ComponentFactory.Krypton.Toolkit.KryptonCheckedListBox.OnListBoxDrawItem C# (CSharp) Method

        private void OnListBoxDrawItem(object sender, DrawItemEventArgs e)
        {
            // We cannot do anything with an invalid index
            if (e.Index < 0)
                return;

            // Update our content object with values from the list item
            UpdateContentFromItemIndex(e.Index);

            // By default the button is in the normal state
            PaletteState buttonState = PaletteState.Normal;

            // Is this item disabled
            if ((e.State & DrawItemState.Disabled) == DrawItemState.Disabled)
                buttonState = PaletteState.Disabled;
            else
            {
                // Is the mouse over the item about to be drawn
                bool mouseOver = (e.Index >= 0) && (e.Index == _listBox.MouseIndex);

                // If selected then show as a checked item
                if ((e.State & DrawItemState.Selected) == DrawItemState.Selected)
                {
                    if (SelectionMode == CheckedSelectionMode.None)
                        _drawButton.Checked = false;
                    else
                    {
                        _drawButton.Checked = true;
                        buttonState = (mouseOver ? PaletteState.CheckedTracking : PaletteState.CheckedNormal);
                    }
                }
                else
                {
                    _drawButton.Checked = false;
                    if (mouseOver && (SelectionMode != CheckedSelectionMode.None))
                        buttonState = PaletteState.Tracking;
                }

                // Do we need to show item as having the focus
                bool hasFocus = false;
                if (((e.State & DrawItemState.Focus) == DrawItemState.Focus) &&
                    ((e.State & DrawItemState.NoFocusRect) != DrawItemState.NoFocusRect))
                    hasFocus = true;

                _overrideNormal.Apply = hasFocus;
                _overrideTracking.Apply = hasFocus;
                _overridePressed.Apply = hasFocus;
                _overrideCheckedTracking.Apply = hasFocus;
                _overrideCheckedNormal.Apply = hasFocus;
                _overrideCheckedPressed.Apply = hasFocus;
            }

            // Update the view with the calculated state
            _drawButton.ElementState = buttonState;

            // Update check box to show correct checked image
            _drawCheckBox.CheckState = GetItemCheckState(e.Index);

            // Grab the raw device context for the graphics instance
            IntPtr hdc = e.Graphics.GetHdc();

            try
            {
                // Create bitmap that all drawing occurs onto, then we can blit it later to remove flicker
                IntPtr hBitmap = PI.CreateCompatibleBitmap(hdc, e.Bounds.Right, e.Bounds.Bottom);

                // If we managed to get a compatible bitmap
                if (hBitmap != IntPtr.Zero)
                {
                    try
                    {
                        // Must use the screen device context for the bitmap when drawing into the
                        // bitmap otherwise the Opacity and RightToLeftLayout will not work correctly.
                        PI.SelectObject(_screenDC, hBitmap);

                        // Easier to draw using a graphics instance than a DC!
                        using (Graphics g = Graphics.FromHdc(_screenDC))
                        {
                            // Ask the view element to layout in given space, needs this before a render call
                            using (ViewLayoutContext context = new ViewLayoutContext(this, Renderer))
                            {
                                context.DisplayRectangle = e.Bounds;
                                _listBox.ViewDrawPanel.Layout(context);
                                _layoutDocker.Layout(context);
                            }

                            // Ask the view element to actually draw
                            using (RenderContext context = new RenderContext(this, g, e.Bounds, Renderer))
                            {
                                _listBox.ViewDrawPanel.Render(context);
                                _layoutDocker.Render(context);
                            }

                            // Now blit from the bitmap from the screen to the real dc
                            PI.BitBlt(hdc, e.Bounds.X, e.Bounds.Y, e.Bounds.Width, e.Bounds.Height, _screenDC, e.Bounds.X, e.Bounds.Y, PI.SRCCOPY);
                        }
                    }
                    finally
                    {
                        // Delete the temporary bitmap
                        PI.DeleteObject(hBitmap);
                    }
                }
            }
            finally
            {
                // Must reserve the GetHdc() call before
                e.Graphics.ReleaseHdc();
            }
        }