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PODelphi: Changing the Button Color using a Class Helper
 

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  1. PODelphi: Changing the Button Color using a Class Helper
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    <p>I need to change the visual style of my delphi form controls inorder to show them from a .Net environment. To do this, I need to change the colors of delphi controls to blue ($00FCF5EE). I have used "TButton" controls widely which doesn't have a "Color" property.So, instead of changing the buttons to speed buttons, I have tried a different approach by introducing a parent form and inheriting all the other forms from this parent form. In the parent form, I have a class helper to change the color of buttons. Here is the code: (I am using Delphi 2007) </p> <pre><code>TButtonHelper=class helper for TButton private procedure doChangeColor; public procedure DrawChangeColor; end; TParentForm = class(TForm) public procedure AfterConstruction; override; end; </code></pre> <p>And in the implementation section, I have</p> <pre><code> procedure TButtonHelper.doChangeColor; var SaveIndex: Integer; FCanvas:TCanvas; rect:TRect; begin if csDestroying in ComponentState then exit; FCanvas:=TCanvas.Create; SaveIndex := SaveDC(Self.Handle); FCanvas.Lock; try FCanvas.Handle := Handle; FCanvas.Font := Font; FCanvas.Brush := self.Brush; FCanvas.Brush.Color:=$00FCF5EE; FCanvas.FillRect(BoundsRect);//Omitting the code to draw the text finally FCanvas.Handle := 0; FCanvas.Unlock; RestoreDC(handle, SaveIndex); FCanvas.Free; end; end; procedure TButtonHelper.DrawChangeColor; begin doChangeColor; self.Repaint; end; procedure TParentForm.AfterConstruction; var i : Integer; wc: TControl; begin inherited; for i := 0 to self.ControlCount - 1 do begin wc:=Controls[i]; if wc is TButton then TButton(wc).DrawChangeColor; end; end; </code></pre> <p>But this doesn't work. Although the doChangeColor method is executed, it is not changing the color of the button.Please let me know what I am missing here.</p> <p>Thanking you all,</p> <p>Pradeep</p>
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    1. USDavid Heffernan
    1. USPradeep
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    1. COThat code can't change the colour of the button. That's not how windows works. You need to override the `Paint` method for the buttons.
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      1. PODelphi: Changing the Button Color using a Class Helper
      1. USDavid Heffernan
    2. COThank you for the comment. Since the button doesn't have a Paint method, I have created a child class TColorButton (similar to whosrdaddy's class below) and overridden the parent form's Readstate method as mentioned by you at http://stackoverflow.com/questions/4685863/replacing-a-component-class-in-delphi/4686920#4686920 and changing the color in form's Create/Paint methods. Butin both the cases, the TColorButton class did not receive the CN_DRAWITEM message. What could be the reason?
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      1. PODelphi: Changing the Button Color using a Class Helper
      1. USPradeep
    3. CO`TButton` does have a `Paint` method. Perhaps it uses the inherited one in `TWinControl`. Since it reflects the Windows `BUTTON` class, it doesn't implement the painting in Delphi. Instead it passes the message on to the Windows API.
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      1. PODelphi: Changing the Button Color using a Class Helper
      1. USDavid Heffernan
 

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