TBgraBitmap.TakeScreenShot not working on Lazarus 1.x 64 bits - Ubuntu
16.04
lazarus / 39-Graphics

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Jurassic Pork · 2017-07-15 07:25

hello,
on Lazarus 1.x 64 bits - Ubuntu 16.04   gtk2 interface with this code
:
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 procedure
TForm1.Button3Click(Sender: TObject);var MyCapture : TBgraBitmap;var
MyArea : TRect;begin  MyArea := Bounds(400,400,500,500);  MyCapture :=
TBgraBitmap.Create();  MyCapture.TakeScreenShot(MyArea); 
MyCapture.SaveToFile('/home/jurassic/MyCapture.png');end;i have this
error message when i call TakeScreenShot :
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 Cannot get
raw image from device
error in this code :
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 procedure
TBGRALCLBitmap.LoadFromDevice(DC: System.THandle; ARect: TRect);var 
rawImage: TRawImage;begin  if (ARect.Right <= ARect.Left) or
(ARect.Bottom <= ARect.Top) then  begin    SetSize(0,0);    exit; 
end;  try    if not RawImage_FromDevice(rawImage, DC, ARect) then    
raise Exception.Create('Cannot get raw image from device');   
SetSize(rawImage.Description.Width, rawImage.Description.Height);   
LoadFromRawImage(rawImage,255);  finally    rawImage.FreeData; 
end;end;
so what is wrong : 
it seems that it is the DC pointer type . If in all the files of the
tbgrabitmap package, i replace DC : System.THandle by  : DC : PtrUInt
TakeScreenshot works.
Is it a good idea ?

Ami calmant, J.P

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circular · 2017-07-15 11:55

Hi,

PtrUInt seems ok, however it may be better to use a type defined for
such handes. Apparently, System.THandle is not the right one. Is HDC
type available? What about the definition of RawImage_FromDevice, what
type is used in its parameters?

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Jurassic Pork · 2017-07-15 12:32

HDC type seems to be defined in lcltype unit (lcltype.pp) :
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 type HDC =
type THandle;type THandle = type PtrUInt; 
and RawImage_fromdevice seems to use HDC :
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 function
RawImage_FromDevice(out ARawImage: TRawImage; ADC: HDC; const ARect:
TRect): Boolean; override;
may be you can change  some bgrabitmap files. Something like that :
Quotefor lctype :
bgrabitmap-master/bgrabitmap/bgrabitmaptypes.pas
bgrabitmap/bgrabitmaptypes.pas (34,32) Classes, Types,
BGRAGraphics,lcltype,

bgrabitmap-master/bgrabitmap/bgradefaultbitmap.pas
bgrabitmap/bgradefaultbitmap.pas (36,63) BGRACanvas, BGRACanvas2D,
BGRAArrow, BGRAPen, BGRATransform,lcltype;
bgrabitmap-master/bgrabitmap/bgralclbitmap.pas
bgrabitmap/bgralclbitmap.pas (8,42) Classes, SysUtils, Graphics,
GraphType,lcltype, BGRABitmapTypes, BGRADefaultBitm...

for HDC :
bgrabitmap-master/bgrabitmap/bgradefaultbitmap.pas
bgradefaultbitmap.pas (903,35) procedure LoadFromDevice({%H-}DC: HDC);
override;
bgradefaultbitmap.pas (904,35) procedure LoadFromDevice({%H-}DC: HDC;
{%H-}ARect: TRect); override;
bgradefaultbitmap.pas (6077,41) procedure
TBGRAPtrBitmap.LoadFromDevice(DC: HDC);
bgradefaultbitmap.pas (6082,41) procedure
TBGRAPtrBitmap.LoadFromDevice(DC: HDC; ARect: TRect);

bgrabitmap-master/bgrabitmap/bgralclbitmap.pas
bgralclbitmap.pas (31,35) procedure LoadFromDevice({%H-}DC: HDC);
override;
bgralclbitmap.pas (32,35) procedure LoadFromDevice({%H-}DC: HDC;
{%H-}ARect: TRect); override;
bgralclbitmap.pas (878,41) procedure TBGRALCLBitmap.LoadFromDevice(DC:
HDC);
bgralclbitmap.pas (900,41) procedure TBGRALCLBitmap.LoadFromDevice(DC:
HDC; ARect: TRect);

bgrabitmap-master/bgrabitmap/bgracustombitmap.inc
bgracustombitmap.inc (390,31) procedure LoadFromDevice(DC: HDC);
virtual; abstract; overload;
bgracustombitmap.inc (392,31) procedure LoadFromDevice(DC: HDC; ARect:
TRect); virtual; abstract; overload;

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circular · 2017-07-17 18:10

Ok. I applied changes following this idea in "dev-bgrabitmap" branch.
Does it fix the problem?

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Jurassic Pork · 2017-07-17 22:36

hello,
thanks circular, i have downloaded the dev-bgrabitmap version of
bgrapbitmap. It seems to be OK for the TakeScreenshot function on
Ubuntu 16.04  64 bits Lazarus 1.8RC3 64 bits.

Ami calmant, J.P