forked from AuroraMiddleware/gtk
cd3f24d579
Previously, the unpremultiplied values from the GdkRGBA were taken. Now we premultiply the color values as specified by the CSS specs. This is only relevant when transitioning with translucent colors. An example is the halfway transition between transparent (0, 0, 0, 0) and white (1, 1, 1, 1). Previously, all 4 values where transitioned separately and the result was semi-transparent gray (0.5, 0.5, 0.5, 0.5). By depending on the alpha value, the result is now semi-transparent white (1, 1, 1, 0.5) which is what one would naively expect. New reftest: color-transition
128 lines
3.6 KiB
C
128 lines
3.6 KiB
C
/* GTK - The GIMP Toolkit
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* Copyright (C) 2011 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "config.h"
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#include "gtkcssrgbavalueprivate.h"
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#include "gtkcssstylepropertyprivate.h"
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#include "gtkstylecontextprivate.h"
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struct _GtkCssValue {
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GTK_CSS_VALUE_BASE
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GdkRGBA rgba;
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};
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static void
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gtk_css_value_rgba_free (GtkCssValue *value)
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{
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g_slice_free (GtkCssValue, value);
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}
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static GtkCssValue *
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gtk_css_value_rgba_compute (GtkCssValue *value,
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guint property_id,
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GtkStyleProviderPrivate *provider,
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GtkCssStyle *style,
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GtkCssStyle *parent_style)
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{
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return _gtk_css_value_ref (value);
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}
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static gboolean
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gtk_css_value_rgba_equal (const GtkCssValue *rgba1,
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const GtkCssValue *rgba2)
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{
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return gdk_rgba_equal (&rgba1->rgba, &rgba2->rgba);
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}
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static inline double
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transition (double start,
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double end,
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double progress)
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{
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return start + (end - start) * progress;
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}
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static GtkCssValue *
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gtk_css_value_rgba_transition (GtkCssValue *start,
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GtkCssValue *end,
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guint property_id,
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double progress)
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{
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GdkRGBA result;
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progress = CLAMP (progress, 0, 1);
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result.alpha = transition (start->rgba.alpha, end->rgba.alpha, progress);
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if (result.alpha <= 0.0)
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{
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result.red = result.green = result.blue = 0.0;
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}
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else
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{
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result.red = transition (start->rgba.red * start->rgba.alpha,
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end->rgba.red * end->rgba.alpha,
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progress) / result.alpha;
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result.green = transition (start->rgba.green * start->rgba.alpha,
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end->rgba.green * end->rgba.alpha,
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progress) / result.alpha;
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result.blue = transition (start->rgba.blue * start->rgba.alpha,
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end->rgba.blue * end->rgba.alpha,
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progress) / result.alpha;
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}
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return _gtk_css_rgba_value_new_from_rgba (&result);
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}
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static void
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gtk_css_value_rgba_print (const GtkCssValue *rgba,
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GString *string)
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{
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char *s = gdk_rgba_to_string (&rgba->rgba);
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g_string_append (string, s);
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g_free (s);
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}
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static const GtkCssValueClass GTK_CSS_VALUE_RGBA = {
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gtk_css_value_rgba_free,
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gtk_css_value_rgba_compute,
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gtk_css_value_rgba_equal,
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gtk_css_value_rgba_transition,
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gtk_css_value_rgba_print
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};
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GtkCssValue *
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_gtk_css_rgba_value_new_from_rgba (const GdkRGBA *rgba)
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{
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GtkCssValue *value;
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g_return_val_if_fail (rgba != NULL, NULL);
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value = _gtk_css_value_new (GtkCssValue, >K_CSS_VALUE_RGBA);
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value->rgba = *rgba;
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return value;
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}
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const GdkRGBA *
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_gtk_css_rgba_value_get_rgba (const GtkCssValue *rgba)
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{
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g_return_val_if_fail (rgba->class == >K_CSS_VALUE_RGBA, NULL);
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return &rgba->rgba;
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}
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