Displaying a Full View Bitmap Image in a Windows VCL Application
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This procedure loads a bitmap image from a file and displays it in its entirety to a VCL form. The procedure uses the Height and Width properties of the Bitmap object to display a full view of the image.
- 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 > Windows VCL Application - Delphi or File > New > Windows VCL Application - C++Builder .
- From the Standard page of the Tool Palette, place a button component on the form.
- In the Object Inspector, enter Full View for the Caption property and FullView for the name property.
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.FullViewClick (Delphi) or TForm1::FullViewClick (C++) event handler block.
- Enter the following event handling code, replacing MyFile.bmp with the name of 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,Bitmap.Width,Bitmap.Height));
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, Bitmap->Width, Bitmap->Height ) );
} __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.
- For Delphi, add the following variable declaration in the var block:
Bitmap : TBitmap;
To run the program
- Choose Run > Run .
- Click the button to display the image bitmap in a rectangle in the upper left corner of the form.