Defining height for an item in TListView??

[Obeliks]

Hi folks, next question:

I'm building a component based on TListView, and now I have to know how I can define the height of each item like in TListBox with OnMeasureItem.

THX,
Obeliks

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[Ted On The NeT]

try this peace of code I found:

This is not hard depending on the complexity of your DRAWITEM and
MEASUREITEM.

First, subclass from TCustomListView.

Override CreateParams to add the LVS_OWNERDRAWFIXED to the style:

procedure TODListView.CreateParams(var Params: TCreateParams);
begin
inherited;
with Params do
begin
Style := Style or LVS_OWNERDRAWFIXED;
end;
end;

Then provide a handler for CN_MEASUREITEM and CN_DRAWITEM:

procedure CNMeasureItem(var Message: TWMMeasureItem); message
CN_MEASUREITEM;
procedure CNDrawItem(var Message: TWMDrawItem); message CN_DRAWITEM;

Finally, go crazy trying to implement these two.

procedure TODListView.CNMeasureItem(var Message: TWMMeasureItem);
begin
// inherited;
FCanvas.Font := Font;
Message.MeasureItemStruct^.ItemHeight := FCanvas.TextHeight('Xy');
Message.Result := 1;
end;

procedure TODListView.CNDrawItem(var Message: TWMDrawItem);
begin
// inherited;
DrawItem(Message.DrawItemStruct^);
Message.Result := 1;
end;

Also, a hint: The ItemData of the DrawItemStruct in the message passed to
CNDrawItem is a TListItem.

procedure TODListView.DrawItem(const DrawItemStruct: TDrawItemStruct);
var item: TListItem;
begin
with DrawItemStruct do
begin
item := TListItem(ItemData);
...
end;



Greetz,
::TeD On The NeT::

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[Ted On The NeT]

I also found this peace of C++ builder code, which should be ported (shouldn't be to hard..):

====

That shouldn't be happening, as item's display rectangle is handled by Windows
-- i.e., no WM_MEASUREITEM message is sent. Try this API approach, and see if
the results differ...

//in header...
void __fastcall WMDrawItem(TMessage &Msg);

BEGIN_MESSAGE_MAP
MESSAGE_HANDLER(WM_DRAWITEM, TMessage, WMDrawItem)
END_MESSAGE_MAP(TForm)


//in source...
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
DWORD dwStyle = GetWindowLong(ListView1->Handle, GWL_STYLE);
SetWindowLong(ListView1->Handle, GWL_STYLE, dwStyle |
LVS_OWNERDRAWFIXED);
}

void __fastcall TForm1::WMDrawItem(TMessage &Msg)
{
LPDRAWITEMSTRUCT lpdis = (DRAWITEMSTRUCT *)Msg.LParam;
if (lpdis->hwndItem != ListView1->Handle)
{
TForm:ispatch(&Msg);
return;
}

TCanvas *LVCanvas = new TCanvas();
LVCanvas->Handle = lpdis->hDC;
LVCanvas->Font = ListView1->Font;
TRect Rect = lpdis->rcItem;
TListItem *Item = ListView1->Items->Item[lpdis->itemID];

TOwnerDrawState State = TOwnerDrawState();
if (lpdis->itemState & ODS_SELECTED) State = State << odSelected;
if (lpdis->itemState & ODS_FOCUS) State = State << odFocused;
if (lpdis->itemState & ODS_GRAYED) State = State << odGrayed;
if (lpdis->itemState & ODS_DISABLED) State = State << odDisabled;
if (lpdis->itemState & ODS_CHECKED) State = State << odChecked;

if (State.Contains(odSelected))
{
LVCanvas->Font->Color = clHighlightText;
LVCanvas->Brush->Color = clHighlight;
}

RECT rcItem, rcIcon;
ListView_GetItemRect(ListView1->Handle, Item->Index, &rcItem,
LVIR_LABEL);
ListView_GetItemRect(ListView1->Handle, Item->Index, &rcIcon,
LVIR_ICON);
TRect ItemRect = (TRect)rcItem;
TRect IconRect = (TRect)rcIcon;

LVCanvas->TextRect(ItemRect, ItemRect.Left, ItemRect.Top, Item->Caption);
if (State.Contains(odFocused)) LVCanvas->DrawFocusRect(ItemRect);
ListView1->SmallImages->Draw(LVCanvas, IconRect.Left, IconRect.Top,
Item->ImageIndex);

LVCanvas->Handle = 0;
delete LVCanvas;

Msg.Result = true;
}


Greetz,
::TeD On The NeT::

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[Obeliks]

Sounds good, these really seems as it could work...

But already my first problem:
When compiling an error occurs that LVS_OWNERDRAWFIXED is unknown...

Did you forget to tell me a unit? Or did I forget to think?

And btw, doesn't it have to be LVS_OWNDERDRAWVARIABLE? I mean, this style exists in TListBox and I WANT to create items with different heights...

Please help me, as I'd really like to write this component

So long,
Obeliks

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[Ted On The NeT]

I forgot to send you my reply. You can find this variable in the COMMCTRL unit. add it to your uses clause. that should fix your problem.


Greetz,
::TeD On The NeT::

=[ QUESTIONS ]=========================================
don't forget to accept this reply if it helped you!
================================================== =====

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Location : Netherlands (GMT +01.00)
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================================================== =====

[Obeliks]

Yeah, thanks man, but too late *g* Posted already another thread...

But I've got another problem, as I'm a little bit unfamiliar with this stuff...

You told me to call DrawItem(Message.DrawItemStruct^).
But DrawItem is the function of TListView, so it wants as parameters a TListItem, a TRect and a TOwnerDrawState...

I tried to use the following:
with Message.DrawItemStruct^ do
DrawItem(TListItem(ItemData),rcItem,S);

as I wasnt capable to convert itemState to TOwnerDrawState I tried to use a variable S: TOwnerDrawState, check for every possibility (e.g. ODS_SELECTED) and add it to S.

But I didn't figure it out how to check if e.g. ODS_SELECTED was in itemState...

How can I do this, or better, how can I convert itemState to TOwnerDrawState?

THX,
Obeliks

PS: I'll accept your answer now, but please keep helping me

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[Obeliks]

You could also contact me per ICQ or per eMail...

UIN: 65632051 (click here:
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MAIL: Delphi@obeliks.de

Please add me first to the contact list, and wait for me adding you as I block all msgs not coming from someone on my contact list... (Damned spam :/ )

So long,
Obeliks

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