Displaying a Bitmap Image in a VCL Forms Application
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This procedure loads a bitmap image from a file and displays it to a VCL form.
- Create a VCL form with a button control.
- Provide a bitmap image.
- Code the button's onClick event handler to load and display a bitmap image.
- Build and run the application.
To create a VCL form and button
- Choose File > New > Other > Delphi Projects (or File > New > Other > C++Builder Projects) and double-click the VCL Forms Application icon.The VCL Forms Designer is displayed.
- From the Standard page of the Tool Palette, place a TButton component on the form.
To provide a bitmap image
- Create a directory in which to store your project files.
- Locate a bitmap image on your local drive, and copy it to your project directory.
- Save all files in your project to your project directory.
To write the OnClick event handler
- In the Object Inspector, double-click the Button1 OnClick event on the Events tab.The Code Editor displays with the cursor in the TForm1.Button1Click (Delphi) or TForm1::Button1Click (C++) event handler block.
- Enter the following event handling code, replacing MyFile.bmp with path to the bitmap image in your project directory:
Bitmap := TBitmap.Create;
try
Bitmap.LoadFromFile('MyFile.bmp');
Form1.Canvas.Brush.Bitmap := Bitmap;
Form1.Canvas.FillRect(Rect(0,0,100,100));
finally
Form1.Canvas.Brush.Bitmap := nil;
Bitmap.Free;
end;
Graphics::TBitmap *Bitmap = new Graphics::TBitmap();
try {
Bitmap->LoadFromFile( "..\\MyFile.bmp" );
Form1->Canvas->Brush->Bitmap = Bitmap;
Form1->Canvas->FillRect( Rect(0,0,100,100) );
} __finally {
Form1->Canvas->Brush->Bitmap = NULL;
Bitmap->Free();
}
Note: For C++ projects, the code assumes the target output directory is located in the project directory.
Tip: You can change the size of the rectangle to be displayed by adjusting the Rect parameter values.
- For Delphi, add the following variable declaration in the var block:
Bitmap : TBitmap;
To run the program
- Select Run > Run .
- Click the button to display the image bitmap in a 100 x 100-pixel rectangle in the upper left corner of the form.