在 C++ 中获取像素颜色
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Getting pixel color in C++
提问by rectangletangle
I would like to get the RGB values of a pixel at different x, y coordinates on the screen. How would I go about this in C++?
我想在屏幕上的不同 x、y 坐标处获取像素的 RGB 值。我将如何在 C++ 中解决这个问题？
I'm trying to create my own gaussian blur effect.
我正在尝试创建自己的高斯模糊效果。
This would be in Windows 7.
这将在 Windows 7 中。
Edit
编辑
What libraries need to be included for this to run?
需要包含哪些库才能运行？
What I have going:
我要做什么：
#include <iostream>
using namespace std ;
int main(){
HDC dc = GetDC(NULL);
COLORREF color = GetPixel(dc, 0, 0);
ReleaseDC(NULL, dc);
cout << color;
}
回答by templatetypedef
You can use GetDCon the NULLwindow to get a device context for the whole screen, and can follow that up with a call to GetPixel:
您可以GetDC在NULL窗口上使用以获取整个屏幕的设备上下文，然后可以调用以下方法进行跟进GetPixel：
HDC dc = GetDC(NULL);
COLORREF color = GetPixel(dc, x, y);
ReleaseDC(NULL, dc);
Of course, you'd want to only acquire and release the device context once while doing all the pixel-reading for efficiency.
当然，为了提高效率，在执行所有像素读取时，您只想获取和释放设备上下文一次。
回答by syllogism
As mentioned in a previous post, you want the GetPixelfunction from the Win32 API.
如前一篇文章所述，您需要来自 Win32 API的GetPixel函数。
GetPixel sits inside gdi32.dll, so if you have a proper environment setup, you should be able to include windows.h(which includes wingdi.h) and you should be golden.
GetPixel 位于 gdi32.dll 中，因此如果您有适当的环境设置，您应该能够包含 windows.h（其中包含 wingdi.h），并且您应该很成功。
If you have a minimal environment setup for whatever reason, you could also use LoadLibrary on gdi32.dll directly.
如果您出于某种原因设置了最少的环境，也可以直接在 gdi32.dll 上使用 LoadLibrary。
The first parameter to GetPixel is a handle to the device context, which can be retrieved by calling the GetDC function(which is also available via <windows.h>).
GetPixel 的第一个参数是设备上下文的句柄，可通过调用 GetDC 函数（也可通过 获得<windows.h>）检索该句柄。
A basic example that loads GetPixel from the dll and prints out the color of the pixel wherever your cursor is is as follows.
从 dll 加载 GetPixel 并打印出光标所在位置的像素颜色的基本示例如下。
#include<windows.h>
#include<stdio.h>
int main(int argc, char** argv)
{
FARPROC pGetPixel;
HINSTANCE _hGDI = LoadLibrary("gdi32.dll");
if(_hGDI)
{
pGetPixel = GetProcAddress(_hGDI, "GetPixel");
HDC _hdc = GetDC(NULL);
if(_hdc)
{
POINT _cursor;
GetCursorPos(&_cursor);
COLORREF _color = (*pGetPixel) (_hdc, _cursor.x, _cursor.y);
int _red = GetRValue(_color);
int _green = GetGValue(_color);
int _blue = GetBValue(_color);
printf("Red: 0x%02x\n", _red);
printf("Green: 0x%02x\n", _green);
printf("Blue: 0x%02x\n", _blue);
}
FreeLibrary(_hGDI);
}
return 0;
}
