src/gpu/SkGr.h

/*
 * Copyright 2017 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkGr_DEFINED
#define SkGr_DEFINED

#include "include/core/SkCanvas.h"
#include "include/core/SkColor.h"
#include "include/core/SkImageInfo.h"
#include "include/core/SkSamplingOptions.h"
#include "include/gpu/GrTypes.h"
#include "include/private/SkColorData.h"
#include "src/core/SkBlendModePriv.h"
#include "src/gpu/GrBlend.h"
#include "src/gpu/GrCaps.h"
#include "src/gpu/GrColor.h"
#include "src/gpu/GrSamplerState.h"

class GrCaps;
class GrColorInfo;
class GrColorSpaceXform;
class GrDirectContext;
class GrFragmentProcessor;
class GrPaint;
class GrRecordingContext;
class GrResourceProvider;
class GrTextureProxy;
class GrUniqueKey;
class SkBitmap;
class SkData;
class SkMatrix;
class SkMatrixProvider;
class SkPaint;
class SkPixelRef;
class SkPixmap;
struct SkIRect;

////////////////////////////////////////////////////////////////////////////////
// Color type conversions

static inline GrColor SkColorToPremulGrColor(SkColor c) {
    SkPMColor pm = SkPreMultiplyColor(c);
    unsigned r = SkGetPackedR32(pm);
    unsigned g = SkGetPackedG32(pm);
    unsigned b = SkGetPackedB32(pm);
    unsigned a = SkGetPackedA32(pm);
    return GrColorPackRGBA(r, g, b, a);
}

static inline GrColor SkColorToUnpremulGrColor(SkColor c) {
    unsigned r = SkColorGetR(c);
    unsigned g = SkColorGetG(c);
    unsigned b = SkColorGetB(c);
    unsigned a = SkColorGetA(c);
    return GrColorPackRGBA(r, g, b, a);
}

/** Similar, but using SkPMColor4f. */
SkPMColor4f SkColorToPMColor4f(SkColor, const GrColorInfo&);

/** Converts an SkColor4f to the destination color space. */
SkColor4f SkColor4fPrepForDst(SkColor4f, const GrColorInfo&);

////////////////////////////////////////////////////////////////////////////////
// SkTileMode conversion

static constexpr GrSamplerState::WrapMode SkTileModeToWrapMode(SkTileMode tileMode) {
    switch (tileMode) {
        case SkTileMode::kClamp:  return GrSamplerState::WrapMode::kClamp;
        case SkTileMode::kDecal:  return GrSamplerState::WrapMode::kClampToBorder;
        case SkTileMode::kMirror: return GrSamplerState::WrapMode::kMirrorRepeat;
        case SkTileMode::kRepeat: return GrSamplerState::WrapMode::kRepeat;
    }
    SkUNREACHABLE;
}

////////////////////////////////////////////////////////////////////////////////
// Paint conversion

/** Converts an SkPaint to a GrPaint for a given GrRecordingContext. The matrix is required in order
    to convert the SkShader (if any) on the SkPaint. The primitive itself has no color. */
bool SkPaintToGrPaint(GrRecordingContext*,
                      const GrColorInfo& dstColorInfo,
                      const SkPaint& skPaint,
                      const SkMatrixProvider& matrixProvider,
                      GrPaint* grPaint);

/** Replaces the SkShader (if any) on skPaint with the passed in GrFragmentProcessor. The processor
    should expect an unpremul input color and produce a premultiplied output color. There is
    no primitive color. */
bool SkPaintToGrPaintReplaceShader(GrRecordingContext*,
                                   const GrColorInfo& dstColorInfo,
                                   const SkPaint& skPaint,
                                   const SkMatrixProvider& matrixProvider,
                                   std::unique_ptr<GrFragmentProcessor> shaderFP,
                                   GrPaint* grPaint);

/** Blends the SkPaint's shader (or color if no shader) with the color which specified via a
    GrOp's GrPrimitiveProcesssor. */
bool SkPaintToGrPaintWithBlend(GrRecordingContext*,
                               const GrColorInfo& dstColorInfo,
                               const SkPaint& skPaint,
                               const SkMatrixProvider& matrixProvider,
                               SkBlendMode primColorMode,
                               GrPaint* grPaint);

/** This is used when there is a primitive color, but the shader should be ignored. Currently,
    the expectation is that the primitive color will be premultiplied, though it really should be
    unpremultiplied so that interpolation is done in unpremul space. The paint's alpha will be
    applied to the primitive color after interpolation. */
inline bool SkPaintToGrPaintWithPrimitiveColor(GrRecordingContext* context,
                                               const GrColorInfo& dstColorInfo,
                                               const SkPaint& skPaint,
                                               const SkMatrixProvider& matrixProvider,
                                               GrPaint* grPaint) {
    return SkPaintToGrPaintWithBlend(context, dstColorInfo, skPaint, matrixProvider,
                                     SkBlendMode::kDst, grPaint);
}

////////////////////////////////////////////////////////////////////////////////
// Misc Sk to Gr type conversions

static_assert((int)kZero_GrBlendCoeff == (int)SkBlendModeCoeff::kZero);
static_assert((int)kOne_GrBlendCoeff == (int)SkBlendModeCoeff::kOne);
static_assert((int)kSC_GrBlendCoeff == (int)SkBlendModeCoeff::kSC);
static_assert((int)kISC_GrBlendCoeff == (int)SkBlendModeCoeff::kISC);
static_assert((int)kDC_GrBlendCoeff == (int)SkBlendModeCoeff::kDC);
static_assert((int)kIDC_GrBlendCoeff == (int)SkBlendModeCoeff::kIDC);
static_assert((int)kSA_GrBlendCoeff == (int)SkBlendModeCoeff::kSA);
static_assert((int)kISA_GrBlendCoeff == (int)SkBlendModeCoeff::kISA);
static_assert((int)kDA_GrBlendCoeff == (int)SkBlendModeCoeff::kDA);
static_assert((int)kIDA_GrBlendCoeff == (int)SkBlendModeCoeff::kIDA);
// static_assert(SkXfermode::kCoeffCount == 10);

////////////////////////////////////////////////////////////////////////////////
// Texture management

/**
 * Policies for how to create textures for SkImages (and SkBitmaps).
 */
enum class GrImageTexGenPolicy : int {
    // Choose the cheapest way to generate the texture. Use GrResourceCache if appropriate.
    kDraw,
    // Always make a new texture that is uncached and unbudgeted.
    kNew_Uncached_Unbudgeted,
    // Always make a new texture that is uncached and budgeted.
    kNew_Uncached_Budgeted
};

/**
 * Creates a new texture with mipmap levels and copies the baseProxy into the base layer.
 */
sk_sp<GrSurfaceProxy> GrCopyBaseMipMapToTextureProxy(GrRecordingContext*,
                                                     sk_sp<GrSurfaceProxy> baseProxy,
                                                     GrSurfaceOrigin origin,
                                                     SkBudgeted = SkBudgeted::kYes);
/**
 * Same as GrCopyBaseMipMapToTextureProxy but takes the src as a view and returns a view with same
 * origin and swizzle as the src view.
 */
GrSurfaceProxyView GrCopyBaseMipMapToView(GrRecordingContext*,
                                          GrSurfaceProxyView,
                                          SkBudgeted = SkBudgeted::kYes);

/*
 * Create a texture proxy from the provided bitmap and add it to the texture cache using the key
 * also extracted from the bitmap. If GrMipmapped is kYes a non-mipmapped result may be returned
 * if mipmapping isn't supported or for a 1x1 bitmap. If GrMipmapped is kNo it indicates mipmaps
 * aren't required but a previously created mipmapped texture may still be returned. A color type is
 * returned as color type conversion may be performed if there isn't a texture format equivalent of
 * the bitmap's color type.
 */
std::tuple<GrSurfaceProxyView, GrColorType>
GrMakeCachedBitmapProxyView(GrRecordingContext*,
                            const SkBitmap&,
                            GrMipmapped = GrMipmapped::kNo);

/**
 * Like above but always uploads the bitmap and never inserts into the cache. Unlike above, the
 * texture may be approx or scratch and budgeted or not.
 */
std::tuple<GrSurfaceProxyView, GrColorType>
GrMakeUncachedBitmapProxyView(GrRecordingContext*,
                              const SkBitmap&,
                              GrMipmapped = GrMipmapped::kNo,
                              SkBackingFit = SkBackingFit::kExact,
                              SkBudgeted = SkBudgeted::kYes);

/**
 *  Our key includes the offset, width, and height so that bitmaps created by extractSubset()
 *  are unique.
 *
 *  The imageID is in the shared namespace (see SkNextID::ImageID())
 *      - SkBitmap/SkPixelRef
 *      - SkImage
 *      - SkImageGenerator
 */
void GrMakeKeyFromImageID(GrUniqueKey* key, uint32_t imageID, const SkIRect& imageBounds);

/**
 * Makes a SkIDChangeListener from a GrUniqueKey. The key will be invalidated in the resource
 * cache if the ID becomes invalid. This also modifies the key so that it will cause the listener
 * to be deregistered if the key is destroyed (to prevent unbounded listener growth when resources
 * are purged before listeners trigger).
 */
sk_sp<SkIDChangeListener> GrMakeUniqueKeyInvalidationListener(GrUniqueKey*, uint32_t contextID);

static inline bool GrValidCubicResampler(SkCubicResampler cubic) {
    return cubic.B >= 0 && cubic.C >= 0;
}

#endif