Fix: Changing default color palette affects opengl child drawing on Wayland (#989)

src/drivers/Wayland/Fl_Wayland_Gl_Window_Driver.H

@@ -56,8 +56,6 @@ private:
   void redraw_overlay() FL_OVERRIDE;
   void gl_start() FL_OVERRIDE;
   void gl_visual(Fl_Gl_Choice *c) FL_OVERRIDE;
-  char *alpha_mask_for_string(
-      const char *str, int n, int w, int h, Fl_Fontsize fs) FL_OVERRIDE;
   void init();
 public:
   //virtual bool need_scissor() { return true; } // CONTROL_LEAKING_SUB_GL_WINDOWS

src/drivers/Wayland/Fl_Wayland_Gl_Window_Driver.cxx

@@ -107,35 +107,6 @@ void Fl_Wayland_Gl_Window_Driver::init() {
 }
 
 
-char *Fl_Wayland_Gl_Window_Driver::alpha_mask_for_string(const char *str, int n,
-                                                         int w, int h, Fl_Fontsize fs)
-{
-  // write str to a bitmap just big enough
-  Fl_Image_Surface *surf = new Fl_Image_Surface(w, h);
-  Fl_Font f = fl_font();
-  Fl_Surface_Device::push_current(surf);
-  fl_color(FL_BLACK);
-  fl_rectf(0, 0, w, h);
-  fl_color(FL_WHITE);
-  fl_font(f, fs);
-  fl_draw(str, n, 0, fl_height() - fl_descent());
-  // get the R channel only of the bitmap
-  char *alpha_buf = new char[w*h], *r = alpha_buf;
-  struct Fl_Wayland_Graphics_Driver::draw_buffer *off =
-    Fl_Wayland_Graphics_Driver::offscreen_buffer(surf->offscreen());
-  for (int i = 0; i < h; i++) {
-    uchar *q = off->buffer + i * off->stride;
-    for (int j = 0; j < w; j++) {
-      *r++ = *q;
-      q += 4;
-    }
-  }
-  Fl_Surface_Device::pop_current();
-  delete surf;
-  return alpha_buf;
-}
-
-
 Fl_Gl_Choice *Fl_Wayland_Gl_Window_Driver::find(int m, const int *alistp)
 {
   m |= FL_DOUBLE;