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Fix ImGui DPI scaling by using DPI-scaled fonts and removing inverse global scaling #261

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Fix ImGui DPI scaling by using DPI-scaled fonts and removing inverse global scaling #261

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6be5a35
Fix font size
alxbilger Jan 13, 2026
0c1717d
refactoring
alxbilger Jan 13, 2026
c36a900
reload fonts when content scale change
alxbilger Jan 13, 2026
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1 change: 1 addition & 0 deletions SofaGLFW/src/SofaGLFW/BaseGUIEngine.h
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Expand Up @@ -50,6 +50,7 @@ class BaseGUIEngine
virtual sofa::type::Vec2i getFrameBufferPixels(std::vector<uint8_t>& pixels) = 0;
virtual void openFile(SofaGLFWBaseGUI* baseGUI, sofa::core::sptr<sofa::simulation::Node>& groot) {};
virtual void loadFile(SofaGLFWBaseGUI* baseGUI, sofa::core::sptr<sofa::simulation::Node>& groot, std::string filePathName, bool reload = false) {};
virtual void contentScaleChanged(float xscale, float yscale) {}
};

} // namespace sofaglfw
10 changes: 10 additions & 0 deletions SofaGLFW/src/SofaGLFW/SofaGLFWBaseGUI.cpp
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Expand Up @@ -305,6 +305,7 @@ bool SofaGLFWBaseGUI::createWindow(int width, int height, const char* title, boo
glfwSetCursorEnterCallback(glfwWindow, cursor_enter_callback);
glfwSetMonitorCallback(monitor_callback);
glfwSetCharCallback(glfwWindow, character_callback);
glfwSetWindowContentScaleCallback(glfwWindow, content_scale_callback);

glfwSetWindowUserPointer(glfwWindow, this);

Expand Down Expand Up @@ -995,6 +996,15 @@ void SofaGLFWBaseGUI::translateToViewportCoordinates (SofaGLFWBaseGUI* gui,doubl
gui->m_translatedCursorPos = Vec2d{xpos, ypos} - (gui->m_viewPortPosition - gui->m_windowPosition);
}

void SofaGLFWBaseGUI::content_scale_callback(GLFWwindow *window, float xscale, float yscale)
{
auto currentGUI = s_mapGUIs[window];
if (currentGUI && currentGUI->m_guiEngine)
{
currentGUI->m_guiEngine->contentScaleChanged(xscale, yscale);
}
}

void SofaGLFWBaseGUI::cursor_position_callback(GLFWwindow* window, double xpos, double ypos)
{
auto currentGUI = s_mapGUIs.find(window);
Expand Down
1 change: 1 addition & 0 deletions SofaGLFW/src/SofaGLFW/SofaGLFWBaseGUI.h
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Expand Up @@ -156,6 +156,7 @@ class SOFAGLFW_API SofaGLFWBaseGUI : public BaseViewer
static void window_pos_callback(GLFWwindow* window, int xpos, int ypos);
static int handleArrowKeys(int key);
static void translateToViewportCoordinates (SofaGLFWBaseGUI* gui,double xpos, double ypos);
static void content_scale_callback(GLFWwindow* window, float xscale, float yscale);

void makeCurrentContext(GLFWwindow* sofaWindow);
void runStep();
Expand Down
193 changes: 107 additions & 86 deletions SofaImGui/src/SofaImGui/ImGuiGUIEngine.cpp
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Expand Up @@ -166,85 +166,14 @@ void ImGuiGUIEngine::initBackend(GLFWwindow* glfwWindow)
ImGui_ImplOpenGL3_Init(nullptr);
#endif // SOFAIMGUI_FORCE_OPENGL2 == 1

GLFWmonitor* windowMonitor = glfwGetWindowMonitor(glfwWindow);
if (!windowMonitor)
float yscale { 1.f };
if (GLFWmonitor* windowMonitor = findMyMonitor(glfwWindow))
{
windowMonitor = glfwGetPrimaryMonitor();
}
if (windowMonitor)
{
float xscale{}, yscale{};
float xscale{};
glfwGetMonitorContentScale(windowMonitor, &xscale, &yscale);

ImGuiIO& io = ImGui::GetIO();

io.Fonts->AddFontFromMemoryCompressedTTF(ROBOTO_MEDIUM_compressed_data, ROBOTO_MEDIUM_compressed_size, 16 * yscale);

ImFontConfig config;
config.MergeMode = true;
config.GlyphMinAdvanceX = 16.0f; // Use if you want to make the icon monospaced
static const ImWchar icon_ranges[] = { ICON_MIN_FA, ICON_MAX_FA, 0 };
io.Fonts->AddFontFromMemoryCompressedTTF(FA_REGULAR_400_compressed_data, FA_REGULAR_400_compressed_size, 16 * yscale, &config, icon_ranges);
io.Fonts->AddFontFromMemoryCompressedTTF(FA_SOLID_900_compressed_data, FA_SOLID_900_compressed_size, 16 * yscale, &config, icon_ranges);

// restore the global scale stored in the Settings ini file
const float globalScale = static_cast<float>(ini.GetDoubleValue("Visualization", "globalScale", 1.0));
this->setScale(globalScale, windowMonitor);
}

// restore window settings if set
const bool rememberWindowPosition = ini.GetBoolValue("Window", "rememberWindowPosition", true);
if(rememberWindowPosition)
{
if(ini.KeyExists("Window", "windowPosX") && ini.KeyExists("Window", "windowPosY"))
{
const long windowPosX = ini.GetLongValue("Window", "windowPosX");
const long windowPosY = ini.GetLongValue("Window", "windowPosY");

int monitorCount;
GLFWmonitor** monitors = glfwGetMonitors(&monitorCount);

bool foundValidMonitor = false;
for (int i = 0; i < monitorCount; ++i)
{
if (GLFWmonitor* monitor = monitors[i])
{
//retrieve the work area of the monitor in the whole desktop space, in screen coordinates
int monitorXPos{0}, monitorYPos{0}, monitorWidth{0}, monitorHeight{0};
glfwGetMonitorWorkarea(monitor, &monitorXPos, &monitorYPos, &monitorWidth, &monitorHeight);
if(!monitorWidth || !monitorHeight)
{
msg_error("ImGuiGUIEngine") << "Unknown error while trying to fetch the monitor information.";
}
else
{
constexpr long margin = 5; // avoid the case where the window is positioned on the border of the monitor (almost invisible/non-selectable)

if(windowPosX >= (monitorXPos) &&
windowPosX <= (monitorXPos + monitorWidth-margin) &&
windowPosY >= (monitorYPos) &&
windowPosY <= (monitorYPos + monitorHeight-margin))
{
glfwSetWindowPos(glfwWindow, static_cast<int>(windowPosX), static_cast<int>(windowPosY));
foundValidMonitor = true;
break;
}

}
}
}

if (!foundValidMonitor)
{
msg_error("ImGuiGUIEngine") << "The window position from settings is invalid for any monitor.";
}
}
else
{
msg_error("ImGuiGUIEngine") << "Cannot set window position from settings.";
}

}
loadFont(yscale);

const bool rememberWindowSize = ini.GetBoolValue("Window", "rememberWindowSize", true);
if(rememberWindowSize)
Expand Down Expand Up @@ -805,6 +734,103 @@ void ImGuiGUIEngine::resetView(ImGuiID dockspace_id, const char* windowNameScene
firstRunState.setState(true);// Mark first run as complete
}

GLFWmonitor* ImGuiGUIEngine::findMyMonitor(GLFWwindow* glfwWindow)
{
GLFWmonitor* foundMonitor { nullptr };

const bool rememberWindowPosition = ini.GetBoolValue("Window", "rememberWindowPosition", true);
if(rememberWindowPosition)
{
if(ini.KeyExists("Window", "windowPosX") && ini.KeyExists("Window", "windowPosY"))
{
const long windowPosX = ini.GetLongValue("Window", "windowPosX");
const long windowPosY = ini.GetLongValue("Window", "windowPosY");

int monitorCount;
GLFWmonitor** monitors = glfwGetMonitors(&monitorCount);

bool foundValidMonitor = false;
for (int i = 0; i < monitorCount; ++i)
{
if (GLFWmonitor* monitor = monitors[i])
{
//retrieve the work area of the monitor in the whole desktop space, in screen coordinates
int monitorXPos{0}, monitorYPos{0}, monitorWidth{0}, monitorHeight{0};
glfwGetMonitorWorkarea(monitor, &monitorXPos, &monitorYPos, &monitorWidth, &monitorHeight);
if(!monitorWidth || !monitorHeight)
{
msg_error("ImGuiGUIEngine") << "Unknown error while trying to fetch the monitor information.";
}
else
{
constexpr long margin = 5; // avoid the case where the window is positioned on the border of the monitor (almost invisible/non-selectable)

if(windowPosX >= (monitorXPos) &&
windowPosX <= (monitorXPos + monitorWidth-margin) &&
windowPosY >= (monitorYPos) &&
windowPosY <= (monitorYPos + monitorHeight-margin))
{
glfwSetWindowPos(glfwWindow, static_cast<int>(windowPosX), static_cast<int>(windowPosY));
foundValidMonitor = true;
foundMonitor = monitor;
break;
}

}
}
}

if (!foundValidMonitor)
{
msg_error("ImGuiGUIEngine") << "The window position from settings is invalid for any monitor.";
}
}
else
{
msg_error("ImGuiGUIEngine") << "Cannot set window position from settings.";
}
}

if (!foundMonitor)
{
foundMonitor = glfwGetPrimaryMonitor();
}

return foundMonitor;
}

void ImGuiGUIEngine::loadFont(float yscale)
{
constexpr float fontSize = 16.f;

ImGuiIO& io = ImGui::GetIO();
io.Fonts->Clear();

io.Fonts->AddFontFromMemoryCompressedTTF(ROBOTO_MEDIUM_compressed_data, ROBOTO_MEDIUM_compressed_size, fontSize * yscale);

ImFontConfig config;
config.MergeMode = true;
config.GlyphMinAdvanceX = fontSize * yscale;

static const ImWchar icon_ranges[] = { ICON_MIN_FA, ICON_MAX_FA, 0 };
io.Fonts->AddFontFromMemoryCompressedTTF(FA_REGULAR_400_compressed_data, FA_REGULAR_400_compressed_size, fontSize * yscale, &config, icon_ranges);
io.Fonts->AddFontFromMemoryCompressedTTF(FA_SOLID_900_compressed_data, FA_SOLID_900_compressed_size, fontSize * yscale, &config, icon_ranges);

// restore the global scale stored in the Settings ini file
const float globalScale = static_cast<float>(ini.GetDoubleValue("Visualization", "globalScale", 1.0));
this->setScale(globalScale);

io.Fonts->Build();

#if SOFAIMGUI_FORCE_OPENGL2 == 1
ImGui_ImplOpenGL2_DestroyFontsTexture();
ImGui_ImplOpenGL2_CreateFontsTexture();
#else
ImGui_ImplOpenGL3_DestroyFontsTexture();
ImGui_ImplOpenGL3_CreateFontsTexture();
#endif
}

void ImGuiGUIEngine::beforeDraw(GLFWwindow*)
{

Expand Down Expand Up @@ -884,20 +910,15 @@ bool ImGuiGUIEngine::dispatchMouseEvents()
return !ImGui::GetIO().WantCaptureMouse || isMouseOnViewport;
}

void ImGuiGUIEngine::contentScaleChanged(float xscale, float yscale)
{
loadFont(yscale);
}

void ImGuiGUIEngine::setScale(double globalScale, GLFWmonitor* monitor)
void ImGuiGUIEngine::setScale(float globalScale)
{
if(!monitor)
{
monitor = glfwGetPrimaryMonitor();
}

ImGuiIO& io = ImGui::GetIO();

float xscale{}, yscale{};
glfwGetMonitorContentScale(monitor, &xscale, &yscale);

io.FontGlobalScale = globalScale / yscale;
io.FontGlobalScale = globalScale;
}

type::Vec2i ImGuiGUIEngine::getFrameBufferPixels(std::vector<uint8_t>& pixels)
Expand Down
5 changes: 4 additions & 1 deletion SofaImGui/src/SofaImGui/ImGuiGUIEngine.h
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Expand Up @@ -60,9 +60,10 @@ class ImGuiGUIEngine : public sofaglfw::BaseGUIEngine
void terminate() override;
bool isTerminated() const override { return m_isTerminated; };
bool dispatchMouseEvents() override;
void contentScaleChanged(float xscale, float yscale) override;

// apply global scale on the given monitor (if null, it will fetch the main monitor)
void setScale(double globalScale, GLFWmonitor* monitor);
void setScale(float globalScale);

// reset counters
void resetCounter() override;
Expand All @@ -85,6 +86,8 @@ class ImGuiGUIEngine : public sofaglfw::BaseGUIEngine
bool isMouseOnViewport { false };
CSimpleIniA ini;
void resetView(ImGuiID dockspace_id, const char *windowNameSceneGraph, const char *winNameSelectionDescription, const char *windowNameLog, const char *windowNameViewport) ;
GLFWmonitor* findMyMonitor(GLFWwindow* glfwWindow);
void loadFont(float yscale);

// WindowState members
windows::WindowState winManagerProfiler;
Expand Down
2 changes: 1 addition & 1 deletion SofaImGui/src/SofaImGui/windows/Settings.cpp
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Expand Up @@ -74,7 +74,7 @@ namespace windows
constexpr float MAX_SCALE = 2.0f;
ImGui::DragFloat("global scale", &globalScale, 0.005f, MIN_SCALE, MAX_SCALE, "%.2f", ImGuiSliderFlags_AlwaysClamp); // Scale everything

engine->setScale(globalScale, nullptr);
engine->setScale(globalScale);

ini.SetDoubleValue("Visualization", "globalScale", static_cast<double>(globalScale));
if (std::abs(iniGlobalScale - globalScale) > 0.005f)
Expand Down
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