一个简单问题，有一个bmp图片太大，我如何按比例缩小后显示！

[gaoxiaopai]

CString head_name1="C:\\history\\20061114084845_head.bmp";
HBITMAP hBitmap =(HBITMAP)LoadImage(NULL, head_name1, IMAGE_BITMAP,
0, 0, LR_CREATEDIBSECTION | LR_DEFAULTSIZE | LR_LOADFROMFILE);
m_picture.ModifyStyle(0xF,SS_BITMAP|SS_CENTERIMAGE);
m_picture.SetBitmap(hBitmap);
其中m_picture是STATIC控件。目前我显示不完整张图片（图片太大），而STATIC控件不能设置得太大，我该如何处理呢？

[LiChenYue]

另存为JPG格式，可以自动大小吧？

[taianmonkey]

使用StretchBlt

[zhshgap]

直接用画图工具把图缩小．．

[tuke0001]

StretchBlt可以，但可能图象会失真

[laolaoliu2002]

SetStretchBltMode
StretchBlt

[碧螺春的马甲]

1 自己用算法缩小。抽点、平均等
2 用Bitblt DrawDibDraw画到你的倥件上，这些函数有拉伸的参数。
3 嘿嘿，不要找大的图片了。

[laolaoliu2002]

The following example code is taken from an application that displays an image either at its original size or at twice its original size. (This application uses the default stretch mode.)

hdcScaled = CreateCompatibleDC(hdcScreen);

hbmScaled = CreateCompatibleBitmap(hdcScreen,
GetDeviceCaps(hdcScreen, HORZRES) * 2,
GetDeviceCaps(hdcScreen, VERTRES) * 2);

if (hbmScaled == 0)
errhandler("hbmScaled", hwnd);

// Select the bitmaps into the compatible DC.

if (!SelectObject(hdcScaled, hbmScaled))
errhandler("Scaled Bitmap Selection", hwnd);

case WM_COMMAND: // message: command from application menu
switch(wParam)
{
case IDM_SCALEX1:
if (fBlt)
{
fScaled = FALSE;
hdcWin = GetDC(hwnd);
BitBlt(hdcWin,
0,0,
bmp.bmWidth, bmp.bmHeight,
hdcCompatible,
0,0,
SRCCOPY);
ReleaseDC(hwnd, hdcWin);
}
break;

case IDM_SCALEX2:
if (fBlt)
{
fScaled = TRUE;
StretchBlt(hdcScaled,
0, 0,
bmp.bmWidth * 2, bmp.bmHeight * 2,
hdcCompatible,
0, 0,
bmp.bmWidth, bmp.bmHeight,
SRCCOPY);

hdcWin = GetDC(hwnd);
BitBlt(hdcWin,
0,0,
bmp.bmWidth, bmp.bmHeight,
hdcScaled,
0,0,
SRCCOPY);
ReleaseDC(hwnd, hdcWin);
}
break;

[yzcurry]

你可以在上面就可以解决了,在HBITMAP里面有一个Pens参数,然后它有两种方式的,你选其中的geometric pen 来用就可以了
具体我把我msdn上面的原文给你看一下
About Pens
There are two types of pen: cosmetic and geometric. A cosmetic pen is used with applications requiring lines of fixed width and lines that are quickly drawn. A CAD application, for example, uses a cosmetic pen to generate hidden, section, center, and dimension lines that are between .015 and .022 inches wide — regardless of the scale factor. A geometric pen is used with applications requiring scalable lines, lines with unique end or join styles, and lines that are wider than a single pixel. A spreadsheet application, for example, uses a geometric pen to define each of the bars in a bar graph as a wide line.
具体怎么操作我就不详细讲解了,自己去看一下吧,.本人上班之中.

[zhucde]

例子:

http://www.vckbase.com/document/viewdoc/?id=527

[yangpan116]

GetClientRect得到static控件的大小。
然后再StretchBlt，缩放就可以了。

[xyz666]

HBITMAP hbitmap = (HBITMAP) LoadImage(NULL,
filename,
IMAGE_BITMAP,
0,0,
LR_LOADFROMFILE);
bitmap.Attach(hbitmap);
bitmap.GetObject(sizeof(bmInfo),&bmInfo);
dcMemory.SelectObject(&bitmap);
bitmap.Detach();
sz.cx = bmInfo.bmWidth;
sz.cy = bmInfo.bmHeight;
pDC->StretchBlt(200,100,sz.cx/2,sz.cy/2,&dcMemory,0,0,sz.cx,sz.cy,SRCCOPY);

[xyz666]

缩小为原来的1/2

[smallfishff]

楼上写得正确 理论得分.