skia2/gpu/include/GrContext_impl.h

/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */


#ifndef GrContext_impl_DEFINED
#define GrContext_impl_DEFINED

template <typename POS_SRC, typename TEX_SRC,
          typename COL_SRC, typename IDX_SRC>
inline void GrContext::drawCustomVertices(const GrPaint& paint,
                                          GrPrimitiveType primitiveType,
                                          const POS_SRC& posSrc,
                                          const TEX_SRC* texCoordSrc,
                                          const COL_SRC* colorSrc,
                                          const IDX_SRC* idxSrc) {

    GrDrawTarget::AutoReleaseGeometry geo;

    GrDrawTarget* target = this->prepareToDraw(paint, kUnbuffered_DrawCategory);

    bool hasTexCoords[GrPaint::kTotalStages] = {
        NULL != texCoordSrc, // texCoordSrc provides explicit stage 0 coords
        0                    // remaining stages use positions
    };
    GrVertexLayout layout = PaintStageVertexLayoutBits(paint, hasTexCoords);

    if (NULL != colorSrc) {
        layout |= GrDrawTarget::kColor_VertexLayoutBit;
    }

    int vertexCount = posSrc.count();
    int indexCount = (NULL != idxSrc) ? idxSrc->count() : 0;

    if (!geo.set(target, layout, vertexCount, indexCount)) {
        GrPrintf("Failed to get space for vertices!");
        return;
    }

    int texOffsets[GrDrawTarget::kMaxTexCoords];
    int colorOffset;
    int vsize = GrDrawTarget::VertexSizeAndOffsetsByIdx(layout,
                                                        texOffsets,
                                                        &colorOffset);
    void* curVertex = geo.vertices();

    for (int i = 0; i < vertexCount; ++i) {
        posSrc.writeValue(i, (GrPoint*)curVertex);

        if (texOffsets[0] > 0) {
            texCoordSrc->writeValue(i, (GrPoint*)((intptr_t)curVertex + texOffsets[0]));
        }
        if (colorOffset > 0) {
            colorSrc->writeValue(i, (GrColor*)((intptr_t)curVertex + colorOffset));
        }
        curVertex = (void*)((intptr_t)curVertex + vsize);
    }

    uint16_t* indices = (uint16_t*) geo.indices();
    for (int i = 0; i < indexCount; ++i) {
        idxSrc->writeValue(i, indices + i);
    }

    // we don't currently apply offscreen AA to this path. Need improved 
    // management of GrDrawTarget's geometry to avoid copying points per-tile.

    if (NULL == idxSrc) {
        target->drawNonIndexed(primitiveType, 0, vertexCount);
    } else {
        target->drawIndexed(primitiveType, 0, 0, vertexCount, indexCount);
    }
}

class GrNullTexCoordSource {
public:
    void writeValue(int i, GrPoint* dstCoord) const { GrAssert(false); }
};

class GrNullColorSource {
public:
    void writeValue(int i, GrColor* dstColor) const { GrAssert(false); }
};

class GrNullIndexSource {
public:
    void writeValue(int i, uint16_t* dstIndex) const { GrAssert(false); }
    int count() const { GrAssert(false); return 0; }
};

template <typename POS_SRC>
inline void GrContext::drawCustomVertices(const GrPaint& paint,
                                          GrPrimitiveType primitiveType,
                                          const POS_SRC& posSrc) {
    this->drawCustomVertices<POS_SRC,
                             GrNullTexCoordSource,
                             GrNullColorSource,
                             GrNullIndexSource>(paint, primitiveType, posSrc,
                                                NULL, NULL, NULL);
}

template <typename POS_SRC, typename TEX_SRC>
inline void GrContext::drawCustomVertices(const GrPaint& paint,
                                          GrPrimitiveType primitiveType,
                                          const POS_SRC& posSrc,
                                          const TEX_SRC* texCoordSrc) {
    this->drawCustomVertices<POS_SRC, TEX_SRC,
                             GrNullColorSource,
                             GrNullIndexSource>(paint, primitiveType, posSrc,
                                                texCoordSrc, NULL, NULL);
}

template <typename POS_SRC, typename TEX_SRC, typename COL_SRC>
inline void GrContext::drawCustomVertices(const GrPaint& paint,
                                          GrPrimitiveType primitiveType,
                                          const POS_SRC& posSrc,
                                          const TEX_SRC* texCoordSrc,
                                          const COL_SRC* colorSrc) {
    drawCustomVertices<POS_SRC, TEX_SRC, COL_SRC,
                       GrNullIndexSource>(paint, primitiveType, posSrc, 
                                          texCoordSrc, colorSrc, NULL);
}

#endif