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mutter/clutter/pango/cogl-pango-render.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 Matthew Allum <mallum@openedhand.com>
*
* Copyright (C) 2008 OpenedHand
*
* 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
#ifndef PANGO_ENABLE_BACKEND
#define PANGO_ENABLE_BACKEND 1
#endif
#include <pango/pango-fontmap.h>
#include <pango/pangocairo.h>
#include <pango/pango-renderer.h>
#include <cairo.h>
#include "cogl-pango-private.h"
#include "cogl-pango-glyph-cache.h"
#include "cogl-pango-display-list.h"
struct _CoglPangoRenderer
{
PangoRenderer parent_instance;
/* The material used to texture from the glyph cache with */
CoglHandle glyph_material;
/* The material used for solid fills. (boxes, rectangles + trapezoids) */
CoglHandle solid_material;
/* Caches of glyphs as textures */
CoglPangoGlyphCache *glyph_cache;
/* The current display list that is being built */
CoglPangoDisplayList *display_list;
};
struct _CoglPangoRendererClass
{
PangoRendererClass class_instance;
};
typedef struct _CoglPangoRendererQdata CoglPangoRendererQdata;
/* An instance of this struct gets attached to each PangoLayout to
cache the VBO and to detect changes to the layout */
struct _CoglPangoRendererQdata
{
/* The cache of the geometry for the layout */
CoglPangoDisplayList *display_list;
/* A reference to the first line of the layout. This is just used to
detect changes */
PangoLayoutLine *first_line;
};
static void
cogl_pango_renderer_draw_glyph (CoglPangoRenderer *priv,
CoglPangoGlyphCacheValue *cache_value,
float x1,
float y1)
{
float x2, y2;
g_return_if_fail (priv->display_list != NULL);
x2 = x1 + (float) cache_value->draw_width;
y2 = y1 + (float) cache_value->draw_height;
_cogl_pango_display_list_add_texture (priv->display_list,
cache_value->texture,
x1, y1, x2, y2,
cache_value->tx1,
cache_value->ty1,
cache_value->tx2,
cache_value->ty2);
}
static void cogl_pango_renderer_finalize (GObject *object);
static void cogl_pango_renderer_draw_glyphs (PangoRenderer *renderer,
PangoFont *font,
PangoGlyphString *glyphs,
int x,
int y);
static void cogl_pango_renderer_draw_rectangle (PangoRenderer *renderer,
PangoRenderPart part,
int x,
int y,
int width,
int height);
static void cogl_pango_renderer_draw_trapezoid (PangoRenderer *renderer,
PangoRenderPart part,
double y1,
double x11,
double x21,
double y2,
double x12,
double x22);
G_DEFINE_TYPE (CoglPangoRenderer, cogl_pango_renderer, PANGO_TYPE_RENDERER);
static void
cogl_pango_renderer_init (CoglPangoRenderer *priv)
{
priv->glyph_material = cogl_material_new ();
/* The default combine mode of materials is to modulate (A x B) the texture
* RGBA channels with the RGBA channels of the previous layer (which in our
* case is just the font color)
*
* Since the RGB for an alpha texture is defined as 0, this gives us:
*
* result.rgb = color.rgb * 0
* result.a = color.a * texture.a
*
* What we want is premultiplied rgba values:
*
* result.rgba = color.rgb * texture.a
* result.a = color.a * texture.a
*/
cogl_material_set_layer_combine (priv->glyph_material, 0, /* layer */
"RGBA = MODULATE (PREVIOUS, TEXTURE[A])",
NULL);
priv->solid_material = cogl_material_new ();
priv->glyph_cache = cogl_pango_glyph_cache_new ();
_cogl_pango_renderer_set_use_mipmapping (priv, FALSE);
}
static void
cogl_pango_renderer_class_init (CoglPangoRendererClass *klass)
{
GObjectClass *object_class = G_OBJECT_CLASS (klass);
PangoRendererClass *renderer_class = PANGO_RENDERER_CLASS (klass);
object_class->finalize = cogl_pango_renderer_finalize;
renderer_class->draw_glyphs = cogl_pango_renderer_draw_glyphs;
renderer_class->draw_rectangle = cogl_pango_renderer_draw_rectangle;
renderer_class->draw_trapezoid = cogl_pango_renderer_draw_trapezoid;
}
static void
cogl_pango_renderer_finalize (GObject *object)
{
CoglPangoRenderer *priv = COGL_PANGO_RENDERER (object);
cogl_pango_glyph_cache_free (priv->glyph_cache);
G_OBJECT_CLASS (cogl_pango_renderer_parent_class)->finalize (object);
}
static CoglPangoRenderer *
cogl_pango_get_renderer_from_context (PangoContext *context)
{
PangoFontMap *font_map;
PangoRenderer *renderer;
CoglPangoFontMap *font_map_priv;
font_map = pango_context_get_font_map (context);
g_return_val_if_fail (COGL_PANGO_IS_FONT_MAP (font_map), NULL);
font_map_priv = COGL_PANGO_FONT_MAP (font_map);
renderer = cogl_pango_font_map_get_renderer (font_map_priv);
g_return_val_if_fail (COGL_PANGO_IS_RENDERER (renderer), NULL);
return COGL_PANGO_RENDERER (renderer);
}
static GQuark
cogl_pango_render_get_qdata_key (void)
{
static GQuark key = 0;
if (G_UNLIKELY (key == 0))
key = g_quark_from_static_string ("CoglPangoDisplayList");
return key;
}
static void
cogl_pango_render_qdata_destroy (CoglPangoRendererQdata *qdata)
{
if (qdata->display_list)
_cogl_pango_display_list_free (qdata->display_list);
if (qdata->first_line)
pango_layout_line_unref (qdata->first_line);
g_slice_free (CoglPangoRendererQdata, qdata);
}
/**
* cogl_pango_render_layout_subpixel:
* @layout: a #PangoLayout
* @x: FIXME
* @y: FIXME
* @color: color to use when rendering the layout
* @flags: flags to pass to the renderer
*
* FIXME
*
* Since: 1.0
*/
void
cogl_pango_render_layout_subpixel (PangoLayout *layout,
int x,
int y,
const CoglColor *color,
int flags)
{
PangoContext *context;
CoglPangoRenderer *priv;
CoglPangoRendererQdata *qdata;
context = pango_layout_get_context (layout);
priv = cogl_pango_get_renderer_from_context (context);
if (G_UNLIKELY (!priv))
return;
qdata = g_object_get_qdata (G_OBJECT (layout),
cogl_pango_render_get_qdata_key ());
if (qdata == NULL)
{
qdata = g_slice_new0 (CoglPangoRendererQdata);
g_object_set_qdata_full (G_OBJECT (layout),
cogl_pango_render_get_qdata_key (),
qdata,
(GDestroyNotify)
cogl_pango_render_qdata_destroy);
}
/* Check if the layout has changed since the last build of the
display list. This trick was suggested by Behdad Esfahbod here:
http://mail.gnome.org/archives/gtk-i18n-list/2009-May/msg00019.html */
if (qdata->display_list && qdata->first_line
&& qdata->first_line->layout != layout)
{
_cogl_pango_display_list_free (qdata->display_list);
qdata->display_list = NULL;
}
if (qdata->display_list == NULL)
{
qdata->display_list = _cogl_pango_display_list_new ();
priv->display_list = qdata->display_list;
pango_renderer_draw_layout (PANGO_RENDERER (priv), layout, 0, 0);
priv->display_list = NULL;
}
cogl_push_matrix ();
cogl_translate (x / (gfloat) PANGO_SCALE, y / (gfloat) PANGO_SCALE, 0);
_cogl_pango_display_list_render (qdata->display_list,
color,
priv->glyph_material,
priv->solid_material);
cogl_pop_matrix ();
/* Keep a reference to the first line of the layout so we can detect
changes */
if (qdata->first_line)
{
pango_layout_line_unref (qdata->first_line);
qdata->first_line = NULL;
}
if (pango_layout_get_line_count (layout) > 0)
{
qdata->first_line = pango_layout_get_line (layout, 0);
pango_layout_line_ref (qdata->first_line);
}
}
/**
* cogl_pango_render_layout:
* @layout: a #PangoLayout
* @x: X coordinate to render the layout at
* @y: Y coordinate to render the layout at
* @color: color to use when rendering the layout
* @flags: flags to pass to the renderer
*
* Renders @layout.
*
* Since: 1.0
*/
void
cogl_pango_render_layout (PangoLayout *layout,
int x,
int y,
const CoglColor *color,
int flags)
{
cogl_pango_render_layout_subpixel (layout,
x * PANGO_SCALE,
y * PANGO_SCALE,
color,
flags);
}
/**
* cogl_pango_render_layout_line:
* @line: a #PangoLayoutLine
* @x: X coordinate to render the line at
* @y: Y coordinate to render the line at
* @color: color to use when rendering the line
*
* Renders @line at the given coordinates using the given color.
*
* Since: 1.0
*/
void
cogl_pango_render_layout_line (PangoLayoutLine *line,
int x,
int y,
const CoglColor *color)
{
PangoContext *context;
CoglPangoRenderer *priv;
context = pango_layout_get_context (line->layout);
priv = cogl_pango_get_renderer_from_context (context);
if (G_UNLIKELY (!priv))
return;
priv->display_list = _cogl_pango_display_list_new ();
pango_renderer_draw_layout_line (PANGO_RENDERER (priv), line, x, y);
_cogl_pango_display_list_render (priv->display_list,
color,
priv->glyph_material,
priv->solid_material);
_cogl_pango_display_list_free (priv->display_list);
priv->display_list = NULL;
}
void
_cogl_pango_renderer_clear_glyph_cache (CoglPangoRenderer *renderer)
{
cogl_pango_glyph_cache_clear (renderer->glyph_cache);
}
void
_cogl_pango_renderer_set_use_mipmapping (CoglPangoRenderer *renderer,
gboolean value)
{
if (value)
cogl_material_set_layer_filters (renderer->glyph_material, 0,
COGL_MATERIAL_FILTER_LINEAR_MIPMAP_LINEAR,
COGL_MATERIAL_FILTER_LINEAR);
else
cogl_material_set_layer_filters (renderer->glyph_material, 0,
COGL_MATERIAL_FILTER_LINEAR,
COGL_MATERIAL_FILTER_LINEAR);
}
gboolean
_cogl_pango_renderer_get_use_mipmapping (CoglPangoRenderer *renderer)
{
const GList *layers = cogl_material_get_layers (renderer->glyph_material);
g_return_val_if_fail (layers != NULL, FALSE);
return (cogl_material_layer_get_min_filter (layers->data)
== COGL_MATERIAL_FILTER_LINEAR_MIPMAP_LINEAR);
}
static CoglPangoGlyphCacheValue *
cogl_pango_renderer_get_cached_glyph (PangoRenderer *renderer,
PangoFont *font,
PangoGlyph glyph)
{
CoglPangoRenderer *priv = COGL_PANGO_RENDERER (renderer);
CoglPangoGlyphCacheValue *value;
value = cogl_pango_glyph_cache_lookup (priv->glyph_cache, font, glyph);
if (value == NULL)
{
cairo_surface_t *surface;
cairo_t *cr;
cairo_scaled_font_t *scaled_font;
PangoRectangle ink_rect;
cairo_glyph_t cairo_glyph;
pango_font_get_glyph_extents (font, glyph, &ink_rect, NULL);
pango_extents_to_pixels (&ink_rect, NULL);
surface = cairo_image_surface_create (CAIRO_FORMAT_A8,
ink_rect.width,
ink_rect.height);
cr = cairo_create (surface);
scaled_font = pango_cairo_font_get_scaled_font (PANGO_CAIRO_FONT (font));
cairo_set_scaled_font (cr, scaled_font);
cairo_glyph.x = -ink_rect.x;
cairo_glyph.y = -ink_rect.y;
/* The PangoCairo glyph numbers directly map to Cairo glyph
numbers */
cairo_glyph.index = glyph;
cairo_show_glyphs (cr, &cairo_glyph, 1);
cairo_destroy (cr);
cairo_surface_flush (surface);
/* Copy the glyph to the cache */
value =
cogl_pango_glyph_cache_set (priv->glyph_cache, font, glyph,
cairo_image_surface_get_data (surface),
cairo_image_surface_get_width (surface),
cairo_image_surface_get_height (surface),
cairo_image_surface_get_stride (surface),
ink_rect.x, ink_rect.y);
cairo_surface_destroy (surface);
COGL_NOTE (PANGO, "cache fail %i", glyph);
}
else
COGL_NOTE (PANGO, "cache success %i", glyph);
return value;
}
void
cogl_pango_ensure_glyph_cache_for_layout (PangoLayout *layout)
{
PangoContext *context;
PangoRenderer *renderer;
PangoLayoutIter *iter;
g_return_if_fail (PANGO_IS_LAYOUT (layout));
if ((iter = pango_layout_get_iter (layout)) == NULL)
return;
context = pango_layout_get_context (layout);
renderer =
PANGO_RENDERER (cogl_pango_get_renderer_from_context (context));
do
{
PangoLayoutLine *line;
GSList *l;
line = pango_layout_iter_get_line_readonly (iter);
for (l = line->runs; l; l = l->next)
{
PangoLayoutRun *run = l->data;
PangoGlyphString *glyphs = run->glyphs;
int i;
for (i = 0; i < glyphs->num_glyphs; i++)
{
PangoGlyphInfo *gi = &glyphs->glyphs[i];
cogl_pango_renderer_get_cached_glyph (renderer,
run->item->analysis.font,
gi->glyph);
}
}
}
while (pango_layout_iter_next_line (iter));
pango_layout_iter_free (iter);
}
static void
cogl_pango_renderer_set_color_for_part (PangoRenderer *renderer,
PangoRenderPart part)
{
PangoColor *pango_color = pango_renderer_get_color (renderer, part);
CoglPangoRenderer *priv = COGL_PANGO_RENDERER (renderer);
if (pango_color)
{
CoglColor color;
cogl_color_set_from_4ub (&color,
pango_color->red >> 8,
pango_color->green >> 8,
pango_color->blue >> 8,
0xff);
_cogl_pango_display_list_set_color_override (priv->display_list, &color);
}
else
_cogl_pango_display_list_remove_color_override (priv->display_list);
}
static void
cogl_pango_renderer_draw_box (PangoRenderer *renderer,
int x,
int y,
int width,
int height)
{
CoglPangoRenderer *priv = COGL_PANGO_RENDERER (renderer);
g_return_if_fail (priv->display_list != NULL);
_cogl_pango_display_list_add_rectangle (priv->display_list,
x,
y - height,
x + width,
y);
}
static void
cogl_pango_renderer_get_device_units (PangoRenderer *renderer,
int xin,
int yin,
float *xout,
float *yout)
{
const PangoMatrix *matrix;
if ((matrix = pango_renderer_get_matrix (renderer)))
{
/* Convert user-space coords to device coords */
*xout = ((xin * matrix->xx + yin * matrix->xy)
/ PANGO_SCALE + matrix->x0);
*yout = ((yin * matrix->yy + xin * matrix->yx)
/ PANGO_SCALE + matrix->y0);
}
else
{
*xout = PANGO_PIXELS (xin);
*yout = PANGO_PIXELS (yin);
}
}
static void
cogl_pango_renderer_draw_rectangle (PangoRenderer *renderer,
PangoRenderPart part,
int x,
int y,
int width,
int height)
{
CoglPangoRenderer *priv = COGL_PANGO_RENDERER (renderer);
float x1, x2, y1, y2;
g_return_if_fail (priv->display_list != NULL);
cogl_pango_renderer_set_color_for_part (renderer, part);
cogl_pango_renderer_get_device_units (renderer,
x, y,
&x1, &y1);
cogl_pango_renderer_get_device_units (renderer,
x + width, y + height,
&x2, &y2);
_cogl_pango_display_list_add_rectangle (priv->display_list,
x1, y1, x2, y2);
}
static void
cogl_pango_renderer_draw_trapezoid (PangoRenderer *renderer,
PangoRenderPart part,
double y1,
double x11,
double x21,
double y2,
double x12,
double x22)
{
CoglPangoRenderer *priv = COGL_PANGO_RENDERER (renderer);
float points[8];
g_return_if_fail (priv->display_list != NULL);
points[0] = (x11);
points[1] = (y1);
points[2] = (x12);
points[3] = (y2);
points[4] = (x22);
points[5] = points[3];
points[6] = (x21);
points[7] = points[1];
cogl_pango_renderer_set_color_for_part (renderer, part);
_cogl_pango_display_list_add_trapezoid (priv->display_list,
y1,
x11,
x21,
y2,
x12,
x22);
}
static void
cogl_pango_renderer_draw_glyphs (PangoRenderer *renderer,
PangoFont *font,
PangoGlyphString *glyphs,
int xi,
int yi)
{
CoglPangoRenderer *priv = (CoglPangoRenderer *) renderer;
CoglPangoGlyphCacheValue *cache_value;
int i;
cogl_pango_renderer_set_color_for_part (renderer,
PANGO_RENDER_PART_FOREGROUND);
for (i = 0; i < glyphs->num_glyphs; i++)
{
PangoGlyphInfo *gi = glyphs->glyphs + i;
float x, y;
cogl_pango_renderer_get_device_units (renderer,
xi + gi->geometry.x_offset,
yi + gi->geometry.y_offset,
&x, &y);
if ((gi->glyph & PANGO_GLYPH_UNKNOWN_FLAG))
{
PangoFontMetrics *metrics;
if (font == NULL ||
(metrics = pango_font_get_metrics (font, NULL)) == NULL)
{
cogl_pango_renderer_draw_box (renderer,
x,
y,
PANGO_UNKNOWN_GLYPH_WIDTH,
PANGO_UNKNOWN_GLYPH_HEIGHT);
}
else
{
cogl_pango_renderer_draw_box (renderer,
x,
y,
metrics->approximate_char_width
/ PANGO_SCALE,
metrics->ascent / PANGO_SCALE);
pango_font_metrics_unref (metrics);
}
}
else
{
/* Get the texture containing the glyph. This will create
the cache entry if there isn't already one */
cache_value =
cogl_pango_renderer_get_cached_glyph (renderer,
font,
gi->glyph);
if (cache_value == NULL)
cogl_pango_renderer_draw_box (renderer,
x,
y,
PANGO_UNKNOWN_GLYPH_WIDTH,
PANGO_UNKNOWN_GLYPH_HEIGHT);
else
{
float width, height;
x += (float)(cache_value->draw_x);
y += (float)(cache_value->draw_y);
width = x + (float)(cache_value->draw_width);
height = y + (float)(cache_value->draw_height);
cogl_pango_renderer_draw_glyph (priv, cache_value, x, y);
}
}
xi += gi->geometry.width;
}
}
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