/*

 * Copyright 2014 Google Inc.

 *

 * Use of this source code is governed by a BSD-style license that can be

 * found in the LICENSE file.

 */

#include "src/gpu/GrCaps.h"

#include "src/gpu/GrFragmentProcessor.h"

#include "src/gpu/GrGeometryProcessor.h"

#include "src/gpu/GrProcessorAnalysis.h"

GrColorFragmentProcessorAnalysis::GrColorFragmentProcessorAnalysis(

        const GrProcessorAnalysisColor& input,

        std::unique_ptr<GrFragmentProcessor> const fps[],

        int count) {

    fCompatibleWithCoverageAsAlpha = true;

    fIsOpaque = input.isOpaque();

    fUsesLocalCoords = false;

    fWillReadDstColor = false;

    fProcessorsToEliminate = 0;

    fOutputColorKnown = input.isConstant(&fLastKnownOutputColor);

    for (int i = 0; i < count; ++i) {

        const GrFragmentProcessor* fp = fps[i].get();

        if (fOutputColorKnown && fp->hasConstantOutputForConstantInput(fLastKnownOutputColor,

                                                                       &fLastKnownOutputColor)) {

            ++fProcessorsToEliminate;

            fIsOpaque = fLastKnownOutputColor.isOpaque();

            // We reset these flags since the earlier fragment processors are being eliminated.

            fCompatibleWithCoverageAsAlpha = true;

            fUsesLocalCoords = false;

            fWillReadDstColor = false;

            continue;

        }

        fOutputColorKnown = false;

        if (fIsOpaque && !fp->preservesOpaqueInput()) {

            fIsOpaque = false;

        }

        if (fCompatibleWithCoverageAsAlpha && !fp->compatibleWithCoverageAsAlpha()) {

            fCompatibleWithCoverageAsAlpha = false;

        }

        if (fp->usesSampleCoords()) {

            fUsesLocalCoords = true;

        }

        if (fp->willReadDstColor()) {

            fWillReadDstColor = true;

        }

    }

}

bool GrColorFragmentProcessorAnalysis::requiresDstTexture(const GrCaps& caps) const {

    return this->willReadDstColor() && !caps.shaderCaps()->dstReadInShaderSupport();

}