KryptonThemeListView / theme previews

Overview

Issue #3870 adds preview images for custom palettes so KryptonThemeListView can show them in Large Icon, Tile, Small Icon, and Details views.

Custom palettes persist KryptonCustomPaletteBase.Thumbnail as base64 PNG in .kthemex (issue #2117). Palette Designer and Theme Browser Export write a generated window mock-up into that property on save. If a custom palette has no thumbnail, the list view uses the Stable Kr tile.

Package: Krypton.Toolkit.

Architecture

Palette Designer save / Theme Browser Export
        │
        ▼
KryptonThemePreview.AssignGeneratedThumbnail(customPalette)
        │  64×64 window mock-up from ColorTable + HeaderForm / PanelClient / ButtonStandalone
        ▼
KryptonCustomPaletteBase.Thumbnail  →  .kthemex / .ktheme persist
        │
        ▼
KryptonThemeListView
        │  stored Thumbnail → KryptonPaletteFile.CreateThemeIcon (Kr overlay)
        │  no Thumbnail (custom) → Kr tile alone
        │  builtin theme → generated mock-up + Kr overlay
        ▼
LargeImageList 48×48 / SmallImageList 16×16

KryptonThemePreview.Create paints without showing a form. KryptonThemePreview.Resolve is the selector lookup.

Public API

  • KryptonThemeListView — KryptonListView + IKryptonThemeSelectorBase. DefaultPalette, ShowExtraThemes, ShowThemePreviews (default true), LivePreviewOnHover (default true). Default View is LargeIcon. Image lists are owned by the control.
  • KryptonThemePreview.Create(PaletteBase, Size|int) — new bitmap; caller disposes.
  • KryptonThemePreview.AssignGeneratedThumbnail(KryptonCustomPaletteBase) — replaces Thumbnail (disposes the previous image).
  • KryptonThemePreview.Resolve(themeName, localCustom, generateWhenMissing) — stored custom thumbnail, else generated builtin mock-up, else null (Kr tile).
  • ThemeManager.TryCreateRegisteredTheme — factory peek without applying globally.

Usage

Drop KryptonThemeListView next to KryptonThemeComboBox / KryptonThemeListBox. Switch View to LargeIcon, Tile, or Details to see previews.

Register a custom theme with a stored preview:

ThemeManager.RegisterCustomTheme("My Theme", () =>
{
    var palette = new KryptonCustomPaletteBase();
    palette.Import(@"C:\Themes\MyTheme.kthemex", silent: true);
    return palette;
});

To embed a preview from code (same as Palette Designer save):

KryptonThemePreview.AssignGeneratedThumbnail(palette);
palette.Export(path, ignoreDefaults: true, silent: true);

Live hover preview

LivePreviewOnHover (default on) applies the theme under the pointer without changing the committed (clicked) selection. Leaving the list restores the last clicked theme. Click still commits. Set the property to false to turn it off.

Mouse events are hooked on the inner ListView, not the Krypton chrome. Apply is immediate on MouseMove when the hovered row changes (the same row is skipped). Empty space between icons keeps the last hovered preview.

Palette apply recreates the inner list handle. That path:

  • Ignores MouseLeave while RecreatingHandle is set, or while the pointer is still over the selector.
  • Ignores SelectedIndexChanged for the committed row while a hover preview is active, so recreate does not snap back to the clicked theme.

Do not enable HoverSelection; that would change the committed selection.

Palette Designer

On Save / Save As / save into a .ktheme collection, MainForm calls AssignGeneratedThumbnail before export so the file carries the mock-up.