fbf58140eb
The existing usage of the mask value was as interpolation variable, which is a different usage. If we werent doing this, trying to paint with tool opacity to 100 and a paint dynamics changing opacity, we'd still have 100% opaque pixels instead of lowered opacity.
140 lines
4.8 KiB
C
140 lines
4.8 KiB
C
/* GIMP - The GNU Image Manipulation Program
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* Copyright (C) 1995 Spencer Kimball and Peter Mattis
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*
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* gimpoperationoverwrite.c
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* Copyright (C) 2025 Woynert <woynertgamer@gmail.com>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#include "config.h"
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#include <gegl-plugin.h>
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#include "../operations-types.h"
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#include "gimpoperationoverwrite.h"
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static gboolean
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gimp_operation_overwrite_process (GeglOperation *op,
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void *in,
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void *layer,
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void *mask,
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void *out,
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glong samples,
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const GeglRectangle *roi,
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gint level);
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G_DEFINE_TYPE (GimpOperationOverwrite, gimp_operation_overwrite,
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GIMP_TYPE_OPERATION_LAYER_MODE)
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static void
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gimp_operation_overwrite_class_init (GimpOperationOverwriteClass *klass)
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{
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GeglOperationClass *operation_class = GEGL_OPERATION_CLASS (klass);
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GimpOperationLayerModeClass *layer_mode_class = GIMP_OPERATION_LAYER_MODE_CLASS (klass);
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gegl_operation_class_set_keys (operation_class,
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"name", "gimp:overwrite",
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"description", "GIMP overwrite mode operation",
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NULL);
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layer_mode_class->process = gimp_operation_overwrite_process;
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}
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static void
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gimp_operation_overwrite_init (GimpOperationOverwrite *self)
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{
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}
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static gboolean
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gimp_operation_overwrite_process (GeglOperation *op,
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void *in_p,
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void *layer_p,
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void *mask_p,
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void *out_p,
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glong samples,
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const GeglRectangle *roi,
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gint level)
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{
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GimpOperationLayerMode *layer_mode = (gpointer) op;
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gfloat *in = in_p;
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gfloat *out = out_p;
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gfloat *layer = layer_p;
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gfloat *mask = mask_p;
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gfloat opacity = layer_mode->opacity;
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const gboolean has_mask = mask != NULL;
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gfloat mask_value;
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gfloat layer_alpha;
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switch (layer_mode->composite_mode)
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{
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case GIMP_LAYER_COMPOSITE_UNION:
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case GIMP_LAYER_COMPOSITE_AUTO:
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while (samples--)
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{
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if (has_mask)
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mask_value = *(mask++);
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else
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mask_value = 1.0;
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layer_alpha = layer[ALPHA] * opacity * mask_value;
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if (layer_alpha > 0.0f)
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{
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gint b;
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/* We still interpolate both the alpha and RGB channels,
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* using the mask value which gives us smoother transition
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* in paintbrush style tools while the pencil tool
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* provides hard pixel replacement as expected.
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*
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* Note that mask_value is used both as part of
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* layer_alpha and as interpolation variable. This is on
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* purpose because we are interpolating between the
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* input's opacity and the applied one (based on layer
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* opacity, tool opacity and mask value). In particular,
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* without this, painting with dynamics changing opacity
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* could not lower the pixel's opacity.
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*/
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out[ALPHA] = in[ALPHA] + mask_value * (layer_alpha - in[ALPHA]);
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for (b = RED; b < ALPHA; b++)
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out[b] = in[b] + mask_value * (layer[b] - in[b]);
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}
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else
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{
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gint b;
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for (b = RED; b <= ALPHA; b++)
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out[b] = in[b];
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}
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in += 4;
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layer += 4;
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out += 4;
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}
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break;
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case GIMP_LAYER_COMPOSITE_CLIP_TO_BACKDROP:
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case GIMP_LAYER_COMPOSITE_CLIP_TO_LAYER:
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case GIMP_LAYER_COMPOSITE_INTERSECTION:
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g_return_val_if_reached (FALSE);
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}
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return TRUE;
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}
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