GHOST/Wayland: store fractional scaling in each window instead of DPI

This makes it possible to access the fractional scaling for a window,
there is no need to store the DPI which can be returned by getDPIHint().

1 files changed, 22 insertions, 29 deletions

diff --git a/intern/ghost/intern/GHOST_WindowWayland.cpp b/intern/ghost/intern/GHOST_WindowWayland.cpp
index f9d7f5c25e2..edcbcc14a37 100644
--- a/intern/ghost/intern/GHOST_WindowWayland.cpp
+++ b/intern/ghost/intern/GHOST_WindowWayland.cpp
@@ -90,13 +90,8 @@ struct GWL_Window {
 
   /** The scale value written to #wl_surface_set_buffer_scale. */
   int scale = 0;
-  /**
-   * The DPI, either:
-   * - `scale * base_dpi`
-   * - `wl_fixed_to_int(scale_fractional * base_dpi)`
-   * When fractional scaling is available.
-   */
-  uint32_t dpi = 0;
+  /** The fractional scale used to calculate the DPI. */
+  wl_fixed_t scale_fractional = 0;
 
 #ifdef WITH_GHOST_WAYLAND_LIBDECOR
   WGL_LibDecor_Window *libdecor = nullptr;
@@ -147,7 +142,7 @@ static int output_scale_cmp(const GWL_Output *output_a, const GWL_Output *output
 
 static int outputs_max_scale_or_default(const std::vector<GWL_Output *> &outputs,
                                         const int32_t scale_default,
-                                        uint32_t *r_dpi)
+                                        wl_fixed_t *r_scale_fractional)
 {
   const GWL_Output *output_max = nullptr;
   for (const GWL_Output *reg_output : outputs) {
@@ -157,18 +152,16 @@ static int outputs_max_scale_or_default(const std::vector<GWL_Output *> &outputs
   }
 
   if (output_max) {
-    if (r_dpi) {
-      *r_dpi = output_max->has_scale_fractional ?
-                   /* Fractional DPI. */
-                   wl_fixed_to_int(output_max->scale_fractional * base_dpi) :
-                   /* Simple non-fractional DPI. */
-                   (output_max->scale * base_dpi);
+    if (r_scale_fractional) {
+      *r_scale_fractional = output_max->has_scale_fractional ?
+                                output_max->scale_fractional :
+                                wl_fixed_from_int(output_max->scale);
     }
     return output_max->scale;
   }
 
-  if (r_dpi) {
-    *r_dpi = scale_default * base_dpi;
+  if (r_scale_fractional) {
+    *r_scale_fractional = wl_fixed_from_int(scale_default);
   }
   return scale_default;
 }
@@ -479,7 +472,7 @@ GHOST_WindowWayland::GHOST_WindowWayland(GHOST_SystemWayland *system,
    *
    * Using the maximum scale is best as it results in the window first being smaller,
    * avoiding a large window flashing before it's made smaller. */
-  window_->scale = outputs_max_scale_or_default(system_->outputs(), 1, &window_->dpi);
+  window_->scale = outputs_max_scale_or_default(system_->outputs(), 1, &window_->scale_fractional);
 
   /* Window surfaces. */
   window_->wl_surface = wl_compositor_create_surface(system_->wl_compositor());
@@ -751,7 +744,9 @@ GHOST_WindowWayland::~GHOST_WindowWayland()
 
 uint16_t GHOST_WindowWayland::getDPIHint()
 {
-  return window_->dpi;
+  /* Using the physical DPI will cause wrong scaling of the UI
+   * use a multiplier for the default DPI as a workaround. */
+  return wl_fixed_to_int(window_->scale_fractional * base_dpi);
 }
 
 GHOST_TSuccess GHOST_WindowWayland::setWindowCursorVisibility(bool visible)
@@ -962,14 +957,14 @@ GHOST_Context *GHOST_WindowWayland::newDrawingContext(GHOST_TDrawingContextType
  * Expose some members via methods.
  * \{ */
 
-uint16_t GHOST_WindowWayland::dpi() const
+int GHOST_WindowWayland::scale() const
 {
-  return window_->dpi;
+  return window_->scale;
 }
 
-int GHOST_WindowWayland::scale() const
+wl_fixed_t GHOST_WindowWayland::scale_fractional() const
 {
-  return window_->scale;
+  return window_->scale_fractional;
 }
 
 wl_surface *GHOST_WindowWayland::wl_surface() const
@@ -1035,13 +1030,13 @@ GHOST_TSuccess GHOST_WindowWayland::notify_size()
  */
 bool GHOST_WindowWayland::outputs_changed_update_scale()
 {
-  uint32_t dpi_next;
-  const int scale_next = outputs_max_scale_or_default(outputs(), 0, &dpi_next);
+  wl_fixed_t scale_fractional_next = 0;
+  const int scale_next = outputs_max_scale_or_default(outputs(), 0, &scale_fractional_next);
   if (UNLIKELY(scale_next == 0)) {
     return false;
   }
 
-  const uint32_t dpi_curr = window_->dpi;
+  const wl_fixed_t scale_fractional_curr = window_->scale_fractional;
   const int scale_curr = window_->scale;
   bool changed = false;
 
@@ -1055,10 +1050,8 @@ bool GHOST_WindowWayland::outputs_changed_update_scale()
     changed = true;
   }
 
-  if (dpi_next != dpi_curr) {
-    /* Using the real DPI will cause wrong scaling of the UI
-     * use a multiplier for the default DPI as workaround. */
-    window_->dpi = dpi_next;
+  if (scale_fractional_next != scale_fractional_curr) {
+    window_->scale_fractional = scale_fractional_next;
     changed = true;
 
     /* As this is a low-level function, we might want adding this event to be optional,