90         /**
     91          * Call this from GrGLEffect::setData() to upload uniforms necessary for the texture domain.
     92          * The rectangle is automatically adjusted to account for the texture's origin.
     93          */
     94         void setData(const GrGLUniformManager& uman, const GrTextureDomain& textureDomain,
     95                      GrSurfaceOrigin textureOrigin);
     96 
     97         enum {
     98             kDomainKeyBits = 2, // See DomainKey().
     99         };
    100 
    101         /**
    102          * GrGLEffect::GenKey() must call this and include the returned value in it's computed key.
    103          * The returned will be limited to the lower kDomainKeyBits bits.
    104          */
    105         static GrGLEffect::EffectKey DomainKey(const GrTextureDomain& domain) {
    106             GR_STATIC_ASSERT(kModeCount <= 4);
    107             return domain.mode();
    108         }
    109 
    110     private:
    111         SkDEBUGCODE(Mode                  fMode;)
    112         GrGLUniformManager::UniformHandle fDomainUni;
    113         SkString                          fDomainName;
    114         GrGLfloat                         fPrevDomain[4];
    115     };
    116 
    117 protected:
    118     Mode    fMode;
    119     SkRect  fDomain;
    120     int     fIndex;
    121 
    122     typedef GrSingleTextureEffect INHERITED;
    123 };
    124 
    125 class GrGLTextureDomainEffect;
    126 
    127 /**
    128  * A basic texture effect that uses GrTextureDomain.
    129  */
    130 class GrTextureDomainEffect : public GrSingleTextureEffect {
    131 
    132 public:
    133     static GrEffectRef* Create(GrTexture*,
    134                                const SkMatrix&,
    135                                const SkRect& domain,
    136                                GrTextureDomain::Mode,
    137                                GrTextureParams::FilterMode filterMode,
    138                                GrCoordSet = kLocal_GrCoordSet);
    139 
    140     virtual ~GrTextureDomainEffect();
    141 
    142     static const char* Name() { return "TextureDomain"; }
    143 
    144     typedef GrGLTextureDomainEffect GLEffect;
    145 
    146     virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
    147     virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
    148 
    149     const GrTextureDomain& textureDomain() const { return fTextureDomain; }
    150 
    151 protected:
    152     GrTextureDomain fTextureDomain;
    153 
    154 private:
    155     GrTextureDomainEffect(GrTexture*,
    156                           const SkMatrix&,
    157                           const SkRect& domain,
    158                           GrTextureDomain::Mode,
    159                           GrTextureParams::FilterMode,
    160                           GrCoordSet);
    161 
    162     virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE;
    163 
    164     GR_DECLARE_EFFECT_TEST;
    165 
    166     typedef GrSingleTextureEffect INHERITED;
    167 };
    168 
    169 #endif
    170