I simply can't figure out what I'm doing wrong when trying to paint a control.
I've tried using TCanvas.BeginScene()/TCanvas.EndScene(), tried painting in other methods (for example main form OnPaint()).
I've tried TControl.InvalidateRect().
I get nothing.
Here's what I have in my test app:
type
TTestControl = class(TControl)
protected
procedure Paint; override;
end;
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
private
fTestControl: TTestControl;
end;
procedure TTestControl.Paint;
begin
Canvas.Fill.Color := TColorRec.Blueviolet;
Canvas.FillEllipse(ClipRect, AbsoluteOpacity);
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
fTestControl := TTestControl.Create(Self);
fTestControl.Parent := Self;
fTestControl.Align := TAlignLayout.Client;
end;
It ought to be enough, according to what's online.
Any suggestions?
The Canvas.Fill.Color is a TAlphaColor.
Change the line
Canvas.Fill.Color := TColorRec.Blueviolet;
to
Canvas.Fill.Color := TAlphaColors.Blueviolet;
Your Paint methods should be like this:
procedure TTestControl.Paint;
begin
inherited;
Canvas.BeginScene;
Canvas.Fill.Color := claBlueviolet;
Canvas.FillEllipse(ClipRect, AbsoluteOpacity);
Canvas.EndScene;
end;
I, also, think you should override the DoPaint method of TControl and not the Paint.
Related
Using some answers in StackOverflow I've created a searcheable TComboBox in Delphi. It works fine when you add it directly to a Form, but breaks as soon as you add it to a TPanel and I can't seem to figure out why.
Directly on the form:
After typing t:
Inside a panel:
After typing t:
Here is the component's code:
unit uSmartCombo;
interface
uses
Vcl.StdCtrls, Classes, Winapi.Messages, Controls;
type
TSmartComboBox = class(TComboBox)
private
FStoredItems: TStringList;
procedure FilterItems;
procedure CNCommand(var AMessage: TWMCommand); message CN_COMMAND;
procedure RedefineCombo;
procedure SetStoredItems(const Value: TStringList);
procedure StoredItemsChange(Sender: TObject);
protected
procedure KeyPress(var Key: Char); override;
procedure CloseUp; override;
procedure Loaded; override;
procedure DoExit; override;
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
property StoredItems: TStringList read FStoredItems write SetStoredItems;
end;
procedure Register;
implementation
uses
SysUtils, Winapi.Windows, Vcl.Forms;
procedure Register;
begin
RegisterComponents('Standard', [TSmartComboBox]);
end;
constructor TSmartComboBox.Create(AOwner: TComponent);
begin
inherited;
FStoredItems := TStringList.Create;
FStoredItems.OnChange := StoredItemsChange;
end;
destructor TSmartComboBox.Destroy;
begin
FStoredItems.Free;
inherited;
end;
procedure TSmartComboBox.DoExit;
begin
inherited;
RedefineCombo;
end;
procedure TSmartComboBox.Loaded;
var LParent: TWinControl;
LPoint: TPoint;
begin
inherited;
if Items.Count > 0 then
FStoredItems.Assign(Items);
AutoComplete := False;
Style := csDropDownList;
// The ComboBox doesn't behave properly if the parent is not the form.
// Workaround to pull it from any parenting
//if not (Parent is TForm) then
//begin
// LParent := Parent;
// while (not (LParent is TForm)) and Assigned(LParent) do
// LParent := LParent.Parent;
// LPoint := ClientToParent(Point(0,0), LParent);
// Parent := LParent;
// Left := LPoint.X;
// Top := LPoint.Y;
// BringToFront;
//end;
end;
procedure TSmartComboBox.RedefineCombo;
var S: String;
begin
if Style = csDropDown then
begin
if ItemIndex <> -1 then
S := Items[ItemIndex];
Style := csDropDownList;
Items.Assign(FStoredItems);
if S <> '' then
ItemIndex := Items.IndexOf(S);
end;
end;
procedure TSmartComboBox.SetStoredItems(const Value: TStringList);
begin
if Assigned(FStoredItems) then
FStoredItems.Assign(Value)
else
FStoredItems := Value;
end;
procedure TSmartComboBox.StoredItemsChange(Sender: TObject);
begin
if Assigned(FStoredItems) then
begin
RedefineCombo;
Items.Assign(FStoredItems);
end;
end;
procedure TSmartComboBox.KeyPress(var Key: Char);
begin
if CharInSet(Key, ['a'..'z']) and not (Style = csDropDown) then
begin
DroppedDown := False;
Style := csDropDown;
end;
inherited;
if not (Ord(Key) in [13,27]) then
DroppedDown := True;
end;
procedure TSmartComboBox.CloseUp;
begin
if Style = csDropDown then
RedefineCombo;
inherited;
end;
procedure TSmartComboBox.CNCommand(var AMessage: TWMCommand);
begin
inherited;
if (AMessage.Ctl = Handle) and (AMessage.NotifyCode = CBN_EDITUPDATE) then
FilterItems;
end;
procedure TSmartComboBox.FilterItems;
var I: Integer;
Selection: TSelection;
begin
SendMessage(Handle, CB_GETEDITSEL, WPARAM(#Selection.StartPos), LPARAM(#Selection.EndPos));
Items.BeginUpdate;
Try
if Text <> '' then
begin
Items.Clear;
for I := 0 to FStoredItems.Count - 1 do
if (Pos(Uppercase(Text), Uppercase(FStoredItems[I])) > 0) then
Items.Add(FStoredItems[I]);
end
else
Items.Assign(FStoredItems);
Finally
Items.EndUpdate;
End;
SendMessage(Handle, CB_SETEDITSEL, 0, MakeLParam(Selection.StartPos, Selection.EndPos));
end;
end.
Any help in how I can proceed to figure out why this is happening would be greatly appreciated!
Edit 1:
After doing some extra debugging, I've noticed the messages being sent to the ComboBox differ from the ones inside the panel.
A CBN_EDITUPDATE is never sent, like #Sherlock70 mentioned in the comments, which makes the FilterItems procedure never trigger.
I've also noticed the form behaves strangely after using the ComboBox inside the panel, sometimes freezing and even not responding, like it gets stuck in a loop.
This unpredictable behavior has made me move away from this approach, and I'm probably going to take an alternate route to create a "searchable ComboBox".
Going to leave the question open if someone wants to figure it out and maybe even use the component.
I hope this will help someone in future even after 7 months of the question. Setting the style of a Combobox will destroy the window handle of that Combobox and create a new one. This means windows will free your control's Window Handle and create a new one.
You are setting your Combobx style while searching and this is wrong. Try removing Style := from your code and test it again you will get the same results for Combobox on a form and Combobox on a panel or other TWinControl. As you can see in the following code, setting Style will call RecreateWnd.
procedure TCustomComboBox.SetStyle(Value: TComboBoxStyle);
begin
if FStyle <> Value then
begin
FStyle := Value;
if Value = csSimple then
ControlStyle := ControlStyle - [csFixedHeight] else
ControlStyle := ControlStyle + [csFixedHeight];
RecreateWnd;
end;
end;
RecreateWnd will call DestroyHandle()
procedure TWinControl.CMRecreateWnd(var Message: TMessage);
var
WasFocused: Boolean;
begin
WasFocused := Focused;
DestroyHandle;
UpdateControlState;
if WasFocused and (FHandle <> 0) then Windows.SetFocus(FHandle);
end;
Then DestroyHandle will call DestroyWnd() which will call DestroyWindowHandle().
I try to create a TComboBox like component, inherited from TMaskEdit with a TSpeedButton inside the edit itself.
The problem when I type something into the edit the most of the button disappears (the right and the bottom edge still visible). If I move the mouse over the component or exit using TAB, the button appears again.
Here is the code:
interface
uses
Windows, Messages, SysUtils, Classes, Controls, Forms, Mask, Buttons;
type
TMyEdit = class(TCustomMaskEdit)
private
FButton: TSpeedButton;
protected
procedure CreateButton;
public
constructor Create(AOwner: TComponent); override;
procedure CreateWnd; override;
destructor Destroy; override;
end;
implementation
constructor TMyEdit.Create(AOwner: TComponent);
begin
inherited;
CreateButton;
end;
procedure TMyEdit.CreateButton;
begin
FButton := TSpeedButton.Create(Self);
FButton.Parent := Self;
FButton.Align := alRight;
FButton.Width := 16;
FButton.Caption := '';
FButton.Transparent := False;
end;
destructor TMyEdit.Destroy;
begin
FreeAndNil(FButton);
inherited;
end;
procedure TMyEdit.CreateWnd;
begin
inherited;
Perform(EM_SETMARGINS, EC_RIGHTMARGIN, (FButton.Width + 4) shl 16);
end;
What do I miss?
Solved.
WS_CLIPCHILDREN flag have to be included in the CreateParams() AND the button must be placed on TWinControl descendant (TPanel in my case) OR the button itself must be a TWinControl descendant (for example TButton). Graphic controls has no Handle, thats the problem.
Modified code:
procedure TMyEdit.CreateButton;
var
xDrawRect: TRect;
xPanel : TPanel;
begin
xPanel := TPanel.Create(Self);
xPanel.Parent := Self;
xPanel.SetBounds(Width - Height, 0, Height, Height);
xPanel.BevelOuter := bvNone;
FButton := TSpeedButton.Create(Self);
FButton.Parent := xPanel;
FButton.Align := alClient;
FButton.Caption := '';
end;
procedure TMyEdit.CreateParams(var Params: TCreateParams);
begin
inherited CreateParams(Params);
Params.Style := Params.Style or WS_CLIPCHILDREN;
end;
Quick question in regard to Delphi XE.
I'm trying to make a customized circle-shape component that has transparent background, so that when added on a form, the component can overlap other components. I've tried Brush.Style:=bsTransparent; or ellipse() and more on... but still couldn't find a way to make the edge area transparent.
Is there anyway I can make the edge area of the component transparent without using other lib or api?
Well here's a quick answer, that should get you going.
type
TEllipticPanel = class(Vcl.ExtCtrls.TPanel)
procedure CreateWnd; override;
procedure Paint; override;
procedure Resize; override;
procedure RecreateHRGN;
end;
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
panl: TEllipticPanel;
public
{ Public declarations }
end;
implementation
procedure TForm1.FormCreate(Sender: TObject);
begin
panl := TEllipticPanel.Create(self);
panl.Left := 10;
panl.Top := 10;
panl.Width := 100;
panl.Height := 50;
panl.ParentBackground := False;
panl.ParentColor := False;
panl.Color := clYellow;
panl.Parent := self;
end;
{ TEllipticPanel }
procedure TEllipticPanel.RecreateHRGN;
var
hr: hRgn;
begin
inherited;
hr := CreateEllipticRgn(0,0,Width,Height);
SetWindowRgn(Handle, hr, True);
end;
procedure TEllipticPanel.CreateWnd;
begin
inherited;
RecreateHRGN;
end;
procedure TEllipticPanel.Paint;
begin
inherited;
Canvas.Brush.Style := bsClear;
Canvas.Pen.Style := TPenStyle(psSolid);
Canvas.Pen.Width := 1;
Canvas.Pen.Color := clGray;
Canvas.Ellipse(1,1,Width-2,Height-2);
end;
procedure TEllipticPanel.Resize;
begin
inherited;
RecreateHRGN;
end;
The key is the Windows CreateEllipticRgn and the GDI SetWindowRgn functions.
For more information about windows regions see Regions.
I'm trying to display a truly alpha blended TPanel in Delphi XE2. I've found quite a few attempts online, but none of them work correctly.
What I'm trying to achieve is a 'semi modal' form. A form that is displayed over the top of other controls with a faded background in a similar manner to that seen in web browsers.
I've got it working in a basic form, but it suffers from the following problems:
A large amount of flicker when resizing the panel.
If a control is moved over the top of the panel it leaves a trail.
Here's my efforts thus far (based on some code I found here).
unit SemiModalFormU;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, ExtCtrls;
type
ISemiModalResultHandler = interface
['{0CC5A5D0-1545-4257-A936-AD777E0DAFCF}']
procedure SemiModalFormClosed(Form: TForm);
end;
TTransparentPanel = class(TCustomPanel)
private
FBackground: TBitmap;
FBlendColor: TColor;
FBlendAlpha: Byte;
procedure ColorBlend(const ACanvas: TCanvas; const ARect: TRect; const ABlendColor: TColor; const ABlendValue: Byte);
procedure SetBlendAlpha(const Value: Byte);
procedure SetBlendColor(const Value: TColor);
protected
procedure CaptureBackground;
procedure Paint; override;
procedure WMEraseBkGnd(var msg: TWMEraseBkGnd); message WM_ERASEBKGND;
procedure WMMove(var Message: TMessage); message WM_MOVE;
procedure WMParentNotify(var Message: TWMParentNotify); message WM_PARENTNOTIFY;
public
constructor Create(aOwner: TComponent); override;
destructor Destroy; override;
procedure ClearBackground;
procedure SetBounds(ALeft, ATop, AWidth, AHeight: Integer); override;
published
property BlendColor: TColor read FBlendColor write SetBlendColor;
property BlendAlpha: Byte read FBlendAlpha write SetBlendAlpha;
property Align;
property Alignment;
property Anchors;
end;
TSemiModalForm = class(TComponent)
strict private
FFormParent: TWinControl;
FBlendColor: TColor;
FBlendAlpha: Byte;
FSemiModalResultHandler: ISemiModalResultHandler;
FForm: TForm;
FTransparentPanel: TTransparentPanel;
FOldFormOnClose: TCloseEvent;
private
procedure OnTransparentPanelResize(Sender: TObject);
procedure RepositionForm;
procedure SetFormParent(const Value: TWinControl);
procedure OnFormClose(Sender: TObject; var Action: TCloseAction);
protected
procedure Notification(AComponent: TComponent; Operation: TOperation); override;
public
procedure ShowSemiModalForm(AForm: TForm; SemiModalResultHandler: ISemiModalResultHandler); virtual;
property ModalPanel: TTransparentPanel read FTransparentPanel;
published
constructor Create(AOwner: TComponent); override;
property BlendColor: TColor read FBlendColor write FBlendColor;
property BlendAlpha: Byte read FBlendAlpha write FBlendAlpha;
property FormParent: TWinControl read FFormParent write SetFormParent;
end;
implementation
procedure TTransparentPanel.CaptureBackground;
var
canvas: TCanvas;
dc: HDC;
sourcerect: TRect;
begin
FBackground := TBitmap.Create;
with Fbackground do
begin
width := clientwidth;
height := clientheight;
end;
sourcerect.TopLeft := ClientToScreen(clientrect.TopLeft);
sourcerect.BottomRight := ClientToScreen(clientrect.BottomRight);
dc := CreateDC('DISPLAY', nil, nil, nil);
try
canvas := TCanvas.Create;
try
canvas.handle := dc;
Fbackground.Canvas.CopyRect(clientrect, canvas, sourcerect);
finally
canvas.handle := 0;
canvas.free;
end;
finally
DeleteDC(dc);
end;
end;
constructor TTransparentPanel.Create(aOwner: TComponent);
begin
inherited;
ControlStyle := controlStyle - [csSetCaption];
FBlendColor := clWhite;
FBlendAlpha := 200;
end;
destructor TTransparentPanel.Destroy;
begin
FreeAndNil(FBackground);
inherited;
end;
procedure TTransparentPanel.Paint;
begin
if csDesigning in ComponentState then
inherited
end;
procedure TTransparentPanel.SetBounds(ALeft, ATop, AWidth, AHeight: Integer);
begin
if (Visible) and
(HandleAllocated) and
(not (csDesigning in ComponentState)) then
begin
FreeAndNil(Fbackground);
Hide;
inherited;
Parent.Update;
Show;
end
else
inherited;
end;
procedure TTransparentPanel.WMEraseBkGnd(var msg: TWMEraseBkGnd);
var
ACanvas: TCanvas;
begin
if csDesigning in ComponentState then
inherited
else
begin
if not Assigned(FBackground) then
Capturebackground;
ACanvas := TCanvas.create;
try
ACanvas.handle := msg.DC;
ACanvas.draw(0, 0, FBackground);
ColorBlend(ACanvas, Rect(0, 0, Width, Height), FBlendColor, FBlendAlpha);
finally
FreeAndNil(ACanvas);
end;
msg.result := 1;
end;
end;
procedure TTransparentPanel.WMMove(var Message: TMessage);
begin
CaptureBackground;
end;
procedure TTransparentPanel.WMParentNotify(var Message: TWMParentNotify);
begin
CaptureBackground;
end;
procedure TTransparentPanel.ClearBackground;
begin
FreeAndNil(FBackground);
end;
procedure TTransparentPanel.ColorBlend(const ACanvas: TCanvas; const ARect: TRect;
const ABlendColor: TColor; const ABlendValue: Byte);
var
BMP: TBitmap;
begin
BMP := TBitmap.Create;
try
BMP.Canvas.Brush.Color := ABlendColor;
BMP.Width := ARect.Right - ARect.Left;
BMP.Height := ARect.Bottom - ARect.Top;
BMP.Canvas.FillRect(Rect(0,0,BMP.Width, BMP.Height));
ACanvas.Draw(ARect.Left, ARect.Top, BMP, ABlendValue);
finally
FreeAndNil(BMP);
end;
end;
procedure TTransparentPanel.SetBlendAlpha(const Value: Byte);
begin
FBlendAlpha := Value;
Paint;
end;
procedure TTransparentPanel.SetBlendColor(const Value: TColor);
begin
FBlendColor := Value;
Paint;
end;
{ TSemiModalForm }
constructor TSemiModalForm.Create(AOwner: TComponent);
begin
inherited;
FBlendColor := clWhite;
FBlendAlpha := 150;
FTransparentPanel := TTransparentPanel.Create(Self);
end;
procedure TSemiModalForm.SetFormParent(const Value: TWinControl);
begin
FFormParent := Value;
end;
procedure TSemiModalForm.ShowSemiModalForm(AForm: TForm;
SemiModalResultHandler: ISemiModalResultHandler);
begin
if FForm = nil then
begin
FForm := AForm;
FSemiModalResultHandler := SemiModalResultHandler;
FTransparentPanel.Align := alClient;
FTransparentPanel.BringToFront;
FTransparentPanel.Parent := FFormParent;
FTransparentPanel.BlendColor := FBlendColor;
FTransparentPanel.BlendAlpha := FBlendAlpha;
FTransparentPanel.OnResize := OnTransparentPanelResize;
AForm.Parent := FTransparentPanel;
FOldFormOnClose := AForm.OnClose;
AForm.OnClose := OnFormClose;
RepositionForm;
AForm.Show;
FTransparentPanel.ClearBackground;
FTransparentPanel.Visible := TRUE;
end;
end;
procedure TSemiModalForm.OnFormClose(Sender: TObject; var Action: TCloseAction);
begin
FForm.OnClose := FOldFormOnClose;
try
FForm.Visible := FALSE;
FSemiModalResultHandler.SemiModalFormClosed(FForm);
finally
FForm.Parent := nil;
FForm := nil;
FTransparentPanel.Visible := FALSE;
end;
end;
procedure TSemiModalForm.Notification(AComponent: TComponent;
Operation: TOperation);
begin
inherited Notification(AComponent, Operation);
if (Operation = opRemove) then
begin
if AComponent = FFormParent then
SetFormParent(nil);
end;
end;
procedure TSemiModalForm.OnTransparentPanelResize(Sender: TObject);
begin
RepositionForm;
end;
procedure TSemiModalForm.RepositionForm;
begin
FForm.Left := (FTransparentPanel.Width div 2) - (FForm.Width div 2);
FForm.Top := (FTransparentPanel.Height div 2) - (FForm.Height div 2);
end;
end.
Can anybody help me with the problems or point me to an alpha blend panel that already exists?
Thanks for all your suggestions. I've taken the input and created a new component that does exactly what I need. Here's what it looks like:
The comment that pointed me in the right direction was the one by NGLN that I upvoted. If you post it as the answer I'll accept it.
I tried to add the component code to this answer, but StackOverflow wouldn't format it correctly. However, you can download the source and a full demo application here.
The component provides the following functionality:
The semi modal form is a child of the main form. This means that it
can be tabbed to just like the other controls.
The overlay area is drawn correctly with no artefacts.
The controls under the overlay area are automatically disabled.
The semi modal form/overlay can be shown/hidden if required e.g.
switching tabs.
A SemiModalResult is passed back in an event.
There are still a number of small issues that I would like to iron out. If anybody knows how to fix them, please let me know.
When the parent form is moved or resized it needs to call the
ParentFormMoved procedure. This allows the component to
resize/reposition the overlay form. Is there any way to hook into
the parent form and detect when it is moved?
If you mimimise the main form, then restore it, the overlay form appears immediately, then the main form is animated back to it's previous position. Is there a way to detect when the main form has finished animating?
The rounded corners of the semi modal window are not too pretty. I'm
not sure there's much that can be done about this as it's down to the
rectangular region.
Your code does not show the form modally, and I wonder why you would not. But then, maybe I do not understand the term semi modal.
In any case, I think the idea to create a half-transparent form on which to show the actual dialog will do just fine:
function ShowObviousModal(AForm: TForm; AParent: TWinControl = nil): Integer;
var
Layer: TForm;
begin
if AParent = nil then
AParent := Application.MainForm;
Layer := TForm.Create(nil);
try
Layer.AlphaBlend := True;
Layer.AlphaBlendValue := 128;
Layer.BorderStyle := bsNone;
Layer.Color := clWhite;
with AParent, ClientOrigin do
SetWindowPos(Layer.Handle, HWND_TOP, X, Y, ClientWidth, ClientHeight,
SWP_SHOWWINDOW);
Result := AForm.ShowModal;
finally
Layer.Free;
end;
end;
Usage:
procedure TForm1.Button1Click(Sender: TObject);
begin
FDialog := TForm2.Create(Self);
try
if ShowObviousModal(FDialog) = mrOk then
Caption := 'OK';
finally
FDialog.Free;
end;
end;
how can i have a image for Editbox background ?
This is very possible, indeed. In your form, define
private
{ Private declarations }
FBitmap: TBitmap;
FBrush: HBRUSH;
protected
procedure WndProc(var Message: TMessage); override;
and do
procedure TForm1.FormCreate(Sender: TObject);
begin
FBitmap := TBitmap.Create;
FBitmap.LoadFromFile('C:\Users\Andreas Rejbrand\Pictures\AS20Utv.bmp');
FBrush := 0;
FBrush := CreatePatternBrush(FBitmap.Handle);
end;
and
procedure TForm1.WndProc(var Message: TMessage);
begin
inherited;
case Message.Msg of
WM_CTLCOLOREDIT, WM_CTLCOLORSTATIC:
if (Message.LParam = Edit1.Handle) and (FBrush <> 0) then
begin
SetBkMode(Message.WParam, TRANSPARENT);
Message.Result := FBrush;
end;
end;
end;
Of course you can wrap this into a component of your own, say TEditEx. If I get time over, I might do this. (And, notice that there is no need to buy an expensive (and maybe not that high-quality) component pack from a third-party company.)