Hello-
I have written code that automatically generates a bitmap image at runtime. However, after I draw this image to a canvas, the canvas size becomes fixed to the size of the pasted image. For example, in the code below, pressing either of the 3 buttons works the first time, creating a small (128x128), medium (256x256) or large (512x512) bitmap. However, if you first create a smaller image, you will be unable to see all of a larger image. Is there a way to resize the convas's bitmap dynamically?
//the code GenerateBMP will create a bitmap image on a TImage Component named 'Image1'
const
PixelCountMax = 32768;
gDown : boolean = False;
type
TRGBquad = PACKED RECORD
rgbRed,rgbGreen,rgbBlue,rgbreserved: byte;
//note order of bytes is RGB for Lazarus
end;
pRGBQuadArray = ^TRGBQuad;
TRGBQuadeArray = ARRAY[0..PixelCountMax-1] OF TRGBQuad;
RGBQuadRA = array [1..1] of TRGBQuad;
RGBQuadp = ^RGBQuadRA;
LongIntRA = array [1..1] of LongInt;
LongIntp = ^LongIntRA;
procedure DrawBMP( lx, ly: integer; lRGBBuff: RGBQuadp);
var
x, y,lPos: Integer;
Bitmap: TBitmap;
CurColor: TFPColor;
lLongBuff: LongIntp;
begin
Bitmap := TBitmap.Create;
lLongBuff := LongIntp(lRGBBuff);
try
Bitmap.Height := ly;
Bitmap.Width := lx;
lPos := 0;
for y:=0 to ly-1 do begin
for x:=0 to lx-1 do begin
inc(lPos);
Bitmap.Canvas.Pixels[x,y] := lLongBuff^[lPos];
end;
end;
Form1.Image1.Width := lx;
Form1.Image1.Height := ly;
Form1.Image1.Canvas.Draw(0, 0, Bitmap);
finally
Bitmap.Free;
end;
end;
procedure GenerateBMP (lX,lY: integer);
var
lPos,lXp,lYp: integer;
lRGB : TRGBQuad;
lRGBBuff: RGBQuadp;
begin
//initialize RGB values - note rgbreserved not used by Lazarus
lRGB.rgbRed := 0;
lRGB.rgbgreen := 0;
lRGB.rgbblue := 0;
lRGB.rgbreserved := 0;
GetMem ( lRGBBuff , lX*lY*sizeof(TRGBquad));
lPos := 0;
for lXp := 0 to lX-1 do
for lYp := 0 to lY-1 do begin
inc(lPos);
lRGB.rgbgreen := lXp and 255;
lRGB.rgbRed := lYp and 255;
lRGBBuff^[lPos] := lRGB;
end;
DrawBMP(lX,lY,lRGBBuff);
Freemem(lRGBBuff);
end;
procedure TForm1.SpeedButton1Click(Sender: TObject);
begin
GenerateBMP(128,128);
end;
procedure TForm1.SpeedButton2Click(Sender: TObject);
var
lID: TClipBoardFormat;
begin
GenerateBMP(255,255);
end;
procedure TForm1.SpeedButton3Click(Sender: TObject);
begin
GenerateBMP(512,512);
end;
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