Source/core/platform/graphics/GraphicsContextState.h

// Copyright (C) 2013 Google Inc. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//    * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//    * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//    * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef GraphicsContextState_h
#define GraphicsContextState_h

#include "core/platform/graphics/Gradient.h"
#include "core/platform/graphics/Path.h"
#include "core/platform/graphics/Pattern.h"
#include "core/platform/graphics/StrokeData.h"
#include "platform/graphics/GraphicsTypes.h"
#include "third_party/skia/include/core/SkColorFilter.h"
#include "third_party/skia/include/core/SkColorPriv.h"
#include "third_party/skia/include/core/SkDrawLooper.h"
#include "third_party/skia/include/effects/SkDashPathEffect.h"
#include "wtf/PassOwnPtr.h"
#include "wtf/RefPtr.h"

namespace WebCore {

// Encapsulates the state information we store for each pushed graphics state.
// Only GraphicsContext can use this class.
class GraphicsContextState {
private:
    friend class GraphicsContext;

    GraphicsContextState()
        : m_fillColor(Color::black)
        , m_fillRule(RULE_NONZERO)
        , m_textDrawingMode(TextModeFill)
        , m_alpha(1)
        , m_xferMode(0)
        , m_compositeOperator(CompositeSourceOver)
        , m_blendMode(BlendModeNormal)
#if USE(LOW_QUALITY_IMAGE_INTERPOLATION)
        , m_interpolationQuality(InterpolationLow)
#else
        , m_interpolationQuality(InterpolationHigh)
#endif
        , m_shouldAntialias(true)
        , m_shouldSmoothFonts(true)
        , m_shouldClampToSourceRect(true)
    {
    }

    GraphicsContextState(const GraphicsContextState& other)
        : m_strokeData(other.m_strokeData)
        , m_fillColor(other.m_fillColor)
        , m_fillRule(other.m_fillRule)
        , m_fillGradient(other.m_fillGradient)
        , m_fillPattern(other.m_fillPattern)
        , m_looper(other.m_looper)
        , m_textDrawingMode(other.m_textDrawingMode)
        , m_alpha(other.m_alpha)
        , m_xferMode(other.m_xferMode)
        , m_colorFilter(other.m_colorFilter)
        , m_compositeOperator(other.m_compositeOperator)
        , m_blendMode(other.m_blendMode)
        , m_interpolationQuality(other.m_interpolationQuality)
        , m_shouldAntialias(other.m_shouldAntialias)
        , m_shouldSmoothFonts(other.m_shouldSmoothFonts)
        , m_shouldClampToSourceRect(other.m_shouldClampToSourceRect)
    {
    }

    // Helper function for applying the state's alpha value to the given input
    // color to produce a new output color.
    SkColor applyAlpha(SkColor c) const
    {
        int s = roundf(m_alpha * 256);
        if (s >= 256)
            return c;
        if (s < 0)
            return 0;

        int a = SkAlphaMul(SkColorGetA(c), s);
        return (c & 0x00FFFFFF) | (a << 24);
    }

    // Returns a new State with all of this object's inherited properties copied.
    PassOwnPtr<GraphicsContextState> clone() { return adoptPtr(new GraphicsContextState(*this)); }

    // Not supported. No implementations.
    void operator=(const GraphicsContextState&);

    // Stroke.
    StrokeData m_strokeData;

    // Fill.
    Color m_fillColor;
    WindRule m_fillRule;
    RefPtr<Gradient> m_fillGradient;
    RefPtr<Pattern> m_fillPattern;

    // Shadow. (This will need tweaking if we use draw loopers for other things.)
    RefPtr<SkDrawLooper> m_looper;

    // Text. (See TextModeFill & friends.)
    TextDrawingModeFlags m_textDrawingMode;

    // Common shader state.
    float m_alpha;
    RefPtr<SkXfermode> m_xferMode;
    RefPtr<SkColorFilter> m_colorFilter;

    // Compositing control, for the CSS and Canvas compositing spec.
    CompositeOperator m_compositeOperator;
    BlendMode m_blendMode;

    // Image interpolation control.
    InterpolationQuality m_interpolationQuality;

    bool m_shouldAntialias : 1;
    bool m_shouldSmoothFonts : 1;
    bool m_shouldClampToSourceRect : 1;
};

} // namespace WebCore

#endif // GraphicsContextState_h