Displaying a Bitmap Image in a VCL Forms Application

From RAD Studio
Jump to: navigation, search

Go Up to How To Build a VCL Forms Application with Graphics

This procedure loads a bitmap image from a file and displays it to a VCL form.

  1. Create a VCL form with a button control.
  2. Provide a bitmap image.
  3. Code the button's onClick event handler to load and display a bitmap image.
  4. Build and run the application.

To create a VCL form and button

  1. 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.
  2. From the Standard page of the Tool Palette, place a TButton component on the form.

To provide a bitmap image

  1. Create a directory in which to store your project files.
  2. Locate a bitmap image on your local drive, and copy it to your project directory.
  3. Save all files in your project to your project directory.

To write the OnClick event handler

  1. 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.
  2. Enter the following event handling code, replacing MyFile.bmp with path to the bitmap image in your project directory:
Bitmap := TBitmap.Create;
  Form1.Canvas.Brush.Bitmap := Bitmap;
  Form1.Canvas.Brush.Bitmap := nil;
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;

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

  1. Select Run > Run .
  2. Click the button to display the image bitmap in a 100 x 100-pixel rectangle in the upper left corner of the form.

See Also