[gimp] Bug 740634 - Color picker crashes when there are multiple monitors

[Michael Natterer <mitch src gnome org>]

commit c585c99e8084998b3203b6ebf854499d074f3ee4
Author: Éric Hoffman <ehoffman videotron ca>
Date:   Thu Apr 6 23:50:26 2017 +0200

    Bug 740634 - Color picker crashes when there are multiple monitors
    
    Use Windows API directly to get a screen pixel, works for all kinds of
    monitor layouts.

 libgimpwidgets/gimppickbutton-default.c |   40 ++++++++++++++++++++++++++++--
 1 files changed, 37 insertions(+), 3 deletions(-)
---
diff --git a/libgimpwidgets/gimppickbutton-default.c b/libgimpwidgets/gimppickbutton-default.c
index 3fec04a..683b65e 100644
--- a/libgimpwidgets/gimppickbutton-default.c
+++ b/libgimpwidgets/gimppickbutton-default.c
@@ -22,6 +22,11 @@
 #include <gtk/gtk.h>
 #include <gdk/gdkkeysyms.h>
 
+#ifdef G_OS_WIN32
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#endif
+
 #include "libgimpcolor/gimpcolor.h"
 
 #include "gimpwidgetstypes.h"
@@ -199,14 +204,41 @@ gimp_pick_button_pick (GdkScreen      *screen,
                        gint            y_root,
                        GimpPickButton *button)
 {
+  GimpRGB           rgb;
+  GimpColorProfile *monitor_profile;
+  gint              monitor;
+
+#ifdef G_OS_WIN32
+
+  HDC               hdc;
+  RECT              rect;
+  COLORREF          win32_color;
+
+  /* For MS Windows, use native GDI functions to get the pixel, as
+   * cairo does not handle the case where you have multiple monitors
+   * with a monitor on the left or above the primary monitor.  That
+   * scenario create a cairo primary surface with negative extent,
+   * which is not handled properly (bug 740634).
+   */
+
+  hdc = GetDC (HWND_DESKTOP);
+  GetClipBox (hdc, &rect);
+  win32_color = GetPixel (hdc, x_root + rect.left, y_root + rect.top);
+  ReleaseDC (HWND_DESKTOP, hdc);
+
+  gimp_rgba_set_uchar (&rgb,
+                       GetRValue (win32_color),
+                       GetGValue (win32_color),
+                       GetBValue (win32_color),
+                       255);
+
+#else
+
   GdkWindow        *root_window = gdk_screen_get_root_window (screen);
   cairo_surface_t  *image;
   cairo_t          *cr;
   guchar           *data;
   guchar            color[3];
-  GimpRGB           rgb;
-  GimpColorProfile *monitor_profile;
-  gint              monitor;
 
   image = cairo_image_surface_create (CAIRO_FORMAT_RGB24, 1, 1);
 
@@ -224,6 +256,8 @@ gimp_pick_button_pick (GdkScreen      *screen,
 
   gimp_rgba_set_uchar (&rgb, color[0], color[1], color[2], 255);
 
+#endif
+
   monitor = gdk_screen_get_monitor_at_point (screen, x_root, y_root);
   monitor_profile = gimp_screen_get_color_profile (screen, monitor);