function GetImageCountPerRow: Integer;
var
i: Integer;
begin
Result := -1;
for i := 0 to ImageEnMView1.ImageCount - 1 do
begin
if ImageEnMView1.ImageRow[i] = 1 then
begin
Result := i;
BREAK;
end;
end;
end;
CodeSite.Send('Index of first visible Image',
(ImageEnMView1.ViewY div ImageEnMView1.ThumbHeight) * GetImageCountPerRow);
It works. But do you think that this could be always reliable?
function TForm2.GetImageCountPerRow(const AImageEnMView: TImageEnMView): Integer;
var
i: Integer;
begin
Result := -1;
for i := 0 to AImageEnMView.ImageCount - 1 do
begin
if AImageEnMView.ImageRow[i] = 1 then
begin
Result := i;
BREAK;
end;
end;
end;
function TForm2.GetIndexOfFirstVisibleImage(const AImageEnMView: TImageEnMView): Integer;
var
c: Integer;
begin
c := GetImageCountPerRow(AImageEnMView);
if c = -1 then
Result := -1
else
Result := (AImageEnMView.ViewY div AImageEnMView.ThumbHeight) * c;
end;
CodeSite.Send('Index of first visible Image', GetIndexOfFirstVisibleImage(ImageEnMView1));
There was a bug in my code. So here is the (hopefully) bugfree code:
function TForm2.GetImageCountPerRow(const AImageEnMView: TImageEnMView): Integer;
var
i: Integer;
begin
Result := -1;
for i := 0 to AImageEnMView.ImageCount - 1 do
begin
if AImageEnMView.ImageRow[i] = 1 then
begin
Result := i;
BREAK;
end;
end;
end;
function TForm2.GetIndexOfFirstVisibleImage(const AImageEnMView: TImageEnMView): Integer;
var
c: Integer;
begin
c := GetImageCountPerRow(AImageEnMView);
if c = -1 then
begin
// not enough images to fill a row + 1
Result := 0;
end
else
Result := (AImageEnMView.ViewY div AImageEnMView.ThumbHeight) * c;
end;
CodeSite.Send('Index of first visible Image', GetIndexOfFirstVisibleImage(ImageEnMView1));
I'm out of the office, so I cannot confirm whether it includes partial thumbnails. If not, you can at least use it to set the range for your iteration which will greatly speed up the process.
Thank you, Nigel. In my function GetIndexOfFirstVisibleImage I do use ViewY. It works well and it really helps me to speed things up. It does indeed support partial view. Thank you!
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Detect the index of the first visible image?
Posted - Jan 02 2017 : 06:40:57
