Proportionally Resize an Image:Thumbnail Graphics

Thumbnail Graphics,In snap shots “programming” a thumbnail is a reduced-length model of a photograph.

Here’s an concept for your subsequent application: create a “shape picker” to let users easily pick out and navigate through open paperwork by using displaying thumbnails of them all in a dialog window.

Interesting concept? Sounds just like the “Quick Tabs” feature of the IE 7 browser 🙂

Before absolutely developing this kind of neat function for your next Delphi utility,

you want to realize the way to snatch the picture of the shape (“shape-display screen shot”) and how to proportionally resize it to the preferred thumbnail photo.

Proportional Picture Resizing: Creating Thumbnail Graphics

Thumbnail Graphics,Below you may discover a block of code to take the photograph of a form (Form1) with the aid of using the GetFormImage technique.

The ensuing TBitmap is then resized to fit the maximum thumbnail width (200 pixels) and/or height (150 pixels). Resizing keeps the element ratio of the image.

The ensuing photo is then displayed in a TImage manipulate, named “Image1”.

rtional Picture Resizing: Creating Thumbnail Graphics

const
  maxWidth = 200;
  maxHeight = 150;
var
  thumbnail : TBitmap;
  thumbRect : TRect;
begin
  thumbnail := Form1.GetFormImage;
  try
    thumbRect.Left := 0;
    thumbRect.Top := 0;
    //proportional resize
    if thumbnail.Width > thumbnail.Height then
    begin
      thumbRect.Right := maxWidth;
      thumbRect.Bottom := (maxWidth * thumbnail.Height) div thumbnail.Width;
    end
    else
    begin
      thumbRect.Bottom := maxHeight;
      thumbRect.Right := (maxHeight * thumbnail.Width) div thumbnail.Height;
    end;
    thumbnail.Canvas.StretchDraw(thumbRect, thumbnail) ;
//resize image
    thumbnail.Width := thumbRect.Right;
    thumbnail.Height := thumbRect.Bottom;
    //display in a TImage control
    Image1.Picture.Assign(thumbnail) ;
  finally
    thumbnail.Free;
  end;
end;

Note:The GetFormImage only copies the shape client place – if you need to take the whole “display screen shot” of a shape (which includes its border) you will want a special technique …Greater about it next time.