"MFC" Cdc::bitblt Introduction

CDC::BITBLT Introduction

2011-11-04 08:25 19576 People read review (6) Favorite Report

From

http://blog.csdn.net/bberdong/article/details/6934270

There are many ways to draw a device context. For example, by creating a bit drawing brush, you can use it to fill an area to achieve image rendering. In addition, you can use the CDC class's bitmap function to output a bitmap to the device context.

The BitBlt is used to copy bitmaps from the original device to the target device in the following syntax format:

Boolbitblt (int x,int y,int nwidth,int nheight,cdc*psrcdc,int xsrc,int ysrc,dworddwrop);

X: The x-axis coordinate point of the upper-left corner of the target rectangle area.

Y: the y-axis coordinate point of the upper-left corner of the target rectangle area.

Nwidth: Draws the width of the bitmap in the target device.

Nhight: The height of the bitmap is drawn on the target device.

PSRCDC: Pointer to the source device context object.

XSRC: The origin x-axis coordinate of the source device context from which the function copies the bitmap to the target device.

YSRC: The Origin y-coordinate of the source device context from which the function copies the bitmap to the target device.

Dwrop: Raster Operation code

Dwrop has the following options:

Blackness fill the target area with black

Dstinvert target matrix region color inversion

Mergecopy the color of the rectangular area of the original device and the paint brush of the target device using the combined operation

Mergepaint uses or operations to merge the color of the source rectangle area of the inverse and the color of the destination rectangle area

Notsrccopy Copy the reverse color from the source device region to the target device

Notsrcerase uses or operations to combine the color of the source device area with the target device area and then reverse the resulting color

Patcopy Copy the currently selected brush from the source device to the target device

Patinvert the color of the brush and target device area selected by the target device using the XOR operation

Patpaint the color of the currently selected brush and source device area of the target area through or operations

Srcand the color of the source device and target device area using the combined operation

Srccopy Direct replication of the source device area to the target device

Srcerase using the inverse color of the target device area with the operation and the color of the source device area

Srcinvert combination of source device area color and target device area color using XOR operation

Srcpaint use or operation combination source device area color and target device area color

Whiteness fill the target area with white

StretchBlt differs from BitBlt in that the StretchBlt method can extend or shrink a bitmap to fit the size of the target area. The format is as follows:boolstrevhblt (int x,int y,int nwidth,int nheight,cdc* psrcdc,int xsrc,int ysrc,intnsrcwidth,int nSrcHeight, DWORD dwrop);

X: The x-axis coordinate point of the upper-left corner of the target rectangle area.

Y: the y-axis coordinate point of the upper-left corner of the target rectangle area.

Nwidth: Draws the width of the bitmap in the target device.

Nhight: The height of the bitmap is drawn on the target device.

PSRCDC: Pointer to the source device context object.

XSRC: The origin x-axis coordinate of the source device context from which the function copies the bitmap to the target device.

YSRC: The Origin y-coordinate of the source device context from which the function copies the bitmap to the target device.

Nsrcwidth; the width of the bitmap that needs to be copied.

Nsrcheight; the bitmap height to copy.

Dwrop: Raster operation code.

Here are the two methods of comparing the program, the program code is as follows:

void Coutoutbmpview::ondraw (cdc* pDC)

{

coutputbmpdoc* PDoc =getdocument ();//Get Document Object

Assert_valid (PDOC);//Validate Document Object

CDC memdc;//defines a device context

Memdc.createcompatibledc (PDC);//Create a compatible device context

CBitmap bmp;//defining Bitmap objects

Bmp. LoadBitmap (IDB_BKBITMAP);//Load bitmap

Memdc.selectobject (&bmp);//Select Bitmap Object

Pdc->bitblt (30,20,180,180,&memdc,1,1,srccopy);//Draw bitmap

The above is the use of BitBlt to draw bitmaps

CRect RC (30,20,210,200);//define an area

CBrush Brush (RGB (0,0,0));//define a black paint brush

Pdc->framerect (Rc,&brush);//Draw a rectangular border

Just to see the difference between the two, draw a rectangular box

Rc. Offsetrect (220,0);//Mobile Area

Below is a bitmap drawn using StretchBlt.

BITMAP bitinfo;//defining a bitmap structure

Bmp. Getbitmap (&bitinfo);//Get bitmap information

int x = bitinfo.bmwidth;//Gets the bitmap width

int y = bitinfo.bmheight; get bitmap height

Pdc->stretchblt (RC.LEFT,RC.TOP,RC. Width (), RC. Height (), &memdc,0,0,x,y,srccopy);//Draw bitmap

Pdc->framerect (Rc,&brush);//Draw Border

Brush. DeleteObject ();//Release Paint brush

Memdc.deletedc ();//Release device context

Bmp. DeleteObject ();//Release Bitmap object

}

"MFC" Cdc::bitblt Introduction