Add option to load images from Resources rather than as include files

[GrahamNZ]

In my version of 1.4.1 I have replaced the loading of images using fpgImages.AddMaskedBMP so that the images are saved as resources rather than hard coded as include files. This also means I can use PNG files as well as BMP ones.

My main reason for this was that I couldn't work out how to implement High DPI (issue #59) and ended up scaling my forms manually, so when I load the image I resample it to the size I want. But it might be useful in general as creating and maintaining the include files is a bit inconvenient. My code is:

    procedure FPGAddMask(ResName:string; MaskId:string; siz:integer);
    var   ResPng        : TBGRABitmap;
          WrkStream     : TMemoryStream;
    begin
       ResPng:=TBGRABitmap.Create;
       ResPng.LoadFromResource(ResName);
       BGRAReplace(ResPng, ResPng.Resample(siz, siz, rmFineResample));
     
       WrkStream:=TMemoryStream.Create;
       ResPng.SaveToStreamAs(WrkStream, ifBmp);    // force conversion to BMP
       ResPng.Free;
     
       fpgImages.AddMaskedBMP(
          MaskId,
          WrkStream.Memory,
          WrkStream.Size, 0,0);
     
      WrkStream.Free;
    end;

So then I have code like:

   NewSiz:=round(scale * 16);
   FPGAddMask('FPG_ROTATE','myimg.rotate',NewSiz);

But it uses BGRAbitmap so maybe you won't want to add it as a standard option.

[graemeg]

Hi Graham. I'll have a look at this shortly. That's a very nice idea, especially for allowing various scalled images. I'm thinking for fpGUI, having source svg images and then dynamically scalling during runtime should work pretty well too.

Note to self: These are the instructions using only what's included with FPC (no external libraries are needed).

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Example Code

To include the .res file in your application and ensure it is packaged correctly with your binary, follow these guidelines:

Including the .res File

Step 1: Compile the Resource File

First, compile your resource file into a .res format using a command like:

fpc -F. images.rc

Step 2: Include the .res File in Your Code

You can include the .res file in your Pascal code using the {$R} directive. This directive tells the compiler to link the resource file into your application binary.

Example Code

Here's how you modify your code to include the .res file:

program ReadPNGAndSaveToMemoryStream;

{$mode objfpc}{$H+}

uses
  SysUtils, Classes, FPImage, FPReadPNG, FPWriteBMP;

{$R images.res}  // Include the resource file

var
  PNGReader: TFPReaderPNG;
  BMPWriter: TFPWriterBMP;
  Image: TFPImage;
  ResourceStream: TResourceStream;
  MemoryStream: TMemoryStream;

begin
  PNGReader := TFPReaderPNG.Create;
  BMPWriter := TFPWriterBMP.Create;
  Image := TFPImage.Create;
  MemoryStream := TMemoryStream.Create;

  try
    // Load the PNG image from the resource
    ResourceStream := TResourceStream.Create(HInstance, 'MYIMAGE', RT_RCDATA);
    try
      Image.LoadFromStream(ResourceStream, PNGReader);
      
      // Save the image to the MemoryStream in BMP format
      Image.SaveToStream(MemoryStream, BMPWriter);
      
      // Optionally, you can save the MemoryStream to a file for verification
      MemoryStream.SaveToFile('output.bmp');
      
    finally
      ResourceStream.Free;
    end;

  finally
    BMPWriter.Free;
    PNGReader.Free;
    Image.Free;
    MemoryStream.Free;
  end;

  WriteLn('PNG image has been loaded and saved to memory stream in BMP format');
end.

Step 3: Compile Your Application

When you compile your application, make sure that the .res file is in the same directory as your source code or specify its path correctly. You can compile your program with:

fpc your_program.pas

Deployment

• The .res file is embedded in the compiled executable, so you do not need to ship the .res file separately; it's part of your application binary.
• Ensure the resource name in your code matches the name used in your resource file definition.

This method allows you to manage resources more effectively and keep your application self-contained.

[GrahamNZ]

I haven't looked at TFPImage. My main reason for using BGRA was the resampling to change the size based on my scale calculation:

if fpgApplication.Screen_dpi=96 then begin
   is96DPI:=true;
   scale:=1.00000;
end else begin
   is96DPI:=false;
   scale:=fpgApplication.Screen_dpi/96;
end;

BGRAReplace(ResPng, ResPng.Resample(siz, siz, rmFineResample));

Can I do the same with TFPImage?

[graemeg]

Yes, FPC's fp-image package has support for that, and many different algorithms can be used to match your needs.

Note: I'll still look into improving fpGUI. At the time I created fpGUI (well over 15 years now), Free Pascal didn't have a built-in resource compiler. These days they do, so yes, I think it's time fpGUI improves how it handles images.