I noticed that the resize flicker gets much better when I set TPanel.FullRepaint to False. Since the property exists and is True by default, there must be some reason for that.
How to decide whether it should be set or not?
The help just states:
FullRepaint controls how the panel responds when it is resized. When FullRepaint is true, the entire panel, including the beveled border repaints when the size changes. When FullRepaint is false, only the area inside the beveled border repaints.
http://docwiki.embarcadero.com/Libraries/XE3/en/Vcl.ExtCtrls.TPanel.FullRepaint
That text says what it does, but not why ...
The effect of a missing Fullrepaint can be shown and you will have to decide if you need it or not.
Place a panel on a form, set anchors to all directions
Set PaintCaption to false or use a empty caption
Place another panel on the form, so that if you are resizing the
form, parts of the first panel will be covered by the second panel.
Run the program and size the form, somtimes the borders of the first panel will not be refreshed.
This happens because in WMWindowPosChanged in case of (FullRepaint or (ShowCaption and (Caption <> ''))) a invalidate will be called, otherwise only InvalidateRect(Handle, Rect, True) of a rects only containing the right and/or bottom border are invalidated. (thanks to Sertac Akyuz for correction)
As you mentioned avoiding invalidate reduces flicker and in many cases the need for a full invalidate is not given, so the user can decide on his own how to proceed.
Panels as the rarely will be used, upper without Fullrepaint
In previous versions of Windows (not sure up to which version, exactly) FullRepaint was required to prevent graphical artefacting on panel borders when a form was resized.
To the best of my knowledge, this hasn't been an issue since at least Windows XP.
Related
I have noticed something very strange. I am persisting the top, left, width, and height properties of a form when it is closing, and using this information to restore the form's last position when it is once again opened by calling SetBounds using the previously stored information. This works well, but only if the form's Position property is set to poDefault at design time. If set to something else, such as poDesigned, poScreenCenter, or poMainFormCenter, SetBounds does not restore the form's previous position and size.
Here's the strange part. What appears to matter is what the Position property is set to at design time. I can change the value of this property at runtime to poDefault and the call to SetBounds still does not work correctly. I have tried something like the following
if Self.Position <> poDefault then
Self.Position := poDefault;
in both the form's OnCreate event handler, as well as from an overridden constructor (and have set Position to poDefault in the constructor, and called SetBounds in the OnCreate event handler). In all cases, changing the form's Position property to poDefault at runtime does not fix the problem that I've observed with SetBounds. The only consistent pattern that I have found is that SetBounds works as it should only if the form's Position property was poDefault at design time.
There are other things that I've noticed with respect to how SetBounds works when a form's Position property is not set to poDefault at design time. For example, a form whose Position property is set to poScreenCenter at design time will not necessarily appear centered on the screen if you call SetBounds. However, it does not appear in the top-left location defined by SetBounds, nor does it respect the width and height specified in the call to SetBounds. Let me repeat, however, that I am setting the Position property of the form to poDefault before calling SetBounds. I've even stuck a call to Application.ProcessMessages between the two operations, but that doesn't fix the problem.
I have tested this extensively with Delphi 10.1 Berlin running on Windows 10. I have also tested it using Delphi XE6 on Windows 7. Same results.
If you have doubts, create a VCL application with four forms. On the first form place three buttons, and add something like the following OnClick to each button:
with TForm2.Create(nil) do
try
ShowModal;
finally
Release;
end;
where the constructor creates TForm2, then TForm3 and TForm4.
On the OnCreate of forms 2 through 4, add the following code:
if Self.Position <> poDefault then
Self.Position := poDefault;
Self.SetBounds(500,500,500,500);
On form2, set Position to poDefault, on form3 set Position to poScreenCenter, and on form4 leave Position set to the default, poDefaultPosOnly. Only form2 will appear at 500, 500, with a width of 500 and a height of 500.
Does anyone have a logical explanation for this result?
poDefault and friends mean "let Microsoft Windows position this form's window when the form would create and show it".
You just created Delphi object - but I wonder if it also has created/shown Windows object (HWND handle and all corresponding Windows internal structures). Especially with themed applications, not ones using standard pre-XP look and feel - they tend to ReCreateHWND when showing, because pre-loading those fancy Windows Themes is relatively expensive operation and only should be done when needed.
I think your default bounds (every property value set in the constructor might be considered a default non-tuned value, to be tuned later after object being constructed) are correctly ignored when you (or TApplication - that makes little difference for the topic) finally do FormXXX.Show.
It is during "make me a window and display it" sequence when your form looks at its properties and tells to MS Windows something like "now I want to create your internal HWND-object and position it at default coordinates/size at your discretion".
And that is absolutely correct behaviour - otherwise WHEN and HOW could TForm apply the Position property??? It just makes no sense to ask Windows for coordinates of a window that does not exists on the screen yet and maybe never would. Windows offers default coords/sizes for the this very second it being asked, looking how many other windows are there and where they are positioned ( and AMD/NVidia video drivers might also apply their correction to it).
It would make little sense, to acquire defaults now, and apply them two hours later when everything would probably be different - different amount of other windows and different positions of those, different set of monitors attached and with different resolutions, etc.
Just consider a "desktop replacement" type of notebook. It was set upon the table connected to large stationary external monitor. Then - let's imagine it - I run your application and it created the tform Delphi object and in the constructor it asked MS Windows for position - and Windows rightfully offered the position at that very secondary large monitor. But then an hour later I unplugged the notebook and walked away with it. Now an hour later I tell your application to show the form - and it will do what? display it with coordinates belonging to that now-detached external display? Outside of the viewport of the notebook's internal display that I only have at the moment? Should this form be displayed in the now "invisible" position just because when I started the application back then that spot was still visible there yet??? Way to confuse users for no gain, I think.
So the only correct behaviour would be to ask Windows for default coords this very second WHEN the form is going from hidden to visible and not a second earlier.
And that means that if you want to move your form - you should do it after it was being show. Place your Self.SetBounds(500,500,500,500); into OnShow event handler. So let the MS Windows materialize your form into default position like required by poDefault in Position property - and move your Window after that. Attempts to move the window that does not exist yet look correctly futile to me.
Either PRESET your form ( in constructing sequence) to explicitly ignore MS Windows defaults and use pre-set cords (via poDesigned value), or let the form ask Windows coordinates, but MOVE it with SetBounds after it got visible via OnShow handler.
I put some code that happens on a Form OnResize event. But it Seems to only call the event when the resize is bigger. Is there any way to change this?
Say i have
procedure TForm1.Resize(Sender: TObject);
begin
RePaint();
end
I would like to run repaint every time the form is re-sized (big or small). I guess you could add a check that checks width / height but if your going to do that why even use the event resize? Maybe there is another event besides resize that does both?
thanks
Glen
There are two questions being asked here.
First, OnResize is triggered when the form resizes, in either direction. Period.
Second, on why Repaint does not work when the form gets smaller is probably because you do your own painting. Normally, only Canvas.Cliprect needs to be repainted. When the form gets smaller, the shown area is not changed and the clipping area is empty. After all, there is not more to paint than there was before. When the form gets bigger in one direction, a similar thing happens: the clipping area consists of only the part which is added to the form's surface. Again, the previous shown area remains intact and is not updated. Only when the form expands in both directions, the clipping area cannot be made of a single rectangle any more, and so it becomes the complete surface.
The solution for you is to signal Windows to repaint the whole contents of the form at any resize, by calling Invalidate (or Update when it has to be repainted instantly), and to perform your custom drawing in the OnPaint event.
The OnResize event is triggered when the form is resized by any means, despite it is larger or smaller than before.
To prove this, create a new project, put a Memo on a clean form and add this code to the OnResize event:
procedure TForm1.FormResize(Sender: TObject);
begin
Memo1.Lines.Add(Format('%d,%d', [Width, Height]));
end;
Execute your project, and drag an edge of the form to make it greater and smaller, you'll notice it is fired always, and how many times the event is triggered also.
Notice also the form has a OnPaint event that maybe is what you're after.
I have a form with several splitters and panels. In the middle is a panel that ends up with a TWebBrowser set to align alClient.
In the past this has worked well. However, on Windows 7 with Internet Explorer 8 the the browser is not correctly resized. Everything else (i.e. the panels) are the correct size, just not the web browser. Sometimes when you click into the browser, or more often when you scroll the browser will jump to the correct size. That does not happen 100% of the time though.
I'm trying to deal with the resize directly and force the control to change size. I can't seem to find a method that makes any difference (i.e. .Invalidate; .Repaint; .Update;)
TWebBrowser is an OLE control (ActiveX) that wraps the Internet Explorer control. Any ideas on how I can make the resize happen?
Updated Background:
I narrowed this down to only happening when I have a child form that I change the parent to site it inside another form. My TWebBrowser control is on a child form that I use anytime I need to show an HTML document.
In my parent form I have a Grid, a splitter, and a panel with the grid set to Align top and the panel set to align client. My child form (called THtmlViewer) has its parent set to the panel. The THtmlViewer form is set to alClient and TWebBrowser control on the child form is also set to align client.
If I do anything in the form resize of the THtmlViewer form I run into this issue. Anything being directly in FormResize or indirectly using the align properties. However, if I call my resize from the parent form everything works fine.
The key seems to be turning off the resize code in the THtmlViewer form. If I leave a OnResize handler or the alignment set then it does not matter what I do in the parent, the resize is not done correctly.
I am still confused why this is needed and why I can't force it to update in the correct resize (THtmlViewer).
As a side note I also noticed that Delphi 2007 on Windows 7 has the exactly same problem with the "Welcome Page" in the IDE.
I have worked around the issue by adding a method to set OnResize of the child form to nil and then call my internal ForceResize from the parent's OnResize handler. I would still like to deal with this all from the THtmlViewer form and would accept an answer that let's me avoid this hack.
To resize controls when their container changes size, you have two other options besides using "just" the Align property:
Use the Anchors property without the Align property, that is, set the Align property to alCustom or alNone, then set the anchors according to your needs. As the Align property is sort of short-hand for setting the Anchors, this is dependent upon the same alignment processing so may not work in your case.
Provide a handler for the OnResize event of the container on which the TWebBrowser sits and manually set the TWebBrowser's height and width to those of the container (optionally adjusted for any margins you want to have within the container).
That said, I don't have Windows7, so I can't vouch that this won't take more twiddling.
If your TWebBrowser jumps to the correct size on a scroll or click, it indicates that the control was sized correctly, just never received or processed the messages to actually respond to the changes.
This can be because realigning controls tries to prevent unnecessary repaints and recursions and somehow got mixed up. Using the OnResize method may then get better results as it "speaks to the TWebBrowser directly".
Repaint is "just" shorthand for Invalidate and Update unless the control has csOpaque in its ControlStyle, in which case painting seems more immediate. So you could try to fiddle with the Transparent property of the TWebBrowser and/or the container it sits on.
If all else fails, you could try to send a WM_PAINT (or similar) to the TWebBrowser directly. For exmample in the OnResize event of the TWebBrowser or the container it sits on. The a WM_Paint handler of the TWebBrowser calls OleDraw, which talks to the ActiveX directly using the ClientRect, which should have the correct dimensions when called from an OnResize event.
I had a similar problem.
It was solved by putting a TPanel "underneath" the TWebBrowser, and aligning the web browser to alClient.
Maybe the same solution for this question works: Resize problem using AcroPDF in Delphi
In OnResize:
if Visible and (WebBrowser1 <> nil) then
begin
FocusControl(nil);
FocusControl(WebBrowser1);
end;
I'd try something like
changing WebBrowser1.Align to alLeft,
setting WebBrowser1.Width to WebBrowser1.Width - 1 and
setting WebBrowser1.Align to alClient again
in an OnResize handler.
I have an application that uses a frame extensively and needs to hide/show certain buttons depending on which form is active at the time. In order to keep the buttons neat and organized appropriately, I have put them on panels and show or hide the panels as needed for each form. My problem is when each form is initially created, the panels on the frame are out of order even though I am explicitly telling them which order to put themselves into. After I hide and re-show the form, the panels are in the correct order. Any suggestions on how to keep them in the proper order from the very beginning?
Instead of giving the panels explicit positions, try giving them alignments. They tend to stick better than way, and they do a better job of resizing if you resize the form.
You can also try using a stackpanel (or was it flowpanel?) as parent for the panels. Then you will have a order instead of a position to manipulate.
Maybe you can have a look at the DevExpress LAyoutControl? It helps us creating interfaces that always look good, no matter if we show or hide certain groups / panels. It even allows for run-time customization of the interface, if you want that!
You may try to organize them by coordinates i.e.: setting Top and Left. Unless your panels are aligned, this will always work (but it takes bit lot of work).
I had this problem and I found that the solution was to do this in FormCreate (or in a CMShowingChanged method of your frame):
MyPanel1.Align := alNone;
MyPanel2.Align := alNone;
MyPanel1.Align := alBottom;
MyPanel2.Align := alBottom;
Restore in the order that you need - this seemed to sort out the order visually.
I'm having a problem with a component I use.Its aligned to bottom ,and ,when form is maximized,the control is placed at the correct position,but when I attempt to minimize the form,the control stays at the position where it is.
I tried using a timer that always sets the align to bottom,but I'm sure a timer is the worst solution to my issue.
Please suggest a way to set the align to Bottom when the form is restored from maximize.(maximize->restore only).
My current idea is to check if form is maximized at FormResize event,but that won't work,because I need to do it when its restored,not maximized.
You can check if a form is maximised by using
Self.WindowState = wsMaximized
Other states are
wsNormal
wsMinimized
wsMaximized
Depending on what you are doing, you could also place the control on a panel and align the panel to the bottom of the form, if you turn the borders off and use the parent colour, you cant see the panel, that way it will stay at the bottom of the form without additional code.