滚动大图像故障的 MSDN 示例
MSDN example for scrolling large image malfunctions
简介和相关信息：
我正在尝试以自然大小绘制主 window 中的图像。目前我需要渲染 EMF。
通过互联网浏览后，我发现 this MSDN example。
问题：
我已经试过了，发现效果不佳。
用户右键单击后，如说明所述，桌面屏幕截图已正确绘制在主 window 中。
但是，当用户调整 window 的大小时，会出现如下图所示的绘画瑕疵。当用户稍微滚动然后调整 window.
大小时，也会出现以下效果
图片如下：
这是我第一次尝试滚动图像并使用滚动条，所以我真的很难找到解决方案。
问题：
How to fix article code to remove this visual artifact?
Can you recommend another example, like tutorial/code example/etc that
I can study?
Can you provide "verbal" instructions/guidelines that could help me?
为了使您的任务更轻松，这里是重现问题的最小代码。请注意，我只是 copy/pasted window 过程并为程序添加了最少的代码来创建工作演示：
#include <windows.h>
LRESULT CALLBACK WndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
HDC hdc;
PAINTSTRUCT ps;
SCROLLINFO si;
// These variables are required by BitBlt.
static HDC hdcWin; // window DC
static HDC hdcScreen; // DC for entire screen
static HDC hdcScreenCompat; // memory DC for screen
static HBITMAP hbmpCompat; // bitmap handle to old DC
static BITMAP bmp; // bitmap data structure
static BOOL fBlt; // TRUE if BitBlt occurred
static BOOL fScroll; // TRUE if scrolling occurred
static BOOL fSize; // TRUE if fBlt & WM_SIZE
// These variables are required for horizontal scrolling.
static int xMinScroll; // minimum horizontal scroll value
static int xCurrentScroll; // current horizontal scroll value
static int xMaxScroll; // maximum horizontal scroll value
// These variables are required for vertical scrolling.
static int yMinScroll; // minimum vertical scroll value
static int yCurrentScroll; // current vertical scroll value
static int yMaxScroll; // maximum vertical scroll value
switch (uMsg)
{
case WM_CREATE:
// Create a normal DC and a memory DC for the entire
// screen. The normal DC provides a snapshot of the
// screen contents. The memory DC keeps a copy of this
// snapshot in the associated bitmap.
hdcScreen = CreateDC(L"DISPLAY", (PCTSTR)NULL,
(PCTSTR)NULL, (CONST DEVMODE *) NULL);
hdcScreenCompat = CreateCompatibleDC(hdcScreen);
// Retrieve the metrics for the bitmap associated with the
// regular device context.
bmp.bmBitsPixel =
(BYTE)GetDeviceCaps(hdcScreen, BITSPIXEL);
bmp.bmPlanes = (BYTE)GetDeviceCaps(hdcScreen, PLANES);
bmp.bmWidth = GetDeviceCaps(hdcScreen, HORZRES);
bmp.bmHeight = GetDeviceCaps(hdcScreen, VERTRES);
// The width must be byte-aligned.
bmp.bmWidthBytes = ((bmp.bmWidth + 15) &~15) / 8;
// Create a bitmap for the compatible DC.
hbmpCompat = CreateBitmap(bmp.bmWidth, bmp.bmHeight,
bmp.bmPlanes, bmp.bmBitsPixel, (CONST VOID *) NULL);
// Select the bitmap for the compatible DC.
SelectObject(hdcScreenCompat, hbmpCompat);
// Initialize the flags.
fBlt = FALSE;
fScroll = FALSE;
fSize = FALSE;
// Initialize the horizontal scrolling variables.
xMinScroll = 0;
xCurrentScroll = 0;
xMaxScroll = 0;
// Initialize the vertical scrolling variables.
yMinScroll = 0;
yCurrentScroll = 0;
yMaxScroll = 0;
break;
case WM_SIZE:
{
int xNewSize;
int yNewSize;
xNewSize = LOWORD(lParam);
yNewSize = HIWORD(lParam);
if (fBlt)
fSize = TRUE;
// The horizontal scrolling range is defined by
// (bitmap_width) - (client_width). The current horizontal
// scroll value remains within the horizontal scrolling range.
xMaxScroll = max(bmp.bmWidth - xNewSize, 0);
xCurrentScroll = min(xCurrentScroll, xMaxScroll);
si.cbSize = sizeof(si);
si.fMask = SIF_RANGE | SIF_PAGE | SIF_POS;
si.nMin = xMinScroll;
si.nMax = bmp.bmWidth;
si.nPage = xNewSize;
si.nPos = xCurrentScroll;
SetScrollInfo(hwnd, SB_HORZ, &si, TRUE);
// The vertical scrolling range is defined by
// (bitmap_height) - (client_height). The current vertical
// scroll value remains within the vertical scrolling range.
yMaxScroll = max(bmp.bmHeight - yNewSize, 0);
yCurrentScroll = min(yCurrentScroll, yMaxScroll);
si.cbSize = sizeof(si);
si.fMask = SIF_RANGE | SIF_PAGE | SIF_POS;
si.nMin = yMinScroll;
si.nMax = bmp.bmHeight;
si.nPage = yNewSize;
si.nPos = yCurrentScroll;
SetScrollInfo(hwnd, SB_VERT, &si, TRUE);
break;
}
case WM_PAINT:
{
PRECT prect;
hdc = BeginPaint(hwnd, &ps);
// If the window has been resized and the user has
// captured the screen, use the following call to
// BitBlt to paint the window's client area.
if (fSize)
{
BitBlt(ps.hdc,
0, 0,
bmp.bmWidth, bmp.bmHeight,
hdcScreenCompat,
xCurrentScroll, yCurrentScroll,
SRCCOPY);
fSize = FALSE;
}
// If scrolling has occurred, use the following call to
// BitBlt to paint the invalid rectangle.
//
// The coordinates of this rectangle are specified in the
// RECT structure to which prect points.
//
// Note that it is necessary to increment the seventh
// argument (prect->left) by xCurrentScroll and the
// eighth argument (prect->top) by yCurrentScroll in
// order to map the correct pixels from the source bitmap.
if (fScroll)
{
prect = &ps.rcPaint;
BitBlt(ps.hdc,
prect->left, prect->top,
(prect->right - prect->left),
(prect->bottom - prect->top),
hdcScreenCompat,
prect->left + xCurrentScroll,
prect->top + yCurrentScroll,
SRCCOPY);
fScroll = FALSE;
}
EndPaint(hwnd, &ps);
break;
}
case WM_HSCROLL:
{
int xDelta; // xDelta = new_pos - current_pos
int xNewPos; // new position
int yDelta = 0;
switch (LOWORD(wParam))
{
// User clicked the scroll bar shaft left of the scroll box.
case SB_PAGEUP:
xNewPos = xCurrentScroll - 50;
break;
// User clicked the scroll bar shaft right of the scroll box.
case SB_PAGEDOWN:
xNewPos = xCurrentScroll + 50;
break;
// User clicked the left arrow.
case SB_LINEUP:
xNewPos = xCurrentScroll - 5;
break;
// User clicked the right arrow.
case SB_LINEDOWN:
xNewPos = xCurrentScroll + 5;
break;
// User dragged the scroll box.
case SB_THUMBPOSITION:
xNewPos = HIWORD(wParam);
break;
default:
xNewPos = xCurrentScroll;
}
// New position must be between 0 and the screen width.
xNewPos = max(0, xNewPos);
xNewPos = min(xMaxScroll, xNewPos);
// If the current position does not change, do not scroll.
if (xNewPos == xCurrentScroll)
break;
// Set the scroll flag to TRUE.
fScroll = TRUE;
// Determine the amount scrolled (in pixels).
xDelta = xNewPos - xCurrentScroll;
// Reset the current scroll position.
xCurrentScroll = xNewPos;
// Scroll the window. (The system repaints most of the
// client area when ScrollWindowEx is called; however, it is
// necessary to call UpdateWindow in order to repaint the
// rectangle of pixels that were invalidated.)
ScrollWindowEx(hwnd, -xDelta, -yDelta, (CONST RECT *) NULL,
(CONST RECT *) NULL, (HRGN)NULL, (PRECT)NULL,
SW_INVALIDATE);
UpdateWindow(hwnd);
// Reset the scroll bar.
si.cbSize = sizeof(si);
si.fMask = SIF_POS;
si.nPos = xCurrentScroll;
SetScrollInfo(hwnd, SB_HORZ, &si, TRUE);
break;
}
case WM_VSCROLL:
{
int xDelta = 0;
int yDelta; // yDelta = new_pos - current_pos
int yNewPos; // new position
switch (LOWORD(wParam))
{
// User clicked the scroll bar shaft above the scroll box.
case SB_PAGEUP:
yNewPos = yCurrentScroll - 50;
break;
// User clicked the scroll bar shaft below the scroll box.
case SB_PAGEDOWN:
yNewPos = yCurrentScroll + 50;
break;
// User clicked the top arrow.
case SB_LINEUP:
yNewPos = yCurrentScroll - 5;
break;
// User clicked the bottom arrow.
case SB_LINEDOWN:
yNewPos = yCurrentScroll + 5;
break;
// User dragged the scroll box.
case SB_THUMBPOSITION:
yNewPos = HIWORD(wParam);
break;
default:
yNewPos = yCurrentScroll;
}
// New position must be between 0 and the screen height.
yNewPos = max(0, yNewPos);
yNewPos = min(yMaxScroll, yNewPos);
// If the current position does not change, do not scroll.
if (yNewPos == yCurrentScroll)
break;
// Set the scroll flag to TRUE.
fScroll = TRUE;
// Determine the amount scrolled (in pixels).
yDelta = yNewPos - yCurrentScroll;
// Reset the current scroll position.
yCurrentScroll = yNewPos;
// Scroll the window. (The system repaints most of the
// client area when ScrollWindowEx is called; however, it is
// necessary to call UpdateWindow in order to repaint the
// rectangle of pixels that were invalidated.)
ScrollWindowEx(hwnd, -xDelta, -yDelta, (CONST RECT *) NULL,
(CONST RECT *) NULL, (HRGN)NULL, (PRECT)NULL,
SW_INVALIDATE);
UpdateWindow(hwnd);
// Reset the scroll bar.
si.cbSize = sizeof(si);
si.fMask = SIF_POS;
si.nPos = yCurrentScroll;
SetScrollInfo(hwnd, SB_VERT, &si, TRUE);
break;
}
case WM_RBUTTONDOWN:
{
// Get the compatible DC of the client area.
hdcWin = GetDC(hwnd);
// Fill the client area to remove any existing contents.
RECT rect;
GetClientRect(hwnd, &rect);
FillRect(hdcWin, &rect, (HBRUSH)(COLOR_WINDOW + 1));
// Copy the contents of the current screen
// into the compatible DC.
BitBlt(hdcScreenCompat, 0, 0, bmp.bmWidth,
bmp.bmHeight, hdcScreen, 0, 0, SRCCOPY);
// Copy the compatible DC to the client area.
BitBlt(hdcWin, 0, 0, bmp.bmWidth, bmp.bmHeight,
hdcScreenCompat, 0, 0, SRCCOPY);
ReleaseDC(hwnd, hdcWin);
fBlt = TRUE;
break;
}
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
// WinMain
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine,
int nCmdShow)
{
WNDCLASSEX wc;
HWND hwnd;
MSG Msg;
// register main window class
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = 0;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(hInstance, IDI_APPLICATION);
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = GetSysColorBrush(COLOR_WINDOW);
wc.lpszMenuName = NULL;
wc.lpszClassName = L"Main_Window";
wc.hIconSm = LoadIcon(hInstance, IDI_APPLICATION);
if (!RegisterClassEx(&wc))
{
MessageBox(NULL, L"Window Registration Failed!", L"Error!",
MB_ICONEXCLAMATION | MB_OK);
return 0;
}
// create main window
hwnd = CreateWindowEx(0, L"Main_Window", L"Scrollable map",
WS_OVERLAPPEDWINDOW | WS_VSCROLL | WS_HSCROLL,
50, 50, 400, 400, NULL, NULL, hInstance, 0);
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
while (GetMessage(&Msg, NULL, 0, 0) > 0)
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
return Msg.wParam;
}
根据您的描述，问题似乎很简单，就是您的 window 在调整大小时没有重新绘制。
在 window 放大时使用 InvalidateRect 强制重新绘制新发现的区域，或者在 [=] 上设置 CS_VREDRAW 和 CS_HREDRAW 样式18=] class 自动重绘客户区。
简介和相关信息：
我正在尝试以自然大小绘制主 window 中的图像。目前我需要渲染 EMF。
通过互联网浏览后，我发现 this MSDN example。
问题：
我已经试过了，发现效果不佳。
用户右键单击后，如说明所述，桌面屏幕截图已正确绘制在主 window 中。
但是，当用户调整 window 的大小时，会出现如下图所示的绘画瑕疵。当用户稍微滚动然后调整 window.
大小时，也会出现以下效果图片如下：
这是我第一次尝试滚动图像并使用滚动条，所以我真的很难找到解决方案。
问题：
How to fix article code to remove this visual artifact?
Can you recommend another example, like tutorial/code example/etc that I can study?
Can you provide "verbal" instructions/guidelines that could help me?
为了使您的任务更轻松，这里是重现问题的最小代码。请注意，我只是 copy/pasted window 过程并为程序添加了最少的代码来创建工作演示：
#include <windows.h>
LRESULT CALLBACK WndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
HDC hdc;
PAINTSTRUCT ps;
SCROLLINFO si;
// These variables are required by BitBlt.
static HDC hdcWin; // window DC
static HDC hdcScreen; // DC for entire screen
static HDC hdcScreenCompat; // memory DC for screen
static HBITMAP hbmpCompat; // bitmap handle to old DC
static BITMAP bmp; // bitmap data structure
static BOOL fBlt; // TRUE if BitBlt occurred
static BOOL fScroll; // TRUE if scrolling occurred
static BOOL fSize; // TRUE if fBlt & WM_SIZE
// These variables are required for horizontal scrolling.
static int xMinScroll; // minimum horizontal scroll value
static int xCurrentScroll; // current horizontal scroll value
static int xMaxScroll; // maximum horizontal scroll value
// These variables are required for vertical scrolling.
static int yMinScroll; // minimum vertical scroll value
static int yCurrentScroll; // current vertical scroll value
static int yMaxScroll; // maximum vertical scroll value
switch (uMsg)
{
case WM_CREATE:
// Create a normal DC and a memory DC for the entire
// screen. The normal DC provides a snapshot of the
// screen contents. The memory DC keeps a copy of this
// snapshot in the associated bitmap.
hdcScreen = CreateDC(L"DISPLAY", (PCTSTR)NULL,
(PCTSTR)NULL, (CONST DEVMODE *) NULL);
hdcScreenCompat = CreateCompatibleDC(hdcScreen);
// Retrieve the metrics for the bitmap associated with the
// regular device context.
bmp.bmBitsPixel =
(BYTE)GetDeviceCaps(hdcScreen, BITSPIXEL);
bmp.bmPlanes = (BYTE)GetDeviceCaps(hdcScreen, PLANES);
bmp.bmWidth = GetDeviceCaps(hdcScreen, HORZRES);
bmp.bmHeight = GetDeviceCaps(hdcScreen, VERTRES);
// The width must be byte-aligned.
bmp.bmWidthBytes = ((bmp.bmWidth + 15) &~15) / 8;
// Create a bitmap for the compatible DC.
hbmpCompat = CreateBitmap(bmp.bmWidth, bmp.bmHeight,
bmp.bmPlanes, bmp.bmBitsPixel, (CONST VOID *) NULL);
// Select the bitmap for the compatible DC.
SelectObject(hdcScreenCompat, hbmpCompat);
// Initialize the flags.
fBlt = FALSE;
fScroll = FALSE;
fSize = FALSE;
// Initialize the horizontal scrolling variables.
xMinScroll = 0;
xCurrentScroll = 0;
xMaxScroll = 0;
// Initialize the vertical scrolling variables.
yMinScroll = 0;
yCurrentScroll = 0;
yMaxScroll = 0;
break;
case WM_SIZE:
{
int xNewSize;
int yNewSize;
xNewSize = LOWORD(lParam);
yNewSize = HIWORD(lParam);
if (fBlt)
fSize = TRUE;
// The horizontal scrolling range is defined by
// (bitmap_width) - (client_width). The current horizontal
// scroll value remains within the horizontal scrolling range.
xMaxScroll = max(bmp.bmWidth - xNewSize, 0);
xCurrentScroll = min(xCurrentScroll, xMaxScroll);
si.cbSize = sizeof(si);
si.fMask = SIF_RANGE | SIF_PAGE | SIF_POS;
si.nMin = xMinScroll;
si.nMax = bmp.bmWidth;
si.nPage = xNewSize;
si.nPos = xCurrentScroll;
SetScrollInfo(hwnd, SB_HORZ, &si, TRUE);
// The vertical scrolling range is defined by
// (bitmap_height) - (client_height). The current vertical
// scroll value remains within the vertical scrolling range.
yMaxScroll = max(bmp.bmHeight - yNewSize, 0);
yCurrentScroll = min(yCurrentScroll, yMaxScroll);
si.cbSize = sizeof(si);
si.fMask = SIF_RANGE | SIF_PAGE | SIF_POS;
si.nMin = yMinScroll;
si.nMax = bmp.bmHeight;
si.nPage = yNewSize;
si.nPos = yCurrentScroll;
SetScrollInfo(hwnd, SB_VERT, &si, TRUE);
break;
}
case WM_PAINT:
{
PRECT prect;
hdc = BeginPaint(hwnd, &ps);
// If the window has been resized and the user has
// captured the screen, use the following call to
// BitBlt to paint the window's client area.
if (fSize)
{
BitBlt(ps.hdc,
0, 0,
bmp.bmWidth, bmp.bmHeight,
hdcScreenCompat,
xCurrentScroll, yCurrentScroll,
SRCCOPY);
fSize = FALSE;
}
// If scrolling has occurred, use the following call to
// BitBlt to paint the invalid rectangle.
//
// The coordinates of this rectangle are specified in the
// RECT structure to which prect points.
//
// Note that it is necessary to increment the seventh
// argument (prect->left) by xCurrentScroll and the
// eighth argument (prect->top) by yCurrentScroll in
// order to map the correct pixels from the source bitmap.
if (fScroll)
{
prect = &ps.rcPaint;
BitBlt(ps.hdc,
prect->left, prect->top,
(prect->right - prect->left),
(prect->bottom - prect->top),
hdcScreenCompat,
prect->left + xCurrentScroll,
prect->top + yCurrentScroll,
SRCCOPY);
fScroll = FALSE;
}
EndPaint(hwnd, &ps);
break;
}
case WM_HSCROLL:
{
int xDelta; // xDelta = new_pos - current_pos
int xNewPos; // new position
int yDelta = 0;
switch (LOWORD(wParam))
{
// User clicked the scroll bar shaft left of the scroll box.
case SB_PAGEUP:
xNewPos = xCurrentScroll - 50;
break;
// User clicked the scroll bar shaft right of the scroll box.
case SB_PAGEDOWN:
xNewPos = xCurrentScroll + 50;
break;
// User clicked the left arrow.
case SB_LINEUP:
xNewPos = xCurrentScroll - 5;
break;
// User clicked the right arrow.
case SB_LINEDOWN:
xNewPos = xCurrentScroll + 5;
break;
// User dragged the scroll box.
case SB_THUMBPOSITION:
xNewPos = HIWORD(wParam);
break;
default:
xNewPos = xCurrentScroll;
}
// New position must be between 0 and the screen width.
xNewPos = max(0, xNewPos);
xNewPos = min(xMaxScroll, xNewPos);
// If the current position does not change, do not scroll.
if (xNewPos == xCurrentScroll)
break;
// Set the scroll flag to TRUE.
fScroll = TRUE;
// Determine the amount scrolled (in pixels).
xDelta = xNewPos - xCurrentScroll;
// Reset the current scroll position.
xCurrentScroll = xNewPos;
// Scroll the window. (The system repaints most of the
// client area when ScrollWindowEx is called; however, it is
// necessary to call UpdateWindow in order to repaint the
// rectangle of pixels that were invalidated.)
ScrollWindowEx(hwnd, -xDelta, -yDelta, (CONST RECT *) NULL,
(CONST RECT *) NULL, (HRGN)NULL, (PRECT)NULL,
SW_INVALIDATE);
UpdateWindow(hwnd);
// Reset the scroll bar.
si.cbSize = sizeof(si);
si.fMask = SIF_POS;
si.nPos = xCurrentScroll;
SetScrollInfo(hwnd, SB_HORZ, &si, TRUE);
break;
}
case WM_VSCROLL:
{
int xDelta = 0;
int yDelta; // yDelta = new_pos - current_pos
int yNewPos; // new position
switch (LOWORD(wParam))
{
// User clicked the scroll bar shaft above the scroll box.
case SB_PAGEUP:
yNewPos = yCurrentScroll - 50;
break;
// User clicked the scroll bar shaft below the scroll box.
case SB_PAGEDOWN:
yNewPos = yCurrentScroll + 50;
break;
// User clicked the top arrow.
case SB_LINEUP:
yNewPos = yCurrentScroll - 5;
break;
// User clicked the bottom arrow.
case SB_LINEDOWN:
yNewPos = yCurrentScroll + 5;
break;
// User dragged the scroll box.
case SB_THUMBPOSITION:
yNewPos = HIWORD(wParam);
break;
default:
yNewPos = yCurrentScroll;
}
// New position must be between 0 and the screen height.
yNewPos = max(0, yNewPos);
yNewPos = min(yMaxScroll, yNewPos);
// If the current position does not change, do not scroll.
if (yNewPos == yCurrentScroll)
break;
// Set the scroll flag to TRUE.
fScroll = TRUE;
// Determine the amount scrolled (in pixels).
yDelta = yNewPos - yCurrentScroll;
// Reset the current scroll position.
yCurrentScroll = yNewPos;
// Scroll the window. (The system repaints most of the
// client area when ScrollWindowEx is called; however, it is
// necessary to call UpdateWindow in order to repaint the
// rectangle of pixels that were invalidated.)
ScrollWindowEx(hwnd, -xDelta, -yDelta, (CONST RECT *) NULL,
(CONST RECT *) NULL, (HRGN)NULL, (PRECT)NULL,
SW_INVALIDATE);
UpdateWindow(hwnd);
// Reset the scroll bar.
si.cbSize = sizeof(si);
si.fMask = SIF_POS;
si.nPos = yCurrentScroll;
SetScrollInfo(hwnd, SB_VERT, &si, TRUE);
break;
}
case WM_RBUTTONDOWN:
{
// Get the compatible DC of the client area.
hdcWin = GetDC(hwnd);
// Fill the client area to remove any existing contents.
RECT rect;
GetClientRect(hwnd, &rect);
FillRect(hdcWin, &rect, (HBRUSH)(COLOR_WINDOW + 1));
// Copy the contents of the current screen
// into the compatible DC.
BitBlt(hdcScreenCompat, 0, 0, bmp.bmWidth,
bmp.bmHeight, hdcScreen, 0, 0, SRCCOPY);
// Copy the compatible DC to the client area.
BitBlt(hdcWin, 0, 0, bmp.bmWidth, bmp.bmHeight,
hdcScreenCompat, 0, 0, SRCCOPY);
ReleaseDC(hwnd, hdcWin);
fBlt = TRUE;
break;
}
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
// WinMain
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine,
int nCmdShow)
{
WNDCLASSEX wc;
HWND hwnd;
MSG Msg;
// register main window class
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = 0;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(hInstance, IDI_APPLICATION);
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = GetSysColorBrush(COLOR_WINDOW);
wc.lpszMenuName = NULL;
wc.lpszClassName = L"Main_Window";
wc.hIconSm = LoadIcon(hInstance, IDI_APPLICATION);
if (!RegisterClassEx(&wc))
{
MessageBox(NULL, L"Window Registration Failed!", L"Error!",
MB_ICONEXCLAMATION | MB_OK);
return 0;
}
// create main window
hwnd = CreateWindowEx(0, L"Main_Window", L"Scrollable map",
WS_OVERLAPPEDWINDOW | WS_VSCROLL | WS_HSCROLL,
50, 50, 400, 400, NULL, NULL, hInstance, 0);
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
while (GetMessage(&Msg, NULL, 0, 0) > 0)
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
return Msg.wParam;
}
根据您的描述，问题似乎很简单，就是您的 window 在调整大小时没有重新绘制。
在 window 放大时使用 InvalidateRect 强制重新绘制新发现的区域，或者在 [=] 上设置 CS_VREDRAW 和 CS_HREDRAW 样式18=] class 自动重绘客户区。