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Questions tagged [vcl]

This tag is used for questions regarding the Visual Component Library used in Borland/CodeGear/Embarcadero Delphi and C++Builder products as well as Python GUI apps. Do not confuse this with the Varnish Configuration Language (VCL). Use the "varnish-vcl" tag for questions related to that product.

Visual Component Library is a visual component-based object-oriented framework tightly integrated with Delphi and C++Builder. It's also available for Python as a GUI framework.

VCL components cover visual and non-visual components like:

  • Windows common controls
  • Database access components
  • Internet connection components

The component approach allows programmers to extend easily the VCL.

Resources:

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Delphi - form within form

For aesthetic reasons, I want to show a form on top of another form, just as if it were a component, say like a TPanel. It should resize with the parent, move around as the parent is dragged by its title bar, etc. ----------------------------- |…
Mawg says reinstate Monica
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Why RegisterClass fails with ERROR_NOT_ENOUGH_MEMORY?

Shortly, my question is, why can WinAPI RegisterClass fail with ERROR_NOT_ENOUGH_MEMORY, when there is a lot of memory free, and what can I do to prevent it? Background: I'm developing an application (WinSCP FTP/SFTP client) that many people use for…
Martin Prikryl
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How to fix TPageControl Background Color without losing the system theme?

In a Delphi 2010 application with themes enabled I have two TPageControls (one inside the other) in a Form with a clMoneyGreen Background: The outer page control correctly draw its background with the color of the parent component, the inner page…
Daniel Santos
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Ctrl+Backspace in Delphi Controls

the Ctrl+Backspace keyboard shortcut normally deletes the word to the left from the caret. But it does not work in any of the standard Delphi controls you would expect (TEdit, TMemo, TComboBox ect.). Interestingly, Ctrl+Delete works just fine. Does…
oxo
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Adding non-VCL window into VCL align queue

Some background (kind of a continuation of TLabel and TGroupbox Captions Flicker on Resize): So, I have an application that loads different plugins and creates a new tab on a TPageControl for each one. Each DLL has a TForm associated with it. The…
ThievingSix
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Can code running in a background thread be faster than in the main VCL thread in Delphi?

If anybody has had a lot of experience timing code running on the main VCL thread vs a background thread, I'd like to get an opinion. I have some code that does some heavy string processing running in my Delphi 6 application on the main thread. …
Robert Oschler
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Hide VCL Classes

There are some program tools such as WinSpy++ which will allow you to hover over the Handle of any Control/Component and return the Class Name of that Handle. So for example, if I dropped a TMemo on a Delphi Form and compiled the Application, if I…
user741875
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Delphi form creation without freezing main thread

I am having trouble with something i wanna do. I have some big forms which take some time to create. To make the app load faster i thought of letting the forms be created in a thread which is created at main form's OnCreate event. The thread has a…
Aldo
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How to avoid issues when embedding a TForm in another TForm?

I often embed a TForm descendant into another TForm descendant like this: var Form1: TForm1; Form2: TForm2; begin Form2.Parent := Form1; Form2.BorderStyle := bsNone; Form2.Align := alClient; Form2.Show; end; Usually this…
Jens Mühlenhoff
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Visual bug in Windows title bar with VCL Styles enabled application and display scaling

Currently I am testing various aspects of VCL styles enabled applications. I noticed, that with Windows scaling higher than the default 96 dpi/100%, the icon and the title bar text of the VCL Form are too big in size - and both are to close…
Tom Major
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How to intercept control move when editing a Delphi form

I'm developing a visual component (VCL), a specialized TPanel. I need to intercept when the user moves a control dropped on my special panel while editing the form. I need to intercept the move to adjust visual properties of other controls dropped…
fpiette
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Disabling progress bar animation on Vista Aero

I'm using a Delphi 2009 VCL TProgressBar as a kind of "empty/full" gauge. On Vista, with Aero theme enabled, this has an animation associated with it, which is annoying and inappropriate for an gauge. Is there any way of disabling this (NOT by…
Roddy
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TVirtualStringTree - resetting non-visual nodes and memory consumption

I have an app that loads records from a binary log file and displays them in a virtual TListView. There are potentially millions of records in a file, and the display can be filtered by the user, so I do not load all of the records in memory at one…
Remy Lebeau
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Delphi VCL ShadowEffect like FMX TShadowEffect

In Firemonkey we can use a TShadowEffect to draw a nice looking shadow. This shadow also adjusts its opacity and translucency so it displays the correct component beneath it if a control is overlapping. Without TShadowEffect: With…
Tommy
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Drawing windows dropshadow on specific control

I am trying to get the same dropshadow windows uses this one: on a treeview control in my form. On my researching i found out that one can use CS_DROPSHADOW (link) to create this shadow effect on forms. Is it somehow possible to assign…
ChrisB
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