how to write picture to stream?
lazarus / 39-Graphics

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Godfather · 2017-08-16 08:34

i need a little help. My picture is already saved in bytes in a file.
I want to show it with the help of any sort of Stream( Stream,
Memorystream ... ),

this is how I save my picture to file.

    AssignFile( SourceFile, PictFilename );  // Picture
    Reset( SourceFIle );                              // Open picture 

    SizeOfPict := FileSize( SourceFile );      

    Write( MyFile, SizeOfPict SHR 24 );       // save the size of the
picture to the file
    Write( MyFile, SizeOfPict SHR 16 );
    Write( MyFile, SizeOfPict SHR  8 );
    Write( MyFile, SizeOfPict SHR  0 );

    for cntr := 1 to SizeOfPict do begin

     read( SourceFIle, TempByte );                  // read picture in
bytes
     write( MyFile, TempByte );                        // write
picture in bytes to file

    end;

And now I would like some help with how to show the picture in TImage.

Thank you for your help.

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howardpc · 2017-08-16 08:48

What is wrong with
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
Image1.Picture.LoadFromFile(PictFilename);that you avoid it?

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Thaddy · 2017-08-16 08:53

Quotethis is how I save my picture to file.

    AssignFile( SourceFile, PictFilename );  // Picture
    Reset( SourceFIle );                              // Open picture 

Then use streams.... OMG....
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i .... oh
well, Handoko will do this...beginend.

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Godfather · 2017-08-16 09:12

Quote from: howardpc on August 16, 2017, 10:48:19 amWhat is wrong with
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
Image1.Picture.LoadFromFile(PictFilename);that you avoid it?

PictFilename is a string, but my picture is saved in bytes in the
file! The thing is that in the file is more data, not only the picture
but a memo text and other stuff, and everything is saved in BYTES, so
its harder to get out the picture from that much data and open it, so
the loadfromfile doesnt work, I tried that. That was the first thing I
tried.

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J-G · 2017-08-16 10:42

Quote from: Godfather on August 16, 2017, 11:12:18 amPictFilename is a
string, but my picture is saved in bytes in the file! The thing is
that in the file is more data, not only the picture but a memo text
and other stuff
WHY ??

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howardpc · 2017-08-16 12:30

Quote from: Godfather on August 16, 2017, 11:12:18 amPictFilename is a
string, but my picture is saved in bytes in the file! The thing is
that in the file is more data, not only the picture but a memo text
and other stuff,

If you are not comfortable with using streams to save and load varied
data types to and from files, it would be much easier for you to keep
to standard file formats and have spearate files for the picture,
memo.txt (Memo.Lines.LoadFromfile/SaveToFile) and other stuff (file of
record routines?). Read three files, and save three files. It will
save you a lot of grief compared with trying to save and subsequently
read varying data types turned into a single stream of bytes
representing composite data arbitrarily strung together in a single
file.

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balazsszekely · 2017-08-16 13:00

What is TempByte? I assume TByte(array of Byte). Then you can do
something like this:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var 
TempByte: TBytes;  Bs: TBytesStream;begin  //...     // read TempByte
from file      Bs := TBytesStream.Create(TempByte);  try   
Bs.Position := 0;    Image1.Picture.LoadFromStream(Bs);  finally   
Bs.Free;  end;

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Remy Lebeau · 2017-08-17 18:20

Quote from: Godfather on August 16, 2017, 11:12:18 amPictFilename is a
string, but my picture is saved in bytes in the file! The thing is
that in the file is more data, not only the picture but a memo text
and other stuff, and everything is saved in BYTES, so its harder to
get out the picture from that much data and open it, so the
loadfromfile doesnt work, I tried that. That was the first thing I
tried.

TPicture has LoadFromStream() and LoadFromStreamWithFileExt() methods.

Since your data file knows where the picture data is located and how
many bytes belong to the picture, you can either:

1. extract just those bytes from the file to a TMemoryStream or
TByteStream, and then load that stream into TImage.

2. use a wrapper TStream that reads from the original file, limiting
its reading to just the offsets of the picture data, and then load
that wrapper stream into TImage.

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Godfather · 2017-08-23 06:16

Thank you, GetMem!