release notes for the PNG encoder and decoder for Delphi 5 version 1.2

This is version 1.2 of the encoder and decoder to the Portable Graphics Network format for Delphi 5. This implementation is capable of reading and saving images with Gamma correction and direct access to all the PNG chunks. This implementation was all worked on Delphi 5 and it can show images progressively, as it is being decoded.

The unit was tested in all the images Willem van Schaik test page, and, it worked with 100% of the images.

 This implementation integrates with Delphi

As the implementation derivates from the class TGraphic, TPNGImage integrates with Delphi booth in run-time and design-time allowing reading PNG images in components like TImage, TOpenPictureDialog thru the class TPicture. This allows, for instance, conversion from any other formats to PNG or from PNG.

 Step by step on how to install TPNGImage in your Delphi 5

1. Execute delphi 5

2. Go to the menu item Tools>Enviroment Options...

3. Select the page Library

4. Add the unit directory in the field path (put a ; before the path)

5. Click OK

Now to install the component:

1. Go to the menu  Component>Install Component

2. In the unit file name field, add the path and name for the PNGImage.DCU

3. Click OK

4. To the message Package will be rebuilt, select No

5. Click on the button Add on the window toolbar

6. In the next window, put the path and name for PNGZLIB.DCU in the unit file name field

7. Click OK

8. Now press the button Compile

Now, the component is installed in Delphi and now you add PNGImage in the uses field inside your form units to use the component.

 It is really easy to use TPNGImage, here goes an example:

{*********************************************}
{* The following app allows to convert BMP   *}
{* images into PNG. To use, call the program *}
{* from MS-DOS prompt:                       *}
{*   CONVERT.EXE [BMP File]                  *}
{*                                           *}
{* And the image in the parameter will be    *}
{* converted to a PNG image with same name.  *}
{*********************************************}
program convert;
{$APPTYPE CONSOLE}
uses SysUtils, Windows, Graphics, PNGImage;

  procedure CallError(Msg: string);
  begin
   WriteLn(Msg);
   WriteLn('');
   WriteLn('Use:');
   WriteLn(ExtractFileName(ParamStr(0)) + ' [File name.BMP]');
   WriteLn('');
   WriteLn('To convert the specified file to PNG format.');
   {Quits the program}
   Halt;
  end;

var
 PNG: TPNGImage;
 BMP: TBitmap;
 Filename: String;
begin
 {Get the file in the command line}
 Filename := GetCommandLine;
 Filename := Copy(Arquivo, Pos(' ', Filename) + 1, Length(Filename));
 
 {Test if the specified file exits}
 if (Filename = '') or (not FileExists(Filename)) then
  CallError('No file was specified, or the specified file does not exists!'); 
 {Creates the TPNGImage and TBitmap}
 PNG := TPNGImage.Create;
 BMP := TBitmap.Create;
 {Do the work}
 BMP.LoadFromFile(Filename);
 PNG.Assign(BMP);
 PNG.SaveToFile(ChangeFileExt(Filename, '.PNG'));
 {Destroy the objects}
 BMP.Free;
 PNG.Free;
 {Shows a message}
 WriteLn(Format('The file:%s%s%sWas successfully saved as::%s%s', 
  [#13#10, Filename, #13#10#13#10, #13#10, ChangeFileExt(Filename, '.PNG')]));
end.

 How to contact the component author to get more information

You may contact the author to answer any doubts you have about the component or to report bugs you find, or even to give ideas for future versions.

GUSTAVODAUD@UOL.COM.BR
Gustavo Huffenbacher Daud

Website:
http://www.overpower.com.br/png