Rewrote preview functionality

Preview now operates *on the layer* with a backup buffer stored for
'clearing'. This is faster and allows 'persistant' previews via not
flushing during processing.

This is a BREAKING CHANGE, as now bsz_gimp_lib has a simple
"gegl_preview" arg that lets the app know the main function is a
'gegl op', aka works by modifying the current drawable's buffer.

Not quite ready for a new release. Gonna revise Pixel Math and work out
edge cases for the new preview system, as I already expect a few.

bsz-dualbloom/bsz-dualbloom.py

@@ -116,16 +116,6 @@ def dual_bloom(self, drawable, thresh_high, thresh_low,
         # }}}
 
 
-# Preview function. Just runs the same thing on a copy
-def dual_bloom_preview(image, drawable, *args):
-    # {{{
-    preview_layer = drawable.copy()
-    image.insert_layer(preview_layer, None, 0)
-    dual_bloom(image, preview_layer, *args)
-    return preview_layer
-    # }}}
-
-
 # Parameters from bsz_gimp_lib
 # {{{
 thresh_high = ParamNumber("Threshold High", 0.80, 0, 1,
@@ -174,7 +164,6 @@ def dual_bloom_preview(image, drawable, *args):
     description="Provides light and dark bloom using thresholds. \
 Based on my own custom bloom methods.",
     images="RGB*, GRAY*",
-    preview_function=dual_bloom_preview,
 )
 
 # register the plugin's Procedure class with gimp

bsz-dualbloom2/bsz-dualbloom2.py

@@ -106,16 +106,6 @@ def dual_bloom_2(image, drawable, amount_high, amount_low,
         # }}}
 
 
-# Preview function. Just runs the same thing on a copy
-def dual_bloom_2_preview(image, drawable, *args):
-    # {{{
-    preview_layer = drawable.copy()
-    image.insert_layer(preview_layer, None, 0)
-    dual_bloom_2(image, preview_layer, *args)
-    return preview_layer
-    # }}}
-
-
 # Parameters from bsz_gimp_lib
 # {{{
 amount_desc = "Glow-area brightness threshold"
@@ -162,7 +152,6 @@ def dual_bloom_2_preview(image, drawable, *args):
     description="Produces both a light and dark bloom. \
 Based on gimp/gegl's existing bloom.",
     images="RGB*, GRAY*",
-    preview_function=dual_bloom_2_preview,
 )
 
 # register the plugin's Procedure class with gimp

bsz-filmic-chroma/bsz-filmic-chroma.py

@@ -107,16 +107,6 @@ def filmic_chroma(image, drawable, scale, offset, invert):
         # }}}
 
 
-# Preview function. Just runs the same thing on a copy
-def filmic_chroma_preview(image, drawable, *args):
-    # {{{
-    preview_layer = drawable.copy()
-    image.insert_layer(preview_layer, None, 0)
-    filmic_chroma(image, preview_layer, *args)
-    return preview_layer
-    # }}}
-
-
 # create the plugin from bsz_gimp_lib
 plugin = PlugIn(
     "Filmic Chroma",  # name
@@ -129,7 +119,6 @@ def filmic_chroma_preview(image, drawable, *args):
     description="Reduces/increases chroma based on intensity.\n"
     "Inspired by Blender's new 'Filmic' tonemapper.",
     images="RGB*",
-    preview_function=filmic_chroma_preview,
 )
 
 # register the plugin's Procedure class with gimp

bsz-goat-exercise/bsz-goat-exercise.py

@@ -92,29 +92,6 @@ def goat_exercise_preview(image, drawable, *args):
     # }}}
 
 
-# Parameters from bsz_gimp_lib
-# {{{
-source_code = "Could not find source code."
-with open(os.path.realpath(__file__), mode='r', encoding='UTF-8') as f:
-    source_code = f.read()
-
-Source_Code_View = ParamString(
-    "Source Code",
-    source_code,
-    description="Source View. Not actually used in-script",
-    ui_multiline=True,
-    ui_min_height=900,
-    ui_min_width=900,
-)
-
-Brightness_Controller = ParamNumber(
-    "Brightness", 0, -1, 1,
-    description="Adjust the image's brightness after the inversion.",
-    ui_step=0.1,
-)
-# }}}
-
-
 # create the plugin from bsz_gimp_lib
 plugin = PlugIn(
     "BSZ Goat Exercise",  # name
@@ -126,7 +103,6 @@ def goat_exercise_preview(image, drawable, *args):
     description="Exercise a goat BSZ style.",
     images="*",
     path="<Image>/Filters/Development/Goat exercises/",
-    preview_function=goat_exercise_preview,
 )
 
 # register the plugin's Procedure class with gimp

bsz-lightgrain/bsz-lightgrain.py

@@ -103,16 +103,6 @@ def lightgrain(image, drawable, dulling, noise_l, noise_c, noise_h, invert):
         # }}}
 
 
-# Preview function. Just runs the same thing on a copy
-def lightgrain_preview(image, drawable, *args):
-    # {{{
-    preview_layer = drawable.copy()
-    image.insert_layer(preview_layer, None, 0)
-    lightgrain(image, preview_layer, *args)
-    return preview_layer
-    # }}}
-
-
 # create the plugin from bsz_gimp_lib
 plugin = PlugIn(
     "Lightgrain",  # name
@@ -129,7 +119,6 @@ def lightgrain_preview(image, drawable, *args):
     ParamBool("Invert", False),
     description="LCH Noise masked to Lightness.",
     images="RGB*, GRAY*",
-    preview_function=lightgrain_preview,
 )
 
 # register the plugin's Procedure class with gimp

bsz-pixel-math/bsz-pixel-math.py

@@ -79,16 +79,6 @@ def pixel_math(image, drawable, babl_format, code,):
         # }}}
 
 
-# Preview function. Just runs the same thing on a copy
-def pixel_math_preview(image, drawable, *args):
-    # {{{
-    preview_layer = drawable.copy()
-    image.insert_layer(preview_layer, None, 0)
-    pixel_math(image, preview_layer, *args)
-    return preview_layer
-    # }}}
-
-
 # create the plugin from bsz_gimp_lib
 plugin = PlugIn(
     "Pixel Math",  # name
@@ -103,7 +93,6 @@ def pixel_math_preview(image, drawable, *args):
                 ui_min_width=400),
     description="Enter custom Python algorithms for pixel math.",
     images="RGB*, GRAY*",
-    preview_function=pixel_math_preview,
 )
 
 # register the plugin's Procedure class with gimp

bsz_gimp_lib.py

@@ -8,8 +8,8 @@
 import gi
 gi.require_version('Gimp', '3.0')
 from gi.repository import Gimp
-# gi.require_version('Gegl', '0.4')
-# from gi.repository import Gegl
+gi.require_version('Gegl', '0.4')
+from gi.repository import Gegl
 from gi.repository import GObject
 from gi.repository import GLib
 # from gi.repository import Gio
@@ -439,7 +439,7 @@ class PlugIn():
     # Get & save properties
     def __init__(self, name: str, function: callable, *params: Param,
                  description: str, alt_description: str = None,
-                 preview_function: callable = None,
+                 gegl_preview: bool = True,
                  procedure_name: str = None, images: str = "RGB*",
                  path: str = "<Image>/Beinsezii/", icon=GimpUi.ICON_GEGL,
                  authors: str = "Beinsezii", copyright: str = None,
@@ -528,7 +528,7 @@ def do_create_procedure(self2, name2):
         self.name = name
         self.function = function
         self.params = params
-        self.preview_function = preview_function
+        self.gegl_preview = gegl_preview
         # }}}
 
     # I decided to name the function called by the PDB procedure 'run'
@@ -584,16 +584,33 @@ def reset_fn(widget):
                     param.ui_reset()
             reset_button = bszgw.Button("Reset", reset_fn)
 
-            self.preview_layers = []
+            Gegl.init(None)
+            self.buffer = drawable.get_buffer().dup()
+            self.has_preview = False
+            self.flush = False
 
             # if any preview layers, delete them and thaw
             # TODO: hide base layers when preview is up
             def clear_preview(*args):
                 # {{{
-                if self.preview_layers:
-                    for layer in self.preview_layers:
-                        image.remove_layer(layer)
-                    self.preview_layers = []
+                if self.has_preview:
+                    # self.drawable.buffer = self.buffer
+                    intersect, x, y, width, height = drawable.mask_intersect()
+                    if intersect:
+                        Gegl.init(None)
+                        tree = Gegl.Node()
+                        target = drawable.get_buffer()
+                        Input = tree.create_child("gegl:buffer-source")
+                        Input.set_property("buffer", self.buffer)
+                        Output = tree.create_child("gegl:write-buffer")
+                        Output.set_property("buffer", target)
+                        Input.link(Output)
+                        Output.process()
+                        if self.flush:
+                            target.flush()
+                        drawable.update(x, y, width, height)
+                        Gimp.displays_flush()
+                        self.has_preview = False
                 while not image.undo_is_enabled():
                     image.undo_thaw()
                 # }}}
@@ -602,26 +619,25 @@ def clear_preview(*args):
             # self.preview_function and add them to self.preview_layers
             def preview_fn(*args):
                 # {{{
-                if self.preview_function is not None:
+                if self.gegl_preview:
                     clear_preview()
                     if preview_check.value:
                         image.undo_freeze()
-                        result = self.preview_function(
-                            image, drawable,
-                            *ui_vals())
-                        if isinstance(result, Gimp.Layer):
-                            self.preview_layers.append(result)
-                        elif isinstance(result, list):
-                            self.preview_layers += result
+                        self.function(image, drawable, *ui_vals())
+                        self.has_preview = True
                 # }}}
 
             # creates preview_check, starts the live preview thread,
             # and has the widgets connect to function
             preview_thread = PreviewThread(preview_fn)
             preview_thread.start()
-            if self.preview_function is not None:
+            if self.gegl_preview:
                 # {{{
                 preview_check = bszgw.CheckButton("'Live' Preview", True)
+
+                def onclick(*args):
+                    self.flush = not preview_check.value
+                preview_check.connect("clicked", onclick)
                 preview_check.connect("clicked", preview_fn)
                 for param in self.params:
                     param.connect_preview(preview_thread.request_preview)
@@ -660,6 +676,7 @@ def preview_fn(*args):
             # clear preview on destroy
             def destroy_fn(*args):
                 preview_thread.stop()
+                self.flush = True
                 clear_preview()
             app.connect("destroy", destroy_fn)