Win32 portability

[xournal.git] / src / xo-paint.c

diff --git a/src/xo-paint.c b/src/xo-paint.c
index 7ab18469f3006edaa2eacc5e3f523cc4f0fbed75..6361af72e2d30cdc83dba3b189f89859330c1a2d 100644 (file)
--- a/src/xo-paint.c
+++ b/src/xo-paint.c
@@ -16,6 +16,76 @@
 #include "xo-misc.h"
 #include "xo-paint.h"
 
+/***** Win32 fix for gdk_cursor_new_from_pixmap() by Dirk Gerrits ****/
+
+#ifdef WIN32
+gboolean colors_too_similar(const GdkColor *colora, const GdkColor *colorb)
+{
+  return (abs(colora->red - colorb->red) < 256 &&
+          abs(colora->green - colorb->green) < 256 &&
+          abs(colora->blue - colorb->blue) < 256);
+}
+
+/* gdk_cursor_new_from_pixmap is broken on Windows.
+   this is a workaround using gdk_cursor_new_from_pixbuf. */
+GdkCursor* fixed_gdk_cursor_new_from_pixmap(GdkPixmap *source, GdkPixmap *mask,
+                                           const GdkColor *fg, const GdkColor *bg,
+                                           gint x, gint y)
+{
+  GdkPixmap *rgb_pixmap;
+  GdkGC *gc;
+  GdkPixbuf *rgb_pixbuf, *rgba_pixbuf;
+  GdkCursor *cursor;
+  int width, height;
+
+  /* HACK!  It seems impossible to work with RGBA pixmaps directly in
+     GDK-Win32.  Instead we pick some third color, different from fg
+     and bg, and use that as the 'transparent color'.  We do this using
+     colors_too_similar (see above) because two colors could be
+     unequal in GdkColor's 16-bit/sample, but equal in GdkPixbuf's
+     8-bit/sample. */
+  GdkColor candidates[3] = {{0,65535,0,0}, {0,0,65535,0}, {0,0,0,65535}};
+  GdkColor *trans = &candidates[0];
+  if (colors_too_similar(trans, fg) || colors_too_similar(trans, bg)) {
+    trans = &candidates[1];
+    if (colors_too_similar(trans, fg) || colors_too_similar(trans, bg)) {
+      trans = &candidates[2];
+    }
+  } /* trans is now guaranteed to be unique from fg and bg */
+
+  /* create an empty pixmap to hold the cursor image */
+  gdk_drawable_get_size(source, &width, &height);
+  rgb_pixmap = gdk_pixmap_new(NULL, width, height, 24);
+
+  /* blit the bitmaps defining the cursor onto a transparent background */
+  gc = gdk_gc_new(rgb_pixmap);
+  gdk_gc_set_fill(gc, GDK_SOLID);
+  gdk_gc_set_rgb_fg_color(gc, trans);
+  gdk_draw_rectangle(rgb_pixmap, gc, TRUE, 0, 0, width, height);
+  gdk_gc_set_fill(gc, GDK_OPAQUE_STIPPLED);
+  gdk_gc_set_stipple(gc, source);
+  gdk_gc_set_clip_mask(gc, mask);
+  gdk_gc_set_rgb_fg_color(gc, fg);
+  gdk_gc_set_rgb_bg_color(gc, bg);
+  gdk_draw_rectangle(rgb_pixmap, gc, TRUE, 0, 0, width, height);
+  gdk_gc_unref(gc);
+
+  /* create a cursor out of the created pixmap */
+  rgb_pixbuf = gdk_pixbuf_get_from_drawable(
+    NULL, rgb_pixmap, gdk_colormap_get_system(), 0, 0, 0, 0, width, height);
+  gdk_pixmap_unref(rgb_pixmap);
+  rgba_pixbuf = gdk_pixbuf_add_alpha(
+    rgb_pixbuf, TRUE, trans->red, trans->green, trans->blue);
+  gdk_pixbuf_unref(rgb_pixbuf);
+  cursor = gdk_cursor_new_from_pixbuf(gdk_display_get_default(), rgba_pixbuf, x, y);
+  gdk_pixbuf_unref(rgba_pixbuf);
+
+  return cursor;
+}
+#define gdk_cursor_new_from_pixmap fixed_gdk_cursor_new_from_pixmap
+#endif
+
+
 /************** drawing nice cursors *********/
 
 static char cursor_pen_bits[] = {