Display preset RGB values in a panel (and call function when clicked)

Have a look into How do i create Palette UI object and How to get a specific color/slot from a Color Palette

Quickly combined the code of both answers to display 50 random generated colors and their rgb values directly on the panel. Notice that Alpha is not supported, PaletteColor is a float array of 3 items: https://docs.blender.org/api/current/bpy.types.PaletteColor.html#bpy.types.PaletteColor

Minor changes to @batFINGERs code from: How do i create Palette UI object

import bpy class PaletteDemoPanel(bpy.types.Panel): """Creates a Panel in the tool panel of image editor""" bl_label = "Palette Demo" bl_idname = "MATERIAL_PT_palette" bl_space_type = 'VIEW_3D' bl_region_type = 'UI' def draw(self, context): layout = self.layout ts = context.tool_settings palette = ts.image_paint.palette sel_r, sel_g, sel_b = palette.colors.active.color if ts.image_paint.palette: layout.template_palette(ts.image_paint, "palette", color=True) layout.label(text="Active Color: {:.2f} {:.2f} {:.2f}".format( sel_r, sel_g, sel_b)) def register(): bpy.utils.register_class(PaletteDemoPanel) def unregister(): bpy.utils.unregister_class(PaletteDemoPanel) if __name__ == "__main__": register() # Add a new pallete pal = bpy.data.palettes.get("CustomPalette") if pal is None: pal = bpy.data.palettes.new("CustomPalette") # Add a single color red = pal.colors.new() red.color = (1, 0, 0) # Add random colors to the palette from random import random for i in range(50): col = pal.colors.new() col.color = (random(), random(), random()) # Make red the active/selected color pal.colors.active = red ts = bpy.context.tool_settings ts.image_paint.palette = pal 

If you want somewhat similar without all the extra elements coming with template_palette() IE +-, a fixed list and also execute an operator when the user clicks one of the colors... you can implement some sort of dynamic operator for all colors, and display only the icon on the panel.

Example script using some of the default icons (If you want to use custom icons, have a look into: How to implement custom icons for my script/addon?).

import bpy colors = { 0: {"Color": (0.3, 0.3, 0.3, 1.0), "Icon": 'COLORSET_01_VEC'}, 1: {"Color": (0.5, 0.4, 0.5, 1.0), "Icon": 'COLORSET_02_VEC'}, 2: {"Color": (1.0, 0.4, 0.5, 1.0), "Icon": 'COLORSET_08_VEC'}, } class SimpleOperator(bpy.types.Operator): """Tooltip""" bl_idname = "object.simple_operator" bl_label = "Simple Object Operator" color: bpy.props.FloatVectorProperty( name = "Color Picker", subtype = "COLOR", size = 4) def execute(self, context): context.scene.active_color = self.color print(self.color[0], self.color[1], self.color[2], self.color[3]) return {'FINISHED'} class HelloWorldPanel(bpy.types.Panel): """Creates a Panel in the Object properties window""" bl_label = "Hello World Panel" bl_idname = "OBJECT_PT_hello" bl_space_type = 'PROPERTIES' bl_region_type = 'WINDOW' bl_context = "object" def draw(self, context): layout = self.layout row = layout.column_flow(columns=18) for k, v in colors.items(): p = row.operator(SimpleOperator.bl_idname, text="", icon=v.get("Icon")) p.color = v.get("Color") r, g, b, a = context.scene.active_color layout.row().label(text=f"Active Color: {r:.2f}, {g:.2f}, {b:.2f}, {a:.2f}") def register(): bpy.utils.register_class(SimpleOperator) bpy.utils.register_class(HelloWorldPanel) bpy.types.Scene.active_color = bpy.props.FloatVectorProperty( name = "Color Picker", subtype = "COLOR", default = (1.0,1.0,1.0,1.0), size = 4) def unregister(): bpy.utils.unregister_class(HelloWorldPanel) bpy.utils.unregister_class(SimpleOperator) del bpy.Scene.active_color if __name__ == "__main__": register() 

UI code comes from Could I see a simple example of using a color picker in a script?

To refute claims in the comments, it works with custom icons (32x32 px) representing the colors as expected:

Another approach to achieve a very similar result and trigger an event is to use a series of BoolProperties (as elements of a collection) which also allows to have an active item.

The principle is the same as in my prevoius answer using operators. You can display the BoolProperty only as an icon and generate the icons for the colors on the fly by adding a new preview collection (as you normally would do for custom icons) and then assigning a pixel array of the color to each new icon added: https://docs.blender.org/api/current/bpy.types.ImagePreview.html

Example of a color palette using BoolProperties and assigning the selected color to the object's diffuse color property using the update function (make sure viewport shading is set to solid).

import bpy import bpy.utils.previews from random import uniform class HelloWorldPanel(bpy.types.Panel): """Creates a Panel in the Object properties window""" bl_label = "Hello World Panel" bl_idname = "OBJECT_PT_hello" bl_space_type = 'PROPERTIES' bl_region_type = 'WINDOW' bl_context = "object" def draw(self, context): layout = self.layout scn = context.scene col = layout.column(align=True) row = col.row(align=True) active_item = None for idx, item in enumerate(scn.color_collection, start=1): row.prop(item, "active", icon_value=item.icon, icon_only=True) if item.active == True: active_item = item if idx % 11 == 0: row = col.row(align=True) if active_item: row = layout.row() r, g, b, a = active_item.color row.label(text=f"Active item: {r:.2f} {g:.2f} {b:.2f} {a:.2f}") def random_rbga(alpha=1): return (uniform(0, 1), uniform(0, 1), uniform(0, 1), alpha) def update_callback(self, context): if self.active: for i in self.id_data.color_collection: if i.name != self.name: i.active = False # set the diffuse color obj = context.object obj.active_material.diffuse_color = self.color class ColorCollection(bpy.types.PropertyGroup): # name: bpy.props.StringProperty active: bpy.props.BoolProperty(default=False, update=update_callback) icon: bpy.props.IntProperty() color: bpy.props.FloatVectorProperty( name = "Color", subtype = "COLOR", default = (1.0,1.0,1.0,1.0), size = 4) # We can store multiple preview collections here, # however in this example we only store "main" preview_collections = {} def register(): # register the classes bpy.utils.register_class(HelloWorldPanel) bpy.utils.register_class(ColorCollection) bpy.types.Scene.color_collection = bpy.props.CollectionProperty(type=ColorCollection) # clear the collection if hasattr(bpy.context.scene, "color_collection"): bpy.context.scene.color_collection.clear() # generate colors and icons pcoll = bpy.utils.previews.new() size = 32, 32 for i in range(32): color_name = f"Color{i}" color = random_rbga(alpha=1) pixels = [*color] * size[0] * size[1] icon = pcoll.new(color_name) # name has to be unique! icon.icon_size = size icon.is_icon_custom = True icon.icon_pixels_float = pixels # add the item to the collection color_item = bpy.context.scene.color_collection.add() color_item.name = color_name color_item.color = color color_item.icon = pcoll[color_name].icon_id preview_collections["main"] = pcoll def unregister(): for pcoll in preview_collections.values(): bpy.utils.previews.remove(pcoll) preview_collections.clear() bpy.utils.unregister_class(ColorCollection) bpy.utils.unregister_class(HelloWorldPanel) del bpy.types.Scene.color_collection if __name__ == "__main__": register()