I'm using Delphi XE2 (Update 3) and GR32. I am unable to use TBitmap32.LoadFromStream()
to load the image data. It raises the following exception:
Project MyApp.exe raised exception class EInvalidGraphic with message 'Bitmap image is not valid'.
Code
uses GR32, GifImg, PngImage, Vcl.Graphics;
var
pic: TBitmap32;
bs: TBytesStream;
begin
bs := TBytesStream.Create(TClientDataSet(cds).FieldByName('filedata').AsBytes);
try
pic := TBitmap32.Create;
try
// bs.SaveToFile('c:\delme.png');
// pic.LoadFromFile('c:\delme.png');
pic.LoadFromStream(bs); // <- EInvalidGraphic exception
// do something with 'pic'
finally
FreeAndNil(pic);
end;
finally
FreeAndNil(bs);
end;
end;
Workaround(s)
If I comment the LoadFromStream()
code and uncomment the prior two lines, it works -- so it is able to determine the image format when loading it from a file. In this example, bs
contains a valid PNG image. However, sometimes it may be a GIF, JPG, BMP or another graphic format.
I also know that I can use an intermediate object (e.g., TPNGImage
, TJPEGImage
, etc.), load the image data using LoadFromStream()
into the intermediate object, and then Assign()
it to the TBitmap32
. However, it would be better if TBitmap32
could handle any type of image without an intermediate object, which I thought it could...
Question
Does anyone know how to use TBitmap32.LoadFromStream()
to load the image and have it auto-recognize the image format without saving the image to the HDD (even temporarily), or using an intermediate object?
This is the code for
LoadFromFile
:As you can see, the code checks to see if the file is a Windows bitmap. If so then it loads it directly by calling
LoadFromStream
.If not then it loads into a
TPicture
and then assigns to this instance.The point is that
LoadFromStream
only understands Windows bitmaps. It does not understand any other file format. And you are trying to load a PNG. So, there's no way to do what you need without using an intermediate object.The solution for you is to:
TPNGImage
object.LoadFromStream
on that instance.Assign
on theTBitmap32
instance passing theTPNGImage
instance.Delphi XE2 includes a class in
Vcl.Graphics
calledTWICImage
that handles images supported by the Windows Imaging Component, including BMP, GIF, ICO, JPEG, PNG, TIF and Windows Media Photo. This means you can load any of the supported image types directly from a stream and it will automatically detect the image type and load it. Then the loaded image can be assigned to theTBitmap32
component (or aTImage
or aTImage32
, etc.).It works without adding
PNGImage
,GIFImg
, orJPEG
to youruses
statement.