To make it simple, let's suppose to have a custom control with fully personalized graphics and that contains also inside a panel (with thin black borders in the picture):
Now, the custom control should provide the user with a mechanism to personalize it further. Let's suppose for instance that the user needs to paint the red vertical line on it (see picture). The line is partly on the user control background and partly on the panel. Like it is now, by using the control_paint event the user will end up on painting below the panel.
What would you suggest in similar cases to make the life easier to the user?
EDIT
The panel is just an example. Instead of that I have two other controls (one for instance is a ruler, which paints labels an ticks according to various parameters) whose logic is quite complex.
You can create a transparent control, and put the transparent control above your other controls for drawing purpose and make it invisible when you don't need.
Here is the code for Transparent control and a simple line, then you can put required logic for painting in OnMouseMove and OnMouseDown and OnMouseUp and draw what you need, simply like I did in OnPaint:
using System.Drawing;
using System.Windows.Forms;
public class TransparentControl : Control
{
public TransparentControl()
{
SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.SupportsTransparentBackColor, true);
}
protected override void OnPaintBackground(PaintEventArgs e)
{
}
protected override void OnPaint(PaintEventArgs e)
{
e.Graphics.DrawLine(Pens.Red, 0, 0, Width, Height);
}
protected override CreateParams CreateParams
{
get
{
CreateParams cp = base.CreateParams;
cp.ExStyle |= 0x20;
return cp;
}
}
}
I use XNA in Windows Forms.
According to Microsoft tutorial, the control that uses XNA should have something like this in OnPaint():
GraphicsDevice.Present(srcRectangle, null, this.Handle);
But I wanted to draw additional things with Windows Forms Graphics object. I can do it just fine placing drawing code after GraphicsDevice.Present(), but I get horrible flickering. That's why I thought of setting double buffering this way:
protected override CreateParams CreateParams
{
get
{
var cp = base.CreateParams;
cp.ExStyle |= 0x02000000; // Turn on WS_EX_COMPOSITED
return cp;
}
}
But unfortunately it will draw only thing drawn with Graphics object (or the internal controls). That's why I would like to render my XNA scene to Graphics object. Is there any way for that?
I have tried:
Built-in WinForms double buffering, but not only each second frame is black but those normal frames are flickering too.
Saving content of window after Present() and then showing it with Graphics object.
Rendering to RenderTarget2D and then created bitmap to show on Graphics object with Image.FromStream(Stream) where stream came from RenderTarget.SaveAsPng().
Every idea failed. Is there anything else?
Actually,
Rendering to Texture is OK. Just rembember to call:
GraphicsDevice.SetRenderTarget(null);
Before you access data from it
Currently I'm trying to do what I thought would be a simple task:
Draw an image onto the full area of a Panel control in Windows Forms. (Please ignore for the moment that I could use the BackgroundImage property)
The image to draw looks like this:
I.e. a yellow box with an 1 pixel blue frame around.
To draw, I'm using the Paint event of the Panel control:
private void panel1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.DrawImage(Resources.MyImage, panel1.ClientRectangle);
}
This looks fine when initially displaying the form:
When resizing the form (and the docked panel, too), it either cuts the edges when being made smaller...
...or it draws artefacts, when being made larger:
I'm pretty sure that there is going on something rather simple and straight-forward but I really cannot understand the reason.
Since I'm ignoring the ClipRectangle and always draw everything, I thought the image would be scaled all the time.
My questions are:
What is the reason for the artefacts? (I love to understand this!)
What do I have to do in order to get rid of the artefacts? (beside calling Invalidate on each resize)
Update, SOLUTION:
Thanks to Ryan's answer, I was able to find an acceptable solution. Basically I derived a class from Panel, did an override of OnPaintBackground and did not call the base method. Last, I added the following code to the constructor of my derived panel:
base.DoubleBuffered = true;
SetStyle(ControlStyles.AllPaintingInWmPaint, true);
SetStyle(ControlStyles.ResizeRedraw, true);
SetStyle(ControlStyles.UserPaint, true);
SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
UpdateStyles();
The reason for the artefacts is that the entire surface isn't redrawn when the form is resized; only the necessary parts are. The generally best solution is what you don't want to do, calling Invalidate on each resize. However, if this is in fact your situation, just use a PictureBox instead. If it's not, you might consider overriding OnPaint in your form instead, and using this.SetStyle(ControlStyles.ResizeRedraw, true) to do this automatically.
how can I make my richtext box transparent
I want this cuz I am trying to put a text on top of a graphic image (which is the background of my form).
That is why I wanted the richTextBox to be transparent,
I am using .NET ,c# and in a windows form application
I know this answer is very late, but I hope it helps others who would like an easy way to get this done.
First, create a new User Control in your project and give it a name, say CustomRTB.cs. Once done, open the partial class and change:
public partial class CustomRTB : UserControl
to:
public partial class CustomRTB : RichTextBox
This will cause an error when you open the Design file so just go to the Designer.cs file and remove/comment the lines which show errors (there will be no more than two lines with errors). Next, add the following to the partial class:
protected override CreateParams CreateParams
{
get
{
//This makes the control's background transparent
CreateParams CP = base.CreateParams;
CP.ExStyle |= 0x20;
return CP;
}
}
The class should look like this now:
public partial class CustomRTB : RichTextBox
{
public CustomRTB()
{
InitializeComponent();
}
protected override CreateParams CreateParams
{
get
{
//This makes the control's background transparent
CreateParams CP = base.CreateParams;
CP.ExStyle |= 0x20;
return CP;
}
}
}
Now build your solution and you will be able to use the control in your forms. This control will be completely transparent and you will not be able to adjust the transparency. You will also be able to create different transparent controls apart from a richtextbox by changing the first line in this code. Hope this helps :)
Edit:
The problem with the above control is that it can only be used to display text programmatically as it is problematic to edit while running or debugging the application (as #nevelis explains in the comment below). However, there is a simple workaround for this:
First, create another User Control in your project and name it TranslucentPanel.cs (Yes, it is a panel and it is going to be translucent whose opacity can be controlled programmatically). Now open the partial class and modify it as:
public partial class TranslucentPanel : Panel
{
public TranslucentPanel()
{
InitializeComponent();
SetStyle(ControlStyles.SupportsTransparentBackColor |
ControlStyles.OptimizedDoubleBuffer |
ControlStyles.AllPaintingInWmPaint |
ControlStyles.ResizeRedraw |
ControlStyles.UserPaint, true);
BackColor = Color.Transparent;
}
}
You will have to take care of the error that crops up when you build the project by simply commenting out the line in the Designer.cs file which throws it. Once done, build your project again and the translucent panel will appear in your toolbox as before. Use this panel as a parent control to your transparent richtextbox i.e. place the panel on your form and place the RTB inside it. You can also set the BorderStyle property as None to remove any trace of the RTB from the UI.
You can also control the opacity of the translucent panel by using its BackColor property in your program:
translucentPanel1.BackColor = Color.FromArgb(50, 0, 0, 0);
Changing the arguments passed above will let you control the opacity and the colour of the panel.
This workaround will solve the cursor and scrolling problems of not only the transparent RTB, but also any other transparent control you create.
There is no such thing as true transparency in a WinForms Control. Transparent mode inherits the default background of its parent. The way I have worked around it in the past has been to use the OnPaint event and then use the Graphics.DrawString method to position the text where I want it.
Have you given this a try?
http://www.codeproject.com/KB/edit/AlphaBlendedTextControls.aspx?artkw=richTextBox%20to%20be%20transparent
There is no way to have Windows Forms controls with a transparent background. Many have tried it before and all have failed. Some came up with exotic hacks, but they all fail at some detail. Use WPF or HTML if you need more advanced rendering capabilities than the old Windows Forms can offer you.
In my application i am constantly moving from one control to another. I have created no. of user controls, but during navigation my controls gets flicker. it takes 1 or 2 sec to update. I tried to set this
SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
or
SetStyle(ControlStyles.UserPaint, true);
SetStyle(ControlStyles.AllPaintingInWmPaint, true);
SetStyle(ControlStyles.DoubleBuffer, true);
but it didn't help... Each control has same background image with different controls.
So what is the solution for it..
Thanks.
It is not the kind of flicker that double-buffering can solve. Nor BeginUpdate or SuspendLayout. You've got too many controls, the BackgroundImage can make it a lot worse.
It starts when the UserControl paints itself. It draws the BackgroundImage, leaving holes where the child control windows go. Each child control then gets a message to paint itself, they'll fill in the hole with their window content. When you have a lot of controls, those holes are visible to the user for a while. They are normally white, contrasting badly with the BackgroundImage when it is dark. Or they can be black if the form has its Opacity or TransparencyKey property set, contrasting badly with just about anything.
This is a pretty fundamental limitation of Windows Forms, it is stuck with the way Windows renders windows. Fixed by WPF btw, it doesn't use windows for child controls. What you'd want is double-buffering the entire form, including the child controls. That's possible, check my code in this thread for the solution. It has side-effects though, and doesn't actually increase painting speed. The code is simple, paste this in your form (not the user control):
protected override CreateParams CreateParams {
get {
CreateParams cp = base.CreateParams;
cp.ExStyle |= 0x02000000; // Turn on WS_EX_COMPOSITED
return cp;
}
}
There are many things you can do to improve painting speed, to the point that the flicker isn't noticeable anymore. Start by tackling the BackgroundImage. They can be really expensive when the source image is large and needs to be shrunk to fit the control. Change the BackgroundImageLayout property to "Tile". If that gives a noticeable speed-up, go back to your painting program and resize the image to be a better match with the typical control size. Or write code in the UC's OnResize() method to create a properly sized copy of the image so that it doesn't have to be resized every time the control repaints. Use the Format32bppPArgb pixel format for that copy, it renders about 10 times faster than any other pixel format.
Next thing you can do is prevent the holes from being so noticeable and contrasting badly with the image. You can turn off the WS_CLIPCHILDREN style flag for the UC, the flag that prevents the UC from painting in the area where the child controls go. Paste this code in the UserControl's code:
protected override CreateParams CreateParams {
get {
var parms = base.CreateParams;
parms.Style &= ~0x02000000; // Turn off WS_CLIPCHILDREN
return parms;
}
}
The child controls will now paint themselves on top of the background image. You might still see them painting themselves one by one, but the ugly intermediate white or black hole won't be visible.
Last but not least, reducing the number of child controls is always a good approach to solve slow painting problems. Override the UC's OnPaint() event and draw what is now shown in a child. Particular Label and PictureBox are very wasteful. Convenient for point and click but their light-weight alternative (drawing a string or an image) takes only a single line of code in your OnPaint() method.
This is a real issue, and the answer Hans Passant gave is great for saving the flicker. However, there are side effects as he mentioned, and they can be ugly (UI ugly). As stated, "You can turn off the WS_CLIPCHILDREN style flag for the UC", but that only turns it off for a UC. The components on the main form still have issues.
Example, a panel scroll bar doesn't paint, because it is technically in the child area. However the child component doesn't draw the scroll bar, so it doesn't get painted until mouse over (or another event triggers it).
Also, animated icons (changing icons in a wait loop) doesn't work. Removing icons on a tabPage.ImageKey doesn't resize/repaint the other tabPages appropriately.
So I was looking for a way to turn off the WS_CLIPCHILDREN on initial painting so my Form will load nicely painted, or better yet only turn it on while resizing my form with a lot of components.
The trick is to get the application to call CreateParams with the desired WS_EX_COMPOSITED/WS_CLIPCHILDREN style. I found a hack here (https://web.archive.org/web/20161026205944/http://www.angryhacker.com/blog/archive/2010/07/21/how-to-get-rid-of-flicker-on-windows-forms-applications.aspx) and it works great. Thanks AngryHacker!
I put the TurnOnFormLevelDoubleBuffering() call in the form ResizeBegin event and TurnOffFormLevelDoubleBuffering() call in the form ResizeEnd event (or just leave it WS_CLIPCHILDREN after it is initially painted properly.)
int originalExStyle = -1;
bool enableFormLevelDoubleBuffering = true;
protected override CreateParams CreateParams
{
get
{
if (originalExStyle == -1)
originalExStyle = base.CreateParams.ExStyle;
CreateParams cp = base.CreateParams;
if (enableFormLevelDoubleBuffering)
cp.ExStyle |= 0x02000000; // WS_EX_COMPOSITED
else
cp.ExStyle = originalExStyle;
return cp;
}
}
public void TurnOffFormLevelDoubleBuffering()
{
enableFormLevelDoubleBuffering = false;
this.MaximizeBox = true;
}
If you are doing any custom painting in the control (i.e. overriding OnPaint) you can try the double buffering yourself.
Image image;
protected override OnPaint(...) {
if (image == null || needRepaint) {
image = new Bitmap(Width, Height);
using (Graphics g = Graphics.FromImage(image)) {
// do any painting in image instead of control
}
needRepaint = false;
}
e.Graphics.DrawImage(image, 0, 0);
}
And invalidate your control with a property NeedRepaint
Otherwise the above answer with SuspendLayout and ResumeLayout is probably what you want.
Put the code bellow in your constructor or OnLoad event and if you're using some sort of custom user control that having sub controls, you'll need to make sure that these custom controls are also double buffered (even though in MS documentation they say it's set to true by default).
If you're making a custom control, you might want to add this flag into your ctor:
SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
Optionally you can use this code in your Form/Control:
foreach (Control control in Controls)
{
typeof(Control).InvokeMember("DoubleBuffered",
BindingFlags.SetProperty | BindingFlags.Instance | BindingFlags.NonPublic,
null, control, new object[] { true });
}
We iterating through all the controls in the form/control and accessing their DoubleBuffered property and then we change it to true in order to make each control on the form double buffered. The reason we do reflection here, is because imagine you have a control that has child controls that are not accessible, that way, even if they're private controls, we'll still change their property to true.
More information about double buffering technique can be found here.
There is another property I usually override to sort this problem:
protected override CreateParams CreateParams
{
get
{
CreateParams parms = base.CreateParams;
parms.ExStyle |= 0x00000020; // WS_EX_COMPOSITED
return parms;
}
}
WS_EX_COMPOSITED - Paints all descendants of a window in bottom-to-top painting order using double-buffering.
You can find more of these style flags here.
Hope that helps!
Try BeginUpdate/EndUpdate OR SuspendLayout/ResumeLayout methods.
See following
How to fix nested winform control flicker issues
Flickering during updates to Controls in WinForms (e.g. DataGridView)
Just to add to the answer Hans gave:
(TLDR version: Transparency is heavier than you think, use only solid colors everywhere)
If WS_EX_COMPOSITED, DoubleBuffered and WS_CLIPCHILDREN did not solve your flicker (for me WS_CLIPCHILDREN made it even worse), try this: go through ALL your controls and all your code, and wherever you have Any transparency or semi-transparency for BackColor, ForeColor, or any other color, just remove it, use only solid colors. In most of the cases where you think you just have to use transparency, you don't. Re-design your code and controls, and use solid colors.
I had terrible, terrible flickering and the program was running sluggish. Once I removed transparency it sped up significantly, and there is 0 flicker.
EDIT: To add further, I just discovered that WS_EX_COMPOSITED doesn't have to be window-wide, it could be applied just to specific controls! This saved me a lot of trouble. Just make a custom control inherited from whatever control you need, and paste the already posted override for WS_EX_COMPOSITED. This way you get low-level double-buffer on this control only, avoiding the nasty side-effects in the rest of the application!
On the main form or user control where background image resides set the BackgroundImageLayout property to Center or Stretch. You will notice a big difference when the user control is rendering.
I tried to add this as a comment but I don't have enough points. This is the only thing that's ever helped my flickering problems so many thanks to Hans for his post. For anyone that's using c++ builder like myself here's the translation
Add the CreateParams declaration to your application's main form .h file e.g.
class TYourMainFrom : public TForm
{
protected:
virtual void __fastcall CreateParams(TCreateParams &Params);
}
and add this to your .cpp file
void __fastcall TYourMainForm::CreateParams(TCreateParams &Params)
{
Params.ExStyle |= 0x02000000; // Turn on WS_EX_COMPOSITED
TForm::CreateParams(Params);
}
I know this question is very old, but want to give my experience on it.
I had a lot of problems with Tabcontrol flickering in a form with overrided OnPaint and/or OnPaintBackGround in Windows 8 using .NET 4.0.
The only think that worked has been NOT USE the Graphics.DrawImage method in OnPaint overrides, in other words, when draw was done directly to the Graphics provided by the PaintEventArgs, even painting all the rectangle, the flickering dissapeared. But if call the DrawImage method, even drawing a clipped Bitmap, (created for double buffering) the flicker appears.
Hope it helps!
I combined this flicker fix and this font fix, then I had to add a bit of my own code to start a timer on paint to Invalidate the TabControl when it goes offscreen and back, etc..
All three make this:
using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;
public class TabControlEx:TabControl
{
[DllImport("user32.dll")]
private static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);
private const int WM_PAINT = 0x0f;
private const int WM_SETFONT = 0x30;
private const int WM_FONTCHANGE = 0x1d;
private System.Drawing.Bitmap buffer;
private Timer timer = new Timer();
public TabControlEx()
{
timer.Interval = 1;
timer.Tick += timer_Tick;
this.SetStyle(ControlStyles.UserPaint | ControlStyles.DoubleBuffer | ControlStyles.AllPaintingInWmPaint, true);
}
void timer_Tick(object sender, EventArgs e)
{
this.Invalidate();
this.Update();
timer.Stop();
}
protected override void WndProc(ref Message m)
{
if (m.Msg == WM_PAINT) timer.Start();
base.WndProc(ref m);
}
protected override void OnPaint(PaintEventArgs pevent)
{
this.SetStyle(ControlStyles.UserPaint, false);
base.OnPaint(pevent);
System.Drawing.Rectangle o = pevent.ClipRectangle;
System.Drawing.Graphics.FromImage(buffer).Clear(System.Drawing.SystemColors.Control);
if (o.Width > 0 && o.Height > 0)
DrawToBitmap(buffer, new System.Drawing.Rectangle(0, 0, Width, o.Height));
pevent.Graphics.DrawImageUnscaled(buffer, 0, 0);
this.SetStyle(ControlStyles.UserPaint, true);
}
protected override void OnResize(EventArgs e)
{
base.OnResize(e);
buffer = new System.Drawing.Bitmap(Width, Height);
}
protected override void OnCreateControl()
{
base.OnCreateControl();
this.OnFontChanged(EventArgs.Empty);
}
protected override void OnFontChanged(EventArgs e)
{
base.OnFontChanged(e);
IntPtr hFont = this.Font.ToHfont();
SendMessage(this.Handle, WM_SETFONT, hFont, (IntPtr)(-1));
SendMessage(this.Handle, WM_FONTCHANGE, IntPtr.Zero, IntPtr.Zero);
this.UpdateStyles();
}
}
I'm not the creator but from what I understand the bitmap does all the bug bypassing.
This was the only thing that definitively solved TabControl (with Icons) flicker for me.
difference result video: vanilla tabcontrol vs tabcontrolex
http://gfycat.com/FineGlitteringDeermouse
ps. you will need to set HotTrack = true, because this fixes that bug too
Did you try Control.DoubleBuffered Property?
Gets or sets a value indicating whether this control should redraw its surface using a secondary buffer to reduce or prevent flicker.
Also this and this might help.
There is no need of any Double buffering and all that stuff guys...
A Simple solution...
If you are using MDI Interface, just paste the code below in the main form. It will remove all flickering from the pages. However some pages which require more time for loading will showup in 1 or 2 secs. But this is better than showing a flickering page in which each item comes one by one.
This is the only best solution for whole application. See the code to put in the main form:
protected override CreateParams CreateParams {
get {
CreateParams cp = base.CreateParams;
cp.ExStyle |= 0x02000000; // Turn on WS_EX_COMPOSITED
return cp;
}
}