得到一个24位BMP文件HBITMAP加载到内存 [英] Get a HBITMAP from an 24bit BMP file loaded into memory

问题描述

我已经加载到RAM中的24位BMP文件，我试图创建此映像文件HBITMAP。我已经发现了一些例子围绕我一直在尝试着，但似乎无法使工作。基本上，我需要一个HBITMAP的文件，这样我就可以卸载文件，只是不停，我可以用DeleteObject的后处理（）的HBITMAP。由于此位是在我的应用程序加载很早，没有应用程序窗口，因此没有HDC。这是我到目前为止有： -

I have a 24bit BMP file loaded into RAM and I'm trying to create a HBITMAP for this image file. I have found some examples around which I've been experimenting with, but can't seem to make work. Basically, I need a HBITMAP for the file, so that I can unload the file and just keep the HBITMAP which I can dispose of later with DeleteObject(). Since this bitmap is loaded very early on in my application, there is no application Window and therefore no HDC. This is what I have so far:-

HBITMAP cBitmap;  // This should be where my bitmap handle ends up.
mem;              // This is a void* pointer to the loaded BMP file


tagBITMAPFILEHEADER bfh = *(tagBITMAPFILEHEADER*)mem;
tagBITMAPINFOHEADER bih = *(tagBITMAPINFOHEADER*)(mem + sizeof(tagBITMAPFILEHEADER));
RGBQUAD rgb = *(RGBQUAD*)(mem + sizeof(tagBITMAPFILEHEADER) + sizeof(tagBITMAPINFOHEADER));

BITMAPINFO bi;
bi.bmiColors[0] = rgb;
bi.bmiHeader = bih;

UINT8* pixels = mem + bfh.bfOffBits;
void* ppv;
HBITMAP hBitmap = CreateDIBSection(NULL, &bi, DIB_RGB_COLORS, &ppv, NULL, 0);
SetDIBits(NULL, hBitmap, 0, bih.biHeight, pixels, &bi, DIB_RGB_COLORS);
GetObject(hBitmap, sizeof(BITMAP), &cBitmap);

由于某种原因，只是令我感到困惑，关于CBitmap最终被NULL。这令我费解另一件事...... DIB_RGB_COLORS意味着BITMAPINFO有一个指针指向字面RGB值，但是这是如何工作的一个24bit的形象，这没有一个调色板？

For some reason that just baffles me, cBitmap ends up being NULL. And another thing that puzzles me... DIB_RGB_COLORS means that the BITMAPINFO has a pointer to literal RGB values, but how does that work with a 24bit image, which doesn't have a palette?

推荐答案

嗯，这不是多么 GetObject的的作品。用法

Um, that's not how GetObject works. The usage is

GetObject(handle, sizeof(object), &object);

在你的情况下，期望的是你怎么称呼它为

In your case, the expectation is that you call it as

BITMAP bitmap;
GetObject(hBitmap, sizeof(BITMAP), &bitmap);

您不是一个指针传递给一个 BITMAP 结构，所以行为是不确定的。

You are not passing a pointer to a BITMAP structure, so the behavior is undefined.

您不需要 GetObject的可言。你已经拥有你的 HBITMAP 。这是在 HBITMAP 变量。

You don't need GetObject at all. You already have your HBITMAP. It's in the hBitmap variable.

cBitmap = hBitmap;

这篇关于得到一个24位BMP文件HBITMAP加载到内存的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！