| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0035085 | Lazarus | LCL | public | 2019-02-14 13:06 | 2019-03-03 22:52 |
| Reporter | Zoran Vučenović | Assigned To | Zoran Vučenović | ||
| Priority | normal | Severity | minor | Reproducibility | always |
| Status | resolved | Resolution | fixed | ||
| Product Version | 2.0.2 | Product Build | 60420 | ||
| Target Version | Fixed in Version | ||||
| Summary | 0035085: Regression - TStringGrid event OnUserCheckboxBitmap shows no check boxes | ||||
| Description | When TStringGrid.OnUserCheckboxBitmap is assigned, no check box is shown at all, just blank fields in grid. | ||||
| Steps To Reproduce | I am uploading the test application which shows the problem. | ||||
| Additional Information | This is regression from Lazarus 1.8. I tracked the problem in trunk and this is what I found out: - since rev. 57746 (30. april 2018) OnUserCheckboxBitmap does not work correctly. However, then the CheckBoxes didn't disappear fully, but the grid shows default CheckBox bitmaps, ignoring the event. - since rev. 57927 (13. may 2018) CheckBoxes disappear totally! | ||||
| Tags | No tags attached. | ||||
| Fixed in Revision | |||||
| LazTarget | - | ||||
| Widgetset | |||||
| Attached Files |
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GridChkIcons.zip (128,907 bytes) |
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InvisibleCheckBox.png (14,051 bytes) |
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Rev59726.png (15,055 bytes) |
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Rev57745.png (15,339 bytes) |
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I am uploading three screenshots which show the same application (the one I attached to this bugreport), compiled with different versions of Lazarus: - InvisibleCheckBox.png - this is how the application looks now (2.0 or trunk), since trunk rev. 57927 - Rev59726 - this is how the application looks between revisions 57746 and 57926. - Rev57745 - this is how it looks before the bug got introduced. |
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The original tests and screenshots were taken on Linux Mint 19.1 xfce, gtk2 widgetset, but then I tested on Windows too (with 2.0-fixes branch, win widgetset) and the bug is there as well. |
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r57746 is by Ondrej: LCL: grids: use LCLBtnGlyphs for checkbox images r57927 is by Ondrej: LCL: grids: remove checkbox images |
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Yes, Juha. Ondrej's intention was obviously to improve the native (themed) looks of the checkboxes in grid. And, by looking in the bottom grid in the screenshots, we can see that he did it well, when native appearance is wanted. However, he obviously overlooked the StrigGrid's feature of user-provided bitmaps, so this is broken now. |
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Sorry - it should be easy to fix. I'll look at it. |
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Thank you, Ondrej! |
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You have to change your code. The ABitmap parameter in OnUserCheckboxBitmap is VAR. In 1.8 it was pre-assigned with the default bitmap. Since 1.9 it is nil. You have to assign a valid bitmap to ABitmap - you cannot just use the original value from ABitmap. IMO this was also the original idea how to use the parameter and your use case is a hack. Use this approach: unit Unit1; {$mode objfpc}{$H+} interface uses Classes, SysUtils, Forms, Controls, Graphics, Dialogs, Grids, StdCtrls; type { TForm1 } TForm1 = class(TForm) ImageListCheck: TImageList; Label1: TLabel; Label2: TLabel; StringGrid1: TStringGrid; StringGrid2: TStringGrid; procedure FormCreate(Sender: TObject); procedure StringGrid1UserCheckboxBitmap(Sender: TObject; const aCol, aRow: Integer; const CheckedState: TCheckboxState; var ABitmap: TBitmap); private FBmpUnchecked: TBitmap; FBmpChecked: TBitmap; public destructor Destroy; override; end; var Form1: TForm1; implementation {$R *.lfm} { TForm1 } procedure TForm1.StringGrid1UserCheckboxBitmap(Sender: TObject; const aCol, aRow: Integer; const CheckedState: TCheckboxState; var ABitmap: TBitmap); begin if CheckedState = cbUnchecked then begin if FBmpUnchecked=nil then begin FBmpUnchecked := TBitmap.Create; ImageListCheck.GetBitmap(0, FBmpUnchecked); end; ABitmap := FBmpUnchecked; end else begin if FBmpChecked=nil then begin FBmpChecked := TBitmap.Create; ImageListCheck.GetBitmap(1, FBmpChecked); end; ABitmap := FBmpChecked; end; end; destructor TForm1.Destroy; begin FBmpUnchecked.Free; FBmpChecked.Free; inherited Destroy; end; procedure TForm1.FormCreate(Sender: TObject); var I: Integer; begin for I := StringGrid1.FixedRows to StringGrid1.RowCount - 1 do begin StringGrid1.Cells[1, I] := IntToStr(I mod 2); end; for I := StringGrid2.FixedRows to StringGrid2.RowCount - 1 do begin StringGrid2.Cells[1, I] := IntToStr(I mod 2); end; end; end. --- This works both in 1.8 and 2.0 and IMO this was also the right way to use OnUserCheckboxBitmap in 1.8. The change should be documented, though. |
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Btw. the grid uses now imagelist & imageindex - so it would be appropriate to add a new event "OnUserCheckboxImage" where you could define custom ImageList and ImageIndex - see procedure TCustomGrid.GetImageForCheckBox, it has already the "var ImageList: TCustomImageList; var ImageIndex: TImageIndex;" parameters. |
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> You have to change your code. I see. Thank you, it works. > The change should be documented, though. Yes. I added a few lines in release notes: http://wiki.lazarus.freepascal.org/Lazarus_2.0.0_release_notes#TCustomGrid:_The_var_parameter_ABitmap_in_event_OnUserCheckBoxBitmap_used_to_be_preassigned_with_default_bitmap.2C_but_now_it_is_nil. > Btw. the grid uses now imagelist & imageindex - so it would be appropriate to add a new event "OnUserCheckboxImage" where you could define custom ImageList and ImageIndex - see procedure TCustomGrid.GetImageForCheckBox, it has already the "var ImageList: TCustomImageList; var ImageIndex: TImageIndex;" parameters. Yes, the implementation seems unfinished, if I didn't miss something, currently there is no place where a user can provide the ImageList and the index. I'll see to make a patch (in new bugreport, for trunk only, not to go in fixes). Thanks a lot, Ondrej, I am resolving this with "no change required". |
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> Yes. I added a few lines in release notes: Thank you for this. > if I didn't miss something, currently there is no place where a user can provide the ImageList and the index. The user can override the virtual method TCustomGrid.GetImageForCheckBox. But an event handler called in this method would be good. |
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> The user can override the virtual method TCustomGrid.GetImageForCheckBox Notice that, as currently implemented that is actually not enough - the OnUserCheckboxBitmap must be assigned, at least with empty body, otherwise GetImageForCheckBox never gets called. :) Anyway, I created the patch which adds OnUserCheckboxImage event - issue 35097. |
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> the OnUserCheckboxBitmap must be assigned, at least with empty body, otherwise GetImageForCheckBox never gets called Huh, that was definitely not my intension. Thanks for finding this. |
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The code does not work for TDBGrid because it uses its own event type for OnUserCheckboxBitmap - when I assign a handler to TDGrid.OnUserCheckboxBitmap the handler to the original TCustomGrid.OnUserCheckboxBitmap remains unassigned. In the checkbox drawing code, TCustomGrid.DrawGridCheckboxBitmaps, the CustomGrid checks whether it has an onUserCheckboxBitmap handler. In case of the TDBGrid, however, the handler is empty and thus never calls the virtual GetImageForCheckBox where the TDBGrid.OnUserCheckboxBitmap handler would be called. |
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Isn't this solved with the (not yet applied) patch in 0035097? |
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Yes, I just did not know of this report. I'll apply that patch. I guess that the OnUserCheckboxImage event should be published for DBGrid as well. |
