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How to change properties of objects just by name?

 
axsoft
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How to change properties of objects just by name?    資料來源:www.delphi3000.com    How can i access properties of classes that are not implemented via  the uses-clause, just knowing their names ( by string)?     You have to use the TypInfo unit.  Simple properties, like strings and integer, can be accessed in the  following manner: 
------------------------------------------------------------- 
Uses TypInfo;     procedure AlterProp(AName, APropName, AValue:string); 
var  i : integer; 
     C : TComponent; 
begin 
    // Run through all Components to find the right Component 
    for i:=0 to Form1.Componentcount-1 do 
    begin 
        C := Form1.Components[i]; 
        if (C.Name = AName) then 
        begin 
            SetPropValue(C,APropName, AValue); 
       end; 
    end; 
end; 
------------------------------------------------------------- 
Now there are also some Properties like Font. How do i reach those sub-properties? Here is a solution to that:
------------------------------------------------------------- 
Uses TypInfo;     procedure AlterFontColor(AName:string; AColor:TColor); 
var  i : integer; 
     C : TComponent; 
     AObj : TObject; 
begin 
    // Run through all Components to find the right Component 
    for i:=0 to Form1.Componentcount-1 do 
    begin 
        C := Form1.Components[i]; 
        if (C.Name = AName) then 
        begin 
            AObj := GetObjectProp(C,'Font'); 
            SetPropValue(AObj,'Color',AColor); 
        end; 
    end; 
end; 
------------------------------------------------------------- 
And finally you have many indexed properties like TStrings or stuff. Now how do i reach those indexed properties? All indexed properties are stored in TCollection-Objects. So you have to Typecast them like in the following function:
------------------------------------------------------------- 
Uses TypInfo;     procedure AlterIndexObject(ACompName, APropName:string; ACaption: string); 
var  i : integer; 
     C : TComponent; 
     ACollectionItem, AObj : TObject; 
begin 
    // Run through all Components to find the right Component 
    for i:=0 to Form1.Componentcount-1 do 
    begin 
        C := Form1.Components[i]; 
        if (C.Name = ACompName) then 
        begin 
            AObj:= GetObjectProp(C,APropName); 
            ACollectionItem := TCollection(AObj).Items[0]; 
            SetPropValue(ACollectionItem, 'Caption', ACaption); 
        end; 
    end; 
end; 
------------------------------------------------------------- 
There are many possibilities for this functions to use in your projects. Mainly there are usefull for language-changings or skin-components. The possibilities are endless. I hope my article was somewhat usefull for you. I like to share knowledge with other developers. keep on coding :-) Jürgen Sommer 聯盟----Visita網站http://www.vista.org.tw ---[ 發問前請先找找舊文章 ]---
系統時間:2017-07-22 2:47:59
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