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How to know whether it is increasing or decreasing when the size of a Window changes

I have a form and I would like to have different logic when its size increases and decreases.
My only idea is to compare the new size with previous size in the function private void MainWindow_SizeChanged(object sender, EventArgs e) and implement the logic accordingly if size increased or decreased.
I am creating this thread because I have suspecision that there is a much more easier also more common with the API way to check whether it increased or decreased.
Edit: comments asked for the logic I am trying to implement.
I have picturebox inside my window
and when windows size increases picturebox adapts however when it decreases it shows scrollbars.
Thanks

It seems that question is left hanging so I better explain my solution.
My intuition was not so off the path, What I simply did is I put the PictureBox in some Panel in my case SplitContainer.Panel1.
PictureBox was already a class global for my Main Window and PictureBox properties Dock set to none and Anchor to Top, Left also mentioned Panel's AutoScroll should be set to True.
Also I rewrote the event Panel.SizeChanged() in such a way where I compare Panel.ClientSize dimensions with PictureBox dimensions if ever PictureBox dimensions are smaller just update them with Panel.ClientSize dimensions.
private void splitContainer1_Panel1_SizeChanged(object sender, EventArgs e)
{
if (pictureBox.Height < splitContainer1.Panel1.ClientSize.Height || pictureBox.Width < splitContainer1.Panel1.ClientSize.Width)
{
pictureBox.Height = splitContainer1.Panel1.ClientSize.Height;
pictureBox.Width = splitContainer1.Panel1.ClientSize.Width;
}
}

How to set initial color of owner drawn control

Scenario
Having a Windows Forms Form-derived form that contains a Panel-derived control:
The form gets a black background color set:
public MyForm()
{
InitializeComponent();
base.BackColor = Color.Black;
}
And the panel control is configured to be double buffered and the like, as described here, here and here:
public MyPanel()
{
base.DoubleBuffered = true;
SetStyle(ControlStyles.AllPaintingInWmPaint, true);
SetStyle(ControlStyles.ResizeRedraw, true);
SetStyle(ControlStyles.UserPaint, true);
SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
UpdateStyles();
}
The actual drawing is done inside these overrides in MyPanel:
protected override void OnPaintBackground(PaintEventArgs e)
{
e.Graphics.Clear(Color.Black);
}
protected override void OnPaint(PaintEventArgs e)
{
e.Graphics.Clear(Color.Black);
}
Wrong behaviour
Every now and then, when the form is initially shown, my owner drawn panel is shortly drawn as white, before my own drawing code is actually called:
After my drawing code is called, everything is drawn correctly and I never can reproduce the white background again:
Even resizing the window and panel does not make it flicker in white.
Enforcing the wrong behavior
I can enforce the initial white-drawn of my panel, if I put a sleep in the Shown event handler of my form:
private void MyForm_Shown(object sender, EventArgs e)
{
Thread.Sleep(1000);
}
The panel is shown in white for 1000 ms just before my owner-drawn paint code is being called.
My question
How can I avoid the initial white displaying when having an owner drawn/custom drawn panel?
My goal is to have the control "know" its initial background color (black in my example) right from the start, not after it is initially shown.
Some thoughts
I've tried to play with all kind of things including the CreateParams property, but with no visible success.
My initial idea was to provide some initial background color through the WNDCLASSEX structure, but after digging through the Reference Source, I still have no clue whether this is possible and would help.
Whole code
Just to be safe, following is my whole code.
MyForm.cs:
public partial class MyForm : Form
{
public MyForm()
{
InitializeComponent();
base.BackColor = Color.Black;
}
private void MyForm_Shown(object sender, EventArgs e)
{
Thread.Sleep(1000);
}
}
MyPanel.cs:
public class MyPanel : Panel
{
public MyPanel()
{
base.DoubleBuffered = true;
SetStyle(ControlStyles.AllPaintingInWmPaint, true);
SetStyle(ControlStyles.ResizeRedraw, true);
SetStyle(ControlStyles.UserPaint, true);
SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
UpdateStyles();
}
protected override void OnPaintBackground(PaintEventArgs e)
{
e.Graphics.Clear(Color.Black);
}
protected override void OnPaint(PaintEventArgs e)
{
e.Graphics.Clear(Color.Black);
}
}

I had a custom control, pretty much completely self-drawn, that was dynamically getting added to a Form in the dropdown mechanism in PropertyGrid.
If I read your problem right, it's basically the same overall issue.
I had BackColor set and was fine. But with DoubleBuffer set, it seems to just ignore it for a bit.
Taking in all of the existing comments on the question, I was able to have this solution, and hope the details help someone else make their own.
Problem 1
My control flickered unless I repainted whole control every OnPaint.
If did proper painting only attempting to paint things that intersected the e.ClipRectangle, then it would flicker in real-time, like effects from invalidates that had to do when the mouse was moved. Attempt to Paint whole thing, no problem.
I watched trace output real-time and watched all of my draws and invalidates print, and never a time where should be introducing flicker myself, on myself directly.
Problem 2
If I turn on DoubleBuffered, then instead it flickered badly as the control was shown every time opening the dropdown. From white background only for 100-200 ms, at least, then to black and rendered foreground suddenly in one step.
Problem 3
I never actually needed double buffer. Both the problem 1 and 2 were always related to WM_ERASEBKGND.
The actual original flicker seems to be caused by WM_ERASEBKGND very briefly visibly whacking my already painted thing, right before I painted it again. Did not really need actual double buffering in my case. For some reason when I was blindly painting the whole list maybe the timing was different and was painting over the erase before could see it.
All that said, if I turn DoubleBuffered on which removes WM_ERASEBKGND via turning on AllPaintingInWmPaint, then initial background won't be painted until I suppose the double buffer and paint process works its way, all the way through the first time.
Problem 4
If I let the WM_ERASEBKGND "just happen", then it's still double painting, and I don't know if or when it might end up flicking anyway for someone else.
If I only turn on SetStyle(OptimizedDoubleBuffer, then I now know I'll be letting the initial background paint and not flicker on show. But I also know I'm using double buffer to mask the WM_ERASEBKGND for the entirety of the life of the control after it is shown.
So....
I did something like this:
Part 1
if the user of the control sees a need to double buffer doing something that might flicker, create a way for them to easily enable it, without forcing AllPaintingInWmPaint. Like if they want to use Paint or a DrawXXX event and doing something that animates or something related to mouse movement.
bool _isDoubleBuffer;
[Category("Behavior")]
public virtual bool DoubleBuffer
{
get { return _isDoubleBuffer; } // dont care about real SetStyle state
set
{
if (value != DoubleBuffer)
{
_isDoubleBuffer = value;
SetStyle(ControlStyles.OptimizedDoubleBuffer, value);
}
}
}
Part 2
Manage WM_ERASEBKGND yourself, as the choice is otherwise 1) always off with AllPaintingInWmPaint, and no background paint on show, or 2) violating what double buffer expects where it would be always masking the WM_ERASEBKGND.
protected override void WndProc(ref Message m)
{
switch (m.Msg)
{
case WM_ERASEBKGND:
if (_hasPaintForeground && _isDoubleBuffer)
return;
}
base.WndProc(ref m);
}
Part 3
You are now your own decider of what AllPaintingInWmPaint means.
In this case would want the initial messages to process like normal. When we knew for sure the .Net and DoubleBuffer side was finally kicking it, by seeing our first real paint happen, then turn WM_ERASEBKGND off for the duration.
bool _hasPaintForeground;
protected override void OnPaint(PaintEventArgs e)
{
// your paint code here, if any
base.OnPaint(e);
if (!_hasPaintForeground) // read cheaper than write every time
{
_hasPaintForeground = true;
}
}
Part 4
In my case, I also had originally gimped the OnBackground draw, which works if you are opaque drawing each element yourself in OnPaint. This allowed me to not have double buffer on for so long until I started following the clip and changed the timing so that I started also seeing the other WM_ERASEBKGND side effects and issues.
protected override void OnPaintBackground(PaintEventArgs e)
{ // Paint default background until first time paint foreground.
if (!_hasPaintForeground) // This will kill background image but stop background flicker
{ // and eliminate a lot of code, and need for double buffer.
base.OnPaintBackground(e);
} // PaintBackground is needed on first show so no white background
}
I may not need this part anymore, but if my DoubleBuffer is off then I would. So long as I'm always painting opaque in OnPaint covering the whole draw Clip area.
Addendum:
In addition to all of that....
Separate issue with text render.
It looks like if I render only 250 x 42, like two rows and two text renders, which all occur in one OnPaint, verified with Diagnostics.Trace.WriteLine, then the text renders at least one monitor frame later, every single time. Making it look like the text is flashing. Is just 2x paint background single color then 2x paint text each for rows.
However, if I attempt to paint the whole client area of like 250 x 512 or whatever, like 17 rows, even though the e.Clip is exactly those two rows, because I'm the one that invalidated it, then no flicker of the text, 0 flicker.
There is either some timing issue or other side effect. But that's 17 chances instead of two, for at least one row to flicker text where the whole background is shown before the text renders, and it never happens. If I try to only render rows that are in the clip area it happens every time.
There is def something going with .Net or Windows. I tried with both g.DrawString and TextRenderer.DrawText and they both do it. Flicker if draw 2, not flicker if attempt to draw 17. Every time.
Maybe has something to do with drawing text near the mouse pointer, when OnPaint comes back too quickly?
Maybe if I draw enough things or OnPaint takes longer to come back, it's doing double buffer anyway? Dunno
So....
It's a good thing I went through this exercise with the original question.
I may choose to just render the whole client every time, but I'll never be able to do it the "right way" without something like my example code above.

Resizing User Control - anchor controls to center of form

I have a user control which consists of two controls and four buttons, arranged on a Form: the two controls are on the sides and the buttons in the middle in a vertical row.
When using the control in an app, I place it on a form.
Now, when re-sizing the form horizontally, the two controls just move left or right w/o changing their size.
What I need is that the controls stay anchored to the middle of the form and grow to the sides (sorry about the lack of clarity, I prepared screenshots but the site wouldn't let me attach them).
Is there a way to accomplish this without overriding the Resize event?

Use a TableLayoutPanel as base for your user control.
You need 3 columns and one row. The middle column needs to have a fixed size, and the other 2 you set to 50%. Not to worry, .Net is smart enough to calculate the percent they actually take.
Inside the right and left columns you put your controls and set the Dock property of both to fill. In the middle column you put a panel and set it's Dock property to fill as wall, and In that panel you put the buttons in the middle.
Set your table layout panel Dock to fill as well, and when adding the user control to the form use Dock top, bottom or fill as well.

Erratum:
The above code works most of the time, but it fails for certain Move-Resize sequences. The solution is to respond to the Move and Resize events of the parent form (the consumer of the control), not of the control itself.
One more thing: due to the event firing order (Move first followed by Resize, had to move the working code from Resize() to Move(), which seems counterintuitive but it seems the right way nevertheless.

It seems indeed that it cannot be done in the Designer, but here is the solution using overrides.
It works ok, except for some control flickering which I haven't been able to overcome.
public partial class SB : UserControl
{
//variables to remember sizes and locations
Size parentSize = new Size(0,0);
Point parentLocation = new Point (0,0);
......
// we care only for horizontal changes by dragging the left border;
// all others take care of themselves by Designer code
public void SB_Resize(object sender, EventArgs e)
{
if (this.Parent == null)
return;//we are still in the load process
// get former values
int fcsw = this.parentSize.Width;//former width
int fclx = this.parentLocation.X;//former location
Control control = (Control)sender;//this is our custom control
// get present values
int csw = control.Parent.Size.Width;//present width
int clx = control.Parent.Location.X;//present location
// both parent width and parent location have changed: it means we
// dragged the left border or one of the left corners
if (csw != fcsw && clx != fclx)
{
int delta = clx - fclx;
int lw = (int)this.tableLayoutPanel1.ColumnStyles[0].Width;
int nlw = lw - delta;
if (nlw > 0)
{
this.tableLayoutPanel1.ColumnStyles[0].Width -= delta;
}
}
this.parentSize = control.Parent.Size;//always update it
this.parentLocation = control.Parent.Location;
}
//contrary to documentation, the Resize event is not raised by moving
//the form, so we have to override the Move event too, to update the
//saved location
private void SB_Move(object sender, EventArgs e)
{
if (this.Parent == null)
return;//we are still in the load process
this.parentSize = this.Parent.Size;//always update it
this.parentLocation = this.Parent.Location;
}
}
The above code works most of the time, but it fails for certain Move-Resize sequences. The solution is to respond to the Move and Resize events of the parent form (the consumer of the control), not of the control itself.
One more thing: due to the event firing order (Move first followed by Resize, had to move the working code from Resize() to Move(), which seems counterintuitive but it seems the right way nevertheless.

Invalidate on paint loops C# winforms

I have a panel I draw on, and I'm doing it in the paint event. I want to delete previous changes before drawing, but If I use Invalidate() or Refresh() it is redrawing it forever (it is flickering), and the strange thing is I call Invalidate() before any drawing, so if it's just forcing panel paint I shouldn't see the drawing
Edit: I figured out this:
void _paint(object sender, PaintEventArgs e)
{
Panel P = (Panel)sender;
if (painted = false) { painted = true; P.Invalidate(); }
Shows(30);
painted = false;
}
It stopped flickering. Anyway, turns out I've never needed that, it is repainting the panel even without the Invalidation. But strangely when I hide only part of the panel(either with form resizing or dragging window over the panel),when becoming visible again it is painted, not repainted(I can tell because the anti-aliasing becomes solid color, producing shitty result), that's why I thought I need to Invalidate the panel. Invalidating won't stop it from happening. I think probably another event is triggered, not paint.

I encountered a problem with my control flickering when I called Invalidate with a program I created not too long ago. I found overriding the OnPaintBackGround did the trick, it may work for you too;
protected override void OnPaintBackground(PaintEventArgs e)
{
/* Override to stop the background being repainted -> this stops flashing of the text */
}

First if all, the following condition is lacking an = sign:
if (painted = false) { painted = true; P.Invalidate(); }
It should read
if (painted == false) { painted = true; P.Invalidate(); }
or
if (!painted) { painted = true; P.Invalidate(); }
Secondly, double buffering is in many cases a good idea. To do so, paint all the content into an off-screen bitmap that has the same size as the client area of your control and then draw that bitmap to the target control if needed. Do not draw the off-screen bitmap in the OnPaint event, but whenever the content to be drawn changes!
Example:
private void PaintOffscreen()
{
// Do whatever necessary to draw the offscreen bitmap
...
// Cause the control to repaint itself. Change OnPaint to draw the bitmap only
Invalidate();
}
void _paint(object sender, PaintEventArgs e)
{
e.Graphics.DrawImage(offscreenBitmap, 0, 0);
}
Also, override the OnPaintBackground method as suggested by HorHAY to prevent the control from clearing the background before painting itself.

.NET UserControl: Size property gives incorrect value on Resize event

Excuse the code dump, these are functions within a UserControl
private void PNGQuantPreviewControl_Resize(object sender, EventArgs e)
{
createOffScreenBm();
draw();
}
private void createOffScreenBm()
{
offScreenBm = new Bitmap(this.Size.Width, this.Size.Height);
offScreenGfx = Graphics.FromImage(offScreenBm);
}
private void draw()
{
// draw background
offScreenGfx.FillRectangle(transTexture, 0, 0, offScreenBm.Width, offScreenBm.Height);
// draw image preview
offScreenGfx.DrawImage(pngQuantPreview, getTopLeftPosition());
// apply to picture box
this.CreateGraphics().DrawImage(offScreenBm, 0, 0);
}
So, when the control changes size, it recreates the offscreen bitmap to reflect the new size and redraws the image.
However, if I quickly resize the control the bitmap doesn't fill it, there's a gap left at the right and/or bottom.
I'm fairly new to C#, so there's probably something obvious I'm doing wrong, or I'm reading the size values at the wrong time. Any ideas?

First of all you need to overwrite OnPaint method, or subscribe to Paint event and draw everything there.
Second you do not need to create offscreen bitmap for double buffering, because in .net already exist class for such purposes BufferedGraphics.
And third, it is much better to create UserControl descedant and enable internal .net double buffering, something like this:
public UserControl2
{
SetStyle(ControlStyles.OptimizedDoubleBuffer | ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint, true);
}
Using this approach you will get double-buffering, and all you need is to draw your graphics in OnPaint method. You can read more about this control styles in Msdn.

Have you considered overriding the OnPaint method and placing the code within that method? This would result in your drawing code being executed any time the control needs to be redrawn, regardless of the reason.
A resize event does not necessarily wait until you are finished resizing the parent container. When the resize event is raised it needs to wait until the code exits before it can capture a new resize event so when the window/control is resized quickly, it can't keep up all that well and what you get is the last time it was able to capture the event, not necessarily the final state of the control ... if that makes any sense.

Do you have anything like a splitter on your control, or a MinSize or MaxSize declared?