StretchBlt MFC C ++问题 [英] StretchBlt MFC C++ problem

问题描述

你好！我使用StretchBlt 加载位图图像并将其显示在屏幕上.
我还在基于对话框的应用程序中使用了双缓冲区.

我写了一个显示图像的函数:

Hello! I use StretchBlt to load bitmap image and show it on screen.
I also use double buffer in my application, which is dialog based.

I wrote a function that displays the image:

void CPlay::OnBackground(CBitmap* p, CDC* pDC)
{
    CDC dcMemory;
    BITMAP bm;
    dcMemory.CreateCompatibleDC(pDC);
    dcMemory.SelectObject(p);
    p->GetBitmap(&bm);

	pDC->StretchBlt(0, 0, screenX, screenY, &dcMemory, 0, 0, bm.bmWidth, bm.bmHeight, SRCCOPY);
}

然后，使CBitmap 变量并加载图像:

Then I make CBitmap variable and load the image:

variable.LoadBitmap(RESOURCE);

我称这个功能OnBackground(&variable, &pDC);
pDC 是CDC变量;
screenX，screenY 是我的屏幕分辨率:

I call the function OnBackground(&variable, &pDC);
pDC is CDC variable;
screenX, screenY are my screen resolution:

	screenX = GetSystemMetrics(SM_CXSCREEN);
	screenY = GetSystemMetrics(SM_CYSCREEN);

如果我保留我的分辨率(1280x1024)，则效果很好.但是，如果我更改它，我的CPU开始使用50-60％，并且速度变慢.
如果我使用StretchBlt错误，请通知我.
希望您能明白我的意思，这就是为什么我以前会详细写它的原因. 谢谢！

If I keep my resol(1280x1024), it works well. But if I change it, my CPU starts using 50-60% and it is slowed down.
If I''m wrong using StretchBlt, please let me know.
I hope you can get my point, that''s why I used to write it in a detailed manner.
Thanks!

推荐答案

您可以立即创建调整大小位图，而不必一次又一次地拉伸原始位图.查看我的纯C重采样DLL" [

You may create at once a resized bitmap instead of stretching again and again the original one. See if my "Plain C Resampling DLL"[^] article helps.
:)

是指更改它，还是更改之后?如果要更改它，它会一遍又一遍地绘制图像，因此当然会使用处理器.

Do you mean AS you change it, or AFTER you change it ? If you''re changing it, it''s drawing the image over and over, so of course that uses the processor.

在更改分辨率之前，请尝试清洁DC.我相信它将产生巨大的影响.

Try to clean your DC before you change your resolution. It will produce a great effect I believe.

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