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Home » U++ Library support » U++ Widgets - General questions or Mixed problems » Problem with ColumnList (with example) [BUG/FIXED]
| Problem with ColumnList (with example) [BUG/FIXED] [message #5748] |
Thu, 12 October 2006 19:20  |
James Thomas
Messages: 26
Registered: June 2006
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Promising Member |
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I hope I'm not asking an obvious question (again  ), but I'm having serious problems with ColumnList. I can't get it to work properly at all.
In the example below I fill a list box with entries and after every selection I count the number of selected entries and display it in an EditInt ctrl. However, the behaviour of the list is very strange.
When you click on an item the selection callback is triggered and the item is highlighted, but when I check the items it appears that none has actually been selected. When you hold down the Ctrl or Shift key it correctly registers the selection but the row is not highlighted (unless you use Shift in which case it only highlight the anchor item). This is obviously completely wrong and happens both in single and multi-select modes.
#include <CtrlLib/CtrlLib.h>
class AWindow : public TopWindow {
public:
typedef AWindow CLASSNAME;
Option _optMulti;
ColumnList _List;
Label _Label;
EditInt _intSelCount;
AWindow()
{
Ctrl::LogPos p = GetPos();
p.x.SetB(228);
p.y.SetB(356);
SetPos(p);
_List.LeftPosZ(4, 220).TopPosZ(32, 292);
_intSelCount.LeftPosZ(176, 48).TopPosZ(328, 19);
_Label.SetLabel("Number of items selected:").LeftPosZ(48, 124).TopPosZ(328, 19);
_optMulti.SetLabel("Multi-Select").LeftPosZ(4, 76).TopPosZ(8, 15);
Add(_List);
Add(_intSelCount);
Add(_Label);
Add(_optMulti);
_List.Columns(1);
_List.Multi(false);
_List.WhenSelection = THISBACK(Selection);
String s = "Spam ";
for (int i = 0; i < 20; i++) {
_List.Add(s + AsString(i));
}
_intSelCount.SetData(0);
_intSelCount.SetEditable(false);
_optMulti <<= THISBACK(MultiChange);
}
void Selection()
{
int cnt = 0;
for (int i = 0; i < _List.GetCount(); i++) {
if (_List.IsSelected(i))
cnt++;
}
_intSelCount.SetData(cnt);
}
void MultiChange()
{
_List.Multi(_optMulti.Get());
}
};
GUI_APP_MAIN
{
AWindow w;
w.Run();
}
I suspect I've done something wrong, since this seems like a rather obvious problem, but then I looked at the code in ColumnList.cpp:
void ColumnList::LeftDown(Point p, dword flags) {
int i = GetDragColumn(p.x);
if(i >= 0) {
ci = i;
dx = p.x - GetColumnCx(0) * (i + 1);
mpos = p.x;
SetCapture();
Refresh(mpos - dx, 0, 1, GetSize().cy);
}
else {
int anchor = cursor;
SetWantFocus();
PointDown(p);
p.y %= cy;
p.x %= GetColumnCx(0);
if(cursor >= 0) {
if(flags & K_SHIFT && anchor >= 0) {
ShiftSelect(anchor, cursor);
WhenLeftClickPos(p);
return;
}
else
if(flags & K_CTRL) {
if(anchor >= 0 && !IsSelection())
SelectOne(anchor, true);
SelectOne(cursor, !IsSelected(cursor));
WhenLeftClickPos(p);
return;
}
}
ClearSelection();
WhenLeftClickPos(p);
}
}
And it looks like SelectOne is never called unless Ctrl or Shift are held down. It is still a mystery to me how the row can be highlighted though.
What's going on?
(tested on Dev-2, but the ColumnList source looks the same in 605)
[Updated on: Mon, 16 October 2006 18:04] Report message to a moderator |
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| Re: Problem with ColumnList (with example) [message #5758 is a reply to message #5750] |
Fri, 13 October 2006 13:00  |
James Thomas
Messages: 26
Registered: June 2006
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Promising Member |
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I've looked at the source more closely and I believe I've fixed the selection and highlighting problems.
The first change is to LeftDown. There was no way of selecting an item without using the Shift or Ctrl keys and some of the multi-selection behaviour was being incorrectly applied when in single selection mode. My version is below.
void ColumnList::LeftDown(Point p, dword flags) {
int i = GetDragColumn(p.x);
if(i >= 0) {
ci = i;
dx = p.x - GetColumnCx(0) * (i + 1);
mpos = p.x;
SetCapture();
Refresh(mpos - dx, 0, 1, GetSize().cy);
}
else {
int anchor = cursor;
SetWantFocus();
PointDown(p);
p.y %= cy;
p.x %= GetColumnCx(0);
if(cursor >= 0) {
// JT 13/10/06 Added multi check to if statements
if(multi && flags & K_SHIFT && anchor >= 0) {
ShiftSelect(anchor, cursor);
WhenLeftClickPos(p);
return;
}
else
if(multi && flags & K_CTRL) {
if(anchor >= 0 && !IsSelection())
SelectOne(anchor, true);
SelectOne(cursor, !IsSelected(cursor));
WhenLeftClickPos(p);
return;
}
else if (multi) ClearSelection(); // JT 13/10/06
SelectOne(cursor, true); // JT 13/10/06 Added to fix selection
}
else
ClearSelection();
WhenLeftClickPos(p);
}
}
A change was also required to the GetItemStyle function that decides what colour an item is drawn in. The original code was:
if(m.sel) {
style |= Display::SELECT;
paper = SColorShadow;
if(HasFocus()) {
paper = SColorPaper;
ink = SColorText;
}
}
Which makes no sense. Why would the highlighting behaviour be different depending on focus? And you certainly don't want to not highlight items when the control has focus. My version:
if(m.sel) {
style |= Display::SELECT;
paper = SColorShadow;
}
I would personally prefer to use SColorHighlight, but SColorShadow seems consistent with TheIDE. Perhaps the intention of the original code was to use shadow if the control doesn't have focus and SColorHighlight if it does?
In the same function there is also the code:
if(i == cursor) {
style = isselection ? Display::CURSOR : Display::CURSOR|Display::SELECT;
paper = isselection ? Blend(SColorHighlight, SColorFace) : SColorFace;
if(HasFocus()) {
style |= Display::FOCUS;
paper = isselection ? Blend(SColorHighlight, SColorPaper) : SColorHighlight;
ink = SColorPaper;
}
Which I cannot understand the purpose of. If you would like to explain I would be interested in the reason for this.
Overall this control seems very strangely implemented and works very differently from the ColumnList controls in TheIDE (I haven't checked the IDE source to see how they are implemented, but they definitely aren't using this code!).
To make the control consistent with TheIDE I have made some other changes (in the attached files), and it now works in a much more sensible way. I have also added a GetSelectedItem member to reduce the code required to access the first selected item when using it (most useful in single selection mode). I am also unhappy with the amount of list scanning/iteration required by this control (happens whenever an item is selected or the selected item is retrieved) as it would be horribly inefficient with very large lists, but fixing this is difficult so I haven't done it yet.
All of my changes have been made to the latest dev source (Dev-1) and are maked by // JT 13/10/06.
I hope this is useful 
In addition, here is a modified version of the test code I gave in my first post that also illustrates the us of the new GetSelectedItem function:
#include <CtrlLib/CtrlLib.h>
class AWindow : public TopWindow {
public:
typedef AWindow CLASSNAME;
Option _optMulti;
ColumnList _List;
Label _Label1, _Label2;
EditInt _intSelCount;
EditString _txtItem;
AWindow()
{
Ctrl::LogPos p = GetPos();
p.x.SetB(228);
p.y.SetB(380);
SetPos(p);
_List.LeftPosZ(4, 220).TopPosZ(32, 292);
_intSelCount.LeftPosZ(176, 48).TopPosZ(328, 19);
_Label1.SetLabel("Number of items selected:").LeftPosZ(48, 124).TopPosZ(328, 19);
_Label2.SetLabel("Selected item:").LeftPosZ(100, 72).TopPosZ(352, 19);
_optMulti.SetLabel("Multi-Select").LeftPosZ(4, 76).TopPosZ(8, 15);
_txtItem.LeftPosZ(176, 48).TopPosZ(352, 19);
Add(_List);
Add(_intSelCount);
Add(_Label1);
Add(_Label2);
Add(_optMulti);
Add(_txtItem);
_List.Columns(1);
_List.Multi(false);
_List.WhenSelection = THISBACK(Selection);
String s = "Spam ";
for (int i = 0; i < 20; i++) {
_List.Add(s + AsString(i));
}
_intSelCount.SetData(0);
_intSelCount.SetEditable(false);
_txtItem.SetText("None");
_txtItem.SetEditable(false);
_optMulti <<= THISBACK(MultiChange);
}
void Selection()
{
int cnt = 0, i;
for (i = 0; i < _List.GetCount(); i++) {
if (_List.IsSelected(i))
cnt++;
}
_intSelCount.SetData(cnt);
// Test the new member function
i = _List.GetSelectedItem();
if (i < 0)
_txtItem.SetText("None");
else
_txtItem.SetText((String)_List.Get(i));
}
void MultiChange()
{
_List.Multi(_optMulti.Get());
}
};
GUI_APP_MAIN
{
AWindow w;
w.Run();
}[Updated on: Fri, 13 October 2006 14:40] Report message to a moderator |
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| Re: Problem with ColumnList (with example) [message #5764 is a reply to message #5758] |
Fri, 13 October 2006 16:31 |
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mirek
Messages: 13975
Registered: November 2005
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Ultimate Member |
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Thanks. Actually, the real problem was wrong colors for selected item in GetItemStyle. This bug escaped our attention because ColumnList so far is used just for filelists, where it has different Display.
As for not selecting the item without Shift or Ctrl, that is correct - cursor is not considered to be the selection.
ColumnList returns IsSelection when there are selected items. When there are not, IsCursor still can be true - in that case you have to use GetCursor to find which item has cursor.
My fixed GetItemStyle version:
void ColumnList::GetItemStyle(int i, Color& ink, Color& paper, dword& style)
{
ink = SColorText;
paper = SColorPaper;
const Item& m = item[i];
style = 0;
if(i == cursor) {
style = isselection ? Display::CURSOR : Display::CURSOR|Display::SELECT;
paper = isselection ? Blend(SColorHighlight, SColorFace) : SColorFace;
if(HasFocus()) {
style |= Display::FOCUS;
paper = isselection ? Blend(SColorHighlight, SColorPaper) : SColorHighlight;
ink = SColorPaper;
}
}
if(m.sel) {
style |= Display::SELECT;
paper = SColorShadow;
if(HasFocus())
style |= Display::FOCUS;
}
}
Note: Instead that complicated game with LogPos at the benning of AWindow, SetRect(0, 0, 228, 356); would be a simpler variant.
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) and needs extra code for functionality that could be a single line (like retrieving the first selected item). I appreciate this gives more flexibility but some additional member functions with obvious names would make this control easier to use.
