skia2/include/core/SkPixmap.h

/*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkPixmap_DEFINED
#define SkPixmap_DEFINED

#include "SkColor.h"
#include "SkFilterQuality.h"
#include "SkImageInfo.h"

class SkData;
struct SkMask;

/**
 *  Pairs SkImageInfo with actual pixels and rowbytes. This class does not try to manage the
 *  lifetime of the pixel memory (nor the colortable if provided).
 */
class SK_API SkPixmap {
public:
    SkPixmap()
        : fPixels(NULL), fRowBytes(0), fInfo(SkImageInfo::MakeUnknown(0, 0))
    {}

    SkPixmap(const SkImageInfo& info, const void* addr, size_t rowBytes)
        : fPixels(addr), fRowBytes(rowBytes), fInfo(info)
    {}

    void reset();
    void reset(const SkImageInfo& info, const void* addr, size_t rowBytes);
    void reset(const SkImageInfo& info) {
        this->reset(info, NULL, 0);
    }

    // overrides the colorspace in the SkImageInfo of the pixmap
    void setColorSpace(sk_sp<SkColorSpace>);

    /**
     *  If supported, set this pixmap to point to the pixels in the specified mask and return true.
     *  On failure, return false and set this pixmap to empty.
     */
    bool SK_WARN_UNUSED_RESULT reset(const SkMask&);

    /**
     *  Computes the intersection of area and this pixmap. If that intersection is non-empty,
     *  set subset to that intersection and return true.
     *
     *  On failure, return false and ignore the subset parameter.
     */
    bool SK_WARN_UNUSED_RESULT extractSubset(SkPixmap* subset, const SkIRect& area) const;

    const SkImageInfo& info() const { return fInfo; }
    size_t rowBytes() const { return fRowBytes; }
    const void* addr() const { return fPixels; }

    int width() const { return fInfo.width(); }
    int height() const { return fInfo.height(); }
    SkColorType colorType() const { return fInfo.colorType(); }
    SkAlphaType alphaType() const { return fInfo.alphaType(); }
    SkColorSpace* colorSpace() const { return fInfo.colorSpace(); }
    bool isOpaque() const { return fInfo.isOpaque(); }

    SkIRect bounds() const { return SkIRect::MakeWH(this->width(), this->height()); }

    /**
     *  Return the rowbytes expressed as a number of pixels (like width and height).
     */
    int rowBytesAsPixels() const { return int(fRowBytes >> this->shiftPerPixel()); }

    /**
     *  Return the shift amount per pixel (i.e. 0 for 1-byte per pixel, 1 for 2-bytes per pixel
     *  colortypes, 2 for 4-bytes per pixel colortypes). Return 0 for kUnknown_SkColorType.
     */
    int shiftPerPixel() const { return fInfo.shiftPerPixel(); }

    uint64_t getSize64() const { return sk_64_mul(fInfo.height(), fRowBytes); }
    uint64_t getSafeSize64() const { return fInfo.getSafeSize64(fRowBytes); }
    size_t getSafeSize() const { return fInfo.getSafeSize(fRowBytes); }

    /**
     *  This will brute-force return true if all of the pixels in the pixmap
     *  are opaque. If there are no pixels, or encounters an error, returns false.
     */
    bool computeIsOpaque() const;

    /**
     *  Converts the pixel at the specified coordinate to an unpremultiplied
     *  SkColor. Note: this ignores any SkColorSpace information, and may return
     *  lower precision data than is actually in the pixel. Alpha only
     *  colortypes (e.g. kAlpha_8_SkColorType) return black with the appropriate
     *  alpha set.  The value is undefined for kUnknown_SkColorType or if x or y
     *  are out of bounds, or if the pixtap does not have any pixels.
     */
    SkColor getColor(int x, int y) const;

    const void* addr(int x, int y) const {
        return (const char*)fPixels + fInfo.computeOffset(x, y, fRowBytes);
    }
    const uint8_t* addr8() const {
        SkASSERT(1 == SkColorTypeBytesPerPixel(fInfo.colorType()));
        return reinterpret_cast<const uint8_t*>(fPixels);
    }
    const uint16_t* addr16() const {
        SkASSERT(2 == SkColorTypeBytesPerPixel(fInfo.colorType()));
        return reinterpret_cast<const uint16_t*>(fPixels);
    }
    const uint32_t* addr32() const {
        SkASSERT(4 == SkColorTypeBytesPerPixel(fInfo.colorType()));
        return reinterpret_cast<const uint32_t*>(fPixels);
    }
    const uint64_t* addr64() const {
        SkASSERT(8 == SkColorTypeBytesPerPixel(fInfo.colorType()));
        return reinterpret_cast<const uint64_t*>(fPixels);
    }
    const uint16_t* addrF16() const {
        SkASSERT(8 == SkColorTypeBytesPerPixel(fInfo.colorType()));
        SkASSERT(kRGBA_F16_SkColorType == fInfo.colorType());
        return reinterpret_cast<const uint16_t*>(fPixels);
    }

    // Offset by the specified x,y coordinates

    const uint8_t* addr8(int x, int y) const {
        SkASSERT((unsigned)x < (unsigned)fInfo.width());
        SkASSERT((unsigned)y < (unsigned)fInfo.height());
        return (const uint8_t*)((const char*)this->addr8() + y * fRowBytes + (x << 0));
    }
    const uint16_t* addr16(int x, int y) const {
        SkASSERT((unsigned)x < (unsigned)fInfo.width());
        SkASSERT((unsigned)y < (unsigned)fInfo.height());
        return (const uint16_t*)((const char*)this->addr16() + y * fRowBytes + (x << 1));
    }
    const uint32_t* addr32(int x, int y) const {
        SkASSERT((unsigned)x < (unsigned)fInfo.width());
        SkASSERT((unsigned)y < (unsigned)fInfo.height());
        return (const uint32_t*)((const char*)this->addr32() + y * fRowBytes + (x << 2));
    }
    const uint64_t* addr64(int x, int y) const {
        SkASSERT((unsigned)x < (unsigned)fInfo.width());
        SkASSERT((unsigned)y < (unsigned)fInfo.height());
        return (const uint64_t*)((const char*)this->addr64() + y * fRowBytes + (x << 3));
    }
    const uint16_t* addrF16(int x, int y) const {
        SkASSERT(kRGBA_F16_SkColorType == fInfo.colorType());
        return reinterpret_cast<const uint16_t*>(this->addr64(x, y));
    }

    // Writable versions

    void* writable_addr() const { return const_cast<void*>(fPixels); }
    void* writable_addr(int x, int y) const {
        return const_cast<void*>(this->addr(x, y));
    }
    uint8_t* writable_addr8(int x, int y) const {
        return const_cast<uint8_t*>(this->addr8(x, y));
    }
    uint16_t* writable_addr16(int x, int y) const {
        return const_cast<uint16_t*>(this->addr16(x, y));
    }
    uint32_t* writable_addr32(int x, int y) const {
        return const_cast<uint32_t*>(this->addr32(x, y));
    }
    uint64_t* writable_addr64(int x, int y) const {
        return const_cast<uint64_t*>(this->addr64(x, y));
    }
    uint16_t* writable_addrF16(int x, int y) const {
        return reinterpret_cast<uint16_t*>(writable_addr64(x, y));
    }

    // copy methods

    bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes,
                    int srcX, int srcY, SkTransferFunctionBehavior behavior) const;
    bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes) const {
        return this->readPixels(dstInfo, dstPixels, dstRowBytes, 0, 0);
    }
    bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes, int srcX,
                    int srcY) const {
        return this->readPixels(dstInfo, dstPixels, dstRowBytes, srcX, srcY,
                                SkTransferFunctionBehavior::kRespect);
    }
    bool readPixels(const SkPixmap& dst, int srcX, int srcY) const {
        return this->readPixels(dst.info(), dst.writable_addr(), dst.rowBytes(), srcX, srcY);
    }
    bool readPixels(const SkPixmap& dst) const {
        return this->readPixels(dst.info(), dst.writable_addr(), dst.rowBytes(), 0, 0);
    }

    /**
     *  Copy the pixels from this pixmap into the dst pixmap, converting as needed into dst's
     *  colortype/alphatype. If the conversion cannot be performed, false is returned.
     *
     *  If dst's dimensions differ from the src dimension, the image will be scaled, applying the
     *  specified filter-quality.
     */
    bool scalePixels(const SkPixmap& dst, SkFilterQuality) const;

    /**
     *  Returns true if pixels were written to (e.g. if colorType is kUnknown_SkColorType, this
     *  will return false). If subset does not intersect the bounds of this pixmap, returns false.
     */
    bool erase(SkColor, const SkIRect& subset) const;

    bool erase(SkColor color) const { return this->erase(color, this->bounds()); }
    bool erase(const SkColor4f&, const SkIRect* subset = nullptr) const;

private:
    const void*     fPixels;
    size_t          fRowBytes;
    SkImageInfo     fInfo;
};

#endif