path: root/gst-libs/gst/cairo/gstcairobuffer.c

/* GStreamer
 * Copyright (C) 2009 Benjamin Otte <otte@gnome.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include "gstcairobuffer.h"

#include "gstcairobuffer-private.h"
#include "gstcairoformat-private.h"
#ifdef HAVE_XLIB
#  include "gstcairoxbuffer.h"
#endif

G_DEFINE_TYPE (GstCairoBuffer, gst_cairo_buffer, GST_TYPE_BUFFER)

     static void gst_cairo_buffer_finalize (GstMiniObject * object)
{
  GstCairoBuffer *cbuffer = GST_CAIRO_BUFFER (object);

  gst_cairo_format_free (cbuffer->format);

  GST_MINI_OBJECT_CLASS (gst_cairo_buffer_parent_class)->finalize (object);
}

static void
gst_cairo_buffer_class_init (GstCairoBufferClass * klass)
{
  GstMiniObjectClass *mini_object_class = GST_MINI_OBJECT_CLASS (klass);

  mini_object_class->finalize = gst_cairo_buffer_finalize;
}

static void
gst_cairo_buffer_init (GstCairoBuffer * buffer)
{
}

/**
 * gst_cairo_buffer_is_fixed:
 * @buffer: a buffer
 *
 * Checks if a buffer is fixed. Non-fixed buffers can change the format in
 * use. See gst_cairo_buffer_set_format() for examples of where this is
 * relevant.
 *
 * Returns: %TRUE if the format of the buffer can still be changed
 **/
gboolean
gst_cairo_buffer_is_fixed (GstBuffer * buffer)
{
  g_return_val_if_fail (GST_IS_BUFFER (buffer), TRUE);

  return !GST_IS_CAIRO_BUFFER (buffer) || GST_CAIRO_BUFFER (buffer)->fixed;
}

/**
 * gst_cairo_buffer_set_format:
 * @buffer: a buffer that is not fixed
 * @format: the format to use on @buffer
 *
 * Sets the format to use for a non-fixed buffer. This function is supposed
 * to be used in buffer allocation functions (see 
 * gst_pad_set_bufferalloc_function()) to update the format used by the 
 * buffer. This allows forwarding allocations of cairo buffers through a
 * pipeline even when the caps change.
 **/
void
gst_cairo_buffer_set_format (GstBuffer * buffer, const GstCairoFormat * format)
{
  GstCairoBuffer *cbuffer;

  g_return_if_fail (!gst_cairo_buffer_is_fixed (buffer));
  g_return_if_fail (format != NULL);
  g_return_if_fail (gst_cairo_format_is_native (format));

  cbuffer = GST_CAIRO_BUFFER (buffer);
  gst_cairo_format_free (cbuffer->format);
  cbuffer->format = gst_cairo_format_copy (format);
  GST_BUFFER_SIZE (cbuffer) = 4 * gst_cairo_format_get_width (format)
      * gst_cairo_format_get_height (format);
}

static cairo_surface_t *
gst_cairo_buffer_get_surface (GstCairoBuffer * cbuffer,
    cairo_surface_t * similar)
{
  GstCairoBufferClass *klass;
  cairo_surface_t *surface;

  klass = GST_CAIRO_BUFFER_GET_CLASS (cbuffer);
  surface = klass->get_surface (GST_BUFFER (cbuffer), similar, cbuffer->format);
  /* we only set fixed afterwards, so the get_surface() function can use
   * gst_cairo_buffer_is_fixed() to check if it's the first time it was 
   * called.
   */
  cbuffer->fixed = TRUE;
  return surface;
}

/**
 * gst_cairo_create_surface:
 * @buffer: buffer to create surface from
 * @format: format of the @buffer
 *
 * Creates a cairo surface from the given @buffer. The @buffer must conform 
 * to @format. You may only modify the surface and use it with 
 * cairo_create() if the @buffer is writable. Using it as a source for 
 * drawing operations is fine in all cases.
 *
 * Returns: A new surface referencing the contents of @buffer. 
 *          Use cairo_surface_destroy() after use.
 **/
cairo_surface_t *
gst_cairo_create_surface (GstBuffer * buffer, const GstCairoFormat * format)
{
  return gst_cairo_create_similar_surface (buffer, NULL, format);
}

/**
 * gst_cairo_create_similar_surface:
 * @buffer: buffer to create surface from
 * @surface: surface the returned surface should be similar to or %NULL if
 *           no similarities are desired
 * @format: format of the @buffer
 *
 * Creates a cairo surface from the given @buffer that is as similar as
 * possible to the given @surface. The @buffer must conform to @format.
 * You may only modify the surface and use it with cairo_create() if the 
 * @buffer is writable. Using it as a source for drawing operations is fine
 * in all cases.
 *
 * Returns: A new surface referencing the contents of buffer.
 *          Use cairo_surface_destroy() after use.
 **/
cairo_surface_t *
gst_cairo_create_similar_surface (GstBuffer * buffer,
    cairo_surface_t * surface, const GstCairoFormat * format)
{
  cairo_surface_t *result;

  g_return_val_if_fail (GST_IS_BUFFER (buffer), NULL);
  g_return_val_if_fail (format != NULL, NULL);

  if (GST_IS_CAIRO_BUFFER (buffer)) {
    GstCairoBuffer *cbuffer = GST_CAIRO_BUFFER (buffer);
    result = gst_cairo_buffer_get_surface (cbuffer, surface);
  } else {
    static cairo_user_data_key_t buffer_free;
    guint8 *data = GST_BUFFER_DATA (buffer);
    result =
        cairo_image_surface_create_with_pixman_format (data,
        gst_cairo_format_get_pixman_format (format),
        format->width, format->height,
        gst_cairo_format_get_stride (format, 0),
        data + gst_cairo_format_get_offset (format, 1),
        gst_cairo_format_get_stride (format, 1),
        data + gst_cairo_format_get_offset (format, 2),
        gst_cairo_format_get_stride (format, 2),
        data + gst_cairo_format_get_offset (format, 3),
        gst_cairo_format_get_stride (format, 3));
    gst_buffer_ref (buffer);
    cairo_surface_set_user_data (result, &buffer_free, buffer,
        (cairo_destroy_func_t) gst_buffer_unref);
  }

  return result;
}

/**
 * gst_cairo_buffer_new:
 * @format: format to create a buffer for
 *
 * This is a convenience function for fallback code. Creates a buffer 
 * of the correct size for the given format.
 *
 * <note>This function does never create any accelerated buffer. It 
 * always creates an image surface.</note>
 *
 * Returns: a new buffer
 **/
GstBuffer *
gst_cairo_buffer_new (const GstCairoFormat * format)
{
  g_return_val_if_fail (format != NULL, NULL);

  return gst_buffer_new_and_alloc (gst_cairo_format_get_buffer_size (format));
}

/**
 * gst_cairo_buffer_new_similar:
 * @surface: surface to create a buffer for
 * @format: format to create a buffer for
 *
 * Tries to create a buffer best suited for the given @format and output 
 * on @surface. This function tries to achieve highest possible performance
 * when later using the surface returned from FIXME: what function?
 * for rendering the buffer.
 * 
 * Usually, a special buffer will be created that will do all drawing 
 * operations using the same acceleration method as @surface. However, if this
 * can not be achieved because things like the @format or compile-time options
 * do not allow it, a fallback path is taken and a regular buffer will be
 * created.
 *
 * Returns: a new buffer
 **/
GstBuffer *
gst_cairo_buffer_new_similar (cairo_surface_t * surface,
    const GstCairoFormat * format)
{
  G_GNUC_UNUSED GstBuffer *buffer;

  g_return_val_if_fail (surface != NULL, NULL);
  g_return_val_if_fail (format != NULL, NULL);

  switch (cairo_surface_get_type (surface)) {
    case CAIRO_SURFACE_TYPE_XLIB:
#ifdef HAVE_XLIB
      buffer = gst_cairo_x_buffer_new (surface, format);
      if (buffer)
        return buffer;
#endif
      break;
    default:
      break;
  }

  return gst_cairo_buffer_new (format);
}