自己做个大头贴软件,一些总结

呵呵以前还真没有认真研究过图像处理这块儿东西(其实这回也只是了解一些皮毛),研究一下,才发现自己做这样的大头贴程序还算简单

具体的程序没写完,只是稍微写了一些想法...

大头贴说白了就是个图像叠加程序,两步动作,一个是抠像/照相程序,一个是图像处理及其叠加

抠像比较复杂,不去研究,照相都有现成的Dll,用不着研究,图像处理都有标准算法,以后上了大学会研究

现在主要就看看图像叠加

背景模板是Gif文件,有一块设置为Transparent的区域,也就是用来放大头的

一种方式是直接用Canvas的Draw方法或者是CopyRect方法把模板图像花在大头上边,设置好Transparent颜色,就行了下边是网上拉下来的一段程序(不是我写的,我写的程序比这个漂亮多了呵呵)

procedure TForm1.Button2Click(Sender: TObject);
var
b,s:tbitmap;
begin
b:=tBitmap.create;
s:=tBitmap.create;
s.TransparentMode :=tmAuto; //可以自己设置透明色
b.LoadFromFile('c:/windows/forest.bmp'); //大的
s.LoadFromFile('c:/windows/circles.bmp'); //小的
b.canvas.copymode:=cmSrcCopy; //选择合适的
s.PixelFormat:=pf32bit; //避免调色板问题
b.PixelFormat:=pf32bit;
//b.canvas.draw(b.width-s.width,b.height-s.height,s); 另一种做法
b.Canvas.CopyRect (rect(b.width-s.width,b.height-s.height,b.width,b.height),
s.canvas,rect(0,0,s.width,s.height));
Canvas.Draw (0,0,b);
b.savetofile('d:/temp.bmp');
b.free;
s.free;
end;

还找到一个API函数,BitBlt 以前听说过,倒是没有研究过,下面是MSDN里边的摘录

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 DC
  int nXDest,  // x-coord of destination upper-left corner
  int nYDest,  // y-coord of destination upper-left corner
  int nWidth,  // width of destination rectangle
  int nHeight, // height of destination rectangle
  HDC hdcSrc,  // handle to source DC
  int nXSrc,   // x-coordinate of source upper-left corner
  int nYSrc,   // y-coordinate of source upper-left corner
  DWORD dwRop  // raster operation code
);

Parameters

hdcDest

[in] Handle to the destination device context.

nXDest

[in] Specifies the x-coordinate, in logical units, of the upper-left corner of the destination rectangle.

nYDest

[in] Specifies the y-coordinate, in logical units, of the upper-left corner of the destination rectangle.

nWidth

[in] Specifies the width, in logical units, of the source and destination rectangles.

nHeight

[in] Specifies the height, in logical units, of the source and the destination rectangles.

hdcSrc

[in] Handle to the source device context.

nXSrc

[in] Specifies the x-coordinate, in logical units, of the upper-left corner of the source rectangle.

nYSrc

[in] Specifies the y-coordinate, in logical units, of the upper-left corner of the source rectangle.

dwRop

[in] 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.)
CAPTUREBLT	Windows 98/Me, Windows 2000/XP: Includes any windows that are layered on top of your window in the resulting image. By default, the image only contains your window. Note that this generally cannot be used for printing device contexts.
DSTINVERT	Inverts the destination rectangle.
MERGECOPY	Merges the colors of the source rectangle with the brush currently selected in hdcDest, 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.
NOMIRRORBITMAP	Windows 98/Me, Windows 2000/XP: Prevents the bitmap from being mirrored.
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 brush currently selected in hdcDest, into the destination bitmap.
PATINVERT	Combines the colors of the brush currently selected in hdcDest, with the colors of the destination rectangle by using the Boolean XOR operator.
PATPAINT	Combines the colors of the brush currently selected in hdcDest, 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.

Windows NT/2000/XP: To get extended error information, call GetLastError.

Remarks

BitBlt only does clipping on the destination DC.

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 the GetDeviceCaps function as well as the following functions: MaskBlt, PlgBlt, and StretchBlt.

BitBlt returns an error if the source and destination device contexts represent different devices. To transfer data between DCs for different devices, convert the memory bitmap to a DIB by calling GetDIBits. To display the DIB to the second device, call SetDIBits or StretchDIBits.

ICM: No color management is performed when blits occur.

还有一段Example

Capturing an Image

You can use a bitmap to capture an image, and you can store the captured image in memory, display it at a different location in your application's window, or display it in another window.

In some cases, you may want your application to capture images and store them only temporarily. For example, when you scale or zoom a picture created in a drawing application, the application must temporarily save the normal view of the image and display the zoomed view. Later, when the user selects the normal view, the application must replace the zoomed image with a copy of the normal view that it temporarily saved.

To store an image temporarily, your application must call CreateCompatibleDC to create a DC that is compatible with the current window DC. After you create a compatible DC, you create a bitmap with the appropriate dimensions by calling the CreateCompatibleBitmap function and then select it into this device context by calling the SelectObject function.

After the compatible device context is created and the appropriate bitmap has been selected into it, you can capture the image. The BitBlt function captures images. This function performs a bit block transfer that is, it copies data from a source bitmap into a destination bitmap. However, the two arguments to this function are not bitmap handles. Instead, BitBlt receives handles that identify two device contexts and copies the bitmap data from a bitmap selected into the source DC into a bitmap selected into the target DC. In this case, the target DC is the compatible DC, so when BitBlt completes the transfer, the image has been stored in memory. To redisplay the image, call BitBlt a second time, specifying the compatible DC as the source DC and a window (or printer) DC as the target DC.

The following example code, from an application that captures an image of the entire desktop, creates a compatible device context and a bitmap with the appropriate dimensions, selects the bitmap into the compatible DC, and then copies the image using the BitBlt function.

// Create a normal DC and a memory DC for the entire screen. The
// normal DC provides a "snapshot" of the screen contents. The
// memory DC keeps a copy of this "snapshot" in the associated
// bitmap.
hdcScreen = CreateDC("DISPLAY", NULL, NULL, NULL);
hdcCompatible = CreateCompatibleDC(hdcScreen);
// Create a compatible bitmap for hdcScreen.
hbmScreen = CreateCompatibleBitmap(hdcScreen,
GetDeviceCaps(hdcScreen, HORZRES),
GetDeviceCaps(hdcScreen, VERTRES));
if (hbmScreen == 0)
errhandler("hbmScreen", hwnd);
// Select the bitmaps into the compatible DC.
if (!SelectObject(hdcCompatible, hbmScreen))
errhandler("Compatible Bitmap Selection", hwnd);
// Hide the application window.
ShowWindow(hwnd, SW_HIDE);
//Copy color data for the entire display into a
//bitmap that is selected into a compatible DC.
if (!BitBlt(hdcCompatible,
0,0,
bmp.bmWidth, bmp.bmHeight,
hdcScreen,
0,0,
SRCCOPY))
errhandler("Screen to Compat Blt Failed", hwnd);
// Redraw the application window.
ShowWindow(hwnd, SW_SHOW);

没有时间实际试验了,应该直接用API效果会比较好

还有个想法,GIF文件的后面+上若干字节是不会影响Gif图像文件本身的,so,应该在作为大头贴模板的Gif文件末加上一段数据用以指明此模板的空白区域中心点,大小等等,这样就可以实现让大头像自动匹配到模板中去,不用人工操作,这个实现起来应该不会太难

明天开始去学校了,delphi真得88了,手头的<面向对象的实践之路>虽然精彩,但是也只能去看那一大摞高考的东西.....

特别得好好看看英语,该死的MS资料从来就不出中文版 呵呵