I have put in place a minimum zoom level like this...
procedure ImageViewChange(Sender: TObject; Change: Integer);
begin
if Image.Zoom<50 then Image.Zoom:=50;
end;
I am getting fairly picky now and although it works, when the zoom is 50 and the user tries to go lower the zoom level, the overall effect is that the image 'bounces' between two zoom levels - is there any way I can stop that and don't do anything or is that how it is?
I've tried the
OnChanging
event without any luck either and there doesn't seem to be a minimum zoom level you can set which would solve my problem.
If you use a TTrackbar or TSpinEdit to adjust the zoom the best way is to set the min property to 50. This way you do not get any flicker at all. At this point I do not see a way to eliminate flicker, but you might try:
I didn't want to use any extra controls and just rely on the mouse & keyboard. What I've done is disable the mouse wheel and take control of zooming myself - in that way zooming now just stops if its less than 50% and you don't get the 'bounce' as it resets back exactly to 50%.
procedure TfmMain.ImageMouseWheel(Sender: TObject; Shift: TShiftState; WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
begin
if WheelDelta<0 then
begin
if Image.Zoom>50 then Image.Zoom:=Image.Zoom*0.9;
end
else Image.Zoom:=Image.Zoom*1.1;
handled:=True;
end;
And how about including a stop for "Fit to Window" (untested):
procedure TfmMain.ImageMouseWheel(Sender: TObject; Shift: TShiftState; WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
var
iNewZoom : Double;
begin
iNewZoom := Image.Zoom;
if WheelDelta > 0 then
begin
iNewZoom := iNewZoom * 1.1;
if (Image.GetIdealZoom > Image.Zoom) and
(Image.GetIdealZoom < iNewZoom) then
iNewZoom := Image.GetIdealZoom;
end
else
if iNewZoom > 50 then
begin
iNewZoom := iNewZoom * 0.9;
if (Image.GetIdealZoom > iNewZoom) and
(Image.GetIdealZoom < Image.Zoom) then
iNewZoom := Image.GetIdealZoom;
end;
Image.Zoom := iNewZoom;
handled := True;
end;
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Best way to set a minimum zoom level
Posted - Feb 05 2013 : 09:34:25
