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Fixed Windows preemptive scaling for HiDPI displays #4
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@Stehfyn
Stehfyn committed Nov 23, 2024
1 parent 42407ff commit 5005906
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Showing 2 changed files with 79 additions and 44 deletions.
71 changes: 46 additions & 25 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -24,42 +24,63 @@ msbuild /m /p:Configuration=Release .
## Concept
To enable dragging from some custom client area, our `WndProc` needs to return `HTCAPTION` when we know we're not over an imgui window. Therefore our `WndProc` needs to do those hittests with knowledge of those window rects:
```cpp
BorderlessWindow window; // Instantiate our borderless window
// ...
// (In Render Loop) Update imgui window rects for hit testing
{
// Get ScreenPos offset
ImGuiViewport* vp = ImGui::GetMainViewport();
HWND handle = (HWND)vp->PlatformHandle;
RECT r;
GetWindowRect(handle, &r);

// Only apply offset if Multi-viewports are not enabled
ImVec2 origin = { (float)r.left, (float)r.top };
if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
ImVec2 origin = { 0, 0 };
if (!(io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)) // Only apply offset if Multi-viewports are not enabled
{
origin = { 0, 0 };
RECT r;
GetWindowRect(hWnd, &r); // Get ScreenPos offset
origin = { (float)r.left, (float)r.top };
}

// Add imgui windows that aren't default rects/dockspaces/etc to client area whitelist, but explicitly include imgui demo
// EXAMPLE:
// Add imgui windows that aren't default rects/dockspaces/windows over viewports,
// etc. to client area whitelist, but explicitly include imgui demo
std::vector<RECT> WindowRects;
for (ImGuiWindow* window : ImGui::GetCurrentContext()->Windows)
{
if ((!(std::string(window->Name).find("Default") != std::string::npos) &&
(!(std::string(window->Name).find("Dock") != std::string::npos)) &&
(!(std::string(window->Name).find("Menu") != std::string::npos))) ||
(std::string(window->Name).find("Dear ImGui Demo") != std::string::npos))
{
ImVec2 pos = window->Pos;
ImVec2 size = window->Size;
RECT rect = { origin.x + pos.x,
origin.y + pos.y,
origin.x + (pos.x + size.x),
origin.y + (pos.y + size.y) };
WindowRects.push_back(rect);
if(window->Active)
{
if ((!(std::string(window->Name).find("Default") != std::string::npos) &&
(!(std::string(window->Name).find("Dock") != std::string::npos)) &&
(!(std::string(window->Name).find("Menu") != std::string::npos)) &&
(!(std::string(window->Name).find("WindowOverViewport") != std::string::npos))) ||
(std::string(window->Name).find("Dear ImGui Demo") != std::string::npos))
{
ImVec2 pos = window->Pos;
ImVec2 size = window->Size;
RECT rect = { (LONG)(origin.x + pos.x),
(LONG)(origin.y + pos.y),
(LONG)(origin.x + (pos.x + size.x)),
(LONG)(origin.y + (pos.y + size.y)) };

WindowRects.push_back(rect);
}
}
}
window.set_client_area(WindowRects);
g_ClientCustomClientArea = std::move(WindowRects);
}

// ... (In the WndProc) Update imgui window rects for hit testing
case WM_NCHITTEST: {
switch (result) {
case left: return HTLEFT;
case right: return HTRIGHT;
case top: return HTTOP;
case bottom: return HTBOTTOM;
case top | left: return HTTOPLEFT;
case top | right: return HTTOPRIGHT;
case bottom | left: return HTBOTTOMLEFT;
case bottom | right: return HTBOTTOMRIGHT;
case client: {
for (RECT rect : g_ClientCustomClientArea)
if (PtInRect(&rect, cursor)) return HTCLIENT;
return HTCAPTION;
}
default: return HTNOWHERE;
}
}
```

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52 changes: 33 additions & 19 deletions imgui-borderless-win32/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2,15 +2,17 @@ extern "C"{
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <windowsx.h>
#include <shellscalingapi.h>
#include <dwmapi.h>
#include <GL/gl.h>
#include "win32_window.h"
#include "swcadef.h" // Courtesy of https://gist.github.com/sylveon/9c199bb6684fe7dffcba1e3d383fb609
}

#pragma comment (lib, "shcore")
#pragma comment (lib, "dwmapi")
#pragma comment (lib, "opengl32")
#pragma comment (lib, "glu32")
#pragma comment (lib, "dwmapi")

#include "imgui.h"
#include "imgui_internal.h"
Expand Down Expand Up @@ -52,7 +54,9 @@ static void Hook_Renderer_DestroyWindow(ImGuiViewport* viewport);
static void Hook_Platform_RenderWindow(ImGuiViewport* viewport, void*);
static void Hook_Renderer_SwapBuffers(ImGuiViewport* viewport, void*);

int APIENTRY wWinMain(
int
APIENTRY
wWinMain(
_In_ HINSTANCE hInstance,
_In_opt_ HINSTANCE hPrevInstance,
_In_ LPWSTR lpCmdLine,
Expand All @@ -63,29 +67,37 @@ int APIENTRY wWinMain(
UNREFERENCED_PARAMETER(lpCmdLine);
UNREFERENCED_PARAMETER(nCmdShow);

ImGui_ImplWin32_EnableDpiAwareness();
win32_window_t w32Window = {0};
win32_window_create(&w32Window, 1080, 720, 0, ImGuiBorderlessWin32::windowed);
w32Window.msgHook = (win32_wndproc_hook_t)WndProcHook;
win32_window_t win32_window = { 0 };

if (!CreateDeviceWGL(w32Window.hWnd, &g_MainWindow))
HRESULT hr = SetProcessDpiAwareness(PROCESS_PER_MONITOR_DPI_AWARE); // This can be set by a program's manifest or its corresponding registry settings
if (E_INVALIDARG == hr)
{
CleanupDeviceWGL(w32Window.hWnd, &g_MainWindow);
::DestroyWindow(w32Window.hWnd);
::UnregisterClass(w32Window.tcClassName, GetModuleHandle(NULL));
return 1;
}

win32_window_create(&win32_window, 1080, 720, 0, ImGuiBorderlessWin32::windowed);
win32_window.msgHook = (win32_wndproc_hook_t)WndProcHook;

if (!CreateDeviceWGL(win32_window.hWnd, &g_MainWindow))
{
CleanupDeviceWGL(win32_window.hWnd, &g_MainWindow);
::DestroyWindow(win32_window.hWnd);
::UnregisterClass(win32_window.tcClassName, GetModuleHandle(NULL));
return 1;
}

wglMakeCurrent(g_MainWindow.hDC, g_hRC);

::ShowWindow(w32Window.hWnd, SW_SHOWDEFAULT);
::UpdateWindow(w32Window.hWnd);
::ShowWindow(win32_window.hWnd, SW_SHOWDEFAULT);
::UpdateWindow(win32_window.hWnd);

IMGUI_CHECKVERSION();
ImGui::CreateContext();
ImGuiIO& io = ImGui::GetIO();
io.ConfigFlags |= ImGuiConfigFlags_DockingEnable; // Enable Docking
io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable; // Enable Multi-Viewport / Platform Windows
io.ConfigFlags |= ImGuiConfigFlags_DpiEnableScaleFonts;
io.ConfigFlags |= ImGuiConfigFlags_DpiEnableScaleViewports;

// Setup Dear ImGui style
ImGui::StyleColorsDark();
Expand All @@ -98,8 +110,9 @@ int APIENTRY wWinMain(
}

// Setup Platform/Renderer backends
ImGui_ImplWin32_InitForOpenGL((void*)w32Window.hWnd);
ImGui_ImplWin32_InitForOpenGL((void*)win32_window.hWnd);
ImGui_ImplOpenGL3_Init();
ImGui_ImplWin32_EnableDpiAwareness();

if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
{
Expand All @@ -117,13 +130,14 @@ int APIENTRY wWinMain(
for(;;)
{
MSG msg; //- Pump message loop; break on WM_QUIT
if (!win32_window_pump_message_loop(&w32Window, &msg, FALSE)) break;
if (!win32_window_pump_message_loop(&win32_window, &msg, FALSE)) break;

//- Set the client render function callback if not done so already (So we can also render in sizemoves)
if (!g_ClientRenderFunction)
{
g_ClientRenderFunction = [io](HWND hWnd) {
g_ClientRenderFunction = [](HWND hWnd) {
static ImVec4 clear_color(.0f, .0f, .0f, .0f);
ImGuiIO& io = ImGui::GetIO();

ImGui_ImplOpenGL3_NewFrame();
ImGui_ImplWin32_NewFrame();
Expand Down Expand Up @@ -204,17 +218,17 @@ int APIENTRY wWinMain(
}

//- Then just make that client render call like usual
g_ClientRenderFunction(w32Window.hWnd);
g_ClientRenderFunction(win32_window.hWnd);
}

ImGui_ImplOpenGL3_Shutdown();
ImGui_ImplWin32_Shutdown();
ImGui::DestroyContext();

CleanupDeviceWGL(w32Window.hWnd, &g_MainWindow);
CleanupDeviceWGL(win32_window.hWnd, &g_MainWindow);
wglDeleteContext(g_hRC);
::DestroyWindow(w32Window.hWnd);
::UnregisterClass(w32Window.tcClassName, GetModuleHandle(NULL));
::DestroyWindow(win32_window.hWnd);
::UnregisterClass(win32_window.tcClassName, GetModuleHandle(NULL));

return 0;
} // main
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