/*
 * shaped texture
 *
 * An actor to draw a texture clipped to a list of rectangles
 *
 * Authored By Neil Roberts  <neil@linux.intel.com>
 *
 * Copyright (C) 2008 Intel Corporation
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#include <clutter/clutter-texture.h>
#include <clutter/glx/clutter-glx.h>
#include <cogl/cogl.h>
#include <string.h>

#include "shaped-texture.h"

static void meta_shaped_texture_dispose (GObject *object);
static void meta_shaped_texture_finalize (GObject *object);

static void meta_shaped_texture_paint (ClutterActor *actor);
static void meta_shaped_texture_pick (ClutterActor *actor,
                                      const ClutterColor *color);

static void meta_shaped_texture_dirty_mask (MetaShapedTexture *stex);

G_DEFINE_TYPE (MetaShapedTexture, meta_shaped_texture,
               CLUTTER_GLX_TYPE_TEXTURE_PIXMAP);

#define META_SHAPED_TEXTURE_GET_PRIVATE(obj) \
  (G_TYPE_INSTANCE_GET_PRIVATE ((obj), META_TYPE_SHAPED_TEXTURE, \
                                MetaShapedTexturePrivate))

enum TstMultiTexSupport
  {
    TST_MULTI_TEX_SUPPORT_UNKNOWN = 0,
    TST_MULTI_TEX_SUPPORT_YES,
    TST_MULTI_TEX_SUPPORT_NO
  };

static enum TstMultiTexSupport
tst_multi_tex_support = TST_MULTI_TEX_SUPPORT_UNKNOWN;

typedef void (* TstActiveTextureFunc) (GLenum texture);
typedef void (* TstClientActiveTextureFunc) (GLenum texture);

static TstActiveTextureFunc tst_active_texture;
static TstClientActiveTextureFunc tst_client_active_texture;

struct _MetaShapedTexturePrivate
{
  CoglHandle mask_texture;

  guint mask_width, mask_height;
  GLint mask_gl_width, mask_gl_height;
  GLfloat mask_tex_coords[8];

  GArray *rectangles;
};

static void
meta_shaped_texture_class_init (MetaShapedTextureClass *klass)
{
  GObjectClass *gobject_class = (GObjectClass *) klass;
  ClutterActorClass *actor_class = (ClutterActorClass *) klass;

  gobject_class->dispose = meta_shaped_texture_dispose;
  gobject_class->finalize = meta_shaped_texture_finalize;

  actor_class->paint = meta_shaped_texture_paint;
  actor_class->pick = meta_shaped_texture_pick;

  g_type_class_add_private (klass, sizeof (MetaShapedTexturePrivate));
}

static void
meta_shaped_texture_init (MetaShapedTexture *self)
{
  MetaShapedTexturePrivate *priv;

  priv = self->priv = META_SHAPED_TEXTURE_GET_PRIVATE (self);

  priv->rectangles = g_array_new (FALSE, FALSE, sizeof (ClutterGeometry));

  priv->mask_texture = COGL_INVALID_HANDLE;
}

static void
meta_shaped_texture_dispose (GObject *object)
{
  MetaShapedTexture *self = (MetaShapedTexture *) object;

  meta_shaped_texture_dirty_mask (self);

  G_OBJECT_CLASS (meta_shaped_texture_parent_class)->dispose (object);
}

static void
meta_shaped_texture_finalize (GObject *object)
{
  MetaShapedTexture *self = (MetaShapedTexture *) object;
  MetaShapedTexturePrivate *priv = self->priv;

  g_array_free (priv->rectangles, TRUE);

  G_OBJECT_CLASS (meta_shaped_texture_parent_class)->finalize (object);
}

static void
meta_shaped_texture_dirty_mask (MetaShapedTexture *stex)
{
  MetaShapedTexturePrivate *priv = stex->priv;

  if (priv->mask_texture != COGL_INVALID_HANDLE)
    {
      cogl_texture_unref (priv->mask_texture);
      priv->mask_texture = COGL_INVALID_HANDLE;
    }
}

static gboolean
meta_shaped_texture_is_multi_tex_supported (void)
{
  const gchar *extensions;
  GLint max_tex_units = 0;

  if (tst_multi_tex_support != TST_MULTI_TEX_SUPPORT_UNKNOWN)
    return tst_multi_tex_support == TST_MULTI_TEX_SUPPORT_YES;

  extensions = (const gchar *) glGetString (GL_EXTENSIONS);

  tst_active_texture = (TstActiveTextureFunc)
    cogl_get_proc_address ("glActiveTextureARB");
  tst_client_active_texture = (TstClientActiveTextureFunc)
    cogl_get_proc_address ("glClientActiveTextureARB");

  glGetIntegerv (GL_MAX_TEXTURE_UNITS, &max_tex_units);

  if (extensions
      && cogl_check_extension ("GL_ARB_multitexture", extensions)
      && tst_active_texture
      && tst_client_active_texture
      && max_tex_units > 1)
    {
      tst_multi_tex_support = TST_MULTI_TEX_SUPPORT_YES;
      return TRUE;
    }
  else
    {
      g_warning ("multi texturing not supported");
      tst_multi_tex_support = TST_MULTI_TEX_SUPPORT_NO;
      return FALSE;
    }
}

static void
meta_shaped_texture_set_coord_array (GLfloat x1, GLfloat y1,
                                     GLfloat x2, GLfloat y2,
                                     GLfloat *coords)
{
  coords[0] = x1;
  coords[1] = y2;
  coords[2] = x2;
  coords[3] = y2;
  coords[4] = x1;
  coords[5] = y1;
  coords[6] = x2;
  coords[7] = y1;
}

static void
meta_shaped_texture_ensure_mask (MetaShapedTexture *stex)
{
  MetaShapedTexturePrivate *priv = stex->priv;
  CoglHandle paint_tex;
  guint tex_width, tex_height;
  GLuint mask_gl_tex;

  paint_tex = clutter_texture_get_cogl_texture (CLUTTER_TEXTURE (stex));

  if (paint_tex == COGL_INVALID_HANDLE)
    return;

  tex_width = cogl_texture_get_width (paint_tex);
  tex_height = cogl_texture_get_height (paint_tex);

  /* If the mask texture we have was created for a different size then
     recreate it */
  if (priv->mask_texture != COGL_INVALID_HANDLE
      && (priv->mask_width != tex_width || priv->mask_height != tex_height))
    meta_shaped_texture_dirty_mask (stex);

  /* If we don't have a mask texture yet then create one */
  if (priv->mask_texture == COGL_INVALID_HANDLE)
    {
      guchar *mask_data;
      const ClutterGeometry *rect;

      /* Create data for an empty image */
      mask_data = g_malloc0 (tex_width * tex_height);
      
      /* Cut out a hole for each rectangle */
      for (rect = (ClutterGeometry *) priv->rectangles->data
             + priv->rectangles->len;
           rect-- > (ClutterGeometry *) priv->rectangles->data;)
        {
          gint x1 = rect->x, x2 = x1 + rect->width;
          gint y1 = rect->y, y2 = y1 + rect->height;
          guchar *p;

          /* Clip the rectangle to the size of the texture */
          x1 = CLAMP (x1, 0, (gint) tex_width - 1);
          x2 = CLAMP (x2, x1, (gint) tex_width);
          y1 = CLAMP (y1, 0, (gint) tex_height - 1);
          y2 = CLAMP (y2, y1, (gint) tex_height);

          /* Fill the rectangle */
          for (p = mask_data + y1 * tex_width + x1;
               y1 < y2;
               y1++, p += tex_width)
            memset (p, 255, x2 - x1);
        }

      priv->mask_texture = cogl_texture_new_from_data (tex_width, tex_height,
                                                       -1, FALSE,
                                                       COGL_PIXEL_FORMAT_A_8,
                                                       COGL_PIXEL_FORMAT_ANY,
                                                       tex_width,
                                                       mask_data);

      g_free (mask_data);

      priv->mask_width = tex_width;
      priv->mask_height = tex_height;

      cogl_texture_get_gl_texture (priv->mask_texture, &mask_gl_tex, NULL);

      glBindTexture (GL_TEXTURE_2D, mask_gl_tex);

      glGetTexLevelParameteriv (GL_TEXTURE_2D, 0,
                                GL_TEXTURE_WIDTH,
                                &priv->mask_gl_width);
      glGetTexLevelParameteriv (GL_TEXTURE_2D, 0,
                                GL_TEXTURE_HEIGHT,
                                &priv->mask_gl_height);

      if ((guint) priv->mask_gl_width == tex_width
          && (guint) priv->mask_gl_height == tex_height)
        meta_shaped_texture_set_coord_array (0.0f, 0.0f, 1.0f, 1.0f,
                                             priv->mask_tex_coords);
      else
        meta_shaped_texture_set_coord_array (0.0f, 0.0f,
                                             tex_width
                                             / (GLfloat) priv->mask_gl_width,
                                             tex_height
                                             / (GLfloat) priv->mask_gl_height,
                                             priv->mask_tex_coords);
    }
}

static void
meta_shaped_texture_paint (ClutterActor *actor)
{
  MetaShapedTexture *stex = (MetaShapedTexture *) actor;
  MetaShapedTexturePrivate *priv = stex->priv;
  CoglHandle paint_tex;
  guint tex_width, tex_height;
  GLboolean texture_was_enabled, blend_was_enabled;
  GLboolean vertex_array_was_enabled, tex_coord_array_was_enabled;
  GLboolean color_array_was_enabled;
  GLuint paint_gl_tex, mask_gl_tex;
  GLint paint_gl_width, paint_gl_height;
  GLfloat vertex_coords[8], paint_tex_coords[8];
  ClutterActorBox alloc;
  static const ClutterColor white = { 0xff, 0xff, 0xff, 0xff };

  /* If there are no rectangles or multi-texturing isn't supported,
     fallback to the regular paint method */
  if (priv->rectangles->len < 1
      || !meta_shaped_texture_is_multi_tex_supported ())
    {
      CLUTTER_ACTOR_CLASS (meta_shaped_texture_parent_class)
        ->paint (actor);
      return;
    }

  if (!CLUTTER_ACTOR_IS_REALIZED (CLUTTER_ACTOR (stex)))
    clutter_actor_realize (CLUTTER_ACTOR (stex));

  paint_tex = clutter_texture_get_cogl_texture (CLUTTER_TEXTURE (stex));

  if (paint_tex == COGL_INVALID_HANDLE)
    return;

  tex_width = cogl_texture_get_width (paint_tex);
  tex_height = cogl_texture_get_height (paint_tex);

  meta_shaped_texture_ensure_mask (stex);

  cogl_texture_get_gl_texture (paint_tex, &paint_gl_tex, NULL);
  cogl_texture_get_gl_texture (priv->mask_texture, &mask_gl_tex, NULL);

  /* We need to keep track of the some of the old state so that we
     don't confuse Cogl */
  texture_was_enabled = glIsEnabled (GL_TEXTURE_2D);
  blend_was_enabled = glIsEnabled (GL_BLEND);
  vertex_array_was_enabled = glIsEnabled (GL_VERTEX_ARRAY);
  tex_coord_array_was_enabled = glIsEnabled (GL_TEXTURE_COORD_ARRAY);
  color_array_was_enabled = glIsEnabled (GL_COLOR_ARRAY);

  glEnable (GL_TEXTURE_2D);
  glEnable (GL_BLEND);
  glEnableClientState (GL_VERTEX_ARRAY);
  glEnableClientState (GL_TEXTURE_COORD_ARRAY);
  glDisableClientState (GL_COLOR_ARRAY);
  glVertexPointer (2, GL_FLOAT, 0, vertex_coords);
  glTexCoordPointer (2, GL_FLOAT, 0, paint_tex_coords);
  cogl_color (&white);

  /* Put the main painting texture in the first texture unit */
  glBindTexture (GL_TEXTURE_2D, paint_gl_tex);

  /* We need the actual size of the texture so that we can calculate
     the right texture coordinates if NPOTs textures are not supported
     and Cogl has oversized the texture */
  glGetTexLevelParameteriv (GL_TEXTURE_2D, 0,
                            GL_TEXTURE_WIDTH,
                            &paint_gl_width);
  glGetTexLevelParameteriv (GL_TEXTURE_2D, 0,
                            GL_TEXTURE_HEIGHT,
                            &paint_gl_height);

  /* Put the mask texture in the second texture unit */
  tst_active_texture (GL_TEXTURE1);
  tst_client_active_texture (GL_TEXTURE1);
  glBindTexture (GL_TEXTURE_2D, mask_gl_tex);

  glEnable (GL_TEXTURE_2D);

  glEnableClientState (GL_TEXTURE_COORD_ARRAY);
  glTexCoordPointer (2, GL_FLOAT, 0, priv->mask_tex_coords);

  glTexEnvi (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);

  /* Multiply the alpha by the alpha in the second texture */
  glTexEnvi (GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_MODULATE);
  glTexEnvi (GL_TEXTURE_ENV, GL_SRC0_ALPHA, GL_TEXTURE);
  glTexEnvi (GL_TEXTURE_ENV, GL_SRC1_ALPHA, GL_PREVIOUS);

  /* Replace the RGB in the second texture with that of the first
     texture */
  glTexEnvi (GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_REPLACE);
  glTexEnvi (GL_TEXTURE_ENV, GL_SRC0_RGB, GL_PREVIOUS);

  clutter_actor_get_allocation_box (actor, &alloc);

  meta_shaped_texture_set_coord_array (0, 0,
                                       CLUTTER_UNITS_TO_FLOAT (alloc.x2
                                                               - alloc.x1),
                                       CLUTTER_UNITS_TO_FLOAT (alloc.y2
                                                               - alloc.y1),
                                       vertex_coords);

  if ((guint) paint_gl_width == tex_width
      && (guint) paint_gl_height == tex_height)
    meta_shaped_texture_set_coord_array (0.0f, 0.0f, 1.0f, 1.0f,
                                         paint_tex_coords);
  else
    meta_shaped_texture_set_coord_array (0.0f, 0.0f,
                                         tex_width
                                         / (GLfloat) paint_gl_width,
                                         tex_height
                                         / (GLfloat) paint_gl_height,
                                         paint_tex_coords);

  glDrawArrays (GL_TRIANGLE_STRIP, 0, 4);

  /* Disable the second texture unit and coord array */
  glDisable (GL_TEXTURE_2D);
  glDisableClientState (GL_TEXTURE_COORD_ARRAY);

  /* Go back to operating on the first texture unit */
  tst_active_texture (GL_TEXTURE0);
  tst_client_active_texture (GL_TEXTURE0);

  /* Restore the old state */
  if (!texture_was_enabled)
    glDisable (GL_TEXTURE_2D);
  if (!blend_was_enabled)
    glDisable (GL_BLEND);
  if (!vertex_array_was_enabled)
    glDisableClientState (GL_VERTEX_ARRAY);
  if (!tex_coord_array_was_enabled)
    glDisableClientState (GL_TEXTURE_COORD_ARRAY);
  if (color_array_was_enabled)
    glEnableClientState (GL_COLOR_ARRAY);
}

static void
meta_shaped_texture_pick (ClutterActor *actor,
                          const ClutterColor *color)
{
  MetaShapedTexture *stex = (MetaShapedTexture *) actor;
  MetaShapedTexturePrivate *priv = stex->priv;

  /* If there are no rectangles then use the regular pick */
  if (priv->rectangles->len < 1
      || !meta_shaped_texture_is_multi_tex_supported ())
    CLUTTER_ACTOR_CLASS (meta_shaped_texture_parent_class)
      ->pick (actor, color);
  else if (clutter_actor_should_pick_paint (actor))
    {
      CoglHandle paint_tex;
      ClutterActorBox alloc;

      paint_tex = clutter_texture_get_cogl_texture (CLUTTER_TEXTURE (stex));

      if (paint_tex == COGL_INVALID_HANDLE)
        return;

      meta_shaped_texture_ensure_mask (stex);

      cogl_color (color);

      clutter_actor_get_allocation_box (actor, &alloc);

      /* Paint the mask rectangle in the given color */
      cogl_texture_rectangle (priv->mask_texture,
                              0, 0,
                              CLUTTER_UNITS_TO_FIXED (alloc.x2 - alloc.x1),
                              CLUTTER_UNITS_TO_FIXED (alloc.y2 - alloc.y1),
                              0, 0, CFX_ONE, CFX_ONE);
    }
}

ClutterActor *
meta_shaped_texture_new (void)
{
  ClutterActor *self = g_object_new (META_TYPE_SHAPED_TEXTURE, NULL);

  return self;
}

void
meta_shaped_texture_clear_rectangles (MetaShapedTexture *stex)
{
  MetaShapedTexturePrivate *priv;

  g_return_if_fail (META_IS_SHAPED_TEXTURE (stex));

  priv = stex->priv;

  g_array_set_size (priv->rectangles, 0);
  meta_shaped_texture_dirty_mask (stex);
  clutter_actor_queue_redraw (CLUTTER_ACTOR (stex));
}

void
meta_shaped_texture_add_rectangle (MetaShapedTexture *stex,
                                   const ClutterGeometry *rect)
{
  g_return_if_fail (META_IS_SHAPED_TEXTURE (stex));

  meta_shaped_texture_add_rectangles (stex, 1, rect);
}

void
meta_shaped_texture_add_rectangles (MetaShapedTexture *stex,
                                    size_t num_rects,
                                    const ClutterGeometry *rects)
{
  MetaShapedTexturePrivate *priv;

  g_return_if_fail (META_IS_SHAPED_TEXTURE (stex));

  priv = stex->priv;

  g_array_append_vals (priv->rectangles, rects, num_rects);

  meta_shaped_texture_dirty_mask (stex);
  clutter_actor_queue_redraw (CLUTTER_ACTOR (stex));
}