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mutter/clutter/pango/cogl-pango-display-list.c
Owen W. Taylor c3448314d5 Default to a blend function that expects premultiplied colors 
Many operations, like mixing two textures together or alpha-blending
onto a destination with alpha, are done most logically if texture data
is in premultiplied form. We also have many sources of premultiplied
texture data, like X pixmaps, FBOs, cairo surfaces. Rather than trying
to work with two different types of texture data, simplify things by
always premultiplying texture data before uploading to GL.

Because the default blend function is changed to accommodate this,
uses of pure-color CoglMaterial need to be adapted to add
premultiplication.

gl/cogl-texture.c gles/cogl-texture.c: Always premultiply
  non-premultiplied texture data before uploading to GL.

cogl-material.c cogl-material.h: Switch the default blend functions
  to ONE, ONE_MINUS_SRC_ALPHA so they work correctly with premultiplied
  data.

cogl.c: Make cogl_set_source_color() premultiply the color.

cogl.h.in color-material.h: Add some documentation about
  premultiplication and its interaction with color values.

cogl-pango-render.c clutter-texture.c tests/interactive/test-cogl-offscreen.c:
  Use premultiplied colors.

http://bugzilla.openedhand.com/show_bug.cgi?id=1406

Signed-off-by: Robert Bragg <robert@linux.intel.com>
2009-06-11 14:17:52 +01:00

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/*
* Clutter.
*
* An OpenGL based 'interactive canvas' library.
*
* Authored By Neil Roberts <neil@linux.intel.com>
*
* Copyright (C) 2009 Intel Corporation.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <glib.h>
#include <cogl/cogl.h>
#include <string.h>
#include "cogl-pango-display-list.h"
typedef enum
{
COGL_PANGO_DISPLAY_LIST_TEXTURE,
COGL_PANGO_DISPLAY_LIST_RECTANGLE,
COGL_PANGO_DISPLAY_LIST_TRAPEZOID
} CoglPangoDisplayListNodeType;
typedef struct _CoglPangoDisplayListNode CoglPangoDisplayListNode;
typedef struct _CoglPangoDisplayListVertex CoglPangoDisplayListVertex;
struct _CoglPangoDisplayList
{
gboolean color_override;
CoglColor color;
GSList *nodes;
GSList *last_node;
};
struct _CoglPangoDisplayListNode
{
CoglPangoDisplayListNodeType type;
gboolean color_override;
CoglColor color;
union
{
struct
{
/* The texture to render these coords from */
CoglHandle texture;
/* Array of vertex data to render out of this texture */
GArray *verts;
/* A VBO representing those vertices */
CoglHandle vertex_buffer;
} texture;
struct
{
float x_1, y_1;
float x_2, y_2;
} rectangle;
struct
{
float y_1;
float x_11;
float x_21;
float y_2;
float x_12;
float x_22;
} trapezoid;
} d;
};
struct _CoglPangoDisplayListVertex
{
float x, y, t_x, t_y;
};
CoglPangoDisplayList *
_cogl_pango_display_list_new (void)
{
return g_slice_new0 (CoglPangoDisplayList);
}
static void
_cogl_pango_display_list_append_node (CoglPangoDisplayList *dl,
CoglPangoDisplayListNode *node)
{
if (dl->last_node)
dl->last_node = dl->last_node->next = g_slist_prepend (NULL, node);
else
dl->last_node = dl->nodes = g_slist_prepend (NULL, node);
}
void
_cogl_pango_display_list_set_color_override (CoglPangoDisplayList *dl,
const CoglColor *color)
{
dl->color_override = TRUE;
dl->color = *color;
}
void
_cogl_pango_display_list_remove_color_override (CoglPangoDisplayList *dl)
{
dl->color_override = FALSE;
}
void
_cogl_pango_display_list_add_texture (CoglPangoDisplayList *dl,
CoglHandle texture,
float x_1, float y_1,
float x_2, float y_2,
float tx_1, float ty_1,
float tx_2, float ty_2)
{
CoglPangoDisplayListNode *node;
CoglPangoDisplayListVertex *verts;
/* Add to the last node if it is a texture node with the same
target texture */
if (dl->last_node
&& (node = dl->last_node->data)->type == COGL_PANGO_DISPLAY_LIST_TEXTURE
&& node->d.texture.texture == texture
&& (dl->color_override
? (node->color_override && !memcmp (&dl->color, &node->color,
sizeof (CoglColor)))
: !node->color_override))
{
/* Get rid of the vertex buffer so that it will be recreated */
if (node->d.texture.vertex_buffer != COGL_INVALID_HANDLE)
{
cogl_vertex_buffer_unref (node->d.texture.vertex_buffer);
node->d.texture.vertex_buffer = COGL_INVALID_HANDLE;
}
}
else
{
/* Otherwise create a new node */
node = g_slice_new (CoglPangoDisplayListNode);
node->type = COGL_PANGO_DISPLAY_LIST_TEXTURE;
node->color_override = dl->color_override;
node->color = dl->color;
node->d.texture.texture = cogl_texture_ref (texture);
node->d.texture.verts
= g_array_new (FALSE, FALSE, sizeof (CoglPangoDisplayListVertex));
node->d.texture.vertex_buffer = COGL_INVALID_HANDLE;
_cogl_pango_display_list_append_node (dl, node);
}
g_array_set_size (node->d.texture.verts,
node->d.texture.verts->len + 4);
verts = &g_array_index (node->d.texture.verts,
CoglPangoDisplayListVertex,
node->d.texture.verts->len - 4);
verts->x = x_1;
verts->y = y_1;
verts->t_x = tx_1;
verts->t_y = ty_1;
verts++;
verts->x = x_1;
verts->y = y_2;
verts->t_x = tx_1;
verts->t_y = ty_2;
verts++;
verts->x = x_2;
verts->y = y_2;
verts->t_x = tx_2;
verts->t_y = ty_2;
verts++;
verts->x = x_2;
verts->y = y_1;
verts->t_x = tx_2;
verts->t_y = ty_1;
}
void
_cogl_pango_display_list_add_rectangle (CoglPangoDisplayList *dl,
float x_1, float y_1,
float x_2, float y_2)
{
CoglPangoDisplayListNode *node = g_slice_new (CoglPangoDisplayListNode);
node->type = COGL_PANGO_DISPLAY_LIST_RECTANGLE;
node->color_override = dl->color_override;
node->color = dl->color;
node->d.rectangle.x_1 = x_1;
node->d.rectangle.y_1 = y_1;
node->d.rectangle.x_2 = x_2;
node->d.rectangle.y_2 = y_2;
_cogl_pango_display_list_append_node (dl, node);
}
void
_cogl_pango_display_list_add_trapezoid (CoglPangoDisplayList *dl,
float y_1,
float x_11,
float x_21,
float y_2,
float x_12,
float x_22)
{
CoglPangoDisplayListNode *node = g_slice_new (CoglPangoDisplayListNode);
node->type = COGL_PANGO_DISPLAY_LIST_TRAPEZOID;
node->color_override = dl->color_override;
node->color = dl->color;
node->d.trapezoid.y_1 = y_1;
node->d.trapezoid.x_11 = x_11;
node->d.trapezoid.x_21 = x_21;
node->d.trapezoid.y_2 = y_2;
node->d.trapezoid.x_12 = x_12;
node->d.trapezoid.x_22 = x_22;
_cogl_pango_display_list_append_node (dl, node);
}
static void
_cogl_pango_display_list_render_texture (CoglHandle material,
const CoglColor *color,
CoglPangoDisplayListNode *node)
{
CoglColor premult_color = *color;
cogl_material_set_layer (material, 0, node->d.texture.texture);
cogl_color_premultiply (&premult_color);
cogl_material_set_color (material, &premult_color);
cogl_set_source (material);
if (node->d.texture.vertex_buffer == COGL_INVALID_HANDLE)
{
CoglHandle vb = cogl_vertex_buffer_new (node->d.texture.verts->len);
cogl_vertex_buffer_add (vb, "gl_Vertex", 2,
COGL_ATTRIBUTE_TYPE_FLOAT, FALSE,
sizeof (CoglPangoDisplayListVertex),
&g_array_index (node->d.texture.verts,
CoglPangoDisplayListVertex, 0).x);
cogl_vertex_buffer_add (vb, "gl_MultiTexCoord0", 2,
COGL_ATTRIBUTE_TYPE_FLOAT, FALSE,
sizeof (CoglPangoDisplayListVertex),
&g_array_index (node->d.texture.verts,
CoglPangoDisplayListVertex,
0).t_x);
cogl_vertex_buffer_submit (vb);
node->d.texture.vertex_buffer = vb;
}
#ifdef CLUTTER_COGL_HAS_GL
cogl_vertex_buffer_draw (node->d.texture.vertex_buffer,
GL_QUADS,
0, node->d.texture.verts->len);
#else /* CLUTTER_COGL_HAS_GL */
{
/* GLES doesn't support GL_QUADS so instead we use a VBO with
indexed vertices to generate GL_TRIANGLES from the quads */
int n_indices = node->d.texture.verts->len / 4 * 6;
CoglHandle indices_vbo
= cogl_vertex_buffer_indices_get_for_quads (n_indices);
cogl_vertex_buffer_draw_elements (node->d.texture.vertex_buffer,
COGL_VERTICES_MODE_TRIANGLES,
indices_vbo,
0, node->d.texture.verts->len - 1,
0, n_indices);
}
#endif /* CLUTTER_COGL_HAS_GL */
}
void
_cogl_pango_display_list_render (CoglPangoDisplayList *dl,
const CoglColor *color,
CoglHandle glyph_material,
CoglHandle solid_material)
{
GSList *l;
for (l = dl->nodes; l; l = l->next)
{
CoglPangoDisplayListNode *node = l->data;
CoglColor draw_color;
if (node->color_override)
/* Use the override color but preserve the alpha from the
draw color */
cogl_color_set_from_4ub (&draw_color,
cogl_color_get_red_byte (&node->color),
cogl_color_get_green_byte (&node->color),
cogl_color_get_blue_byte (&node->color),
cogl_color_get_alpha_byte (color));
else
draw_color = *color;
cogl_color_premultiply (&draw_color);
switch (node->type)
{
case COGL_PANGO_DISPLAY_LIST_TEXTURE:
_cogl_pango_display_list_render_texture (glyph_material,
&draw_color, node);
break;
case COGL_PANGO_DISPLAY_LIST_RECTANGLE:
cogl_material_set_color (solid_material, &draw_color);
cogl_set_source (solid_material);
cogl_rectangle (node->d.rectangle.x_1,
node->d.rectangle.y_1,
node->d.rectangle.x_2,
node->d.rectangle.y_2);
break;
case COGL_PANGO_DISPLAY_LIST_TRAPEZOID:
{
float points[8];
points[0] = node->d.trapezoid.x_11;
points[1] = node->d.trapezoid.y_1;
points[2] = node->d.trapezoid.x_12;
points[3] = node->d.trapezoid.y_2;
points[4] = node->d.trapezoid.x_22;
points[5] = node->d.trapezoid.y_2;
points[6] = node->d.trapezoid.x_21;
points[7] = node->d.trapezoid.y_1;
cogl_material_set_color (solid_material, &draw_color);
cogl_set_source (solid_material);
cogl_path_polygon (points, 4);
cogl_path_fill ();
}
break;
}
}
}
static void
_cogl_pango_display_list_node_free (CoglPangoDisplayListNode *node)
{
if (node->type == COGL_PANGO_DISPLAY_LIST_TEXTURE)
{
g_array_free (node->d.texture.verts, TRUE);
if (node->d.texture.texture != COGL_INVALID_HANDLE)
cogl_texture_unref (node->d.texture.texture);
if (node->d.texture.vertex_buffer != COGL_INVALID_HANDLE)
cogl_vertex_buffer_unref (node->d.texture.vertex_buffer);
}
g_slice_free (CoglPangoDisplayListNode, node);
}
void
_cogl_pango_display_list_clear (CoglPangoDisplayList *dl)
{
g_slist_foreach (dl->nodes, (GFunc) _cogl_pango_display_list_node_free, NULL);
g_slist_free (dl->nodes);
dl->nodes = NULL;
dl->last_node = NULL;
}
void
_cogl_pango_display_list_free (CoglPangoDisplayList *dl)
{
_cogl_pango_display_list_clear (dl);
g_slice_free (CoglPangoDisplayList, dl);
}
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