michael@0: /*
michael@0:  * Copyright 2013 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #ifndef GrCoordTransform_DEFINED
michael@0: #define GrCoordTransform_DEFINED
michael@0: 
michael@0: #include "GrEffect.h"
michael@0: #include "SkMatrix.h"
michael@0: #include "GrTexture.h"
michael@0: #include "GrTypes.h"
michael@0: 
michael@0: /**
michael@0:  * Coordinates available to GrEffect subclasses for requesting transformations. Transformed
michael@0:  * coordinates are made available in the the portion of fragment shader emitted by the effect.
michael@0:  */
michael@0: enum GrCoordSet {
michael@0:     /**
michael@0:      * The user-space coordinates that map to the fragment being rendered. These coords account for
michael@0:      * any change of coordinate system done on the CPU by GrContext before rendering, and also are
michael@0:      * correct for draws that take explicit local coords rather than inferring them from the
michael@0:      * primitive's positions (e.g. drawVertices). These are usually the coords a GrEffect wants.
michael@0:      */
michael@0:     kLocal_GrCoordSet,
michael@0: 
michael@0:     /**
michael@0:      * The actual vertex position. Note that GrContext may not draw using the original view matrix
michael@0:      * specified by the caller, as it may have transformed vertices into another space. These are
michael@0:      * usually not the coordinates a GrEffect wants.
michael@0:      */
michael@0:     kPosition_GrCoordSet
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * A class representing a linear transformation from one of the built-in coordinate sets (local or
michael@0:  * position). GrEffects just define these transformations, and the framework does the rest of the
michael@0:  * work to make the transformed coordinates available in their fragment shader.
michael@0:  */
michael@0: class GrCoordTransform : public SkNoncopyable {
michael@0: public:
michael@0:     GrCoordTransform() { SkDEBUGCODE(fInEffect = false); }
michael@0: 
michael@0:     /**
michael@0:      * Create a transformation that maps [0, 1] to a texture's boundaries.
michael@0:      */
michael@0:     GrCoordTransform(GrCoordSet sourceCoords, const GrTexture* texture) {
michael@0:         SkDEBUGCODE(fInEffect = false);
michael@0:         this->reset(sourceCoords, texture);
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Create a transformation from a matrix. The optional texture parameter is used to infer if the
michael@0:      * framework should internally do a y reversal to account for it being upside down by Skia's
michael@0:      * coord convention.
michael@0:      */
michael@0:     GrCoordTransform(GrCoordSet sourceCoords, const SkMatrix& m, const GrTexture* texture = NULL) {
michael@0:         SkDEBUGCODE(fInEffect = false);
michael@0:         this->reset(sourceCoords, m, texture);
michael@0:     }
michael@0: 
michael@0:     void reset(GrCoordSet sourceCoords, const GrTexture* texture) {
michael@0:         SkASSERT(!fInEffect);
michael@0:         SkASSERT(NULL != texture);
michael@0:         this->reset(sourceCoords, GrEffect::MakeDivByTextureWHMatrix(texture), texture);
michael@0:     }
michael@0: 
michael@0:     void reset(GrCoordSet sourceCoords, const SkMatrix& m, const GrTexture* texture = NULL) {
michael@0:         SkASSERT(!fInEffect);
michael@0:         fSourceCoords = sourceCoords;
michael@0:         fMatrix = m;
michael@0:         fReverseY = NULL != texture && kBottomLeft_GrSurfaceOrigin == texture->origin();
michael@0:     }
michael@0: 
michael@0:     GrCoordTransform& operator= (const GrCoordTransform& other) {
michael@0:         SkASSERT(!fInEffect);
michael@0:         fSourceCoords = other.fSourceCoords;
michael@0:         fMatrix = other.fMatrix;
michael@0:         fReverseY = other.fReverseY;
michael@0:         return *this;
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Access the matrix for editing. Note, this must be done before adding the transform to an
michael@0:      * effect, since effects are immutable.
michael@0:      */
michael@0:     SkMatrix* accessMatrix() {
michael@0:         SkASSERT(!fInEffect);
michael@0:         return &fMatrix;
michael@0:     }
michael@0: 
michael@0:     bool operator== (const GrCoordTransform& other) const {
michael@0:         return fSourceCoords == other.fSourceCoords &&
michael@0:                fMatrix.cheapEqualTo(other.fMatrix) &&
michael@0:                fReverseY == other.fReverseY;
michael@0:     }
michael@0: 
michael@0:     GrCoordSet sourceCoords() const { return fSourceCoords; }
michael@0:     const SkMatrix& getMatrix() const { return fMatrix; }
michael@0:     bool reverseY() const { return fReverseY; }
michael@0: 
michael@0: private:
michael@0:     GrCoordSet fSourceCoords;
michael@0:     SkMatrix   fMatrix;
michael@0:     bool       fReverseY;
michael@0: 
michael@0:     typedef SkNoncopyable INHERITED;
michael@0: 
michael@0: #ifdef SK_DEBUG
michael@0: public:
michael@0:     void setInEffect() const { fInEffect = true; }
michael@0: private:
michael@0:     mutable bool fInEffect;
michael@0: #endif
michael@0: };
michael@0: 
michael@0: #endif