Mega Code Archive
How to Move a cross in canvas to show XY values
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Title: How to Move a cross in canvas to show X/Y values
// TPanel, TImage e TLabel components
// Insert Image into Panel...
private
BmpH, BmpV : TBitmap;
OldX, OldY: Integer;
end;
var
RectSaved : boolean = false;
procedure TFormMain.FormCreate(Sender: TObject);
begin
PanelImage.DoubleBuffered := true; // This prevents that the image is blinking
LabelHint.Transparent := true;
LabelHint.Font.Color := clNave;
end;
procedure TFormMain.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
Cross(X, Y);
end;
procedure TFormMain.Cross(X, Y: Integer);
begin
Image.Canvas.Pen.Color := clBlack;
// Restore last image to erase line
if RectSaved then
begin
Image.Canvas.CopyRect(Rect(OldX - 5, 0, OldX + 5, BmpV.Height),
BmpV.Canvas, Rect(0,0,BmpV.Width,BmpV.Height));
Image.Canvas.CopyRect(Rect(0, OldY - 5, BmpH.Width, OldY + 5),
BmpH.Canvas, Rect(0,0,BmpH.Width,BmpH.Height));
BmpH.Free;
BmpV.Free;
end;
// Now save the image at new position for each line
// horizontal line
BmpH := TBitmap.Create;
BmpH.Width := Image.Width;
BmpH.Height := 10;
BmpH.Canvas.CopyRect(Rect(0,0,BmpH.Width,BmpH.Height),
Image.Canvas,Rect(0, Y - 5, BmpH.Width, Y + 5));
// Vertical line
BmpV := TBitmap.Create;
BmpV.Width := 10;
BmpV.Height := Image.Height;
BmpV.Canvas.CopyRect(Rect(0,0,BmpV.Width,BmpV.Height),
Image.Canvas,Rect(X - 5, 0, X + 5, BmpV.Height));
// Now draw the current position
Image.Canvas.MoveTo(0, Y);
Image.Canvas.LineTo(Image.Width, Y);
Image.Canvas.MoveTo(X, 0);
Image.Canvas.LineTo(X, Image.Height);
RectSaved := true;
OldX := X;
OldY := Y;
LabelHint.Left := X + 36;
LabelHint.Top := Y - 15;
LabelHint.Caption := '(X:' + IntToStr(X) + ' x Y:' + IntToStr(Y) +')';
end;
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