Effect of temporary variable on erasing the background of a GroupBox

Effect of temporary variable on erasing the background of a GroupBox - c#

The context:
Consider drawing a GroupBox with a gradient as a part of it's background.
Example:
Let's perform the following actions:
Create a class that inherits GroupBox.
Set it's FlatStyle property to FlatStyle.System.
override it's WndProc method.
Handle the WM_ERASEBKGND message, in which we draw the gradient.
Handle the WM_PRINTCLIENT message, where we call DefWndProc and return.(Will be needed later.)
Add a Label as it's child Control.(The Label's background must be transparent to be able to see the gradient behind it's Text.
Create a class that inherits Label.
override the WndProc method.
"Simulate transparency" by calling the DrawThemeParentBackground function to draw the GroupBox's background on the Label's Graphics.
The issue:
Depending on whether a temporary variable is used to hold the Graphics object, the end result varies, depicted with the code sample and image below:
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace MCVE
{
class GroupBox : System.Windows.Forms.GroupBox
{
const int WM_ERASEBKGND = 0x14;
const int WM_PRINTCLIENT = 0x318;
protected override void WndProc(ref Message m)
{
switch (m.Msg)
{
case WM_ERASEBKGND:
base.WndProc(ref m);
using (var g = Graphics.FromHdc(m.WParam))//CASE 1
//using (var e = new PaintEventArgs(Graphics.FromHdc(m.WParam), ClientRectangle))//CASE 2
{
var e = new PaintEventArgs(g, ClientRectangle);//CASE 1
var r = new Rectangle(2, 12, Width - 4, Height - 2);
using (var b = new LinearGradientBrush(r, BackColor, SystemColors.Window, LinearGradientMode.Vertical))
{
e.Graphics.FillRectangle(b, r);//Draw the gradient.
}
}
m.Result = new IntPtr(1);//Signal that no further drawing of the background is necessary by WM_PAINT.
return;
case WM_PRINTCLIENT:
DefWndProc(ref m);//Bypass GroupBox's internal handling so that actual painting is handled by Windows.
return;
}
base.WndProc(ref m);//Default processing of the rest of the messages.
}
};
class Label : System.Windows.Forms.Label
{
const int WM_ERASEBKGND = 0x14;
const int WM_PAINT = 0xF;
[DllImport("user32.dll")] static extern IntPtr BeginPaint(IntPtr hWnd, out PAINTSTRUCT lpPaint);
[DllImport("user32.dll")] static extern IntPtr EndPaint(IntPtr hWnd, ref PAINTSTRUCT lpPaint);
//Ask Windows to send a message to the parent to draw it's background in the current device context.
[DllImport("uxtheme.dll")] extern static int DrawThemeParentBackground(IntPtr hWnd, IntPtr hdc, ref Rectangle pRect);
[StructLayout(LayoutKind.Sequential)]
struct PAINTSTRUCT
{
public IntPtr hdc;
public bool fErase;
public Rectangle rcPaint;
public bool fRestore;
public bool fIncUpdate;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)] public byte[] rgcReserved;
};
protected override void WndProc(ref Message m)
{
switch (m.Msg)
{
case WM_ERASEBKGND:
var r = ClientRectangle;
DrawThemeParentBackground(Handle, m.WParam, ref r);
m.Result = new IntPtr(1);//Signal that no further drawing of the background is necessary by WM_PAINT.
return;
case WM_PAINT:
PAINTSTRUCT ps;
var hdc = BeginPaint(Handle, out ps);
EndPaint(Handle, ref ps);//Don't paint any text so that the gradient remains visible.
m.Result = IntPtr.Zero;
return;
}
base.WndProc(ref m);//Default processing of the rest of the messages.
}
};
static class Program
{
[STAThread] static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
var form = new Form() { BackColor = SystemColors.Highlight };
var groupbox = new GroupBox() { Anchor = (AnchorStyles)15, FlatStyle = FlatStyle.System, Location = new Point(10, 10), Text = "groupBox1" };
form.Controls.Add(groupbox);
groupbox.Controls.Add(new Label() { FlatStyle = FlatStyle.System, Location = new Point(50, 50) });
Application.Run(form);
}
};
}
Running the above MCVE (CASE 1) produces the expected ouput as shown in the example image.
On commenting out the lines remarked CASE 1 and uncommenting the line marked CASE 2 gives the following undesired output:
The question:
Why does the removal of the temporary variable produce such a vastly different output?

Posting this as an answer for the sake of completeness.
As pointed out by Ivan Stoev, the non-owning PaintEventArgs does not call Dispose on the Graphics object.
This has visible side effects as the DC is reused by Windows in the WM_PRINTCLIENT Message, that is sent next to the WndProc.
Manually calling Dispose on the Graphics object confirms this.
using (var g = Graphics.FromHdc(m.WParam))
{
using (var e = new PaintEventArgs(g, ClientRectangle))
{
var r = new Rectangle(2, 12, Width - 4, Height - 2);
using (var b = new LinearGradientBrush(r, BackColor, SystemColors.Window, LinearGradientMode.Vertical))
{
e.Graphics.FillRectangle(b, r);//Draw the gradient.
}
}
}

Can all this boil down to a simple derived class, without PInvoking?
This class derives from GroupBox, set it as Transparent using CreateParams CreateParams.ExStyle proeprty, enables support for Transparent colors with Control.SetStyle() and ControlStyles.SupportsTransparentBackColor style (this way you can better control the effect of the LinearGradientBrush) and overrides the OnPaintBackground() method to perform the painting.
It's just a basic example, but it can be tweaked in any other way and still be more portable.
You can drop any control on it.
class GradientGroupBox : GroupBox
{
private const int WS_EX_TRANSPARENT = 0x20;
public GradientGroupBox() => this.SetStyle(ControlStyles.SupportsTransparentBackColor, true);
protected override void OnPaintBackground(PaintEventArgs e)
{
base.OnPaintBackground(e);
Color gradFillTo = Color.FromArgb(200, SystemColors.Window);
Color gradFillFrom = Color.FromArgb(128, this.Parent.BackColor);
using (LinearGradientBrush gradientBrush = new LinearGradientBrush(this.ClientRectangle, gradFillFrom, gradFillTo, LinearGradientMode.Vertical))
{
e.Graphics.FillRectangle(gradientBrush, this.ClientRectangle);
}
}
protected override CreateParams CreateParams
{
get
{
CreateParams parameters = base.CreateParams;
parameters.ExStyle |= WS_EX_TRANSPARENT;
return parameters;
}
}
}

Related

Customizing Border and Button of the DateTimePicker

Goal is to create DateTimePicker similar to the screen shot of this question.
First attempt overriding OnPaint:
public class MyDateTimePicker : DateTimePicker
{
private Image _image;
public MyDateTimePicker() : base()
{
SetStyle(ControlStyles.UserPaint | ControlStyles.ResizeRedraw |
ControlStyles.DoubleBuffer | ControlStyles.AllPaintingInWmPaint, true);
}
[Browsable(true)]
public override Color BackColor
{
get
{
return base.BackColor;
}
set
{
base.BackColor = value;
}
}
[Category("Appearance")]
public Color BorderColor { get; set; } = Color.Black;
[Category("Appearance")]
public Color TextColor { get; set; } = Color.Black;
[Category("Appearance")]
public Image Image
{
get
{
return _image;
}
set
{
_image = value;
Invalidate();
}
}
protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
{
e.Graphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit;
// Fill the Background
e.Graphics.FillRectangle(new SolidBrush(this.BackColor), 0, 0, ClientRectangle.Width, ClientRectangle.Height);
// Draw DateTime text
e.Graphics.DrawString(this.Text, this.Font, new SolidBrush(TextColor), 5, 2);
// Draw Icon
if (_image != null)
{
Rectangle im_rect = new Rectangle(ClientRectangle.Width - 20, 2, ClientRectangle.Height - 4, ClientRectangle.Height - 4);
e.Graphics.DrawImage(_image, im_rect);
}
// Draw Border
e.Graphics.DrawRectangle(Pens.Black, new Rectangle(0, 0, ClientRectangle.Width - 1, ClientRectangle.Height - 1));
}
}
This solution has the following issues: date fields are not clickable, text artifacts when changing date with arrow keys, narrow clickable area of the button.
Second solution overriding WndProc:
public class MyDateTimePicker : DateTimePicker
{
private const int WM_PAINT = 0x000F;
private Color _borderColor = Color.Black;
public MyDateTimePicker() { }
[Category("Appearance")]
public Color BorderColor
{
get { return _borderColor; }
set
{
if (_borderColor != value)
{
_borderColor = value;
this.Invalidate();
}
}
}
protected override void WndProc(ref Message m)
{
switch (m.Msg)
{
case WM_PAINT:
base.WndProc(ref m);
using (var g = Graphics.FromHwnd(m.HWnd))
{
var rect = new Rectangle(0, 0, this.ClientSize.Width - 1, this.ClientSize.Height - 1);
g.DrawRectangle(new Pen(this.BorderColor), rect);
}
m.Result = IntPtr.Zero;
break;
default:
base.WndProc(ref m);
break;
}
}
}
This solution lacks the customization of the button. Maybe anyone knows how to customize button in this way, or how to solve issues of the first solution?
Also if it is possible I would like to change the height of DateTimePicker to match height of ComboBox (currently they differ by 1px).

You can handle WM_PAINT and draw the border and button yourself. To get the accurate size of the dropdown, send DTM_GETDATETIMEPICKERINFO message.
The width of the dropdown button may vary depending to the size of the control and the space required by the text of the control:
Flat DateTimePicker
using System;
using System.ComponentModel;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;
public class FlatDateTimePicker : DateTimePicker
{
public FlatDateTimePicker()
{
SetStyle(ControlStyles.ResizeRedraw |
ControlStyles.OptimizedDoubleBuffer, true);
}
private Color borderColor = Color.DeepSkyBlue;
[DefaultValue(typeof(Color), "RoyalBlue")]
public Color BorderColor
{
get { return borderColor; }
set
{
if (borderColor != value)
{
borderColor = value;
Invalidate();
}
}
}
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
if (m.Msg == WM_PAINT)
{
var info = new DATETIMEPICKERINFO();
info.cbSize = Marshal.SizeOf(info);
SendMessage(Handle, DTM_GETDATETIMEPICKERINFO, IntPtr.Zero, ref info);
using (var g = Graphics.FromHwndInternal(Handle))
{
var clientRect = new Rectangle(0,0,Width, Height);
var buttonWidth = info.rcButton.R - info.rcButton.L;
var dropDownRect = new Rectangle(info.rcButton.L, info.rcButton.T,
buttonWidth, clientRect.Height);
if (RightToLeft == RightToLeft.Yes && RightToLeftLayout == true)
{
dropDownRect.X = clientRect.Width - dropDownRect.Right;
dropDownRect.Width += 1;
}
var middle = new Point(dropDownRect.Left + dropDownRect.Width / 2,
dropDownRect.Top + dropDownRect.Height / 2);
var arrow = new Point[]
{
new Point(middle.X - 3, middle.Y - 2),
new Point(middle.X + 4, middle.Y - 2),
new Point(middle.X, middle.Y + 2)
};
var borderAndButtonColor = Enabled ? BorderColor : Color.LightGray;
var arrorColor = BackColor;
using (var pen = new Pen(borderAndButtonColor))
g.DrawRectangle(pen, 0, 0,
clientRect.Width - 1, clientRect.Height - 1);
using (var brush = new SolidBrush(borderAndButtonColor))
g.FillRectangle(brush, dropDownRect);
g.FillPolygon(Brushes.Black, arrow);
}
}
}
const int WM_PAINT = 0xF;
const int DTM_FIRST = 0x1000;
const int DTM_GETDATETIMEPICKERINFO = DTM_FIRST + 14;
[DllImport("user32.dll")]
static extern IntPtr SendMessage(IntPtr hWnd, int Msg,
IntPtr wParam, ref DATETIMEPICKERINFO info);
[StructLayout(LayoutKind.Sequential)]
struct RECT
{
public int L, T, R, B;
}
[StructLayout(LayoutKind.Sequential)]
struct DATETIMEPICKERINFO
{
public int cbSize;
public RECT rcCheck;
public int stateCheck;
public RECT rcButton;
public int stateButton;
public IntPtr hwndEdit;
public IntPtr hwndUD;
public IntPtr hwndDropDown;
}
}
Clone or Download Extended version
I have created an extended version of this answer, which supports rendering the up-down button and the checkbox in flat style, also highlighting the arrow on mouse move, something like this:
You can download or close the code:
r-aghaei/FlatDateTimePickerExample
master.zip
Related Posts
You may also want to take a look at the following flat style controls:
Flat TextBox - Change border color of TextBox
Flat ComboBox - Change border color and dropdown button of ComboBox
Flat NumericUpDown - Change border color and spin buttons of NumericUpDown

How to use PrintDocument with a scrollable Panel?

How do I use PrintDocument with a scrollable panel`?
Here is some of my code:
MemoryImage = new Bitmap(pnl.Width, pnl.Height);
Rectangle rect = new Rectangle(0, 0, pnl.Width, pnl.Height);
pnl.DrawToBitmap(MemoryImage, new Rectangle(0, 0, pnl.Width,
pnl.Height));
Rectangle pagearea = e.PageBounds;
e.Graphics.DrawImage(MemoryImage, (pagearea.Width / 2) -
(pannel.Width / 2), pannel.Location.Y);

These sets of methods allow to print the content of a ScrollableControl to a Bitmap.
A description of the procedure:
The control is first scrolled back to the origin (control.AutoScrollPosition = new Point(0, 0); (an exception is raised otherwise: the Bitmap has a wrong size. You may want to store the current scroll position and restore it after).
Verifies and stores the actual size of the Container, returned by the PreferredSize or DisplayRectangle properties (depending on the conditions set by the method arguments and the type of container printed). This property considers the full extent of a container.
This will be the size of the Bitmap.
Clears the Bitmap using the background color of the Container.
Iterates the ScrollableControl.Controls collection and prints all first-level child controls in their relative position (a child Control's Bounds rectangle is relative to the container ClientArea.)
If a first-level Control has children, calls the DrawNestedControls recursive method, which will enumerate and draw all nested child Containers/Controls, preserving the internal clip bounds.
Includes support for RichTextBox controls.
The RichEditPrinter class contains the logic required to print the content of a RichTextBox/RichEdit control. The class sends an EM_FORMATRANGE message to the RichTextBox, using the Device context of the Bitmap where the control is being printed.
More details available in the MSDN Docs: How to Print the Contents of Rich Edit Controls.
The ScrollableControlToBitmap() method takes only a ScrollableControl type as argument: you cannot pass a TextBox control, even if it uses ScrollBars.
▶ Set the fullSize argument to true or false to include all child controls inside a Container or just those that are visible. If set to true, the Container's ClientRectangle is expanded to include and print all its child Controls.
▶ Set the includeHidden argument to true or false to include or exclude the hidden control, if any.
Note: this code uses the Control.DeviceDpi property to evaluate the current Dpi of the container's Device Context. This property requires .Net Framework 4.7+. If this version is not available, you can remove:
bitmap.SetResolution(canvas.DeviceDpi, canvas.DeviceDpi);
or derive the value with other means. See GetDeviceCaps.
Possibly, update the Project's Framework version :)
// Prints the content of the current Form instance,
// include all child controls and also those that are not visible
var bitmap = ControlPrinter.ScrollableControlToBitmap(this, true, true);
// Prints the content of a ScrollableControl inside a Form
// include all child controls except those that are not visible
var bitmap = ControlPrinter.ScrollableControlToBitmap(this.panel1, true, false);
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.Windows.Forms;
public class ControlPrinter
{
public static Bitmap ScrollableControlToBitmap(ScrollableControl canvas, bool fullSize, bool includeHidden)
{
canvas.AutoScrollPosition = new Point(0, 0);
if (includeHidden) {
canvas.SuspendLayout();
foreach (Control child in canvas.Controls) {
child.Visible = true;
}
canvas.ResumeLayout(true);
}
canvas.PerformLayout();
Size containerSize = canvas.DisplayRectangle.Size;
if (fullSize) {
containerSize.Width = Math.Max(containerSize.Width, canvas.ClientSize.Width);
containerSize.Height = Math.Max(containerSize.Height, canvas.ClientSize.Height);
}
else {
containerSize = canvas.ClientSize;;
}
var bitmap = new Bitmap(containerSize.Width, containerSize.Height, PixelFormat.Format32bppArgb);
bitmap.SetResolution(canvas.DeviceDpi, canvas.DeviceDpi);
var graphics = Graphics.FromImage(bitmap);
if (canvas.BackgroundImage != null) {
graphics.DrawImage(canvas.BackgroundImage, new Rectangle(Point.Empty, containerSize));
}
else {
graphics.Clear(canvas.BackColor);
}
var rtfPrinter = new RichEditPrinter(graphics);
try {
DrawNestedControls(canvas, canvas, new Rectangle(Point.Empty, containerSize), bitmap, rtfPrinter);
return bitmap;
}
finally {
rtfPrinter.Dispose();
graphics.Dispose();
}
}
private static void DrawNestedControls(Control outerContainer, Control parent, Rectangle parentBounds, Bitmap bitmap, RichEditPrinter rtfPrinter)
{
for (int i = parent.Controls.Count - 1; i >= 0; i--) {
var ctl = parent.Controls[i];
if (!ctl.Visible || (ctl.Width < 1 || ctl.Height < 1)) continue;
var clipBounds = Rectangle.Empty;
if (parent.Equals(outerContainer)) { clipBounds = ctl.Bounds; }
else {
Size scrContainerSize = parentBounds.Size;
if ((parent != ctl) && parent is ScrollableControl scrctl) {
if (scrctl.VerticalScroll.Visible) scrContainerSize.Width -= (SystemInformation.VerticalScrollBarWidth + 1);
if (scrctl.HorizontalScroll.Visible) scrContainerSize.Height -= (SystemInformation.HorizontalScrollBarHeight + 1);
}
clipBounds = Rectangle.Intersect(new Rectangle(Point.Empty, scrContainerSize), ctl.Bounds);
}
if (clipBounds.Width < 1 || clipBounds.Height < 1) continue;
var bounds = outerContainer.RectangleToClient(parent.RectangleToScreen(clipBounds));
if (ctl is RichTextBox rtb) {
rtfPrinter.DrawRtf(rtb.Rtf, outerContainer.Bounds, bounds, ctl.BackColor);
}
else {
ctl.DrawToBitmap(bitmap, bounds);
}
if (ctl.HasChildren) {
DrawNestedControls(outerContainer, ctl, clipBounds, bitmap, rtfPrinter);
}
}
}
internal class RichEditPrinter : IDisposable
{
Graphics dc = null;
RTBPrinter rtb = null;
public RichEditPrinter(Graphics graphics)
{
this.dc = graphics;
this.rtb = new RTBPrinter() { ScrollBars = RichTextBoxScrollBars.None };
}
public void DrawRtf(string rtf, Rectangle canvas, Rectangle layoutArea, Color color)
{
rtb.Rtf = rtf;
rtb.Draw(dc, canvas, layoutArea, color);
rtb.Clear();
}
public void Dispose() => this.rtb.Dispose();
private class RTBPrinter : RichTextBox
{
public void Draw(Graphics g, Rectangle hdcArea, Rectangle layoutArea, Color color)
{
using (var brush = new SolidBrush(color)) {
g.FillRectangle(brush, layoutArea);
};
IntPtr hdc = g.GetHdc();
var canvasAreaTwips = new RECT().ToInches(hdcArea);
var layoutAreaTwips = new RECT().ToInches(layoutArea);
var formatRange = new FORMATRANGE() {
charRange = new CHARRANGE() { cpMax = -1, cpMin = 0 },
hdc = hdc,
hdcTarget = hdc,
rect = layoutAreaTwips,
rectPage = canvasAreaTwips
};
IntPtr lParam = Marshal.AllocCoTaskMem(Marshal.SizeOf(formatRange));
Marshal.StructureToPtr(formatRange, lParam, false);
SendMessage(this.Handle, EM_FORMATRANGE, (IntPtr)1, lParam);
Marshal.FreeCoTaskMem(lParam);
g.ReleaseHdc(hdc);
}
[DllImport("User32.dll", CharSet = CharSet.Auto, SetLastError = true)]
internal static extern int SendMessage(IntPtr hWnd, int uMsg, IntPtr wParam, IntPtr lParam);
internal const int WM_USER = 0x0400;
// https://learn.microsoft.com/en-us/windows/win32/controls/em-formatrange
internal const int EM_FORMATRANGE = WM_USER + 57;
[StructLayout(LayoutKind.Sequential)]
internal struct RECT
{
public int Left;
public int Top;
public int Right;
public int Bottom;
public Rectangle ToRectangle() => Rectangle.FromLTRB(Left, Top, Right, Bottom);
public RECT ToInches(Rectangle rectangle)
{
float inch = 14.92f;
return new RECT() {
Left = (int)(rectangle.Left * inch),
Top = (int)(rectangle.Top * inch),
Right = (int)(rectangle.Right * inch),
Bottom = (int)(rectangle.Bottom * inch)
};
}
}
// https://learn.microsoft.com/en-us/windows/win32/api/richedit/ns-richedit-formatrange?
[StructLayout(LayoutKind.Sequential)]
internal struct FORMATRANGE
{
public IntPtr hdcTarget; // A HDC for the target device to format for
public IntPtr hdc; // A HDC for the device to render to, if EM_FORMATRANGE is being used to send the output to a device
public RECT rect; // The area within the rcPage rectangle to render to. Units are measured in twips.
public RECT rectPage; // The entire area of a page on the rendering device. Units are measured in twips.
public CHARRANGE charRange; // The range of characters to format (see CHARRANGE)
}
[StructLayout(LayoutKind.Sequential)]
internal struct CHARRANGE
{
public int cpMin; // First character of range (0 for start of doc)
public int cpMax; // Last character of range (-1 for end of doc)
}
}
}
}
This is how it works:
VB.Net version of the same procedure

c# RichTextBox Border Color

I'm trying to create a custom RichTextBox with border color, but i have a problem...
My border color not showing
Here's my code :
public partial class AlXRichTextBox : RichTextBox
{
private RichTextBox textBox;
private Color borderColor;
public AlXRichTextBox()
{
InitializeComponent();
}
public Color BorderColor
{
get { return borderColor; }
set { borderColor = value; Invalidate(); }
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
Pen p = new Pen(borderColor);
Graphics g = e.Graphics;
int variance = 3;
//g.DrawRectangle(p, new Rectangle(base.Location.X - variance, base.Location.Y - variance, base.Width + variance, base.Height + variance));
ControlPaint.DrawBorder(e.Graphics, base.ClientRectangle, borderColor, ButtonBorderStyle.Solid);
}
private void InitializeComponent()
{
this.textBox = new System.Windows.Forms.RichTextBox();
this.SuspendLayout();
//
// richTextBox1
//
this.textBox.Location = new System.Drawing.Point(0, 0);
this.textBox.Name = "richTextBox1";
this.textBox.Size = new System.Drawing.Size(100, 96);
this.textBox.TabIndex = 0;
this.textBox.Text = "";
this.textBox.Multiline = true;
this.textBox.BorderStyle = BorderStyle.None;
//
// AlXRichTextBox
//
this.Size = new System.Drawing.Size(278, 123);
this.ResumeLayout(false);
}
}
What's problem with this ?

Referring to MSDN article :
Overriding OnPaint will not allow you to modify the appearance of all controls. Those controls that have all of their painting done by Windows (for example, TextBox) never call their OnPaint method, and thus will never use the custom code. Refer to the Help documentation for the particular control you want to modify to see if the OnPaint method is available. For a list of all the Windows Form Controls, see Controls to Use on Windows Forms. If a control does not have OnPaint listed as a member method, you cannot alter its appearance by overriding this method. For more information about custom painting, see Custom Control Painting and Rendering.
However there is a "hack", You can achieve calling the Paint method by calling following code:
private const int WM_PAINT = 15;
protected override void WndProc(ref System.Windows.Forms.Message m)
{
base.WndProc(ref m);
if (m.Msg == WM_PAINT && !inhibitPaint)
{
// raise the paint event
using (Graphics graphic = base.CreateGraphics())
OnPaint(new PaintEventArgs(graphic,
base.ClientRectangle));
}
}
private bool inhibitPaint = false;
public bool InhibitPaint
{
set { inhibitPaint = value; }
}
Src: RichTextBox and UserPaint
Other point is that You cannot draw outside of the Rectangle (which is total size of Your RichTB component. So You actually want to provide him with different Coords (smaller inner ones) and You will draw to the outside.
Your class will look like:
public partial class AlXRichTextBox : RichTextBox
{
private Color borderColor = Color.Red;
public Color BorderColor
{
get { return borderColor; }
set { borderColor = value; Invalidate(); }
}
protected override void OnPaint(PaintEventArgs e)
{
int variance = 3;
e = new PaintEventArgs(e.Graphics, new Rectangle(e.ClipRectangle.X + variance, e.ClipRectangle.Y + variance, e.ClipRectangle.Width - variance, e.ClipRectangle.Height - variance));
base.OnPaint(e);
Pen p = new Pen(borderColor, variance);
Graphics g = e.Graphics;
g.DrawRectangle(p, new Rectangle(e.ClipRectangle.X, e.ClipRectangle.Y, e.ClipRectangle.Width, e.ClipRectangle.Height));
}
private const int WM_PAINT = 15;
protected override void WndProc(ref System.Windows.Forms.Message m)
{
base.WndProc(ref m);
if (m.Msg == WM_PAINT && !inhibitPaint)
{
// raise the paint event
using (Graphics graphic = base.CreateGraphics())
OnPaint(new PaintEventArgs(graphic,
base.ClientRectangle));
}
}
private bool inhibitPaint = false;
public bool InhibitPaint
{
set { inhibitPaint = value; }
}
}
IMPORTANT
As it is not expected for this control to be changed by Paint, You will get "not nice" behavior in regards to the drawing changes like border, new elements etc.. If You would like to use such element, consider using WPF - Windows Presentation Foundation. They are much more nicer to templating the items and modifying design.

A little late answer, but I was on same path as you these days and It got me to this solution, It works for me:
using System;
using System.Drawing;
using System.Windows.Forms;
public class MyRichTextBox : RichTextBox
{
private const UInt32 WM_PAINT = 0x000F;
private const UInt32 WM_USER = 0x0400;
private const UInt32 EM_SETBKGNDCOLOR = (WM_USER + 67);
private const UInt32 WM_KILLFOCUS = 0x0008;
public MyRichTextBox()
{
this.BorderStyle = System.Windows.Forms.BorderStyle.None;
}
protected override void WndProc(ref System.Windows.Forms.Message m)
{
base.WndProc(ref m);
Graphics g = Graphics.FromHwnd(Handle);
Rectangle bounds = new Rectangle(0, 0, Width - 1, Height - 1);
Pen p = new Pen(SystemColors.Highlight, 3);
if (m.Msg == WM_PAINT)
{
if (this.Enabled == true)
{
if (this.Focused)
{
g.DrawRectangle(p, bounds);
}
else
{
g.DrawRectangle(SystemPens.ControlDark, bounds);
}
}
else
{
g.FillRectangle(Brushes.White, bounds);
g.DrawRectangle(SystemPens.Control, bounds);
}
}
if (m.Msg == EM_SETBKGNDCOLOR) //color disabled background
{
Invalidate();
}
if (m.Msg == WM_KILLFOCUS) //set border back to normal on lost focus
{
Invalidate();
}
}
}
This Rich Textbox changes 3 border colors - enabled, focused and disabled with disabled background. As you see the code is simple and short. The only trick is to overide KILL_FOCUS and EM_SETBKGNDCOLOR messages (this one is for changing disabled background), and RichTextbox should be BorderStyle=None. Cheers !

Simulate Windows Dragging Effect in a Winform FlowLayoutPanel

I'm currently simulating the windows multiple selection rectangle when the user is dragging the mouse. To synchronize our understanding, this picture shows the effect I want to simulate:
Now I want to simulate this effect on a FlowLayoutPanel with some controls inside.
So far I am managed to get the effect almost done:
What I did here was putting a unfocused border-less semi-transparent (half the opacity) form on top the main form. To get the border simulated, I handled SizeChanged and Paint to draw the border.
However, this solution sometimes flickers, as in the owner border couldn't get cleared on-time:
I have tried using double buffering on the cover form by setting DoubleBuffer to true, and override CreateParam to set WM_EX_COMPOSITED, but neither works.
My question is: How to reduce this artifact?
Thanks a lot!
My code:
For the cover form:
public partial class CoverForm : Form
{
public CoverForm()
{
InitializeComponent();
BackColor = Color.CadetBlue;
FormBorderStyle = FormBorderStyle.None;
SizeChanged += (s, e) => Invalidate();
Paint += (s, e) =>
{
e.Graphics.Clear(BackColor);
using (var pen = new Pen(Color.DodgerBlue))
{
e.Graphics.DrawRectangle(pen, 1, 1, Size.Width - 2, Size.Height - 2);
}
};
}
protected override bool ShowWithoutActivation
{
get { return true; }
}
}
For the main form:
public Form1()
{
InitializeComponent();
// mainPanel is the panel that simulates the dragging effect
mainPanel.MouseDown += (s, e) =>
{
_isMouseDown = true;
_startPosition = e.Location;
coverForm.Location = mainPanel.PointToScreen(e.Location);
coverForm.Show();
};
mainPanel.MouseUp += (s, e) =>
{
_isMouseDown = false;
coverForm.Hide();
};
mainPanel.MouseMove += CoverPanelMouseMoveHandler;
DoubleBuffered = true;
}
~Form1()
{
if (coverForm != null && !coverForm.IsDisposed)
{
coverForm.Dispose();
}
}
# region Dragging Effect
private void CoverPanelMouseMoveHandler(object sender, MouseEventArgs e)
{
if (_isMouseDown)
{
_curPosition = e.Location;
// find the dragging rectangle
var rect = CreateRect(_curPosition, _startPosition);
coverForm.Size = rect.Size;
coverForm.Location = mainPanel.PointToScreen(rect.Location);
foreach (Control control in mainPanel.Controls)
{
// logic to get button backcolor changed
}
mainPanel.Invalidate(true);
}
}
Update
I have tried to override OnPaint and put my drawing there, but it gave even worse result: the old paints wouldn't get erased:
Code I modified for cover form:
public partial class CoverForm : Form
{
public CoverForm()
{
InitializeComponent();
BackColor = Color.CadetBlue;
FormBorderStyle = FormBorderStyle.None;
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
e.Graphics.Clear(BackColor);
using (var pen = new Pen(Color.FromArgb(255, 0, 0, 255)))
{
e.Graphics.DrawRectangle(pen, 0, 0, Size.Width - 1, Size.Height - 1);
}
}
protected override bool ShowWithoutActivation
{
get { return true; }
}
}
Update 2
Actually the problem I am facing is about drawing above a FlowLayoutPanel, not a normal Panel. The reason I put Panel before was I was seeking answer for my flickering 2-layers design. But since someone approach the problem by adding control to the panel to get it drawn above all controls, I would like to point this out: adding control to a panel would be trivial, but FlowLayoutPanel will auto-align the newly added control to the next available position, which may screw up the expected effect.

Video Demo of the Solution: Remember to Switch to 1080p
Recorded in a VM on a crappy machine. So kinda slow.
You are getting those artifacts because you're doing a combination of 3 things all at once.
The two big ones are moving the form to another location and resizing the form. It also doesn't help if the form is semi transparent :) To get a better understanding of what I mean, just open VS2013 up and resize the window very quickly (at the top-left corner, and run in random directions really fast), you will see that around the edges it can't keep up. And yes, you will get different results when you're resizing from a different position around the window (just think about it for a minute and you will figure it out).
Aybe, provided a pretty clever solution but it doesn't allow you to see through it or see if any updates to the panel....since it basically just copies the last output to a bitmap and uses that as a back buffer (much like what you assume someone might do when doing the selection thing in a paint program).
If you really want to do it with an overlay form and keep it semi-transparent then you will need to eliminate those three things if you don't want artifacts.
The code requires quite a bit of WIN32 knowledge.... lucky for you Microsoft has already done the hard part. We are going to enable per pixel transparency in your cover frame by using the PerPixelAlphaForm by Microsoft (you can google it) I will paste the code here. It basically just creates a Window with a Style of WS_EX_LAYERED. Keeps a Backbuffer which is AlphaBlended with the screen (simple huh?).
/******************************** Module Header ********************************\
Module Name: PerPixelAlphaForm.cs
Project: CSWinFormLayeredWindow
Copyright (c) Microsoft Corporation.
This source is subject to the Microsoft Public License.
See http://www.microsoft.com/opensource/licenses.mspx#Ms-PL.
All other rights reserved.
THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
\*******************************************************************************/
#region Using directives
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
#endregion
namespace CSWinFormLayeredWindow
{
public partial class PerPixelAlphaForm : Form
{
public PerPixelAlphaForm()
{
InitializeComponent();
}
protected override CreateParams CreateParams
{
get
{
// Add the layered extended style (WS_EX_LAYERED) to this window.
CreateParams createParams = base.CreateParams;
createParams.ExStyle |= WS_EX_LAYERED;
return createParams;
}
}
/// <summary>
/// Let Windows drag this window for us (thinks its hitting the title
/// bar of the window)
/// </summary>
/// <param name="message"></param>
protected override void WndProc(ref Message message)
{
if (message.Msg == WM_NCHITTEST)
{
// Tell Windows that the user is on the title bar (caption)
message.Result = (IntPtr)HTCAPTION;
}
else
{
base.WndProc(ref message);
}
}
/// <summary>
///
/// </summary>
/// <param name="bitmap"></param>
public void SelectBitmap(Bitmap bitmap)
{
SelectBitmap(bitmap, 255);
}
/// <summary>
///
/// </summary>
/// <param name="bitmap">
///
/// </param>
/// <param name="opacity">
/// Specifies an alpha transparency value to be used on the entire source
/// bitmap. The SourceConstantAlpha value is combined with any per-pixel
/// alpha values in the source bitmap. The value ranges from 0 to 255. If
/// you set SourceConstantAlpha to 0, it is assumed that your image is
/// transparent. When you only want to use per-pixel alpha values, set
/// the SourceConstantAlpha value to 255 (opaque).
/// </param>
public void SelectBitmap(Bitmap bitmap, int opacity)
{
// Does this bitmap contain an alpha channel?
if (bitmap.PixelFormat != PixelFormat.Format32bppArgb)
{
throw new ApplicationException("The bitmap must be 32bpp with alpha-channel.");
}
// Get device contexts
IntPtr screenDc = GetDC(IntPtr.Zero);
IntPtr memDc = CreateCompatibleDC(screenDc);
IntPtr hBitmap = IntPtr.Zero;
IntPtr hOldBitmap = IntPtr.Zero;
try
{
// Get handle to the new bitmap and select it into the current
// device context.
hBitmap = bitmap.GetHbitmap(Color.FromArgb(0));
hOldBitmap = SelectObject(memDc, hBitmap);
// Set parameters for layered window update.
Size newSize = new Size(bitmap.Width, bitmap.Height);
Point sourceLocation = new Point(0, 0);
Point newLocation = new Point(this.Left, this.Top);
BLENDFUNCTION blend = new BLENDFUNCTION();
blend.BlendOp = AC_SRC_OVER;
blend.BlendFlags = 0;
blend.SourceConstantAlpha = (byte)opacity;
blend.AlphaFormat = AC_SRC_ALPHA;
// Update the window.
UpdateLayeredWindow(
this.Handle, // Handle to the layered window
screenDc, // Handle to the screen DC
ref newLocation, // New screen position of the layered window
ref newSize, // New size of the layered window
memDc, // Handle to the layered window surface DC
ref sourceLocation, // Location of the layer in the DC
0, // Color key of the layered window
ref blend, // Transparency of the layered window
ULW_ALPHA // Use blend as the blend function
);
}
finally
{
// Release device context.
ReleaseDC(IntPtr.Zero, screenDc);
if (hBitmap != IntPtr.Zero)
{
SelectObject(memDc, hOldBitmap);
DeleteObject(hBitmap);
}
DeleteDC(memDc);
}
}
#region Native Methods and Structures
const Int32 WS_EX_LAYERED = 0x80000;
const Int32 HTCAPTION = 0x02;
const Int32 WM_NCHITTEST = 0x84;
const Int32 ULW_ALPHA = 0x02;
const byte AC_SRC_OVER = 0x00;
const byte AC_SRC_ALPHA = 0x01;
[StructLayout(LayoutKind.Sequential)]
struct Point
{
public Int32 x;
public Int32 y;
public Point(Int32 x, Int32 y)
{ this.x = x; this.y = y; }
}
[StructLayout(LayoutKind.Sequential)]
struct Size
{
public Int32 cx;
public Int32 cy;
public Size(Int32 cx, Int32 cy)
{ this.cx = cx; this.cy = cy; }
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
struct ARGB
{
public byte Blue;
public byte Green;
public byte Red;
public byte Alpha;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
struct BLENDFUNCTION
{
public byte BlendOp;
public byte BlendFlags;
public byte SourceConstantAlpha;
public byte AlphaFormat;
}
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool UpdateLayeredWindow(IntPtr hwnd, IntPtr hdcDst,
ref Point pptDst, ref Size psize, IntPtr hdcSrc, ref Point pprSrc,
Int32 crKey, ref BLENDFUNCTION pblend, Int32 dwFlags);
[DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
static extern IntPtr CreateCompatibleDC(IntPtr hDC);
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
static extern IntPtr GetDC(IntPtr hWnd);
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC);
[DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool DeleteDC(IntPtr hdc);
[DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
static extern IntPtr SelectObject(IntPtr hDC, IntPtr hObject);
[DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool DeleteObject(IntPtr hObject);
#endregion
}
}
OK, that should eliminate your semi-transparent problem. Remember to get rid of the override of the WndProc (you won't need it). Set Double-Buffer to false and TopMost to true.
Now to eliminate the other two problems. I hope you thought of a way of doing it....but I will give you my solution. Always keep the PerPixelAlphaForm the size of your MainForm. Same location, Same SIZE. :) And resize the PerPixelAlphaForm's backbuffer bitmap to the same size as well. When you do it this way, all you have to do is redraw the Selection Rectangle. Why? because it overlays the entire MainForm perfectly.
So basically
`OnMouseDown` = Save initial point of mouse, show the Cover layer
`OnMouseMove` = clear the PerPixelAlphaForm bitmap, draw your rectangle
call SelectBitmap again update the form
`OnMouseUp` = hide the Cover layer (or whatever you want to do)
I personally have all this hook up to the Control-Key
To clear the PerPixelAlphaForm we need to do in a certain way. Give all values an Alpha of 0.
public void ClearBackbuffer()
{
Graphics g = Graphics.FromImage(_reference_to_your_backbuffer_);
g.CompositingMode = System.Drawing.Drawing2D.CompositingMode.SourceCopy;
SolidBrush sb = new SolidBrush(Color.FromArgb(0x00, 0x00, 0x00, 0x00));
g.FillRectangle(sb, this.ClientRectangle);
sb.Dispose();
g.Dispose();
}
Video Demo of the Solution: Remember to Switch to 1080p
If you need more help, let me know I can find some time to rip the code out of the larger program. But it seems to me you're the kind of person that likes tinkering with stuff :D

EDIT : using an additional PictureBox and Bitmap makes the whole thing working
The following Panel draws a rectangle without flickering:
internal sealed class MyPanel : Panel
{
private readonly PictureBox _pictureBox;
private Bitmap _bitmapContent;
private Bitmap _bitmapForeground;
private Point? _point1;
private Point? _point2;
public MyPanel()
{
DoubleBuffered = true;
_pictureBox = new PictureBox();
}
protected override void OnSizeChanged(EventArgs e)
{
if (_bitmapForeground != null) _bitmapForeground.Dispose();
_bitmapForeground = new Bitmap(Size.Width, Size.Height);
if (_bitmapContent != null) _bitmapContent.Dispose();
_bitmapContent = new Bitmap(Size.Width, Size.Height);
_pictureBox.Size = Size;
_pictureBox.Image = _bitmapForeground;
base.OnSizeChanged(e);
}
protected override void OnMouseDown(MouseEventArgs e)
{
_point1 = e.Location;
DrawToBitmap(_bitmapContent, new Rectangle(0, 0, Size.Width, Size.Height));
SetControlsVisibility(false);
Controls.Add(_pictureBox);
base.OnMouseDown(e);
}
private void SetControlsVisibility(bool visible)
{
IEnumerable<Control> ofType = Controls.OfType<Control>();
foreach (Control control in ofType)
{
control.Visible = visible;
}
}
protected override void OnMouseUp(MouseEventArgs e)
{
Controls.Remove(_pictureBox);
SetControlsVisibility(true);
_point1 = null;
_point2 = null;
Refresh();
base.OnMouseUp(e);
}
protected override void OnMouseMove(MouseEventArgs e)
{
if (_point1 != null)
{
_point2 = e.Location;
if (_point1 != null && _point2 != null)
{
Point p1 = _point1.Value;
Point p2 = _point2.Value;
int x1 = p1.X;
int y1 = p1.Y;
int x2 = p2.X;
int y2 = p2.Y;
int xmin = Math.Min(x1, x2);
int ymin = Math.Min(y1, y2);
int xmax = Math.Max(x1, x2);
int ymax = Math.Max(y1, y2);
using (Graphics graphics = Graphics.FromImage(_bitmapForeground))
{
graphics.DrawImageUnscaled(_bitmapContent, 0, 0, _bitmapContent.Width, _bitmapContent.Height);
graphics.DrawRectangle(Pens.Red, new Rectangle(xmin, ymin, xmax - xmin, ymax - ymin));
}
_pictureBox.Refresh();
}
}
base.OnMouseMove(e);
}
}
However, the rectangle will be below the controls, not sure why ...

C# - Form user button click, get next window clicked by user

This shouldnt be a difficult question, but it is difficult to google the question and get the idea across.
The problem is simple: I have a windows form where the user presses a button, then, it will wait on the user to click another window. It stores that selected window information for manipulation later (specifically the dimensions).
How can I get the active window of the next user click after a button is pressed?
Thanks

You need to get the foreground window.
[DllImport("user32.dll")]
static extern IntPtr GetForegroundWindow();
[DllImport("user32.dll", SetLastError = true)]
static extern bool GetWindowRect(IntPtr hWnd, out Rectangle lpRect);
Rect rect = new Rect ();
GetWindowRect(GetForegroundWindow(), out rect);
//calculate width and height from rect
using (Bitmap bitmap = new Bitmap(width, height))
{
using (Graphics g = Graphics.FromImage(bitmap))
{
Size size = new System.Drawing.Size(width, height);
g.CopyFromScreen(new Point(rect.Left, rect.Top), Point.Empty, size);
}
bitmap.Save("C://test.jpg", ImageFormat.Jpeg);
}
[StructLayout(LayoutKind.Sequential)]
public struct Rect {
public int Left;
public int Top;
public int Right;
public int Bottom;
}
I found most of the code in these two answers on SO. Modifed it to suit your question
Capture window
Find window width and height

Interested by your question i have created this small screen capture app.
It has strange workarounds:
Timer used to capture mouse position outside winform is strange but was easier to implement than using Global System Hooks . You might try to use lib from link or implement it by yourself. You wouldn't need than to use Timer and what is more important you could drop this constant reactivation of form.
I have found somewhere in SE info about overriding CreateParams but i can't find link to it anymore it allows you to click trough form (i think that not all of added params are neccessery but as i said i lost link :) ).
Only visible part of window is captured + all windows overlapping it (probably sinc u got a windowHandle to it u might try to show/activate it somehow).
For some windows it gets controls inside window.
Provided app is probably very unprofessional and unsafe and might blow up your computer so beware ;P
Used form is borderless with opacity set to 80%.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace WindowInfo
{
public partial class CurrentWindow : Form
{
Rectangle GDIrect = new Rectangle(0, 0, 100, 100);
[DllImport("user32.dll")]
public static extern IntPtr WindowFromPoint(Point lpPoint);
[DllImport("user32.dll")]
public static extern bool GetCursorPos(out Point lpPoint);
[DllImport("user32.dll")]
private static extern IntPtr GetWindowRect(IntPtr hWnd, ref Rect rect);
[DllImport("user32.dll")]
static extern IntPtr GetForegroundWindow();
[StructLayout(LayoutKind.Sequential)]
public struct Rect
{
public int Left;
public int Top;
public int Right;
public int Bottom;
}
public CurrentWindow()
{
InitializeComponent();
}
protected override CreateParams CreateParams
{
get
{
CreateParams baseParams = base.CreateParams;
baseParams.ExStyle |= (int)(
0x00080000 |
0x08000000 |
0x00000080 |
0x00000020
);
return baseParams;
}
}
public static IntPtr GetWindowUnderCursor()
{
Point ptCursor = new Point();
GetCursorPos(out ptCursor);
return WindowFromPoint(ptCursor);
}
public Bitmap CaptureScreen()
{
var result = new Bitmap(this.DisplayRectangle.Width, this.DisplayRectangle.Height);
using (var g = Graphics.FromImage(result))
{
g.CopyFromScreen(this.Location.X, this.Location.Y, 0, 0, this.DisplayRectangle.Size);
}
return result;
}
private void timer1_Tick(object sender, EventArgs e)
{
IntPtr windowHandle = GetWindowUnderCursor();
Rect rect = new Rect();
GetWindowRect(windowHandle, ref rect);
GDIrect = new Rectangle(rect.Left, rect.Top, rect.Right - rect.Left, rect.Bottom - rect.Top);
this.Location = new Point(GDIrect.Left, GDIrect.Top);
this.Size = GDIrect.Size;
this.Activate();
}
private void CurrentWindow_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == 'c')
{
this.Visible = false;
Bitmap bmp = CaptureScreen();
bmp.Save(Application.StartupPath + "\\example.png");
this.Visible = true;
}
else if (e.KeyChar == 'x')
{
this.Close();
}
}
}
}
U might add it to your app and run after button click, it should work but i have tested it only separately. Good luck :).

Develop Reference

C# (C-Sharp) is a programming language developed by Microsoft that runs on the .NET Framework.

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