ciderpress/util/MyDIBitmap.h

/*
 * CiderPress
 * Copyright (C) 2007 by faddenSoft, LLC.  All Rights Reserved.
 * See the file LICENSE for distribution terms.
 */
/*
 * DIB (Device-Independent Bitmap) wrapper.
 *
 * [ Ported back from libfadden -- there's a lot of stuff here that we don't
 *   want or need, but it's easier to knock the bugs out if everybody is
 *   using roughly the same code. ]
 */
#ifndef __LF_DIBITMAP__
#define __LF_DIBITMAP__


/*
 * Wraps a device-independent bitmap.
 *
 * When the bitmap is initially loaded, the object may or may not allocate a
 * DIB section in system memory.  If the DIB handle is requested, a conversion
 * will be forced.  This is done for efficiency in situations where the
 * bitmap isn't going to be handed off to GDI, or will only be used as a DDB.
 *
 * Some bitmaps have a transparent color (1-bit alpha) or a full alpha
 * channel.  The behavior works like this:
 *  - If the bitmap is <= 24 bits, alpha defaults to "off".
 *  - If the bitmap is 32 bits, alpha defaults to "full".
 *  - If the app calls SetAlphaColor, alpha is set to "transparency".
 * Calling GetPixelRGB returns a 32-bit value for which the alpha value
 * is always set.  For "none" it's always 255, for "transparency" it's
 * either set to 0 or 255, and for "full" it's set to rgbReserved in a
 * 32-bit bitmap (or 255 for any other value).
 */
class MyDIBitmap {
public:
    typedef enum AlphaType {
        kAlphaUnknown,
        kAlphaOpaque,           // always stuff 255 into rgbReserved
        kAlphaTransparency,     // single-bit alpha
        kAlphaFull              // alpha channel in rgbReserved
    } AlphaType;
    enum { kAlphaMask = 0xff000000 };   // alpha byte in an ARGB DWORD

    MyDIBitmap(void) :
        mhBitmap(nil),
        mpFileBuffer(nil),
        mWidth(-1),
        mHeight(-1),
        mBpp(-1),
        mPitchBytes(0),
        mNumColorsUsed(0),
        mpColorTable(nil),
        mColorTableInitialized(false),
        mpPixels(nil),
        mAlphaType(kAlphaOpaque),
        mTransparentColor(0)
    {
        memset(&mBitmapInfoHdr, 0, sizeof(mBitmapInfoHdr));
    }
    virtual ~MyDIBitmap(void);

    // create an empty bitmap with the specified characteristics; returns a
    // pointer to the pixel storage
    void* Create(int width, int height, int bitsPerPixel, int colorsUsed,
        bool dibSection = false);
    void SetColorTable(const RGBQUAD* pColorTable);
    const RGBQUAD* GetColorTable(void) const { return mpColorTable; }

    // zero out the pixels
    void ClearPixels(void);

    HBITMAP ConvertToDDB(HDC dc) const;

    // create a DIB from a file on disk
    int CreateFromFile(const char* fileName);
    int CreateFromFile(FILE* fp, long len);
    // create from memory buffer; set "doDelete" if object should own mem
    // (if "doDelete" is set, memory will be deleted if function fails)
    // contents of buffer will be analyzed to determine file type
    int CreateFromBuffer(void* buffer, long len, bool doDelete);

    // create a DIB from an embedded resource
    void* CreateFromResource(HINSTANCE hInstance, const char* rsrc);

    // write bitmap to file (for FILE*, make sure it's open in "wb" mode)
    int WriteToFile(const char* fileName) const;
    int WriteToFile(FILE* fp) const;

    // simple getters
    virtual int GetWidth(void) const { return mWidth; }
    virtual int GetHeight(void) const { return mHeight; }
    int GetBpp(void) const { return mBpp; }
    int GetNumColorsUsed(void) const { return mNumColorsUsed; }

    // retrieve current alpha mode
    AlphaType GetAlphaType(void) const { return mAlphaType; }
    // get transparent color; returns "false" if none has been set
    bool GetTransparentColor(RGBQUAD* pColor) const;
    // set transparent color and change alpha to kAlphaTransparency
    void SetTransparentColor(const RGBQUAD* pColor);

    // return the index of the specified color (-1 if not found, -2 on err)
    int LookupColor(const RGBQUAD* pRgbQuad);

    // set/get individual pixel values; the "RGB" functions always set
    //  alpha to zero, while "RGBA" follow the current alpha mode
    void FASTCALL GetPixelRGB(int x, int y, RGBQUAD* pRgbQuad) const;
    void FASTCALL SetPixelRGB(int x, int y, const RGBQUAD* pRgbQuad);
    void FASTCALL GetPixelRGBA(int x, int y, RGBQUAD* pRgbQuad) const;
    void FASTCALL SetPixelRGBA(int x, int y, const RGBQUAD* pRgbQuad);
    void FASTCALL GetPixelIndex(int x, int y, int* pIdx) const;
    void FASTCALL SetPixelIndex(int x, int y, int idx);

    // Return a pointer to the raw pixel storage.
    void* GetPixelBuf(void) const { return mpPixels; }

    // Return the DIB handle; keep in mind that this HBITMAP is different
    // from a DDB HBITMAP, and many calls that take an HBITMAP will fail.
    HBITMAP GetHandle(void) {
        if (mhBitmap == nil && mpFileBuffer != nil)
            ConvertBufToDIBSection();
        return mhBitmap;
    }

    int GetPitch(void) const { return mPitchBytes; }

    // Blit pixels from one bitmap to another.
    static bool Blit(MyDIBitmap* pDstBits, const RECT* pDstRect,
        const MyDIBitmap* pSrcBits, const RECT* pSrcRect);

private:
    enum { kBMPMagic = 0x4d42 };            // "BM"

    /* for .TGA files; does not map directly to file */
    typedef struct TargaHeader {
        unsigned char   idLength;
        unsigned char   colorMapType;
        unsigned char   imageType;
        unsigned short  colorMapOrigin;
        unsigned short  colorMapLen;
        unsigned char   colorMapEntryLen;
        unsigned short  xOffset;
        unsigned short  yOffset;
        unsigned short  width;
        unsigned short  height;
        unsigned char   bitsPerPixel;
        unsigned char   imageDescriptor;
    } TargaHeader;
    enum {
        kTargaHeaderLen = 18,
        kTargaUnmappedRGB = 2,      // for imageType field
    };

    int ImportBMP(void* vbuf, long len);
    int ImportTGA(void* vbuf, long len);
    int ConvertBufToDIBSection(void);
    int CreateFromNewBuffer(void* vbuf, long len);

    BITMAPINFOHEADER    mBitmapInfoHdr;
    /* either mhBitmap or mpFileContents will be non-nil, but not both */
    HBITMAP             mhBitmap;           // DIB section handle, not DDB
    void*               mpFileBuffer;       // buffer with contents of .BMP
    int                 mWidth;
    int                 mHeight;
    int                 mBpp;               // #of bits per pixel
    int                 mPitchBytes;        // memory line pitch, in bytes
    int                 mNumColorsUsed;
    RGBQUAD*            mpColorTable;
    bool                mColorTableInitialized;
    void*               mpPixels;           // points to system-allocated mem
    AlphaType           mAlphaType;
    DWORD               mTransparentColor;  // for single-bit alpha bitmaps
};

#endif /*__LF_DIBITMAP__*/