ownerdrawn

This question is related to my earlier question on SO. I want to combine two layers with alpha applied only to a specific portion of the source layer. One way I tried was to set SourceConstantAlpha to $ff (and have the function use the alpha channel in the source layer). This kind of works - although slow (I guess I can speed it up by using ScanLines), the kind of part is that I cannot figure out what to set the alpha channel to. The documentation suggests that the calculation is: st.Red = Src.Red + (1 - Src.Alpha) * Dst.Red I have tried a few different values by guess work, but my first

I'm using a TComboBox component with the style property set to csOwnerDrawFixed , I implement the OnDrawItem And everything works fine, Now I want which the combobox to behave like when had the csDropDown style (with the csOwnerDrawFixed style behaves like the csDropDownList style) , I mean with a inner editor. is this possible? Delphi's TComboBox wrapper doesn't support an owner draw editable style, but the underlying Windows control does, and it's easy to enable it. Create a new descendant class like so: TComboBox = class(StdCtrls.TComboBox) public procedure CreateParams(var Params:

This question might be considered a follow-up to Flickering in listview with ownerdraw and virtualmode . I've got a ListView control in Virtual mode and I attempt to perform custom drawing. Item rendering is done via the following method override: protected override void OnDrawItem(DrawListViewItemEventArgs eventArgs) As mentioned in the referenced question, custom drawing introduces flickering on mouse over events. Debugger tells me this happens due to an excessive amount of custom draw events which are fired. Now - the accepted answer to the referenced question tells us: This is a bug in

I'm trying to make a trackbar with a custom graphic for the slider thumb. I have started out with the following code: namespace testapp { partial class MyTrackBar : System.Windows.Forms.TrackBar { public MyTrackBar() { InitializeComponent(); } protected override void OnPaint(System.Windows.Forms.PaintEventArgs e) { // base.OnPaint(e); e.Graphics.FillRectangle(System.Drawing.Brushes.DarkSalmon, ClientRectangle); } } } But it never calls OnPaint. Anyone else come across this? I have used this technique before to create an ownerdraw button but for some reason it doesn't work with TrackBar. PS.

I'm doing custom TTreeView drawing from scratch using OnAdvancedCustomDrawItem event, and I wonder how to render these selection and hot rectangles correctly in the background of my owner-draw items? They are Vista/7 styled so I cannot simply fill the background in some solid color. I tried to draw my items at cdPostPaint stage, but if I leave DefaultDraw := True at cdPrePaint stage to draw selection background, the complete default drawing occurs, including text of items. procedure TForm1.TreeView1AdvancedCustomDrawItem(Sender: TCustomTreeView; Node: TTreeNode; State: TCustomDrawState; Stage: