Loading images into TImage, via array - arrays

I'm very new to delphi, doing a project for my A level. When I run my code the images just don't show, I've looked everywhere and my teacher can't help me. Can anyone tell me what I'm missing?
const
Animal : array[0..6] of string = ('Bears','Dogs','Cats','Chickens','Horses','Cows','Monkeys');
ImagePaths : array [0..6] of string
= ('img0.JPG', 'img1.JPG', 'img2.JPG', 'img3.JPG', 'img4.JPG', 'img5.JPG',
'img6.JPG');
var i:integer;
Images : array [0..11] of TImage;
procedure LoadImages;
var
k,l:integer;
begin
Randomize;
k:=Random(11);
for l:= 0 to k do
begin
Images[l] := TImage.Create(nil);
Images[l].Picture.LoadFromFile(ImagePaths[i])
end
end;
procedure TForm4.FormCreate(Sender: TObject);
begin
randomize;
i:=random(6);
QuestionLbl.Caption:=Format('How many %s are there?',[Animal[i]]);
LoadImages;
end;
The idea is that a random number of images of the same randomly selected animal is displayed for a child to then count and input, if that helps. Much appreciate any help.
edit.
as this is only a prototype I have copied it all to a new application and this is all the code I didn't include:
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls,jpeg, ExtCtrls;
type
TForm1 = class(TForm)
QuestionLbl: TLabel;
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
The same error is occurring and I'm afraid I'm too ignorant to follow what I'm sure were very clear instructions.

What appears to be missing is that you need to tell the image which control is its parent so that it can appear on screen. Do that like this:
Images[l].Parent := TheForm;
Obviously your form variable will have a different name, but I'm sure you know what it's called.
When you do this you will find that they all end up on top of each other. Assign to the Top and Left properties to position then. Finally you will likely want to set the Height and Width properties of the images to match the dimensions of the images, Images[l].Picture.Height and Images[l].Picture.Width.
I can't imagine why your code produces an access violation but it's presumably unrelated to the question you asked. The following code proves that what I say above is correct:
procedure TMyForm.FormCreate(Sender: TObject);
var
Image: TImage;
begin
Image := TImage.Create(Self);
Image.Parent := Self;
Image.Picture.LoadFromFile('C:\desktop\image.jpg');
Image.Top := 0;
Image.Left := 0;
Image.Height := Image.Picture.Height;
Image.Width := Image.Picture.Width;
end;
Without your full code I cannot debug your AV.

Why you just don't put your TImages on the form, and just LoadFromFile the ones you want to show ?
Appear to me that would be easier.
But: what you trying to accomplish? From the code, I can imagine you were trying to show a number of images to people count them and answer the question...
So, if you add (and position) the 11 empty(no image) TImages in the form, you can do:
// Any trouble in copying your FormCreate header, David? ;-)
procedure TMyForm.FormCreate(Sender: TObject);
begin
Images[0] := Image_N1; // First TImage
Images[1] := Image_N2;
Images[2] := Image_N3;
// Do that until the 12 slots are filled
// As a exercise for Danny Robinson( the OP ), you can do that in a for..do using
// the Form.Components array property to automate it instead of
// doing one-at-a-line
end;
procedure ClearImages;
var I: Integer;
begin
for I = Low(Images) to High(Images) do
begin
Images.Picture.Graphic := Nil;
end;
end;
procedure LoadImages;
var
k,l:integer;
begin
ClearImages;
Randomize;
k:=Random(11);
for l:= 0 to k do
begin
Images[l].Picture.LoadFromFile(ImagePaths[i])
end;
end;
If you still need to create the TImages on the fly, just create the 12 TImages
once on FormCreate (as in David's answer) and keep calling the LoadImages.
EDIT:
Some ideas, since you are learning.
Creating visual controls on-the-fly is a very boring(in my opinion, of course) task that involves:
Creating the object, obviously
Assigning it to a parent control (forms doesn't need this pass)
Sizing it accordingly to your visual planning
Positioning it in the place of the parent control you want it to be
Set it's anchors, for it to reposition and/or resize when the parent control is resized (if needed)
Only after all this, make it do what you want it to do (in this case, showing images).
Almost all those steps David Heffernan's answer show the code for it. But, unless you really need a dynamic layout, doing all those on design-time is more practical ;-)

You need to set the Parent property of each TImage in order to see them onscreen. You can't use the global Form pointer variable, though, because it has not been assigned yet when the OnCreate event is triggered. So pass in the form's Self pointer as a parameter of LoadImages() instead.
You have another bug - you declared a 12-element TImage array but declared a 7-element String array for the image paths. The way you are using Random(), if it generates a value above 6, you will go out of bounds of the String array.
Try this instead:
const
...
ImagePaths : array [0..6] of string = ('img0.JPG', 'img1.JPG', 'img2.JPG', 'img3.JPG', 'img4.JPG', 'img5.JPG', 'img6.JPG');
var
i: integer;
Images : array [0..6] of TImage;
procedure LoadImages(AParent: TWinControl);
var
i, k: integer;
begin
Randomize;
k := Random(7);
for i := 0 to k do
begin
Images[i] := TImage.Create(nil);
Images[I].Parent := AParent;
// set other properties, like Left/Top...
Images[l].Picture.LoadFromFile(ImagePaths[i]);
end;
end;
procedure TForm4.FormCreate(Sender: TObject);
begin
...
LoadImages(Self);
end;

TImage component must to be painted on the screen,
for do so make a 1pixel panel as the parent to load the graphics.
like in a loading screen so the images can be used as default TImage procedures.

Related

How can I use the value of a stringgrid cell to be stored in an array which should hold the current game state?

I'm new to programming and am trying to make a delphi tictactoe game using a 3x3 array, as a way to help me learn the basics.
I'm using a stringgrid which I wanted to show the state of the board, the user places an X on the cell (via mouse click). I was hoping at this part in the code it would add the 'X' to the gameboard array using the stringgrid.cell(ARow,ACol) for the position. I've now learnt that this cannot work as the array is a char type. Is there a way around this?
I know this is not the best way to make a game, but it's helping me learn. Any help would be very appreciated. Here's my code:
unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants,
System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ButtonGroup,
Vcl.Grids;
type
TForm1 = class(TForm)
Button1: TButton;
label1: TLabel;
StringGrid1: TStringGrid;
Button2: TButton;
procedure StringGrid1SelectCell(Sender: TObject; ACol, ARow: Integer;
var CanSelect: Boolean);
procedure Button2Click(Sender: TObject);
procedure FormShow(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
procedure restart();
procedure compTurn();
end;
var
Form1: TForm1;
gameBoard: array [1 .. 3, 1 .. 3] of char; // array for the game board.
iScore: Integer;
bTurn: Boolean = True; // O's go = false, X's go = true.
implementation
{$R *.dfm}
{ TForm1 }
procedure TForm1.Button2Click(Sender: TObject);
begin
restart;
end;
procedure TForm1.compTurn;
begin
// if (bTurn = false) then
label1.Caption := 'Computer`s turn';
end;
procedure TForm1.FormShow(Sender: TObject);
begin
restart;
end;
procedure TForm1.restart;
var
i, j: Integer;
begin
// place ? in the cells
StringGrid1.Enabled := True;
for i := 1 to 3 do
for j := 1 to 3 do
StringGrid1.cells[i, j] := '?';
label1.Caption := 'Player X`s turn';
end;
procedure TForm1.StringGrid1SelectCell(Sender: TObject; ACol, ARow: Integer;
var CanSelect: Boolean);
Var
sX: string;
pos: Integer;
begin
sX := 'X';
CanSelect := false;
// Place a X or O in the cell depending on whose turn it is
if (bTurn = True) then
StringGrid1.cells[ACol, ARow] := sX // and gameBoard[ACol, ARow]
else
bTurn := false; // computer's turn to move
compTurn; // make sure user can't add an X
StringGrid1.Enabled := false;
end;
end.```
I was hoping at this part in the code it would add the 'X' to the
gameboard array using the stringgrid.cell(ARow,ACol) for the position.
I've now learnt that this cannot work as the array is a char type. Is
there a way around this?
The problem you are facing here is that in your StringGrid1SelectCell event handler you defined your sX variable as string. So if you try to assign value of sX to your array of char Delphi won't let you since you cant store entire string into a sigle char.
To achieve desired functionality you should change your sX variable into a Char type instead. This will then allow you to write its value into your array.
Now you might be thinking that this would lead to problems since you also need to assign value of your sX variable to specific String Grid Cell since String Grid Cells are of String type. You won't.
You can always assign a single char to a string. This will change the length of that string to one an it will contain only the specific character you provided.
So in short:
Assigning String to Char does not work
Assigning Char to string does work
PS Also don't forget that if you need to execute multiple commands when if clause condition is met you need to enclose those commands with begin..end block.
So your code should look something like this (haven't tested it)
procedure TForm1.StringGrid1SelectCell(Sender: TObject; ACol, ARow: Integer;
var CanSelect: Boolean);
Var
sX: Char; //Change type from String to Char
pos: Integer;
begin
sX := 'X';
CanSelect := false;
// Place a X or O in the cell depending on whose turn it is
if (bTurn = True) then
//Enclose multiple commands with begin..end block
begin
StringGrid1.cells[ACol, ARow] := sX // and gameBoard[ACol, ARow]
GameBoard[ACol,ARow] := sX;
else
bTurn := false; // computer's turn to move
compTurn; // make sure user can't add an X
StringGrid1.Enabled := false;
end;

How to correctly declare an array property in Delphi?

I'm trying to create an array to store every item of a TStringList into an array which size may vary depending on the quantity of items in said TStringList.
I know my syntax is wrong and what I want is probably a dynamic array, so the [0..100] is probably wrong aswell but I could not find any alternative syntax online.
ProductAvailabilityResult = Class(TRemotable)
private
FResultArray : array[1..100] of string;
published
property ResultArray[Index: Integer]: array of string read FResultArray write FResultArray;
End;
And this is how I would invoke it and populate it. conditionList being my TStringList which I would populate into my array.
for I := 0 to conditionList.Count - 1 do
begin
aProductAvailabilityResult.ResultArray[I] := conditionList[I];
end;
In case you may or may not have alternative suggestions to what i'm doing, the reason for this setup is because it's a web service app sending results over a SOAP server, and I don't think my PHP/Soap client can read TStringLists, so I need to pass it to an array first.
Let me know, Thanks!
Your syntax for declaring an array property is close, but you need to use getter/setter methods instead of direct field access, and array properties cannot be declared as published:
type
ProductAvailabilityResult = class(TRemotable)
private
FResultArray : array of string;
function GetResultArray(Index: Integer): string;
function GetResultArrayCount: Integer;
procedure SetResultArray(Index: Integer; const Value: string);
procedure SetResultArrayCount(Value: Integer);
public
property ResultArray[Index: Integer]: string read GetResultArray write SetResultArray default;
property ResultArrayCount: Integer read GetResultArrayCount write SetResultArrayCount;
end;
function ProductAvailabilityResult.GetResultArray(Index: Integer): string;
begin
Result := FResultArray[Index];
end;
function ProductAvailabilityResult.GetResultArrayCount: Integer;
begin
Result := Length(FResultArray);
end;
procedure ProductAvailabilityResult.SetResultArray(Index: Integer; const Value: string);
begin
FResultArray[Index] := Value;
end;
procedure ProductAvailabilityResult.SetResultArrayCount(Value: Integer);
begin
SetLength(FResultArray, Value);
end;
Then you can do this:
aProductAvailabilityResult.ResultArrayCount := conditionList.Count;
for I := 0 to conditionList.Count - 1 do
begin
aProductAvailabilityResult[I] := conditionList[I];
end;
You might want to consider adding a method to copy strings from a source TStrings:
type
ProductAvailabilityResult = class(TRemotable)
private
...
public
procedure AssignStrings(AStrings: TStrings);
...
end;
procedure ProductAvailabilityResult.AssignStrings(AStrings: TStrings);
var
I: Integer;
begin
SetLength(FResultArray, AStrings.Count);
for I := 0 to AStrings.Count - 1 do
FResultArray[I] := AStrings[I];
end;
aProductAvailabilityResult.AssignStrings(conditionList);
You've declared an array property, albeit with some syntax errors. However, you state in the question and comments that you want a property that is a dynamic array. That's different from an array property.
Declare a dynamic array property like so:
type
ProductAvailabilityResult = class(TRemotable)
private
FResultArray: TArray<string>;
published
property ResultArray: TArray<string> read FResultArray write FResultArray;
end;
Populate it like this:
var
i: Integer;
List: TStringList;
par: ProductAvailabilityResult;
arr: TArray<string>;
....
List := ...;
par := ...;
SetLength(arr, List.Count);
for i := 0 to List.Count-1 do
arr[i] := List[i];
par.ResultArray := arr;

How to save multiple images from database to TMemoryStream at runtime and extract them later on

I am creating a project at delphi(RAD Studio). There are images stored at database table at some rows. I want to extract images at runtime (for which I am using Array of TMemoryStream) and show them at frxReport.
My code snippet as follows
Public variable TStream is declared as
Stream2 : Array of TStream; i,k: integer
Code segment for view button click event, which is placed on MainForm and expected to show frxReport.
`
procedure TFrmMain.btnViewClick(Sender: TObject);
begin
i := 0;
k := 0;
UniTable1.SQL.Text := 'Select * from userplays order by id';
UniTable1.Execute;
rowcount := UniTable1.RecordCount;
SetLength(myid, rowcount);
SetLength(mydesc, rowcount);
SetLength(myimg, rowcount);
SetLength(Stream2, rowcount);
while not UniTable1.Eof do
begin
try
Stream2[k] := TMemoryStream.Create;
myid[k] := UniTable1.FieldByName('id').Value;
Stream2[k] := UniTable1.CreateBlobStream(TBlobField(UniTable1.FieldByName('image')), bmRead);
mydesc[k] := UniTable1.FieldByName('description').Value;
UniTable1.Next;
inc(k);
finally
//Stream2[k].Free;
end;
end;
frxUserDataSet1.RangeEnd := reCount;
frxUserDataSet1.RangeEndCount := rowcount;
frxReport1.ShowReport;
i := 0;
end;
`
However this method is not loading any image to Stream2 array. There is an option to use array of JPEGImage however if JPEGImage array used then it would be problem to display it on frxRaport at
procedure TFrmMain.frxReport1GetValue(const VarName: string; var Value: Variant);
`
Graphic := TJPEGImage.Create;
Graphic.LoadFromStream(Stream2[j]);
TfrxPictureView(frxreport1.FindObject('Picture1')).Picture.Graphic := Graphic;
`
Kindly let me know how to do this.
However this method is not loading any image to Stream2 array
In your current code you are first assigning a newly created TMemoryStream to Stream2[k]:
Stream2[k] := TMemoryStream.Create;
then you are throwing the TMemoryStream away (creating a memory leak) and replacing it with the blob stream you create:
Stream2[k] := UniTable1.CreateBlobStream(TBlobField(UniTable1.FieldByName('image')), bmRead);
But you never read from the blob stream.
Here's the while loop rewritten (untested)
var
blobstream: TStream;
Stream2: array of TMemoryStream;
....
// read 'id', 'description' and 'image' fields to respective arrays
while not UniTable1.Eof do
begin
myid[k] := UniTable1.FieldByName('id').Value;
mydesc[k] := UniTable1.FieldByName('description').Value;
blobstream := UniTable1.CreateBlobStream(TBlobField(UniTable1.FieldByName('image')), bmRead);
try
Stream2[k] := TMemoryStream.Create;
Stream2[k].LoadFromStream(blobstream);
finally
blobstream.Free;
end;
UniTable1.Next;
inc(k);
end;
Btw, I would recommend to define a record to hold the id, description and image together, and then an array of those records, instead of three separate arrays. Much simpler to manage only one array instead of three.
I think in your situation most obvious thing would be just connect existing DataSet ( Unitable1) directly into DataBand in frxReport. I don't see why you would need to use frxUserDataset instead of frxDBDataset with its DataSet property set to Unitable1 since you created it anyway.
If you really need a list of objects then I would take a different approach.
Your multiple global variables look ugly and are dangerous (i,k...)
I would create a class that holds your data and populate this data into a
TObjectList from System.Generics.Collection:
unit DataPack;
interface
uses ExtCtrls...System.SysUtils;
type
TMyDataPack = class(TObject)
private
Query: TFDQuery; //O r TUniQery
_MyId: Integer;
_MyDescription: String;
_MyImage: TImage;
_Loaded: Boolean;
function LoadData: boolean;
protected
public
constructor Create(Data: TFDQuery); //Or Uniquery
property MyId: Integer read _MyId;
property MyDescription: String read _MyDescription;
property MyImage: TImage read _MyImage;
property Loaded: Boolean read _Loaded;
end;
implementation
{ TMyDataPack }
constructor TMyDataPack.Create(Data: TFDQuery);
begin
Inherited Create;
Query:=Data;
_Loaded:=true;
if not (LoadData) then
_Loaded:=false;
end;
function TMyDataPack.LoadData: boolean;
var
Stream: TStream;
begin
Stream:= TStream.Create;
Stream:=Query.CreateBlobStream(TBlobField(Query.FieldByName('image')), bmRead);
try
_MyImage:=TImage.Create(nil);
_MyImage.Picture.Bitmap.LoadFromStream(Stream);
_MyDescription:=Query.FieldByName('description').AsString;
_MyId:=Query.FieldByName('CategoryId').AsInteger;
except on E: Exception do
begin
FreeAndNil(Stream);
FreeAndNil(_MyImage);
Exit(false);
end;
end;
FreeAndNil(Stream);
Result:=true;
end;
end.
Then in your main code:
procedure TMain.Button2Click(Sender: TObject);
var
DataRow: TMyDataPack;
List: TObjectList<TMyDataPack>;
Num: integer;
CurrentImage: TImage;
CurrentDescription: String;
CurrentId: integer;
begin
UniTable1.SQL.Text:='SELECT * FROM Userplays';
UniTable1.Open();
List:=TObjectList<TMyDataPack>.Create;
while not (UniTable1.Eof) do
begin
DataRow:=TMyDataPack.Create(UniTable1);
if(DataRow.Loaded) then
List.Add(DataRow);
UniTable1.Next;
End;
for Num:=0 to List.Count do
begin
CurrentDescription:=List[Num].MyDescription;
CurrentImage:=List[Num].MyImage;
CurrentId:=List[Num].MyId;
//List[Num].MyImage.Picture.SaveToFile('Some'+IntToStr(Num)+'.bmp');
// You might save it to file then...
end;
end;
end.
Then pass an ObjectList further, just remember to free it at the end.
You might further expand it by creating class factory to create different objects if you'd need for example use different database with same data,
perform check if image is actually Bmp or Jpg and so on.
You might even just pass a query without setting it's SQL and get TobjectList as property.

Delphi 2007 and Dynamic Variant Array as Var Parameter

I have a form which allows a use to select a record and this form then returns the ID of the record and an arbitrary number of fields values that the calling form may need. To do this, I have a function which handles creating the select form and passes all the values to and from the calling form:
Function Execute(AOwner: TComponent; AConnection: TADOConnection;
AEditor: String; AButtons: TViewButtons; Var AID: Integer;
Var ARtnVals: Array of Variant): TModalResult;
Var
I: Integer;
Begin
frmSelectGrid := TfrmSelectGrid.Create(AOwner);
Try
With frmSelectGrid Do
Begin
Connection := AConnection;
Editor := AEditor;
Buttons := AButtons;
ID := AID;
Result := ShowModal;
If Result = mrOK Then
Begin
AID := ID;
//VarArrayRedim(ARtnVals, Length(RtnVals)); !! Won't compile
//SetLength(ARtnVals, Length(RtnVals)); !! Won't compile either
For I := 0 To High(RtnVals) Do
ARtnVals[I] := RtnVals[I]; // Causes runtime exception
End;
End;
Finally
FreeAndNil(frmSelectGrid);
End;
End;
The selector form has the following public properties:
public
Connection: TADOConnection;
Editor: String;
Buttons: TViewButtons;
ID: Integer;
RtnVals: Array of Variant;
end;
And in the OK click, I have the following code:
Var
I, Idx, C: Integer;
// Count how many fields are being returned
C := 0;
For I := 0 To Config.Fields.Count - 1 Do
If Config.Fields[I].Returned Then
Inc(C);
// If no fields to be returned, then just exit.
If C = 0 Then
Exit;
// Set the size of the RtnVals and assign the field values to the array.
SetLength(RtnVals, C);
Idx := 0;
For I := 0 To Config.Fields.Count - 1 Do
If Config.Fields[I].Returned Then
Begin
RtnVals[Idx] := aqItems.FieldByName(Config.Fields[I].FieldName).Value;
Inc(Idx);
End;
So, once the user clicks OK to select a record, the RtnVals array is populated with the field values of the fields to be returned. I now need to copy these values to ARtnVals in the Execute function so that they are returned to the calling form.
My question is how do I set the size of the ARtnVals array so that I can copy the fields? SetLength doesn't work like it does in the OK click function above. VarArrayRedim doesn't work either.
When written in a procedure parameter list, this code
Var ARtnVals: Array of Variant
is an open array, and not a dynamic array. An open array cannot be resized. An open array is no use to you here.
Instead define a type for the array:
type
TDynamicArrayOfVariant = array of Variant;
Use that type for your parameter, which is actually best as an out parameter:
function Execute(..., out RtnVals: TDynamicArrayOfVariant): TModalResult;
And then pass the function a TDynamicArrayOfVariant to be populated.
Now you have a dynamic array rather than an open array in Execute, and you can use SetLength to size it.

Value isnt saved after inputstring on TDBWPRichText to linked MemoField

i have a TDBWPRichText linked to a MemoField on my Database.
when i press a Button i want the formated text to prepend some text.
the visual component shows the the prepended string, but when i Post, the Value of the memo doesnt change.
MyTable.Edit;
DBRichedit1.SelLength := 0;
DBRichedit1.CPPosition := 0;
DBRichedit1.Inserting := True;
DBRichedit.InputString('Test:' + #13);
//it shows the value on the component here
MyTable.Post;
in the MyTableBeforePost the Field has the old value though apparently
Field.Value <> Field.OldValue
If i enter text manually it works just fine
i also tried to save it manually (where the comment is) but the String is the old value
DBRichedit.SaveToString(MyTable.FieldByName('MyMemo').AsString,False);
Is there anyway i can get the prepended String into my Table?
This was a lot trickier than I was expecting it to be, even though I recalled that working with RichText in Delphi code can be a bit of a pain.
Anyway, the following works for me, to add an Rtf header stored in a disk file; see if it does for you. It isn't pretty and I can't help thinking that it's inordinately
long-winded.
procedure TForm1.InsertHeader;
// Prepend an RTF header to an existing RTF DB field
var
TL : TStringList;
ExistingText : String;
RE : TRichEdit;
MS : TMemoryStream;
begin
MS := TMemoryStream.Create;
TL := TStringList.Create;
// The reason for using a temporary RichEdit is to enlist its assistance
// in manipulating the rich text
RE := TRichEdit.Create(Nil);
RE.Parent := Self;
try
ExistingText := AdoQuery1.FieldByName('Memo').AsString;
RE.Clear;
// The reason for using the richedit's SelText in the following is that my
// initial naive attempt to assign to its Lines.Text provoked a "Line Insertion Error"
RE.SelStart := 0;
RE.SelText := ExistingText + #13#10;
TL.LoadFromFile('\d7\demos\richedit\header.rtf');
RE.SelStart := 0;
RE.SelText := RE.SelText + TL.Text;
RE.Lines.SaveToStream(MS);
MS.Position := 0;
AdoQuery1.Edit;
TMemoField(AdoQuery1.FieldByName('Memo')).LoadFromStream(MS);
AdoQuery1.Post;
finally
TL.Free;
RE.Free;
MS.Free;
end;
end;
Btw, there is an answer to how to insert RTF into pre-existing RTF in a TRichEdit here: http://delphidabbler.com/tips/57
After some hours i resorted to the dev of WPtools and he promptly provided me with the answer which is incredible simple:
you have to call
RichEdit.Changing
before interacting with it within the code

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