intern/ghost/GHOST_C-api.h

@@ -764,6 +764,13 @@ extern void GHOST_SetMultitouchGestures(GHOST_SystemHandle systemhandle, const b
  */
 extern void GHOST_SetTabletAPI(GHOST_SystemHandle systemhandle, GHOST_TTabletAPI api);
 
+/**
+ * Get the color of the pixel at the current mouse cursor location
+ * \param r_color: returned sRGB float colors
+ * \return Success value (true == successful and supported by platform)
+ */
+extern GHOST_TSuccess GHOST_GetPixelAtCursor(float r_color[3]);
+
 /**
  * Access to rectangle width.
  * \param rectanglehandle: The handle to the rectangle.

intern/ghost/GHOST_ISystem.hh

@@ -441,6 +441,13 @@ class GHOST_ISystem {
    */
   virtual void setTabletAPI(GHOST_TTabletAPI api) = 0;
 
+  /**
+   * Get the color of the pixel at the current mouse cursor location
+   * \param r_color: returned sRGB float colors
+   * \return Success value (true == successful and supported by platform)
+   */
+  virtual GHOST_TSuccess getPixelAtCursor(float r_color[3]) const = 0;
+
 #ifdef WITH_INPUT_NDOF
   /**
    * Sets 3D mouse deadzone

intern/ghost/GHOST_Types.h

@@ -107,6 +107,10 @@ typedef enum {
    * Set when there is support for system clipboard copy/paste.
    */
   GHOST_kCapabilityClipboardImages = (1 << 4),
+  /**
+   * Support for sampling a color outside of the Blender windows.
+   */
+  GHOST_kCapabilityDesktopSample = (1 << 5),
 } GHOST_TCapabilityFlag;
 
 /**
@@ -115,7 +119,8 @@ typedef enum {
  */
 #define GHOST_CAPABILITY_FLAG_ALL \
   (GHOST_kCapabilityCursorWarp | GHOST_kCapabilityWindowPosition | \
-   GHOST_kCapabilityPrimaryClipboard | GHOST_kCapabilityGPUReadFrontBuffer)
+   GHOST_kCapabilityPrimaryClipboard | GHOST_kCapabilityGPUReadFrontBuffer | \
+   GHOST_kCapabilityClipboardImages | GHOST_kCapabilityDesktopSample)
 
 /* Xtilt and Ytilt represent how much the pen is tilted away from
  * vertically upright in either the X or Y direction, with X and Y the

intern/ghost/intern/GHOST_C-api.cc

@@ -768,6 +768,12 @@ void GHOST_SetTabletAPI(GHOST_SystemHandle systemhandle, GHOST_TTabletAPI api)
   system->setTabletAPI(api);
 }
 
+GHOST_TSuccess GHOST_GetPixelAtCursor(float r_color[3])
+{
+  GHOST_ISystem *system = GHOST_ISystem::getSystem();
+  return system->getPixelAtCursor(r_color);
+}
+
 int32_t GHOST_GetWidthRectangle(GHOST_RectangleHandle rectanglehandle)
 {
   return ((GHOST_Rect *)rectanglehandle)->getWidth();

intern/ghost/intern/GHOST_System.cc

@@ -341,6 +341,11 @@ GHOST_TTabletAPI GHOST_System::getTabletAPI()
   return m_tabletAPI;
 }
 
+GHOST_TSuccess GHOST_System::getPixelAtCursor(float[3] /* r_color */) const
+{
+  return GHOST_kFailure;
+}
+
 #ifdef WITH_INPUT_NDOF
 void GHOST_System::setNDOFDeadZone(float deadzone)
 {

intern/ghost/intern/GHOST_System.hh

@@ -256,6 +256,13 @@ class GHOST_System : public GHOST_ISystem {
   virtual void setTabletAPI(GHOST_TTabletAPI api);
   GHOST_TTabletAPI getTabletAPI(void);
 
+  /**
+   * Get the color of the pixel at the current mouse cursor location
+   * \param r_color: returned sRGB float colors
+   * \return Success value (true == successful and supported by platform)
+   */
+  GHOST_TSuccess getPixelAtCursor(float r_color[3]) const;
+
 #ifdef WITH_INPUT_NDOF
   /***************************************************************************************
    * Access to 3D mouse.

intern/ghost/intern/GHOST_SystemCocoa.mm

@@ -921,6 +921,8 @@ GHOST_TCapabilityFlag GHOST_SystemCocoa::getCapabilities() const
       ~(
           /* Cocoa has no support for a primary selection clipboard. */
           GHOST_kCapabilityPrimaryClipboard |
+          /* Cocoa has no support for sampling colors from the desktop. */
+          GHOST_kCapabilityDesktopSample |
           /* This Cocoa back-end has not yet implemented image copy/paste. */
           GHOST_kCapabilityClipboardImages));
 }

intern/ghost/intern/GHOST_SystemHeadless.hh

@@ -50,6 +50,7 @@ class GHOST_SystemHeadless : public GHOST_System {
                                  /* No windowing functionality supported. */
                                  ~(GHOST_kCapabilityWindowPosition | GHOST_kCapabilityCursorWarp |
                                    GHOST_kCapabilityPrimaryClipboard |
+                                   GHOST_kCapabilityDesktopSample |
                                    GHOST_kCapabilityClipboardImages));
   }
   char *getClipboard(bool /*selection*/) const override

intern/ghost/intern/GHOST_SystemSDL.cc

@@ -772,6 +772,8 @@ GHOST_TCapabilityFlag GHOST_SystemSDL::getCapabilities() const
       ~(
           /* This SDL back-end has not yet implemented primary clipboard. */
           GHOST_kCapabilityPrimaryClipboard |
+          /* This SDL back-end has not yet implemented color sampling the desktop. */
+          GHOST_kCapabilityDesktopSample |
           /* This SDL back-end has not yet implemented image copy/paste. */
           GHOST_kCapabilityClipboardImages));
 }

intern/ghost/intern/GHOST_SystemWayland.cc

@@ -6843,6 +6843,8 @@ GHOST_TCapabilityFlag GHOST_SystemWayland::getCapabilities() const
            * screen-shot and eye-dropper sampling logic, both operations where the overhead
            * is negligible. */
           GHOST_kCapabilityGPUReadFrontBuffer |
+          /* This WAYLAND back-end has not yet implemented desktop color sample. */
+          GHOST_kCapabilityDesktopSample |
           /* This WAYLAND back-end has not yet implemented image copy/paste. */
           GHOST_kCapabilityClipboardImages));
 }

intern/ghost/intern/GHOST_SystemWin32.cc

@@ -448,6 +448,31 @@ GHOST_TSuccess GHOST_SystemWin32::setCursorPosition(int32_t x, int32_t y)
   return ::SetCursorPos(x, y) == TRUE ? GHOST_kSuccess : GHOST_kFailure;
 }
 
+GHOST_TSuccess GHOST_SystemWin32::getPixelAtCursor(float r_color[3]) const
+{
+  POINT point;
+  if (!GetCursorPos(&point)) {
+    return GHOST_kFailure;
+  }
+
+  HDC dc = GetDC(NULL);
+  if (dc == NULL) {
+    return GHOST_kFailure;
+  }
+
+  COLORREF color = GetPixel(dc, point.x, point.y);
+  ReleaseDC(NULL, dc);
+
+  if (color == CLR_INVALID) {
+    return GHOST_kFailure;
+  }
+
+  r_color[0] = GetRValue(color) / 255.0f;
+  r_color[1] = GetGValue(color) / 255.0f;
+  r_color[2] = GetBValue(color) / 255.0f;
+  return GHOST_kSuccess;
+}
+
 GHOST_TSuccess GHOST_SystemWin32::getModifierKeys(GHOST_ModifierKeys &keys) const
 {
   /* `GetAsyncKeyState` returns the current interrupt-level state of the hardware, which is needed

intern/ghost/intern/GHOST_SystemWin32.hh

@@ -182,6 +182,13 @@ class GHOST_SystemWin32 : public GHOST_System {
    */
   GHOST_TSuccess setCursorPosition(int32_t x, int32_t y);
 
+  /**
+   * Get the color of the pixel at the current mouse cursor location
+   * \param r_color: returned sRGB float colors
+   * \return Success value (true == successful and supported by platform)
+   */
+  GHOST_TSuccess getPixelAtCursor(float r_color[3]) const;
+
   /***************************************************************************************
    ** Access to mouse button and keyboard states.
    ***************************************************************************************/

intern/ghost/intern/GHOST_SystemX11.cc

@@ -1693,6 +1693,8 @@ GHOST_TCapabilityFlag GHOST_SystemX11::getCapabilities() const
 {
   return GHOST_TCapabilityFlag(GHOST_CAPABILITY_FLAG_ALL &
                                ~(
+                                   /* No support yet for desktop sampling. */
+                                   GHOST_kCapabilityDesktopSample |
                                    /* No support yet for image copy/paste. */
                                    GHOST_kCapabilityClipboardImages));
 }

source/blender/editors/interface/eyedroppers/eyedropper_color.cc

@@ -315,45 +315,35 @@ static bool eyedropper_cryptomatte_sample_fl(bContext *C,
 
 void eyedropper_color_sample_fl(bContext *C, const int m_xy[2], float r_col[3])
 {
-  /* we could use some clever */
-  Main *bmain = CTX_data_main(C);
-  const char *display_device = CTX_data_scene(C)->display_settings.display_device;
-  ColorManagedDisplay *display = IMB_colormanagement_display_get_named(display_device);
+  wmWindowManager *wm = CTX_wm_manager(C);
+  ScrArea *area = nullptr;
 
   int mval[2];
-  wmWindow *win;
-  ScrArea *area;
-  datadropper_win_area_find(C, m_xy, mval, &win, &area);
+  wmWindow *win = WM_window_find_under_cursor(CTX_wm_window(C), m_xy, mval);
+  if (win) {
+    bScreen *screen = WM_window_get_active_screen(win);
+    area = BKE_screen_find_area_xy(screen, SPACE_TYPE_ANY, mval);
+  }
 
   if (area) {
-    if (area->spacetype == SPACE_IMAGE) {
-      ARegion *region = BKE_area_find_region_xy(area, RGN_TYPE_WINDOW, mval);
-      if (region) {
+    ARegion *region = BKE_area_find_region_xy(area, RGN_TYPE_WINDOW, mval);
+    if (region) {
+      const int region_mval[2] = {mval[0] - region->winrct.xmin, mval[1] - region->winrct.ymin};
+      if (area->spacetype == SPACE_IMAGE) {
         SpaceImage *sima = static_cast<SpaceImage *>(area->spacedata.first);
-        const int region_mval[2] = {mval[0] - region->winrct.xmin, mval[1] - region->winrct.ymin};
-
         if (ED_space_image_color_sample(sima, region, region_mval, r_col, nullptr)) {
           return;
         }
       }
-    }
-    else if (area->spacetype == SPACE_NODE) {
-      ARegion *region = BKE_area_find_region_xy(area, RGN_TYPE_WINDOW, mval);
-      if (region) {
+      else if (area->spacetype == SPACE_NODE) {
         SpaceNode *snode = static_cast<SpaceNode *>(area->spacedata.first);
-        const int region_mval[2] = {mval[0] - region->winrct.xmin, mval[1] - region->winrct.ymin};
-
+        Main *bmain = CTX_data_main(C);
         if (ED_space_node_color_sample(bmain, snode, region, region_mval, r_col)) {
           return;
         }
       }
-    }
-    else if (area->spacetype == SPACE_CLIP) {
-      ARegion *region = BKE_area_find_region_xy(area, RGN_TYPE_WINDOW, mval);
-      if (region) {
+      else if (area->spacetype == SPACE_CLIP) {
         SpaceClip *sc = static_cast<SpaceClip *>(area->spacedata.first);
-        const int region_mval[2] = {mval[0] - region->winrct.xmin, mval[1] - region->winrct.ymin};
-
         if (ED_space_clip_color_sample(sc, region, region_mval, r_col)) {
           return;
         }
@@ -362,9 +352,20 @@ void eyedropper_color_sample_fl(bContext *C, const int m_xy[2], float r_col[3])
   }
 
   if (win) {
-    WM_window_pixels_read_sample(C, win, mval, r_col);
+    /* Other areas within a Blender window. */
+    if (!WM_window_pixels_read_sample(C, win, mval, r_col)) {
+      WM_window_pixels_read_sample_from_offscreen(C, win, mval, r_col);
+    }
+    const char *display_device = CTX_data_scene(C)->display_settings.display_device;
+    ColorManagedDisplay *display = IMB_colormanagement_display_get_named(display_device);
     IMB_colormanagement_display_to_scene_linear_v3(r_col, display);
   }
+  else if ((WM_capabilities_flag() & WM_CAPABILITY_DESKTOP_SAMPLE) &&
+           WM_desktop_cursor_sample_read(r_col))
+  {
+    /* Outside of the Blender window if we support it. */
+    IMB_colormanagement_srgb_to_scene_linear_v3(r_col, r_col);
+  }
   else {
     zero_v3(r_col);
   }

source/blender/windowmanager/WM_api.hh

@@ -170,6 +170,8 @@ enum eWM_CapabilitiesFlag {
   WM_CAPABILITY_GPU_FRONT_BUFFER_READ = (1 << 3),
   /** Ability to copy/paste system clipboard images. */
   WM_CAPABILITY_CLIPBOARD_IMAGES = (1 << 4),
+  /** Ability to sample a color outside of Blender windows. */
+  WM_CAPABILITY_DESKTOP_SAMPLE = (1 << 5),
   /** The initial value, indicates the value needs to be set by inspecting GHOST. */
   WM_CAPABILITY_INITIALIZED = (1 << 31),
 };
@@ -194,6 +196,12 @@ wmWindow *WM_window_find_under_cursor(wmWindow *win, const int mval[2], int r_mv
  */
 wmWindow *WM_window_find_by_area(wmWindowManager *wm, const ScrArea *area);
 
+/**
+ * Return the color of the pixel at the current mouse cursor position on the desktop, whether in a
+ * Blender window or not. Returns false on failure or if not supported by the platform.
+ */
+bool WM_desktop_cursor_sample_read(float r_col[3]);
+
 /**
  * Read pixels from the front-buffer (fast).
  *

source/blender/windowmanager/intern/wm_draw.cc

@@ -1411,6 +1411,11 @@ bool WM_window_pixels_read_sample(bContext *C, wmWindow *win, const int pos[2],
   return WM_window_pixels_read_sample_from_offscreen(C, win, pos, r_col);
 }
 
+bool WM_desktop_cursor_sample_read(float r_col[3])
+{
+  return GHOST_GetPixelAtCursor(r_col);
+}
+
 /** \} */
 
 /* -------------------------------------------------------------------- */

source/blender/windowmanager/intern/wm_window.cc

@@ -1887,6 +1887,9 @@ eWM_CapabilitiesFlag WM_capabilities_flag()
   if (ghost_flag & GHOST_kCapabilityClipboardImages) {
     flag |= WM_CAPABILITY_CLIPBOARD_IMAGES;
   }
+  if (ghost_flag & GHOST_kCapabilityDesktopSample) {
+    flag |= WM_CAPABILITY_DESKTOP_SAMPLE;
+  }
 
   return flag;
 }