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gsk: Support hue interpolation in cairo
Since cairos gradient code isn't flexible enough to let us interpolate in oklch, add additional color stops and let cairo interpolate in the ccs. This isn't as accurate as interpolating in oklch, but it gets an ok result for fallback situations.
This commit is contained in:
Matthias Clasen
parent
4de67b2fe5
commit
df31bbf9e5
@ -358,6 +358,140 @@ gsk_linear_gradient_node_finalize (GskRenderNode *node)
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parent_class->finalize (node);
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}
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static float
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adjust_hue (GskHueInterpolation interp,
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float h1,
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float h2)
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{
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float d;
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d = h2 - h1;
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while (d > 360)
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{
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h2 -= 360;
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d = h2 - h1;
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}
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while (d < -360)
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{
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h2 += 360;
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d = h2 - h1;
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}
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g_assert (fabsf (d) <= 360);
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switch (interp)
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{
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case GSK_HUE_INTERPOLATION_SHORTER:
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{
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if (d > 180)
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h2 -= 360;
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else if (d < -180)
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h2 += 360;
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}
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g_assert (fabsf (h2 - h1) <= 180);
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break;
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case GSK_HUE_INTERPOLATION_LONGER:
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{
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if (0 < d && d < 180)
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h2 -= 360;
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else if (-180 < d && d <= 0)
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h2 += 360;
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g_assert (fabsf (h2 - h1) >= 180);
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}
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break;
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case GSK_HUE_INTERPOLATION_INCREASING:
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if (h2 < h1)
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h2 += 360;
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d = h2 - h1;
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g_assert (h1 <= h2);
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break;
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case GSK_HUE_INTERPOLATION_DECREASING:
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if (h1 < h2)
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h2 -= 360;
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d = h2 - h1;
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g_assert (h1 >= h2);
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break;
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default:
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g_assert_not_reached ();
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}
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return h2;
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}
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#define lerp(t,a,b) ((a) + (t) * ((b) - (a)))
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typedef void (* ColorStopCallback) (float offset,
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GdkColorState *ccs,
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float values[4],
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gpointer data);
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static void
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interpolate_color_stops (GdkColorState *ccs,
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GdkColorState *interpolation,
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GskHueInterpolation hue_interpolation,
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float offset1,
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GdkColor *color1,
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float offset2,
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GdkColor *color2,
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ColorStopCallback callback,
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gpointer data)
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{
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float values1[4];
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float values2[4];
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int n;
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gdk_color_to_float (color1, interpolation, values1);
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gdk_color_to_float (color2, interpolation, values2);
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if (gdk_color_state_equal (interpolation, GDK_COLOR_STATE_OKLCH))
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{
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values2[2] = adjust_hue (hue_interpolation, values1[2], values2[2]);
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/* don't make hue steps larger than 30° */
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n = ceilf (fabsf (values2[2] - values1[2]) / 30);
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}
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else
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{
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/* just some steps */
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n = 4;
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}
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for (int k = 1; k < n; k++)
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{
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float f = k / (float) n;
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float values[4];
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float offset;
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GdkColor c;
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values[0] = lerp (f, values1[0], values2[0]);
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values[1] = lerp (f, values1[1], values2[1]);
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values[2] = lerp (f, values1[2], values2[2]);
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values[3] = lerp (f, values1[3], values2[3]);
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offset = lerp (f, offset1, offset2);
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gdk_color_init (&c, interpolation, values);
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gdk_color_to_float (&c, ccs, values);
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callback (offset, ccs, values, data);
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gdk_color_finish (&c);
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}
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}
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static void
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add_color_stop_to_pattern (float offset,
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GdkColorState *ccs,
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float values[4],
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gpointer data)
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{
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cairo_pattern_t *pattern = data;
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cairo_pattern_add_color_stop_rgba (pattern, offset, values[0], values[1], values[2], values[3]);
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}
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static void
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gsk_linear_gradient_node_draw (GskRenderNode *node,
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cairo_t *cr,
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@ -378,18 +512,42 @@ gsk_linear_gradient_node_draw (GskRenderNode *node,
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ccs,
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0.0,
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&self->stops[0].color);
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for (i = 0; i < self->n_stops; i++)
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{
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if (!gdk_color_state_equal (self->interpolation, ccs))
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interpolate_color_stops (ccs,
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self->interpolation, self->hue_interpolation,
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i > 0 ? self->stops[i-1].offset : 0,
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i > 0 ? &self->stops[i-1].color : &self->stops[i].color,
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self->stops[i].offset,
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&self->stops[i].color,
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add_color_stop_to_pattern,
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pattern);
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gdk_cairo_pattern_add_color_stop_color (pattern,
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ccs,
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self->stops[i].offset,
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&self->stops[i].color);
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}
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if (self->stops[self->n_stops-1].offset < 1.0)
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gdk_cairo_pattern_add_color_stop_color (pattern,
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ccs,
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1.0,
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&self->stops[self->n_stops - 1].color);
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{
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if (!gdk_color_state_equal (self->interpolation, ccs))
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interpolate_color_stops (ccs,
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self->interpolation, self->hue_interpolation,
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self->stops[self->n_stops-1].offset,
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&self->stops[self->n_stops-1].color,
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1,
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&self->stops[self->n_stops-1].color,
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add_color_stop_to_pattern,
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pattern);
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gdk_cairo_pattern_add_color_stop_color (pattern,
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ccs,
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1.0,
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&self->stops[self->n_stops-1].color);
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}
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cairo_set_source (cr, pattern);
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cairo_pattern_destroy (pattern);
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@ -925,18 +1083,42 @@ gsk_radial_gradient_node_draw (GskRenderNode *node,
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ccs,
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0.0,
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&self->stops[0].color);
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for (i = 0; i < self->n_stops; i++)
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{
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if (!gdk_color_state_equal (self->interpolation, ccs))
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interpolate_color_stops (ccs,
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self->interpolation, self->hue_interpolation,
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i > 0 ? self->stops[i-1].offset : 0,
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i > 0 ? &self->stops[i-1].color : &self->stops[i].color,
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self->stops[i].offset,
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&self->stops[i].color,
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add_color_stop_to_pattern,
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pattern);
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gdk_cairo_pattern_add_color_stop_color (pattern,
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ccs,
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self->stops[i].offset,
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&self->stops[i].color);
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}
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if (self->stops[self->n_stops-1].offset < 1.0)
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gdk_cairo_pattern_add_color_stop_color (pattern,
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ccs,
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1.0,
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&self->stops[self->n_stops-1].color);
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{
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if (!gdk_color_state_equal (self->interpolation, ccs))
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interpolate_color_stops (ccs,
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self->interpolation, self->hue_interpolation,
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self->stops[self->n_stops-1].offset,
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&self->stops[self->n_stops-1].color,
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1,
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&self->stops[self->n_stops-1].color,
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add_color_stop_to_pattern,
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pattern);
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gdk_cairo_pattern_add_color_stop_color (pattern,
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ccs,
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1.0,
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&self->stops[self->n_stops-1].color);
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}
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gdk_cairo_rect (cr, &node->bounds);
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cairo_translate (cr, self->center.x, self->center.y);
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@ -1623,6 +1805,29 @@ gdk_rgba_color_interpolate (GdkRGBA *dest,
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}
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}
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static void
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add_color_stop_to_array (float offset,
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GdkColorState *ccs,
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float values[4],
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gpointer data)
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{
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GArray *stops = data;
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GskColorStop2 stop;
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stop.offset = offset;
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gdk_color_init (&stop.color, ccs, values);
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g_array_append_val (stops, stop);
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}
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static void
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clear_stop (gpointer data)
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{
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GskColorStop2 *stop = data;
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gdk_color_finish (&stop->color);
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}
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static void
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gsk_conic_gradient_node_draw (GskRenderNode *node,
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cairo_t *cr,
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@ -1633,6 +1838,7 @@ gsk_conic_gradient_node_draw (GskRenderNode *node,
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graphene_point_t corner;
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float radius;
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gsize i;
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GArray *stops;
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pattern = cairo_pattern_create_mesh ();
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graphene_rect_get_top_right (&node->bounds, &corner);
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@ -1644,10 +1850,41 @@ gsk_conic_gradient_node_draw (GskRenderNode *node,
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graphene_rect_get_top_left (&node->bounds, &corner);
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radius = MAX (radius, graphene_point_distance (&self->center, &corner, NULL, NULL));
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for (i = 0; i <= self->n_stops; i++)
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stops = g_array_new (FALSE, TRUE, sizeof (GskColorStop2));
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g_array_set_clear_func (stops, clear_stop);
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if (gdk_color_state_equal (self->interpolation, ccs))
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{
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GskColorStop2 *stop1 = &self->stops[MAX (i, 1) - 1];
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GskColorStop2 *stop2 = &self->stops[MIN (i, self->n_stops - 1)];
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for (i = 0; i < self->n_stops; i++)
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{
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GskColorStop2 *stop = &self->stops[i];
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g_array_append_val (stops, *stop);
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/* take a ref, since clear_stop removes one */
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gdk_color_state_ref (stop->color.color_state);
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}
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}
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else
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{
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g_array_append_val (stops, self->stops[0]);
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for (i = 1; i < self->n_stops; i++)
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{
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interpolate_color_stops (ccs,
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self->interpolation, self->hue_interpolation,
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self->stops[i-1].offset, &self->stops[i-1].color,
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self->stops[i].offset, &self->stops[i].color,
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add_color_stop_to_array,
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stops);
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g_array_append_val (stops, self->stops[i]);
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/* take a ref, since clear_stop removes one */
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gdk_color_state_ref (self->stops[i].color.color_state);
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}
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}
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for (i = 0; i <= stops->len; i++)
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{
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GskColorStop2 *stop1 = &g_array_index (stops, GskColorStop2, MAX (i, 1) - 1);
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GskColorStop2 *stop2 = &g_array_index (stops, GskColorStop2, MIN (i, stops->len - 1));
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double offset1 = i > 0 ? stop1->offset : 0;
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double offset2 = i < self->n_stops ? stop2->offset : 1;
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double start_angle, end_angle;
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@ -1683,6 +1920,8 @@ gsk_conic_gradient_node_draw (GskRenderNode *node,
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}
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}
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g_array_unref (stops);
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cairo_pattern_set_extend (pattern, CAIRO_EXTEND_PAD);
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gdk_cairo_rect (cr, &node->bounds);
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