我正在学习C ++，但我在将图像放在屏幕上时遇到了问题。
我在互联网上寻求帮助，但我找不到任何帮助。
我正在尝试创建一个窗口，并在调用WM_Paint消息时在客户区放置一个简单的颜色，但程序只是像往常一样显示灰色屏幕。我正在使用code :: blocks 10.05。
#include <windows.h>
#include <iostream>
using namespace std;
int winx = 500;
int winy = 500;
int winbpp = 24;
static char m_bibuf[ sizeof(BITMAPINFOHEADER) + 12 ];
static BITMAPINFO &m_bi = *(BITMAPINFO*)&m_bibuf;
static BITMAPINFOHEADER &m_bih = m_bi.bmiHeader;
int* buffer = new int[winx*winy*winbpp];
int setbuffer()
{
for(int x = 0; x < winx; x++)
{
for(int y=0; y < winy; y++)
{
for(int z =0; z < winbpp; z++)
{
buffer[x*y*z] = 1;
}
}
}
return 0;
}
/* Declare Windows procedure */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);
/* Make the class name into a global variable */
char szClassName[ ] = "CodeBlocksWindowsApp";
int WINAPI WinMain (HINSTANCE hThisInstance,
HINSTANCE hPrevInstance,
LPSTR lpszArgument,
int nCmdShow)
{
HWND hwnd; /* This is the handle for our window */
MSG messages; /* Here messages to the application are saved */
WNDCLASSEX wincl; /* Data structure for the windowclass */
/* The Window structure */
wincl.hInstance = hThisInstance;
wincl.lpszClassName = szClassName;
wincl.lpfnWndProc = WindowProcedure; /* This function is called by windows */
wincl.style = CS_DBLCLKS; /* Catch double-clicks */
wincl.cbSize = sizeof (WNDCLASSEX);
/* Use default icon and mouse-pointer */
wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
wincl.lpszMenuName = NULL; /* No menu */
wincl.cbClsExtra = 0; /* No extra bytes after the window class */
wincl.cbWndExtra = 0; /* structure or the window instance */
/* Use Windows's default colour as the background of the window */
wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;
/* Register the window class, and if it fails quit the program */
if (!RegisterClassEx (&wincl))
return 0;
/* The class is registered, let's create the program*/
hwnd = CreateWindowEx (
0, /* Extended possibilites for variation */
szClassName, /* Classname */
" project 1 ", /* Title Text */
WS_OVERLAPPEDWINDOW, /* default window */
CW_USEDEFAULT, /* Windows decides the position */
CW_USEDEFAULT, /* where the window ends up on the screen */
winx, /* The programs width */
winy, /* and height in pixels */
HWND_DESKTOP, /* The window is a child-window to desktop */
NULL, /* No menu */
hThisInstance, /* Program Instance handler */
NULL /* No Window Creation data */
);
/* Make the window visible on the screen */
ShowWindow (hwnd, nCmdShow);
/* Run the message loop. It will run until GetMessage() returns 0 */
while (GetMessage (&messages, NULL, 0, 0))
{
/* Translate virtual-key messages into character messages */
TranslateMessage(&messages);
/* Send message to WindowProcedure */
DispatchMessage(&messages);
}
/* The program return-value is 0 - The value that PostQuitMessage() gave */
return messages.wParam;
}
/* This function is called by the Windows function DispatchMessage() */
LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message) /* handle the messages */
{
case WM_CREATE:
{
m_bih.biWidth = winx;
m_bih.biHeight = winy;
m_bih.biBitCount = winbpp;
m_bih.biSize = sizeof(m_bih);
m_bih.biPlanes = 1; // DIBs are upside down
m_bih.biCompression = BI_BITFIELDS;
m_bih.biSizeImage = 0;
m_bih.biXPelsPerMeter = 0;
m_bih.biYPelsPerMeter = 0;
m_bih.biClrUsed = 0;
m_bih.biClrImportant = 0;
setbuffer();
InvalidateRect(hwnd, NULL, TRUE);
} break;
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hDC = BeginPaint(hwnd, &ps);
RECT client;
GetClientRect(hwnd, &client);
StretchDIBits ( hDC,
0, // Destination top left hand
// corner X Position
0, // Destination top left hand
// corner Y Position
client.right, // Destinations width
client.bottom, // Destinations height
0, // Source top left hand
// corner's X Position
0, // Source top left hand
// corner's Y Position
winx, // Sources width
winy, // Sources height
buffer, // Source's data
&m_bi, // Bitmap Info
DIB_RGB_COLORS, // operations
SRCCOPY);
EndPaint(hwnd, &ps);
} break;
case WM_DESTROY:
delete buffer;
PostQuitMessage (0); /* send a WM_QUIT to the message queue */
break;
default: /* for messages that we don't deal with */
return DefWindowProc (hwnd, message, wParam, lParam);
}
return 0;
}
程序正常编译，但不是在客户区显示“缓冲区”的内容， 它只是像往常一样显示灰色。
是否正确格式化了'缓冲区'？
=以下更新代码=
#include <windows.h>
int winx = 500;
int winy = 400;
int bpp = 24;
size_t pwidth;
int scanlinewidth = 0;
int numscanlines = 0;
bool setscanline = 1;
bool setbitmap = 1;
BITMAPINFO m_bi;
struct BGR{ char blue; char green; char red;};
BGR* buffer;
void setframebuffer()
{
m_bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
m_bi.bmiHeader.biPlanes = 1;
m_bi.bmiHeader.biBitCount = bpp;
m_bi.bmiHeader.biCompression = BI_RGB;
m_bi.bmiHeader.biSizeImage = 0;
m_bi.bmiHeader.biXPelsPerMeter = 100;
m_bi.bmiHeader.biYPelsPerMeter = 100;
m_bi.bmiHeader.biClrUsed = 0;
m_bi.bmiHeader.biClrImportant = 0;
if (setbitmap)
{
m_bi.bmiHeader.biWidth = scanlinewidth;
m_bi.bmiHeader.biHeight = numscanlines;
setbitmap = 0;
}
if (!setbitmap)
{
pwidth = (scanlinewidth * 3 + 3) & ~3;
buffer = new BGR[(scanlinewidth + pwidth)*numscanlines];
}
for (int i = 0; i < ((scanlinewidth + pwidth) * numscanlines); i++)
{
buffer[i].blue = 0;
buffer[i].green = 0;
buffer[i].red = 255;
}
}
/* Declare Windows procedure */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);
/* Make the class name into a global variable */
char szClassName[ ] = "CodeBlocksWindowsApp";
int WINAPI WinMain (HINSTANCE hThisInstance,
HINSTANCE hPrevInstance,
LPSTR lpszArgument,
int nCmdShow)
{
HWND hwnd; /* This is the handle for our window */
MSG messages; /* Here messages to the application are saved */
WNDCLASSEX wincl; /* Data structure for the windowclass */
/* The Window structure */
wincl.hInstance = hThisInstance;
wincl.lpszClassName = szClassName;
wincl.lpfnWndProc = WindowProcedure; /* This function is called by windows */
wincl.style = CS_DBLCLKS; /* Catch double-clicks */
wincl.cbSize = sizeof (WNDCLASSEX);
/* Use default icon and mouse-pointer */
wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
wincl.lpszMenuName = NULL; /* No menu */
wincl.cbClsExtra = 0; /* No extra bytes after the window class */
wincl.cbWndExtra = 0; /* structure or the window instance */
/* Use Windows's default colour as the background of the window */
wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;
/* Register the window class, and if it fails quit the program */
if (!RegisterClassEx (&wincl))
return 0;
/* The class is registered, let's create the program*/
hwnd = CreateWindowEx (
0, /* Extended possibilites for variation */
szClassName, /* Classname */
"framebuffer project for win32", /* Title Text */
WS_OVERLAPPEDWINDOW, /* default window */
CW_USEDEFAULT, /* Windows decides the position */
CW_USEDEFAULT, /* where the window ends up on the screen */
winx, /* The programs width */
winy, /* and height in pixels */
HWND_DESKTOP, /* The window is a child-window to desktop */
NULL, /* No menu */
hThisInstance, /* Program Instance handler */
NULL /* No Window Creation data */
);
/* Make the window visible on the screen */
ShowWindow (hwnd, nCmdShow);
/* Run the message loop. It will run until GetMessage() returns 0 */
while (GetMessage (&messages, NULL, 0, 0))
{
/* Translate virtual-key messages into character messages */
TranslateMessage(&messages);
/* Send message to WindowProcedure */
DispatchMessage(&messages);
}
/* The program return-value is 0 - The value that PostQuitMessage() gave */
return messages.wParam;
}
/* This function is called by the Windows function DispatchMessage() */
LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
DWORD result;
switch (message) /* handle the messages */
{
case WM_CREATE:
{
InvalidateRect(hwnd,0,0);
}break;
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hDC = BeginPaint(hwnd, &ps);
RECT client;
GetClientRect(hwnd,&client);
if(setscanline) {
scanlinewidth = client.right;
numscanlines = client.bottom;
setscanline = 0;
}
setframebuffer();
result = StretchDIBits(hDC,
0, 0,
client.right, client.bottom,
0, 0,
scanlinewidth, numscanlines,
buffer, &m_bi, DIB_RGB_COLORS, SRCCOPY);
if(result != winy)
{
//Drawing failed
DebugBreak();
}
EndPaint(hwnd, &ps);
}break;
case WM_KEYDOWN:{ int escpressed = GetAsyncKeyState(27); if(escpressed){PostQuitMessage(0);}}break;
case WM_DESTROY: {
PostQuitMessage (0); /* send a WM_QUIT to the message queue */
}break;
default: /* for messages that we don't deal with */
return DefWindowProc (hwnd, message, wParam, lParam);
}
return 0;
}
EDIT将setbuffer更改为WM_create中的setbuffer
编辑＃2改变了getdc以开始绘画。
编辑＃3将bpp更改为24并且还更改了WM_Create以设置所有位图属性
编辑＃4在你的帮助下，我找到了一个解决方案。我以前不懂扫描线填充，但现在我理解它完美。更新的代码在屏幕上打印纯色，您可以自己编译并更改颜色。感谢帮助我解决问题，现在我可以使用我自己的代码开始在屏幕上绘图。答案 0 :(得分：1)
我不确定所有这些问题是否仍然相关，因为我在开始编辑之前复制了代码。无论哪种方式，这都有效，你应该能够很容易地看到差异。
BITMAPINFO结构未正确初始化。
缓冲区创建错误，它太大而且未必正确对齐以用作位图。宽度需要填充到4的倍数，宽度为500，但宽度为499时，宽度可以为正。
我还添加了一项检查以确保StretchDIBits成功，并且如果失败则会将您转储到调试器中。如果您愿意，可以添加更合适的错误检查。
我还删除了一些评论，只是为了让事情尽可能短。
#include <windows.h>
const int winx = 500;
const int winy = 500;
const int winbpp = 3;
BITMAPINFO m_bi;
char* buffer = 0;
void setbuffer()
{
m_bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
m_bi.bmiHeader.biWidth = winx;
m_bi.bmiHeader.biHeight = winy;
m_bi.bmiHeader.biPlanes = 1;
m_bi.bmiHeader.biBitCount = 24;
m_bi.bmiHeader.biCompression = BI_RGB;
m_bi.bmiHeader.biSizeImage = 0;
m_bi.bmiHeader.biXPelsPerMeter = 100;
m_bi.bmiHeader.biYPelsPerMeter = 100;
m_bi.bmiHeader.biClrUsed = 0;
m_bi.bmiHeader.biClrImportant = 0;
size_t paddedWidth = (winx * 3 + 3) & ~3;
buffer = new char[paddedWidth * winy * winbpp];
for(int y = 0; y < winy; ++y)
{
for(int x = 0; x < winx; ++x)
{
for(int z = 0; z < 3; ++z)
{
buffer[y * paddedWidth + x * winbpp + z] = z * x;
}
}
}
}
LRESULT CALLBACK WindowProcedure(HWND, UINT, WPARAM, LPARAM);
char szClassName[] = "CodeBlocksWindowsApp";
int WINAPI WinMain(HINSTANCE hThisInstance,
HINSTANCE hPrevInstance,
LPSTR lpszArgument,
int nCmdShow)
{
HWND hwnd; /* This is the handle for our window */
MSG messages; /* Here messages to the application are saved */
WNDCLASSEX wincl; /* Data structure for the windowclass */
wincl.hInstance = hThisInstance;
wincl.lpszClassName = szClassName;
wincl.lpfnWndProc = WindowProcedure; /* This function is called by windows */
wincl.style = CS_DBLCLKS; /* Catch double-clicks */
wincl.cbSize = sizeof (WNDCLASSEX);
wincl.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wincl.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
wincl.hCursor = LoadCursor(NULL, IDC_ARROW);
wincl.lpszMenuName = NULL; /* No menu */
wincl.cbClsExtra = 0; /* No extra bytes after the window class */
wincl.cbWndExtra = 0; /* structure or the window instance */
wincl.hbrBackground = (HBRUSH)COLOR_BACKGROUND;
if(!RegisterClassEx(&wincl))
return 0;
hwnd = CreateWindowEx(
0, /* Extended possibilites for variation */
szClassName, /* Classname */
" project 1 ", /* Title Text */
WS_OVERLAPPEDWINDOW, /* default window */
CW_USEDEFAULT, /* Windows decides the position */
CW_USEDEFAULT, /* where the window ends up on the screen */
winx, /* The programs width */
winy, /* and height in pixels */
HWND_DESKTOP, /* The window is a child-window to desktop */
NULL, /* No menu */
hThisInstance, /* Program Instance handler */
NULL /* No Window Creation data */
);
ShowWindow(hwnd, nCmdShow);
while(GetMessage(&messages, NULL, 0, 0))
{
TranslateMessage(&messages);
DispatchMessage(&messages);
}
return messages.wParam;
}
LRESULT CALLBACK WindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
PAINTSTRUCT ps;
HDC hDC;
RECT client;
DWORD result;
switch(message) /* handle the messages */
{
case WM_CREATE:
setbuffer();
InvalidateRect(hwnd, NULL, TRUE);
break;
case WM_PAINT:
hDC = BeginPaint(hwnd, &ps);
GetClientRect(hwnd, &client);
result = StretchDIBits(hDC,
0, 0,
client.right, client.bottom,
0, 0,
winx, winy,
buffer, &m_bi, DIB_RGB_COLORS, SRCCOPY);
if(result != winy)
{
//Drawing failed
DebugBreak();
}
EndPaint(hwnd, &ps);
break;
case WM_DESTROY:
delete buffer;
PostQuitMessage(0); /* send a WM_QUIT to the message queue */
break;
default: /* for messages that we don't deal with */
return DefWindowProc(hwnd, message, wParam, lParam);
}
return 0;
}