Mega Code Archive
CopiePaste a Bitmap tofrom the clipboard
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Title: Copie/Paste a Bitmap to/from the clipboard?
{
In order to run this example you will need the GR32 Unit from the package
http://www.g32.org/files/graphics32/graphics32-1_5_1.zip
to run this example.
}
unit EG_ClipboardBitmap32;
{
Author William Egge. egge@eggcentric.com
January 17, 2002
Compiles with ver 1.2 patch #1 of Graphics32
This unit will copy and paste Bitmap32 pixels to the clipboard and retain the
alpha channel.
The clipboard data will still work with regular paint programs because this
unit adds a new format only for the alpha channel and is kept seperate from
the regular bitmap storage.
}
interface
uses
ClipBrd, Windows, SysUtils, GR32;
procedure CopyBitmap32ToClipboard(const Source: TBitmap32);
procedure PasteBitmap32FromClipboard(const Dest: TBitmap32);
function CanPasteBitmap32: Boolean;
implementation
const
RegisterName = 'G32 Bitmap32 Alpha Channel';
GlobalUnlockBugErrorCode = ERROR_INVALID_PARAMETER;
var
FAlphaFormatHandle: Word = 0;
procedure RaiseSysError;
var
ErrCode: LongWord;
begin
ErrCode := GetLastError();
if ErrCode NO_ERROR then
raise Exception.Create(SysErrorMessage(ErrCode));
end;
function GetAlphaFormatHandle: Word;
begin
if FAlphaFormatHandle = 0 then
begin
FAlphaFormatHandle := RegisterClipboardFormat(RegisterName);
if FAlphaFormatHandle = 0 then
RaiseSysError;
end;
Result := FAlphaFormatHandle;
end;
function CanPasteBitmap32: Boolean;
begin
Result := Clipboard.HasFormat(CF_BITMAP);
end;
procedure CopyBitmap32ToClipboard(const Source: TBitmap32);
var
H: HGLOBAL;
Bytes: LongWord;
P, Alpha: PByte;
I: Integer;
begin
Clipboard.Assign(Source);
if not OpenClipboard(0) then
RaiseSysError
else
try
Bytes := 4 + (Source.Width * Source.Height);
H := GlobalAlloc(GMEM_MOVEABLE and GMEM_DDESHARE, Bytes);
if H = 0 then
RaiseSysError;
P := GlobalLock(H);
if P = nil then
RaiseSysError
else
try
PLongWord(P)^ := Bytes - 4;
Inc(P, 4);
// Copy Alpha into Array
Alpha := Pointer(Source.Bits);
Inc(Alpha, 3); // Align with Alpha
for I := 1 to (Source.Width * Source.Height) do
begin
P^ := Alpha^;
Inc(Alpha, 4);
Inc(P);
end;
finally
if (not GlobalUnlock(H)) then
if (GetLastError() GlobalUnlockBugErrorCode) then
RaiseSysError;
end;
SetClipboardData(GetAlphaFormatHandle, H);
finally
if not CloseClipboard then
RaiseSysError;
end;
end;
procedure PasteBitmap32FromClipboard(const Dest: TBitmap32);
var
H: HGLOBAL;
ClipAlpha, Alpha: PByte;
I, Count, PixelCount: LongWord;
begin
if Clipboard.HasFormat(CF_BITMAP) then
begin
Dest.BeginUpdate;
try
Dest.Assign(Clipboard);
if not OpenClipboard(0) then
RaiseSysError
else
try
H := GetClipboardData(GetAlphaFormatHandle);
if H 0 then
begin
ClipAlpha := GlobalLock(H);
if ClipAlpha = nil then
RaiseSysError
else
try
Alpha := Pointer(Dest.Bits);
Inc(Alpha, 3); // Align with Alpha
Count := PLongWord(ClipAlpha)^;
Inc(ClipAlpha, 4);
PixelCount := Dest.Width * Dest.Height;
Assert(Count = PixelCount,
'Alpha Count does not match Bitmap pixel Count,
PasteBitmap32FromClipboard(const Dest: TBitmap32);');
// Should not happen, but if it does then this is a safety catch.
if Count PixelCount then
Count := PixelCount;
for I := 1 to Count do
begin
Alpha^ := ClipAlpha^;
Inc(Alpha, 4);
Inc(ClipAlpha);
end;
finally
if (not GlobalUnlock(H)) then
if (GetLastError() GlobalUnlockBugErrorCode) then
RaiseSysError;
end;
end;
finally
if not CloseClipboard then
RaiseSysError;
end;
finally
Dest.EndUpdate;
Dest.Changed;
end;
end;
end;
end.
// Example Call:
{uses
JPEG;}
procedure TForm1.Button1Click(Sender: TObject);
var
bmp: TBitmap32;
begin
bmp := TBitmap32.Create;
try
bmp.LoadFromFile('C:\test.jpg');
CopyBitmap32ToClipboard(bmp);
finally
bmp.Free;
end;
end;
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