如何在C ++中将两个位图屏幕快照的字节与字节进行比较 [英] How to compare byte to byte of two bitmap screenshots in c++
问题描述
在问题最后，我的最后编辑
IN THE END OF THE QUESTION MY LAST EDIT
大家好， 我必须实现一个功能，该功能可以比较屏幕的一部分的两个镜头，以了解是否存在差异/差异.我写了类似下面的代码，但是我无法管理它.在代码COORDINATES_RECT中是一个结构
Hi all, I have to implement a function that compares two shots of a portion of the screen in order to know if there are differences/variations. I wrote something like the following code but I can't manage it to work. In the code COORDINATES_RECT is a struct
typedef struct _COORDINATES_RECT {
int x;
int y;
int sizeX;
int sizeY;
} COORDINATES_RECT;
在输入中保存的数据知道哪一部分是要分析的屏幕，而在输出中返回的是最大矩形的数据，该函数在其中找到了变化.为了更好地解释问题，我最后看到了if构造:
that in input holds data to know which is the portion of the screen to analyze, and in output returns the data of the biggest rectangle in which the function found variations. To better explain the problem, I saw that if construct in the end:
if(lpbitmap1[(i*bmpScreen1.bmWidth)+j] != lpbitmap2[(i*bmpScreen1.bmWidth)+j])
永远不会执行.我不知道这是否是比较两个位图(转换为char数组)的正确方法.我用谷歌搜索并在msdn中搜索，但没有结果. 完整代码如下:
never get executed. I don't know if it is the right way to compare two bitmaps (converted into char arrays). I googled and searched in msdn but with no result. Full code follows:
void testBitmapVariations(COORDINATES_RECT *c)
{
HDC hdcScreen = GetDC(NULL);
HDC hdcMemDC1 = CreateCompatibleDC(hdcScreen);
HDC hdcMemDC2 = CreateCompatibleDC(hdcScreen);
HBITMAP hBmpScreen1 = NULL;
HBITMAP hBmpScreen2 = NULL;
BITMAP bmpScreen1;
BITMAP bmpScreen2;
if(!hdcMemDC1 || !hdcMemDC2)
{
MessageBox(NULL,L"CreateCompatibleDC failed", L"Failed", MB_OK);
ReleaseDC(NULL, hdcMemDC1);
ReleaseDC(NULL, hdcMemDC2);
return;
}
hBmpScreen1 = CreateCompatibleBitmap(hdcMemDC1, c->sizeX, c->sizeY);
hBmpScreen2 = CreateCompatibleBitmap(hdcMemDC2, c->sizeX, c->sizeY);
SelectObject(hdcMemDC1,hBmpScreen1);
if(!BitBlt(hdcMemDC1,
0,0,
c->sizeX, c->sizeY,
hdcScreen,
c->x,c->y,
SRCCOPY))
{
MessageBox(NULL,L"BitBlt failed", L"Failed", MB_OK);
ReleaseDC(NULL, hdcMemDC1);
ReleaseDC(NULL, hdcMemDC2);
return;
}
GetObject(hBmpScreen1,sizeof(BITMAP),&bmpScreen1);
BITMAPFILEHEADER bmfHeader;
BITMAPINFOHEADER bi;
bi.biSize = sizeof(BITMAPINFOHEADER);
bi.biWidth = bmpScreen1.bmWidth;
bi.biHeight = bmpScreen1.bmHeight;
bi.biPlanes = 1;
bi.biBitCount = 32;
bi.biCompression = BI_RGB;
bi.biSizeImage = 0;
bi.biXPelsPerMeter = 0;
bi.biYPelsPerMeter = 0;
bi.biClrUsed = 0;
bi.biClrImportant = 0;
DWORD dwBmpSize = ((bmpScreen1.bmWidth * bi.biBitCount + 31) / 32) * 4 * bmpScreen1.bmHeight;
// Starting with 32-bit Windows, GlobalAlloc and LocalAlloc are implemented as wrapper functions that
// call HeapAlloc using a handle to the process's default heap. Therefore, GlobalAlloc and LocalAlloc
// have greater overhead than HeapAlloc.
char *lpbitmap1 = (char *)malloc(dwBmpSize);
// Gets the "bits" from the bitmap and copies them into a buffer
// which is pointed to by lpbitmap1.
GetDIBits(hdcScreen, hBmpScreen1, 0,
(UINT)bmpScreen1.bmHeight,
lpbitmap1,
(BITMAPINFO *)&bi, DIB_RGB_COLORS);
Sleep(200);
SelectObject(hdcMemDC2,hBmpScreen2);
if(!BitBlt(hdcMemDC2,
0,0,
c->sizeX, c->sizeY,
hdcScreen,
c->x,c->y,
SRCCOPY))
{
MessageBox(NULL,L"BitBlt failed", L"Failed", MB_OK);
ReleaseDC(NULL, hdcMemDC1);
ReleaseDC(NULL, hdcMemDC2);
return;
}
GetObject(hBmpScreen2,sizeof(BITMAP),&bmpScreen2);
char *lpbitmap2 = (char *)malloc(dwBmpSize);
// Gets the "bits" from the bitmap and copies them into a buffer
// which is pointed to by lpbitmap2.
GetDIBits(hdcScreen, hBmpScreen2, 0,
(UINT)bmpScreen2.bmHeight,
lpbitmap2,
(BITMAPINFO *)&bi, DIB_RGB_COLORS);
int i, j, minX = bmpScreen1.bmWidth, minY = bmpScreen1.bmHeight, maxX = 0, maxY = 0;
bool changed = false;
for(i = 0; i < bmpScreen1.bmHeight; i++)
{
for(j = 0; j < bmpScreen1.bmWidth; j++)
{
// I don't know why this if never get executed
if(lpbitmap1[(i*bmpScreen1.bmWidth)+j] != lpbitmap2[(i*bmpScreen1.bmWidth)+j])
{
changed = true;
if(i < minY)
minY = i;
if(i > maxY)
maxY = i;
if(j < minX)
minX = j;
if(j > maxY)
maxY = j;
}
}
}
if(changed)
{
c->x = minX;
c->y = minY;
c->sizeX = maxX - minX;
c->sizeY = maxY - minY;
}
else
{
c->sizeX = 0;
c->sizeY = 0;
}
//Frees from the heap
free(lpbitmap1);
free(lpbitmap2);
ReleaseDC(NULL, hdcMemDC1);
ReleaseDC(NULL, hdcMemDC2);
}
谢谢
弗朗切斯科
Ps.变量声明放在它们所引用的块旁边，目的只是为了使该问题更清楚.
Ps. Variables declarations are put next to the block they refers to only to achieve more clarity in this question..
我像这样重写了它，它似乎可以工作了:)谢谢大家，但是任何纠正都值得赞赏
I rewrote it like this and it seems to work :) Thanks to all, however any correction is appreciated
void testBitmapVar(COORDINATES_RECT *c)
{
HDC screenDC = GetDC(0),
memDC = CreateCompatibleDC(screenDC);
HBITMAP hBm = CreateCompatibleBitmap(screenDC, c->sizeX, c->sizeY),
oldHBm;
BITMAP bm;
BITMAPFILEHEADER bmfHeader;
BITMAPINFOHEADER bi;
UINT *pixels = (UINT*) malloc ((c->sizeX*c->sizeY) * sizeof(UINT));
std::ostringstream ss;
std::wstring str;
int i, j, minX, maxX, minY, maxY;
if(!pixels)
{
c->sizeX = 0;
c->sizeY = 0;
return;
}
memset(pixels, 0, (c->sizeX*c->sizeY) * sizeof(UINT));
oldHBm = (HBITMAP) SelectObject(memDC, hBm);
// copies to bitmap
BitBlt(memDC, 0, 0, c->sizeX, c->sizeY, screenDC, c->x, c->y, SRCCOPY);
Sleep(500);
BitBlt(memDC, 0, 0, c->sizeX, c->sizeY, screenDC, c->x, c->y, SRCINVERT);
GetObject(hBm, sizeof(BITMAP), &bm);
bi.biSize = sizeof(BITMAPINFOHEADER);
bi.biWidth = bm.bmWidth;
bi.biHeight = bm.bmHeight;
bi.biPlanes = 1;
bi.biBitCount = 32;
bi.biCompression = BI_RGB;
bi.biSizeImage = 0;
bi.biXPelsPerMeter = 0;
bi.biYPelsPerMeter = 0;
bi.biClrUsed = 0;
bi.biClrImportant = 0;
GetDIBits(memDC, hBm, 0,
(UINT)bm.bmHeight,
pixels,
(BITMAPINFO *)&bi, DIB_RGB_COLORS);
for(i = 0, minY = c->sizeY, maxY = -1; i < c->sizeY; i++)
{
for(j = 0, minX = c->sizeX, maxX = -1; j < c->sizeX; j++)
{
if(pixels[(i*c->sizeX)+j])
{
if(i < minY)
minY = i;
if(i > maxY)
maxY = i;
if(j < minX)
minX = j;
if(j > maxX)
maxX = j;
}
}
}
if(maxX != -1 && maxY != -1)
{
c->x = minX;
c->y = minY;
c->sizeX = maxX - minX;
c->sizeY = maxY - minY;
}
else
{
c->sizeX = 0;
c->sizeY = 0;
}
free(pixels);
SelectObject(memDC, oldHBm);
DeleteObject(hBm);
ReleaseDC(0, screenDC);
DeleteDC(memDC);
}
推荐答案
与其完全自己比较两个位图，不如考虑使用BitBlt通过SRCINVERT运算符将它们组合在一起，该运算符将这两个位图进行XOR运算，因此相同将显示为零，而所有非零区域将是不同的.
Rather than comparing the two bitmaps entirely on your own, consider using BitBlt to combine them using the SRCINVERT operator, which XORs the two together, so the parts that are identical will show up as zeros, and all the non-zero areas will be differences.
这篇关于如何在C ++中将两个位图屏幕快照的字节与字节进行比较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！
