1. Когда ты скачал из ресурса битмап при помоши функции LoadBitmap, ты получаеш описатель его
HBITMAP. Затем при помоши функции
The GetObject function obtains information about a specified graphics object. Depending on the graphics object, the function places a filled-in BITMAP, DIBSECTION, EXTLOGPEN, LOGBRUSH, LOGFONT, or LOGPEN structure, or a count of table entries (for a logical palette), into a specified buffer.
int GetObject(
HGDIOBJ hgdiobj, // handle to graphics object of interest
int cbBuffer, // size of buffer for object information
LPVOID lpvObject // pointer to buffer for object information
);
Parameters
hgdiobj
A handle to the graphics object of interest. This can be a handle to one of the following: a logical bitmap, a brush, a font, a palette, a pen, or a device independent bitmap created by calling the CreateDIBSection function.
cbBuffer
Specifies the number of bytes of information to be written to the buffer.
lpvObject
Points to a buffer that is to receive the information about the specified graphics object.
The following table shows the type of information the buffer receives for each type of graphics object you can specify with hgdiobj:
hgdiobj Type Data Written to *lpvObject
HBITMAP BITMAP
HBITMAP returned from a call to CreateDIBSection DIBSECTION, if cbBuffer is set to sizeof(DIBSECTION), or BITMAP, if cbBuffer is set to sizeof(BITMAP)
HPALETTE a WORD count of the number of entries in the logical palette
HPEN returned from a call to ExtCreatePen EXTLOGPEN
HPEN LOGPEN
HBRUSH LOGBRUSH
HFONT LOGFONT
If the lpvObject parameter is NULL, the function return value is the number of bytes required to store the information it writes to the buffer for the specified graphics object.
Return Values
If the function succeeds, and lpvObject is a valid pointer, the return value is the number of bytes stored into the buffer.
If the function succeeds, and lpvObject is NULL, the return value is the number of bytes required to hold the information the function would store into the buffer.
If the function fails, the return value is zero. To get extended error information, call GetLastError.
Remarks
The buffer pointed to by the lpvObject parameter must be sufficiently large to receive the information about the graphics object.
If hgdiobj identifies a bitmap created by calling CreateDIBSection, and the specified buffer is large enough, the GetObject function returns a DIBSECTION structure. In addition, the bmBits member of the BITMAP structure contained within the DIBSECTION will contain a pointer to the bitmap's bit values.
If hgdiobj identifies a bitmap created by any other means, GetObject returns only the width, height, and color format information of the bitmap. You can obtain the bitmap's bit values by calling the GetDIBits or GetBitmapBits function.
If hgdiobj identifies a logical palette, GetObject retrieves a two-byte integer that specifies the number of entries in the palette. The function does not retrieve the LOGPALETTE structure defining the palette. To retrieve information about palette entries, an application can call the GetPaletteEntries function.
ты получиш структуру
BITMAP,
The BITMAP structure defines the type, width, height, color format, and bit values of a bitmap.
typedef struct tagBITMAP { // bm
LONG bmType;
LONG bmWidth;
LONG bmHeight;
LONG bmWidthBytes;
WORD bmPlanes;
WORD bmBitsPixel;
LPVOID bmBits;
} BITMAP;
Members
bmType
Specifies the bitmap type. This member must be zero.
bmWidth
Specifies the width, in pixels, of the bitmap. The width must be greater than zero.
bmHeight
Specifies the height, in pixels, of the bitmap. The height must be greater than zero.
bmWidthBytes
Specifies the number of bytes in each scan line. This value must be divisible by 2, because Windows assumes that the bit values of a bitmap form an array that is word aligned.
bmPlanes
Specifies the count of color planes.
bmBitsPixel
Specifies the number of bits required to indicate the color of a pixel.
bmBits
Points to the location of the bit values for the bitmap. The bmBits member must be a long pointer to an array of character (1-byte) values.
Remarks
The bitmap formats currently used are monochrome and color. The monochrome bitmap uses a one-bit, one-plane format. Each scan is a multiple of 32 bits.
Scans are organized as follows for a monochrome bitmap of height n:
Scan 0
Scan 1
.
.
.
Scan n-2
Scan n-1
The pixels on a monochrome device are either black or white. If the corresponding bit in the bitmap is 1, the pixel is set to the foreground color; if the corresponding bit in the bitmap is zero, the pixel is set to the background color.
All devices that have the RC_BITBLT device capability support bitmaps. For more information, see GetDeviceCaps.
Each device has a unique color format. To transfer a bitmap from one device to another, use the GetDIBits and SetDIBits functions.
2. Принцип прорисовки Битмапа в WinAPI очень простой. Сначало создается подобный совместимый дескриптор окна при помоши функции
The CreateCompatibleDC function creates a memory device context (DC) compatible with the specified device.
HDC CreateCompatibleDC(
HDC hdc // handle to memory device context
);
Parameters
hdc
Identifies the device context. If this handle is NULL, the function creates a memory device context compatible with the application's current screen.
Return Values
If the function succeeds, the return value is the handle to a memory device context.
If the function fails, the return value is NULL.
Remarks
Before an application can use a memory device context for drawing operations, it must select a bitmap of the correct width and height into the device context. Once a bitmap has been selected, the device context can be used to prepare images that will be copied to the screen or printed.
The CreateCompatibleDC function can only be used with devices that support raster operations. An application can determine whether a device supports these operations by calling the GetDeviceCaps function.
When you no longer need the memory device context, call the DeleteDC function to delete it.
Затем заменяется у совместимого дескриптора Битмап твоим Битмапом при помоши функции
The SelectObject function selects an object into the specified device context. The new object replaces the previous object of the same type.
HGDIOBJ SelectObject(
HDC hdc, // handle of device context
HGDIOBJ hgdiobj // handle of object
);
Parameters
hdc
Identifies the device context.
hgdiobj
Identifies the object to be selected. The specified object must have been created by using one of the following functions:
Object Functions
Bitmap CreateBitmap, CreateBitmapIndirect, CreateCompatibleBitmap, CreateDIBitmap, CreateDIBSection
(Bitmaps can be selected for memory device contexts only, and for only one device context at a time.)
Brush CreateBrushIndirect, CreateDIBPatternBrush, CreateDIBPatternBrushPt, CreateHatchBrush, CreatePatternBrush, CreateSolidBrush
Font CreateFont, CreateFontIndirect
Pen CreatePen, CreatePenIndirect
Region CombineRgn, CreateEllipticRgn, CreateEllipticRgnIndirect, CreatePolygonRgn, CreateRectRgn, CreateRectRgnIndirect
Return Values
If the selected object is not a region and the function succeeds, the return value is the handle of the object being replaced. If the selected object is a region and the function succeeds, the return value is one of the following values:
Value Meaning
SIMPLEREGION Region consists of a single rectangle.
COMPLEXREGION Region consists of more than one rectangle.
NULLREGION Region is empty.
If an error occurs and the selected object is not a region, the return value is NULL. Otherwise, it is GDI_ERROR.
Remarks
This function returns the previously selected object of the specified type. An application should always replace a new object with the original, default object after it has finished drawing with the new object.
An application cannot select a bitmap into more than one device context at a time.
Производиш прорисовку с совместимого дескриптора в твой дескриптор окна при помоши функции
The BitBlt function performs a bit-block transfer of the color data corresponding to a rectangle of pixels from the specified source device context into a destination device context.
BOOL BitBlt(
HDC hdcDest, // handle to destination device context
int nXDest, // x-coordinate of destination rectangle's upper-left corner
int nYDest, // y-coordinate of destination rectangle's upper-left corner
int nWidth, // width of destination rectangle
int nHeight, // height of destination rectangle
HDC hdcSrc, // handle to source device context
int nXSrc, // x-coordinate of source rectangle's upper-left corner
int nYSrc, // y-coordinate of source rectangle's upper-left corner
DWORD dwRop // raster operation code
);
Parameters
hdcDest
Identifies the destination device context.
nXDest
Specifies the logical x-coordinate of the upper-left corner of the destination rectangle.
nYDest
Specifies the logical y-coordinate of the upper-left corner of the destination rectangle.
nWidth
Specifies the logical width of the source and destination rectangles.
nHeight
Specifies the logical height of the source and the destination rectangles.
hdcSrc
Identifies the source device context.
nXSrc
Specifies the logical x-coordinate of the upper-left corner of the source rectangle.
nYSrc
Specifies the logical y-coordinate of the upper-left corner of the source rectangle.
dwRop
Specifies a raster-operation code. These codes define how the color data for the source rectangle is to be combined with the color data for the destination rectangle to achieve the final color.
The following list shows some common raster operation codes:
Value Description
BLACKNESS Fills the destination rectangle using the color associated with index 0 in the physical palette. (This color is black for the default physical palette.)
DSTINVERT Inverts the destination rectangle.
MERGECOPY Merges the colors of the source rectangle with the specified pattern by using the Boolean AND operator.
MERGEPAINT Merges the colors of the inverted source rectangle with the colors of the destination rectangle by using the Boolean OR operator.
NOTSRCCOPY Copies the inverted source rectangle to the destination.
NOTSRCERASE Combines the colors of the source and destination rectangles by using the Boolean OR operator and then inverts the resultant color.
PATCOPY Copies the specified pattern into the destination bitmap.
PATINVERT Combines the colors of the specified pattern with the colors of the destination rectangle by using the Boolean XOR operator.
PATPAINT Combines the colors of the pattern with the colors of the inverted source rectangle by using the Boolean OR operator. The result of this operation is combined with the colors of the destination rectangle by using the Boolean OR operator.
SRCAND Combines the colors of the source and destination rectangles by using the Boolean AND operator.
SRCCOPY Copies the source rectangle directly to the destination rectangle.
SRCERASE Combines the inverted colors of the destination rectangle with the colors of the source rectangle by using the Boolean AND operator.
SRCINVERT Combines the colors of the source and destination rectangles by using the Boolean XOR operator.
SRCPAINT Combines the colors of the source and destination rectangles by using the Boolean OR operator.
WHITENESS Fills the destination rectangle using the color associated with index 1 in the physical palette. (This color is white for the default physical palette.)
Return Values
If the function succeeds, the return value is nonzero.
If the function fails, the return value is zero. To get extended error information, call GetLastError.
Remarks
If a rotation or shear transformation is in effect in the source device context, BitBlt returns an error. If other transformations exist in the source device context (and a matching transformation is not in effect in the destination device context), the rectangle in the destination device context is stretched, compressed, or rotated as necessary.
If the color formats of the source and destination device contexts do not match, the BitBlt function converts the source color format to match the destination format.
When an enhanced metafile is being recorded, an error occurs if the source device context identifies an enhanced-metafile device context.
Not all devices support the BitBlt function. For more information, see the RC_BITBLT raster capability entry in GetDeviceCaps.
BitBlt returns an error if the source and destination device contexts represent different devices.
Пример:
HBITMAP hbm = LoadBitmap(..........);
HDC dcc=CreateCompatibleDC(DC);
HBITMAP obm=SelectObject(dcc, hbm);
BitBlt(DC, 0, 0, 100, 100, dcc, 0, 0, SRCCOPY);
SelectObject(dcc, obm);
DeleteDC(dcc);
