I have a TFrame with some components on it, and among all it I have a TPanel and a TPaintBox such that the PaintBox size is the same as the Panel.
I would like that user will see the Panel and not only the PaintBox.
The problem is that when I right click on the Panel and choose Control->Send to Back, it doesn't work.
Any assumption, or suggestion for solution?
*I am working with Borland C++Builder 6.
TPaintBox is a TGraphicControl descendant. It has no HWND of its own, it simply draws on its Parent when the Parent is painted. As such, a TPanel (which has an HWND of its own) can never appear behind a TPaintBox unless the TPaintBox is a child of the TPanel.
Related
I made a graphical component which ancestor has to be TGraphiccontrol because I need to paint to the canvas.
Now I want to convert this component to an activex control but that seems to be only possible when the component is a descendant from TWincontrol.
How do I solve this problem?
It is incorrect that you must only use a TGraphicControl in order to paint. Base your control on TCustomControl instead. This provides you with a canvas which you can use the same way, and is inherited from the TWinControl.
Is it possible to paint a TProgressBar on a TSpeedButton, behind text and icon ?
I have no idea how to get started on this (assuming it's possible).
How would I go about it ?
In this particular case I use the button to start and stop a process, and it would be nice to display the process in that button as well.
No, this is not possible with the standard TSpeedButton without creating your own descendant.
TSpeedButton does all of its drawing in response to the WM_PAINT message, and there is no way for you to inject another control behind the content that is drawn, because the drawing would erase the area where your control is drawing itself. You can see this yourself; you have the source code for TSpeedButton in almost every Delphi and C++ Builder version.
In addition, a TSpeedButton is a graphical control, not a windowed control (it derives from TGraphicControl instead of TWinControl), so it does not have a window handle to be used as the parent for other controls.
I am attempting to develop my first proper custom control for the Firemonkey framework and have ran into what may possibly be an obvious (or not) solution.
Inside my Firemonkey control I have declared FPanel: TPanel; which is then created in the constructor and freed in the destructor. The panel is created along with my control when I add it to a new Multi-Device Form without any problems.
By default the TPanel has borders around the sides of the control which I do not need in my control.
So my question is, what is the ideal way to remove the borders of a TPanel which is child to my custom control? I could not see an obvious property to change, unless I am mistaking I believe we must modify the style of the panel which I assume would be done via a TStyleBook.
Am I right then in thinking that I need to add a TStyleBook to my control, and from there add the panel to the Style book and modify it this way? Unless I am missing something this seems like a lot of extra work for what should be a very quick and simple change.
Assuming this is the correct way, is there an example of modifying a TStyleBook through code?
Thanks.
Because all Firemonkey controls can be parents, one way is to not use TPanel at all and instead replace it with another Firemonkey control such as the TRectangle shape.
The TRectangle shape can then be customised directly through its properties to remove the border which can be achieved by setting the Corners and Sides to False.
Additionally if you don't require any borders whatsoever then the TLayout control behaves just like a TPanel but without the borders.
I have a generic VCL ActiveX Form with a TScrollBox on it. The TScrollBox does not get the OnMouseWheel message when I insert the control into a container. When I create the same control hierarchy in a normal VCL application, the TScrollBox does get the OnMouseWheel as expected.
Is there something special I have to do to receive mouse wheel messages in an ActiveX Form (C++ or Delphi) or does this just not work?
To thwart the nit-pickers, let me start with, I searched here with this and could not find an answer, and yes, also I did scroll through the "Similar questions."...
Adding shortcuts to a TForm
I want to drag and drop some shortcuts from the Desktop to a TForm in my application. I am using Anders Melander's brilliant Drag Drop Suite (DDS).
I tried putting a TImage on the form but the DDS does not drop to an Image so I added a TPanel with a TImage on it. I could then drop on the panel and assign the image to the TImage.Picture. Problem was the Panel has no Transparent Property so the shortcut on the form looks clunky with the visible Panel behind it.
I need to be able to drop to the TImage or make the underlying TPanel transparent.
Can anyone help with code-snippets for either of those options, or better yet, a method of dropping a Shortcut directly on to my Form.
Thanks
Coincidentally I needed to make a TWinControl (the base for every visible control with a window handle, including TPanel) transparent. I found numerous results and applied them to this answer.
It's been a while since I implemented drag and drop, but I assume you call some API and pass it the handle of the panel? That answers the question why you can't use TImage. TImage is a graphic control, a control without a handle, that relies on its parent for recieving messages and drawing itself.
It should be possible to use the form, though, since that has a handle too.
If the TImage is directly on the TForm, then let the TForm handle the drop, no TPanel needed. OLE Drag&Drop operations (which Ander's components implement) provide coordinates where dragging and dropping occurs. The TForm should be able to detect when a drag is over the area occupied by the TImage and what type of data is being dragged, and only allow dropping of supported types within that area, extracting the dropped data and updating the TImageas needed, and denying anything else that does not match that criteria.