Implement per-screen DPI on Windows, DPI change event, wxDialog & wxFrame mixin base classes

src/slic3r/GUI/GUI_App.cpp

@@ -76,6 +76,24 @@ wxString file_wildcards(FileType file_type, const std::string &custom_extension)
 
 static std::string libslic3r_translate_callback(const char *s) { return wxGetTranslation(wxString(s, wxConvUTF8)).utf8_str().data(); }
 
+static void register_dpi_event()
+{
+#ifdef WIN32
+    enum { WM_DPICHANGED_ = 0x02e0 };
+
+    wxWindow::MSWRegisterMessageHandler(WM_DPICHANGED_, [](wxWindow *win, WXUINT nMsg, WXWPARAM wParam, WXLPARAM lParam) {
+        const int dpi = wParam & 0xffff;
+        const auto rect = reinterpret_cast<PRECT>(lParam);
+        const wxRect wxrect(wxPoint(rect->top, rect->left), wxPoint(rect->bottom, rect->right));
+
+        DpiChangedEvent evt(EVT_DPI_CHANGED, dpi, wxrect);
+        win->GetEventHandler()->AddPendingEvent(evt);
+
+        return true;
+    });
+#endif
+}
+
 IMPLEMENT_APP(GUI_App)
 
 GUI_App::GUI_App()
@@ -149,6 +167,8 @@ bool GUI_App::OnInit()
         show_error(nullptr, ex.what());
 	}
 
+    register_dpi_event();
+
     // Let the libslic3r know the callback, which will translate messages on demand.
     Slic3r::I18N::set_translate_callback(libslic3r_translate_callback);
 

src/slic3r/GUI/GUI_Utils.cpp

@@ -4,9 +4,14 @@
 #include <boost/lexical_cast.hpp>
 #include <boost/format.hpp>
 
+#ifdef _WIN32
+#include <Windows.h>
+#endif
+
 #include <wx/toplevel.h>
 #include <wx/sizer.h>
 #include <wx/checkbox.h>
+#include <wx/dcclient.h>
 
 #include "libslic3r/Config.hpp"
 
@@ -48,6 +53,64 @@ void on_window_geometry(wxTopLevelWindow *tlw, std::function<void()> callback)
 #endif
 }
 
+wxDEFINE_EVENT(EVT_DPI_CHANGED, DpiChangedEvent);
+
+#ifdef _WIN32
+template<class F> typename F::FN winapi_get_function(const wchar_t *dll, const char *fn_name) {
+    static HINSTANCE dll_handle = LoadLibraryExW(dll, nullptr, 0);
+
+    if (dll_handle == nullptr) { return nullptr; }
+    return (F::FN)GetProcAddress(dll_handle, fn_name);
+}
+#endif
+
+int get_dpi_for_window(wxWindow *window)
+{
+#ifdef _WIN32
+    enum MONITOR_DPI_TYPE_ {
+        // This enum is inlined here to avoid build-time dependency
+        MDT_EFFECTIVE_DPI_ = 0,
+        MDT_ANGULAR_DPI_ = 1,
+        MDT_RAW_DPI_ = 2,
+        MDT_DEFAULT_ = MDT_EFFECTIVE_DPI_,
+    };
+
+    // Need strong types for winapi_get_function() to work
+    struct GetDpiForWindow_t { typedef HRESULT (WINAPI *FN)(HWND hwnd); };
+    struct GetDpiForMonitor_t { typedef HRESULT (WINAPI *FN)(HMONITOR hmonitor, MONITOR_DPI_TYPE_ dpiType, UINT *dpiX, UINT *dpiY); };
+
+    static auto GetDpiForWindow_fn = winapi_get_function<GetDpiForWindow_t>(L"User32.dll", "GetDpiForWindow");
+    static auto GetDpiForMonitor_fn = winapi_get_function<GetDpiForMonitor_t>(L"Shcore.dll", "GetDpiForMonitor");
+
+    const HWND hwnd = window->GetHandle();
+
+    if (GetDpiForWindow_fn != nullptr) {
+        // We're on Windows 10, we have per-screen DPI settings
+        return GetDpiForWindow_fn(hwnd);
+    } else if (GetDpiForMonitor_fn != nullptr) {
+        // We're on Windows 8.1, we have per-system DPI
+        // Note: MonitorFromWindow() is available on all Windows.
+
+        const HMONITOR monitor = MonitorFromWindow(hwnd, MONITOR_DEFAULTTONEAREST);
+        UINT dpiX;
+        UINT dpiY;
+        return GetDpiForMonitor_fn(monitor, MDT_EFFECTIVE_DPI_, &dpiX, &dpiY) == S_OK ? dpiX : DPI_DEFAULT;
+    } else {
+        // We're on Windows earlier than 8.1, use DC
+
+        const HDC hdc = GetDC(hwnd);
+        if (hdc == NULL) { return DPI_DEFAULT; }
+        return GetDeviceCaps(hdc, LOGPIXELSX);
+    }
+#elif defined __linux__
+    // TODO
+    return DPI_DEFAULT;
+#elif defined __APPLE__
+    // TODO
+    return DPI_DEFAULT;
+#endif
+}
+
 
 CheckboxFileDialog::ExtraPanel::ExtraPanel(wxWindow *parent)
     : wxPanel(parent, wxID_ANY)

src/slic3r/GUI/GUI_Utils.hpp

@@ -8,10 +8,13 @@
 
 #include <boost/optional.hpp>
 
+#include <wx/frame.h>
+#include <wx/dialog.h>
 #include <wx/event.h>
 #include <wx/filedlg.h>
 #include <wx/gdicmn.h>
 #include <wx/panel.h>
+#include <wx/dcclient.h>
 #include <wx/debug.h>
 
 class wxCheckBox;
@@ -27,6 +30,68 @@ wxTopLevelWindow* find_toplevel_parent(wxWindow *window);
 
 void on_window_geometry(wxTopLevelWindow *tlw, std::function<void()> callback);
 
+enum { DPI_DEFAULT = 96 };
+
+int get_dpi_for_window(wxWindow *window);
+
+struct DpiChangedEvent : public wxEvent {
+    int dpi;
+    wxRect rect;
+
+    DpiChangedEvent(wxEventType eventType, int dpi, wxRect rect)
+        : wxEvent(0, eventType), dpi(dpi), rect(rect)
+    {}
+
+    virtual wxEvent *Clone() const
+    {
+        return new DpiChangedEvent(*this);
+    }
+};
+
+wxDECLARE_EVENT(EVT_DPI_CHANGED, DpiChangedEvent);
+
+template<class P> class DPIAware : public P
+{
+public:
+    DPIAware(wxWindow *parent, wxWindowID id, const wxString &title, const wxPoint &pos=wxDefaultPosition,
+        const wxSize &size=wxDefaultSize, long style=wxDEFAULT_FRAME_STYLE, const wxString &name=wxFrameNameStr)
+        : P(parent, id, title, pos, size, style, name)
+    {
+        m_scale_factor = (float)get_dpi_for_window(this) / (float)DPI_DEFAULT;
+        recalc_font();
+
+        this->Bind(EVT_DPI_CHANGED, [this](const DpiChangedEvent &evt) {
+            m_scale_factor = (float)evt.dpi / (float)DPI_DEFAULT;
+            on_dpi_changed(evt.rect);
+        });
+    }
+
+    virtual ~DPIAware() {}
+
+    float scale_factor() const { return m_scale_factor; }
+    int em_unit() const { return m_em_unit; }
+    int font_size() const { return m_font_size; }
+
+protected:
+    virtual void on_dpi_changed(const wxRect &suggested_rect) = 0;
+
+private:
+    int m_scale_factor;
+    int m_em_unit;
+    int m_font_size;
+
+    void recalc_font()
+    {
+        wxClientDC dc(this);
+        const auto metrics = dc.GetFontMetrics();
+        m_font_size = metrics.height;
+        m_em_unit = metrics.averageWidth;
+    }
+};
+
+typedef DPIAware<wxFrame> DPIFrame;
+typedef DPIAware<wxDialog> DPIDialog;
+
 
 class EventGuard
 {

src/slic3r/GUI/MainFrame.cpp

@@ -32,7 +32,7 @@ namespace Slic3r {
 namespace GUI {
 
 MainFrame::MainFrame() :
-wxFrame(NULL, wxID_ANY, SLIC3R_BUILD, wxDefaultPosition, wxDefaultSize, wxDEFAULT_FRAME_STYLE, "mainframe"),
+DPIFrame(NULL, wxID_ANY, SLIC3R_BUILD, wxDefaultPosition, wxDefaultSize, wxDEFAULT_FRAME_STYLE, "mainframe"),
         m_printhost_queue_dlg(new PrintHostQueueDialog(this))
 {
     // Load the icon either from the exe, or from the ico file.
@@ -256,6 +256,11 @@ bool MainFrame::can_delete_all() const
     return (m_plater != nullptr) ? !m_plater->model().objects.empty() : false;
 }
 
+void MainFrame::on_dpi_changed(const wxRect &suggested_rect)
+{
+    // TODO
+}
+
 void MainFrame::init_menubar()
 {
 #ifdef __APPLE__

src/slic3r/GUI/MainFrame.hpp

@@ -9,6 +9,7 @@
 #include <string>
 #include <map>
 
+#include "GUI_Utils.hpp"
 #include "Plater.hpp"
 #include "Event.hpp"
 
@@ -40,7 +41,7 @@ struct PresetTab {
     PrinterTechnology technology;
 };
 
-class MainFrame : public wxFrame
+class MainFrame : public DPIFrame
 {
     bool        m_loaded {false};
 
@@ -68,6 +69,9 @@ class MainFrame : public wxFrame
     bool can_delete() const;
     bool can_delete_all() const;
 
+protected:
+    virtual void on_dpi_changed(const wxRect &suggested_rect);
+
 public:
     MainFrame();
     ~MainFrame() {}