//
// "$Id$"
//
// Double-buffered window code for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2016 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file.  If this
// file is missing or damaged, see the license at:
//
//     http://www.fltk.org/COPYING.php
//
// Please report all bugs and problems on the following page:
//
//     http://www.fltk.org/str.php
//
/** \file
 Fl_Double_Window implementation.
 */

#include "config_lib.h"
#include <FL/Fl.H>
#include <FL/Fl_Double_Window.H>
#include <FL/Fl_Overlay_Window.H>
#include <FL/Fl_Printer.H>
#include <FL/x.H>
#include <FL/fl_draw.H>

// On systems that support double buffering "naturally" the base
// Fl_Window class will probably do double-buffer and this subclass
// does nothing.

#if USE_XDBE

#include <X11/extensions/Xdbe.h>

static int use_xdbe;

static int can_xdbe() {
  static int tried;
  if (!tried) {
    tried = 1;
    int event_base, error_base;
    if (!XdbeQueryExtension(fl_display, &event_base, &error_base)) return 0;
    Drawable root = RootWindow(fl_display,fl_screen);
    int numscreens = 1;
    XdbeScreenVisualInfo *a = XdbeGetVisualInfo(fl_display,&root,&numscreens);
    if (!a) return 0;
    for (int j = 0; j < a->count; j++) {
      if (a->visinfo[j].visual == fl_visual->visualid
	  /*&& a->visinfo[j].perflevel > 0*/) {
        use_xdbe = 1; break;
      }
    }
    XdbeFreeVisualInfo(a);
  }
  return use_xdbe;
}
#endif


Fl_Double_Window::Fl_Double_Window(int W, int H, const char *l)
: Fl_Window(W,H,l),
  force_doublebuffering_(0)
{
  type(FL_DOUBLE_WINDOW);
}


Fl_Double_Window::Fl_Double_Window(int X, int Y, int W, int H, const char *l)
: Fl_Window(X,Y,W,H,l),
  force_doublebuffering_(0)
{
  type(FL_DOUBLE_WINDOW);
}


void Fl_Double_Window::show() {
  Fl_Window::show();
}


/** see fl_copy_offscreen() */
void Fl_Graphics_Driver::copy_offscreen(int x, int y, int w, int h, Fl_Offscreen pixmap, int srcx, int srcy)
{
  fl_begin_offscreen(pixmap);
  uchar *img = fl_read_image(NULL, srcx, srcy, w, h, 0);
  fl_end_offscreen();
  fl_draw_image(img, x, y, w, h, 3, 0);
  delete[] img;
}

char fl_can_do_alpha_blending() {
  return Fl_Display_Device::display_device()->driver()->can_do_alpha_blending();
}

/**
  Forces the window to be redrawn.
*/
void Fl_Double_Window::flush() {flush(0);}

/**
  Forces the window to be redrawn.
  \param[in] eraseoverlay non-zero to erase overlay, zero to ignore

  Fl_Overlay_Window relies on flush(1) copying the back buffer to the
  front everywhere, even if damage() == 0, thus erasing the overlay,
  and leaving the clip region set to the entire window.
*/
void Fl_Double_Window::flush(int eraseoverlay) {
  if (!shown()) return;
  make_current(); // make sure fl_gc is non-zero
  Fl_X *myi = Fl_X::i(this);
  if (!myi) return; // window not yet created
  if (!myi->other_xid) {
#if USE_XDBE
    if (can_xdbe()) {
      myi->other_xid = XdbeAllocateBackBufferName(fl_display, fl_xid(this), XdbeCopied);
      myi->backbuffer_bad = 1;
    } else
#endif
#if defined(USE_X11) || defined(WIN32)
    myi->other_xid = fl_create_offscreen(w(), h());
    clear_damage(FL_DAMAGE_ALL);
#elif defined(__APPLE_QUARTZ__) // PORTME: platform double buffering
    if (force_doublebuffering_) {
      myi->other_xid = fl_create_offscreen(w(), h());
      clear_damage(FL_DAMAGE_ALL);
    }
#elif defined(FL_PORTING)
# pragma message "FL_PORTING: Fl_Window_Driver - call a function to clear any graphics port damage flags"
#else
# error unsupported platform
#endif
  }
#if USE_XDBE
  if (use_xdbe) {
    if (myi->backbuffer_bad || eraseoverlay) {
      // Make sure we do a complete redraw...
      if (myi->region) {XDestroyRegion(myi->region); myi->region = 0;}
      clear_damage(FL_DAMAGE_ALL);
      myi->backbuffer_bad = 0;
    }

    // Redraw as needed...
    if (damage()) {
      fl_clip_region(myi->region); myi->region = 0;
      fl_window = myi->other_xid;
      draw();
      fl_window = myi->xid;
    }

    // Copy contents of back buffer to window...
    XdbeSwapInfo s;
    s.swap_window = fl_xid(this);
    s.swap_action = XdbeCopied;
    XdbeSwapBuffers(fl_display, &s, 1);
    return;
  } else
#endif
  if (damage() & ~FL_DAMAGE_EXPOSE) {
    fl_clip_region(myi->region); myi->region = 0;
#ifdef WIN32
    void* _sgc = fl_graphics_driver->gc();
    HDC gc = fl_makeDC(myi->other_xid);
    fl_graphics_driver->gc(gc);
    int save = SaveDC(gc);
    fl_restore_clip(); // duplicate region into new gc
    draw();
    RestoreDC(gc, save);
    DeleteDC(gc);
    fl_graphics_driver->gc(_sgc);
    //# if defined(FLTK_USE_CAIRO)
    //if Fl::cairo_autolink_context() Fl::cairo_make_current(this); // capture gc changes automatically to update the cairo context adequately
    //# endif
#elif defined(__APPLE__) // PORTME: Fl_Window_Driver - platform double buffering
    if ( myi->other_xid ) {
      fl_begin_offscreen( myi->other_xid );
      fl_clip_region( 0 );
      draw();
      fl_end_offscreen();
    } else {
      draw();
    }
#elif defined(FL_PORTING)
#  pragma message "FL_PORTING: manage double buffered drawing"
#else // X:
    fl_window = myi->other_xid;
    draw();
    fl_window = myi->xid;
#endif
  }
  if (eraseoverlay) fl_clip_region(0);
  // on Irix (at least) it is faster to reduce the area copied to
  // the current clip region:
  int X,Y,W,H; fl_clip_box(0,0,w(),h(),X,Y,W,H);
  if (myi->other_xid) fl_graphics_driver->copy_offscreen(X, Y, W, H, myi->other_xid, X, Y);
}

void Fl_Double_Window::resize(int X,int Y,int W,int H) {
  int ow = w();
  int oh = h();
  Fl_Window::resize(X,Y,W,H);
#if USE_XDBE
  if (use_xdbe) {
    Fl_X* myi = Fl_X::i(this);
    if (myi && myi->other_xid && (ow < w() || oh < h())) {
      // STR #2152: Deallocate the back buffer to force creation of a new one.
      XdbeDeallocateBackBufferName(fl_display,myi->other_xid);
      myi->other_xid = 0;
    }
    return;
  }
#endif
  Fl_X* myi = Fl_X::i(this);
  if (myi && myi->other_xid && (ow != w() || oh != h())) {
    fl_delete_offscreen(myi->other_xid);
    myi->other_xid = 0;
  }
}

void Fl_Double_Window::hide() {
  Fl_X* myi = Fl_X::i(this);
  if (myi && myi->other_xid) {
#if USE_XDBE
    if (!use_xdbe)
#endif
      fl_delete_offscreen(myi->other_xid);
  }
  Fl_Window::hide();
}

/**
  The destructor <I>also deletes all the children</I>. This allows a
  whole tree to be deleted at once, without having to keep a pointer to
  all the children in the user code.
*/
Fl_Double_Window::~Fl_Double_Window() {
  hide();
}


Fl_Overlay_Window::Fl_Overlay_Window(int W, int H, const char *l)
: Fl_Double_Window(W,H,l)
{
  overlay_ = 0;
  force_doublebuffering_=1;
  image(0);
}


Fl_Overlay_Window::Fl_Overlay_Window(int X, int Y, int W, int H, const char *l)
: Fl_Double_Window(X,Y,W,H,l)
{
  overlay_ = 0;
  force_doublebuffering_=1;
  image(0);
}


//
// End of "$Id$".
//