Develop Reference

C# Desktop background displaying incorrect location maybe?

Hi I am currently creating an animated desktop background that uses axWindowsMideaPlayer to play video files in a loop I take the WMP and set its handle to the desktop handle, it works great on single display monitor setup but fails with multiple monitors. Why it is failing is because monitors can have their own set position like left/right/topleft/topright/top/bottom/bottomleft and bottom right of the primary screen which puts their position in the negatives and so forth.. My question is how can I position each WMP correctly on each monitor? Here is what I have so far,
this is how I get each monitor...
public class DisplayInfo
{
public bool isPrimary { get; set; }
public int ScreenHeight { get; set; }
public int ScreenWidth { get; set; }
public Rect MonitorArea { get; set; }
public Rect WorkArea { get; set; }
public string DeviceName { get; set; }
}
/// <summary>
/// Collection of display information
/// </summary>
public class DisplayInfoCollection : List<DisplayInfo>
{
// size of a device name string
private const int CCHDEVICENAME = 32;
/// <summary>
/// The MONITORINFOEX structure contains information about a display monitor.
/// The GetMonitorInfo function stores information into a MONITORINFOEX structure or a MONITORINFO structure.
/// The MONITORINFOEX structure is a superset of the MONITORINFO structure. The MONITORINFOEX structure adds a string member to contain a name
/// for the display monitor.
/// </summary>
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
internal struct MONITORINFOEX
{
/// <summary>
/// The size, in bytes, of the structure. Set this member to sizeof(MONITORINFOEX) (72) before calling the GetMonitorInfo function.
/// Doing so lets the function determine the type of structure you are passing to it.
/// </summary>
public int Size;
/// <summary>
/// A RECT structure that specifies the display monitor rectangle, expressed in virtual-screen coordinates.
/// Note that if the monitor is not the primary display monitor, some of the rectangle's coordinates may be negative values.
/// </summary>
public Rect Monitor;
/// <summary>
/// A RECT structure that specifies the work area rectangle of the display monitor that can be used by applications,
/// expressed in virtual-screen coordinates. Windows uses this rectangle to maximize an application on the monitor.
/// The rest of the area in rcMonitor contains system windows such as the task bar and side bars.
/// Note that if the monitor is not the primary display monitor, some of the rectangle's coordinates may be negative values.
/// </summary>
public Rect WorkArea;
/// <summary>
/// The attributes of the display monitor.
///
/// This member can be the following value:
/// 1 : MONITORINFOF_PRIMARY
/// </summary>
public uint Flags;
/// <summary>
/// A string that specifies the device name of the monitor being used. Most applications have no use for a display monitor name,
/// and so can save some bytes by using a MONITORINFO structure.
/// </summary>
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCHDEVICENAME)]
public string DeviceName;
public void Init()
{
this.Size = 40 + 2 * CCHDEVICENAME;
this.DeviceName = string.Empty;
}
}
[DllImport("user32.dll")]
private static extern bool EnumDisplayMonitors(IntPtr hdc, IntPtr lprcClip,
EnumMonitorsDelegate lpfnEnum, IntPtr dwData);
[DllImport("user32.dll", CharSet = CharSet.Auto)]
private static extern bool GetMonitorInfo(IntPtr hMonitor, ref MONITORINFOEX lpmi);
/*
[DllImport("user32.dll")]
static extern bool GetMonitorInfo(IntPtr hMonitor, ref MONITORINFO lpmi);
*/
/// <summary>
/// Returns the number of Displays using the Win32 functions
/// </summary>
/// <returns>collection of Display Info</returns>
public static DisplayInfoCollection GetDisplays()
{
DisplayInfoCollection col = new DisplayInfoCollection();
EnumDisplayMonitors(IntPtr.Zero, IntPtr.Zero,
delegate (IntPtr hMonitor, IntPtr hdcMonitor, ref Rect lprcMonitor, IntPtr dwData)
{
MONITORINFOEX mi = new MONITORINFOEX();
mi.Size = (int)Marshal.SizeOf(mi);
bool success = GetMonitorInfo(hMonitor, ref mi);
if (success)
{
DisplayInfo di = new DisplayInfo();
di.ScreenWidth = (mi.Monitor.Right - mi.Monitor.Left);
di.ScreenHeight = (mi.Monitor.Bottom - mi.Monitor.Top);
di.MonitorArea = mi.Monitor;
di.WorkArea = mi.WorkArea;
di.isPrimary = Convert.ToBoolean(mi.Flags);
di.DeviceName = mi.DeviceName;
col.Add(di);
}
return true;
}, IntPtr.Zero);
return col;
}
}
this is how I have tried to call it and use it but it puts WMP all over the place depending on where the monitors are positioned.
DisplayInfoCollection dic = DisplayInfoCollection.GetDisplays();
int count = 0;
int totalPosX = 0;
int totalPosY = 0;
DisplayInfo dInfo = null;
List<DisplayInfo> di = dic.OrderByDescending(d => d.isPrimary).ToList();
var or = SystemInformation.VirtualScreen;
foreach (DisplayInfo dm in di)
{
bool zeroOutX = false;
bool zeroOutY = false;
if (dm.isPrimary)
{
totalPosX = or.Left > 0 ? or.Left : -or.Left;
totalPosY = or.Top > 0 ? or.Top : -or.Top;
dInfo = dm;
}
else
{
bool left = false;
bool top = false;
bool right = false;
bool bottom = false;
bool topLeft = false;
bool topRight = false;
bool bottomLeft = false;
bool bottomRight = false;
int posY = dm.MonitorArea.Top > 0 ? dm.MonitorArea.Top : -dm.MonitorArea.Top;
if (dm.MonitorArea.Left < 0)
{
left = true;
}
else
right = dm.MonitorArea.Left > 0;
if (dm.MonitorArea.Top < 0)
{
top = true;
}
else
bottom = dm.MonitorArea.Top > 0;
bool center = (dm.MonitorArea.Left > 0 ?
dm.MonitorArea.Left : -dm.MonitorArea.Left) > 0 ||
(dm.MonitorArea.Left > 0 ?
dm.MonitorArea.Left : -dm.MonitorArea.Left) < dInfo.ScreenWidth;
topLeft = left && top;
topRight = right && top;
bottomLeft = left && bottom;
bottomRight = right && bottom;
if (topLeft || topRight || bottomLeft || bottomRight || left || right)
{
if (dm.MonitorArea.Left < 0)
zeroOutX = true;
else
totalPosX += dInfo.ScreenWidth;
if (dm.MonitorArea.Top < 0)
zeroOutY = true;
else
totalPosY += dm.MonitorArea.Top;
}
dInfo = dm;
}
Display display = new Display(dm.DeviceName, dm.ScreenWidth,
dm.ScreenHeight, zeroOutX ? 0 : totalPosX,
zeroOutY ? 0 : totalPosY, Controls, count);
Displays.Add(display);
count++;
}
I cant find much help on this matter and have tried numerous ways to do this its a c# windows form and I am new-ish to programming my knowledge is limited in this any help will be appreciated thanks in advance.

According to the EnumDisplaySettings:
The EnumDisplaySettings function sets values for the following five
DEVMODE members:
dmBitsPerPel
dmPelsWidth
dmPelsHeight
dmDisplayFlags
dmDisplayFrequency
(Excluding dmPosition), You should try to use EnumDisplaySettingsEx, and specify DM_POSITION to get the correct dmPosition value.

thanks for all that helped I found a solution to my problem here it is if anyone need to know.
var or = SystemInformation.VirtualScreen;
foreach (DisplayInfo dm in dic)
{
int x = or.Left > 0 ? or.Left : -or.Left;
int y = or.Top > 0 ? or.Top : -or.Top;
if (dm.isPrimary)
{
Rect rect = new Rect();
rect.Left = x;
rect.Top = y;
rect.Right = rect.Left + dm.ScreenWidth;
rect.Bottom = rect.Top + dm.ScreenHeight;
dm.MonitorArea = rect;
}
else
{
Rect rect = new Rect();
rect.Left = x + dm.MonitorArea.Left;
rect.Top = y + dm.MonitorArea.Top;
rect.Right = rect.Left + dm.ScreenWidth;
rect.Bottom = rect.Top + dm.ScreenHeight;
dm.MonitorArea = rect;
}

C# Moving programatically through rich textbox without cuting lines

I am doing a WinForms application with image/page scheme (the user is navigating between images by clicking at particular areas of the image). At one page I made rich textbox in which I wanted to load "rules" for the user to accept. Unfortunatelly, the rules are longer than the RTB, so I had to apply some kind of scrolling. I didn't want to let the user use a scrollbar - instead I made two buttons (up & down) by which the user can slide through the rules - user cant select or move text in any other way. Everything works great apart from one thing - after clicking the button, the text slides but part of the 1st and last shown lines are being cut (only part of the height of line is visible in rtb).
Below I list the code used for making such RTB (named "rules"):
rules.Clear();
rules.Cursor = Cursors.Default;
rules.ScrollBars = RichTextBoxScrollBars.Vertical;
rules.ReadOnly = true;
rules.KeyPress += rules_KeyPress;
rules.SelectionChanged += rules_SelectionChanged;
rules.Location = new System.Drawing.Point(450*this.Width/2000, 550*this.Height/1125);
Console.WriteLine(rules.Font);
float size = 16.5F;
rules.Font = new Font("Microsoft Sans Serif", size);
Console.WriteLine(rules.Font);
using (Graphics g = rules.CreateGraphics())
{
rules_line_height = Convert.ToInt32(g.MeasureString("A", rules.Font).Height); //getting the measure of the line
Console.WriteLine(rules_line_height);
}
int rules_h = 400 * this.Height / 1125; //height of the rtb
int lines_n = rules_h / rules_line_height; //max number of lines that can be fit in the height
rules.Size = new System.Drawing.Size(1000 * this.Width / 2000, lines_n*rules_line_height); //height of the rtb adjusted to fill full lines
rules.ForeColor = Color.White;
string fileName = "reg_pl.txt";
string line = "";
StreamReader file = new System.IO.StreamReader(Directory.GetCurrentDirectory() + "/reg/" + fileName, Encoding.GetEncoding("windows-1250"));
while ((line = file.ReadLine()) != null)
{
rules.AppendText(line + "\r\n");
}
file.Close();
rules_max = rules.GetMaxRange(); //getting max range of the rtb
rules_thumb = rules.GetThumb(); //getting size of visible part of the rtb
rules_loc = 0; // current location visible part compared to the whole rtb
rules.ScrollBars = RichTextBoxScrollBars.None;
rules.BorderStyle = BorderStyle.None;
rules.BackColor = Color.FromArgb(18, 25, 56);
rules.BringToFront();
I also used the custom_RTB class for getting max range and thumb of the RTB and scrolling to selected point of the RTB :
public class CustomRTB : System.Windows.Forms.RichTextBox
{
#region API Stuff
public struct SCROLLINFO
{
public int cbSize;
public int fMask;
public int min;
public int max;
public int nPage;
public int nPos;
public int nTrackPos;
}
[DllImport("user32.dll", CharSet = CharSet.Auto)]
public static extern int GetScrollPos(IntPtr hWnd, int nBar);
[DllImport("user32.dll")]
private static extern int SetScrollPos(IntPtr hWnd, int nBar, int nPos, bool bRedraw);
[DllImport("User32.Dll", EntryPoint = "PostMessageA")]
static extern bool PostMessage(IntPtr hWnd, uint msg, int wParam, int lParam);
[DllImport("user32")]
private static extern int GetScrollInfo(IntPtr hwnd, int nBar,
ref SCROLLINFO scrollInfo);
private const int SB_HORZ = 0x0;
private const int SB_VERT = 0x1;
#endregion
public int HorizontalPosition
{
get { return GetScrollPos((IntPtr)this.Handle, SB_HORZ); }
set { SetScrollPos((IntPtr)this.Handle, SB_HORZ, value, true); }
}
public int VerticalPosition
{
get { return GetScrollPos((IntPtr)this.Handle, SB_VERT); }
set { SetScrollPos((IntPtr)this.Handle, SB_VERT, value, true); }
}
public void ScrollTo(int Position)
{
SetScrollPos((IntPtr)this.Handle, 0x1, Position, true);
PostMessage((IntPtr)this.Handle, 0x115, 4 + 0x10000 * Position, 0);
}
public int GetMaxRange()
{
SCROLLINFO scrollInfo = new SCROLLINFO();
scrollInfo.cbSize = Marshal.SizeOf(scrollInfo);
//SIF_RANGE = 0x1, SIF_TRACKPOS = 0x10, SIF_PAGE= 0x2
scrollInfo.fMask = 0x10 | 0x1 | 0x2;
GetScrollInfo((IntPtr)this.Handle, 1, ref scrollInfo);//nBar = 1 -> VScrollbar
return scrollInfo.max;
}
public int GetThumb()
{
SCROLLINFO scrollInfo = new SCROLLINFO();
scrollInfo.cbSize = Marshal.SizeOf(scrollInfo);
//SIF_RANGE = 0x1, SIF_TRACKPOS = 0x10, SIF_PAGE= 0x2
scrollInfo.fMask = 0x10 | 0x1 | 0x2;
GetScrollInfo((IntPtr)this.Handle, 1, ref scrollInfo);//nBar = 1 -> VScrollbar
return scrollInfo.nPage;
}
public int GetCurPos()
{
SCROLLINFO scrollInfo = new SCROLLINFO();
scrollInfo.cbSize = Marshal.SizeOf(scrollInfo);
//SIF_RANGE = 0x1, SIF_TRACKPOS = 0x10, SIF_PAGE= 0x2
scrollInfo.fMask = 0x10 | 0x1 | 0x2;
GetScrollInfo((IntPtr)this.Handle, 1, ref scrollInfo);//nBar = 1 -> VScrollbar
return scrollInfo.nTrackPos;
}
public bool ReachedBottom()
{
SCROLLINFO scrollInfo = new SCROLLINFO();
scrollInfo.cbSize = Marshal.SizeOf(scrollInfo);
//SIF_RANGE = 0x1, SIF_TRACKPOS = 0x10, SIF_PAGE= 0x2
scrollInfo.fMask = 0x10 | 0x1 | 0x2;
GetScrollInfo((IntPtr)this.Handle, 1, ref scrollInfo);//nBar = 1 -> VScrollbar
return scrollInfo.max == scrollInfo.nTrackPos + scrollInfo.nPage;
}
}
And here are the "buttons" for moving the text up:
int lines = rules_thumb / rules_line_height; //getting max number of lines that can be visible
int new_thumb = lines * rules_line_height; //getting the move value so the lines won't be cut
if (rules_loc - (new_thumb) >= 0) //if moving by the move value will be still over 0, then proceed normally
{
rules_loc -= (new_thumb);
rules.ScrollTo(rules_loc);
}
else // if it will pass 0, the move to 0
{
rules_loc = 0;
rules.ScrollTo(rules_loc);
}
And down :
int lines = rules_thumb / rules_line_height;
int new_thumb = lines * rules_line_height;
if (rules_loc + (new_thumb) < rules_max)
{
rules_loc += (new_thumb);
rules.ScrollTo(rules_loc);
}
else
{
rules.ScrollTo(rules_max);
}
What I think I am doing wrong is measuring the lines heigh at given font and setting the good size for the RTB. Does anyone had similar problem and can somehow assist me with it?
Thank you in advance for the answer.
Best regards,
Sarachiel

Graphics.MeasureString() - Finding the relative X,Y coordinates

I am attempting to create a custom ListBox control in WinForms.
I have subclassed it, set DrawMode.OwnerDrawFixed, and am overriding OnDrawItem. I have created a custom ColoredListBoxItem class that has additional properties to deal with the highlighting.
This is all fine. My issue is that this functionality needs to highlight words within the text of a list item.
Here is as far as I've gotten, and it doesn't work, because the X coordinate of the highlight remains constant and does not correspond to the actual X coordinate of the text.
How can I get a Point value (or Rectangle) to use with DrawText that will overlay the highlighted text? I've tried doing some math with the bounds of the original text Rectangle versus the highlight Rectangle but it is not working as expected.
protected override void OnDrawItem(DrawItemEventArgs e) {
ColoredListBoxItem item = this.Items[e.Index] as ColoredListBoxItem;
e.DrawBackground();
e.DrawFocusRectangle();
Rectangle fullMessageRect = e.Bounds;
// Draw the original, full text
TextRenderer.DrawText(e.Graphics, item.Message, e.Font,
new Point(fullMessageRect.X, fullMessageRect.Y),
this.ForeColor);
// Check if we have any text to be highlighted
if (SomethingToHighlight(item)) {
// Find the text to highlight, and get its area
SizeF highlightedAreaSize =
e.Graphics.MeasureString(item.TextToHightlight, e.Font);
PointF highlightAreaPoint = highlightedAreaSize.ToPointF();
Point point = new Point(Convert.ToInt32(highlightAreaPoint.X),
Convert.ToInt32(fullMessageRect.Y));
TextRenderer.DrawText(e.Graphics, item.TextToHightlight, e.Font,
point, this.ForeColor, item.HighlightColor);
}
}
Here is what I'm seeing in a demo app, where the output just shows work being done, and I am trying to highlight one particular word .. in this case "height".
Don't pay any attention to the actual output, it's a bunch of nonsense so I can see exactly how another part of the system is adjusting PictureBox images on the fly.
Lines that it thinks should be highlighted are shown twice, once in the original format and then again with the highlight applied. Notice how the highlighted part is correct in the Y coordinate, but does not change in the X.
Here's what I am seeing in the Watch window when I set a break point prior to writing the highlighted text:
Clearly, I don't need the variable highlightAreaPoint, because it's the same as highlightedAreaSize.
Probably something obvious here but I'm tired of fiddling with it at this point!

I can feel your pain as I have been there before. Actually, I wanted to design my own Textbox not inheriting from Microsoft.Textbox control and when I researched on-line, I sort of discouraged to learn 1000 reasons why one must not reinvent the wheel and why it is so difficult to do from scratch. Highlighting selection text was one of the major challenge among the others like right-to-left, caret positioning, non-fixed fonts etc. But I decided to fly against the wind because I had my reasons to do so and finally got what I wanted. Since my text selection code was for TextBox, I had to change it to suit your requirement as you are dealing with ListBox.
Following is the code snippet:
using System;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace HowToHighlightPortionOfText
{
public static class Helper
{
private static Rectangle dummy
{
get
{
return new Rectangle(0, 0, 10, 10);
}
}
const uint H = 0x00000000;
const uint V = 0x00000001;
const uint T = 0x00000002;
#region api functions
[DllImport("user32.dll")]
static extern int DrawText(IntPtr hdc, string lpStr, int nCount, ref Dimension lpRect, int wFormat);
[DllImport("gdi32.dll")]
public static extern IntPtr SelectObject(this IntPtr hdc, IntPtr hObject);
[DllImport("gdi32.dll")]
public static extern int DeleteObject(this IntPtr hObject);
[DllImport("gdi32.dll", EntryPoint = "GdiGradientFill", ExactSpelling = true)]
static extern bool GradientFill(IntPtr hdc, Trivertex[] pVertex,
uint dwNumVertex, uint[] pMesh, uint dwNumMesh, uint dwMode);
[DllImport("gdi32")]
public static extern int SetBkMode(this IntPtr hdc, int nBkMode);
[DllImport("gdi32.dll")]
public static extern uint SetTextColor(this IntPtr hdc, int crColor);
[DllImport("gdi32.dll")]
public static extern uint SetBkColor(this IntPtr hdc, int crColor);
#endregion
#region public methods
//use this function to hilight portion of listbox item text
public static void HilightItemText(this ListBox control, int itemIndex, int startIndex, int endIndex,
Color highlightForeColor, Color highlightBackColorStart, Color? highlightBackColorEnd = null)
{
var container = control.GetItemRectangle(itemIndex);
var text = control.GetItemText(itemIndex);
using (Graphics g = control.CreateGraphics())
{
g.HighlightText(control.Font, text, container, startIndex, endIndex,
highlightForeColor, highlightBackColorStart, highlightBackColorEnd);
}
}
public static void HighlightText(this IDeviceContext dc, Font font, string text,
Rectangle container, int start, int end, Color highlightForeColor, Color highlightBackColorStart,
Color? highlightBackColorEnd, DrawTextFlags? flags = null)
{
IntPtr hdc = dc.GetHdc();
IntPtr _font = SelectObject(hdc, font.ToHfont());
Dimension dm = container;
var flag = flags.getMeasureFlag(false);
SetBkMode(hdc, ColorTranslator.ToWin32(Color.Transparent));
//first draw whole text
DrawText(hdc, text, text.Length, ref dm, 0);
//now get the highlight rectangle which will draw the highlighted text
Rectangle textBound, uptoIndex;
var rect = hdc.rangeBound(text, container, start, end, out textBound, out uptoIndex, flags: flags);
dm = rect;
var _backColorEnd = highlightBackColorEnd ?? highlightBackColorStart;
hdc.Fill(rect, highlightBackColorStart, _backColorEnd, Angle.A0);
SetTextColor(hdc, ColorTranslator.ToWin32(highlightForeColor));
if (start < 0 || start > text.Length - 1 || end < 0 || end > text.Length - 1)
throw new Exception("start and end value must be with in text length");
var _text = text.Substring(start, end - start + 1);
DrawText(hdc, _text, _text.Length, ref dm, 0);
DeleteObject(SelectObject(hdc, _font));
dc.ReleaseHdc();
}
public static Rectangle RangeBound(this IDeviceContext dc, Font font, string text,
Rectangle container, int start, int end, DrawTextFlags? flags = null)
{
Rectangle textBound, uptoIndex;
return dc.RangeBound(font, text, container, start, end, out textBound, out uptoIndex, flags);
}
public static Rectangle GetPortionRectangleToHighlight(this ListBox control, int itemIndex, int startIndex, int endIndex)
{
var container = control.GetItemRectangle(itemIndex);
var text = control.GetItemText(itemIndex);
Rectangle rect;
using (Graphics g = control.CreateGraphics())
{
rect = g.RangeBound(control.Font, text, container, startIndex, endIndex);
}
return rect;
}
public static bool Fill(this IntPtr hdc, Rectangle rc, Color c1,
Color c2, Angle angle)
{
return hdc.Fill(rc.X, rc.Y, rc.Right, rc.Bottom, c1, c2, angle);
}
public static bool Fill(this IntPtr hdc, int x0, int y0, int x1, int y1, Color c1, Color c2, Angle angle)
{
Trivertex[] t = new Trivertex[4]
{
new Trivertex(x0, y0, c1),
new Trivertex(x1, y1, c2),
new Trivertex(x0, y1, c1, c2),
new Trivertex(x1, y0, c1, c2)
};
uint[] pMesh = new uint[] { 0, 1, 2, 0, 1, 3 };
switch ((int)angle % 180)
{
case 0:
return GradientFill(hdc, t, 2, pMesh, 1, H);
case 45:
return GradientFill(hdc, t, 4, pMesh, 2, T);
case 90:
return GradientFill(hdc, t, 2, pMesh, 1, V);
case 135:
t[0].x = x1;
t[3].x = x0;
t[1].x = x0;
t[2].x = x1;
return GradientFill(hdc, t, 4, pMesh, 2, T);
default:
return false;
}
}
#endregion
#region get the highlight rectangle
static Rectangle RangeBound(this IDeviceContext dc, Font font, string text,
Rectangle container, int start, int end, out Rectangle textBound, out Rectangle uptoIndex, DrawTextFlags? flags = null)
{
textBound = Rectangle.Empty;
uptoIndex = Rectangle.Empty;
if (string.IsNullOrEmpty(text)) return Rectangle.Empty;
IntPtr hdc = dc.GetHdc();
IntPtr _font = SelectObject(hdc, font.ToHfont());
var rc = hdc.rangeBound(text, container, start, end, out textBound, out uptoIndex, flags: flags);
DeleteObject(SelectObject(hdc, _font));
dc.ReleaseHdc();
return rc;
}
static TextMeasurement charRectangle(this IntPtr hdc, string text, Rectangle container,
string wholeText = null, Point? point = null, bool adjustByPoint = false, DrawTextFlags? flags = null)
{
if (string.IsNullOrEmpty(text)) return TextMeasurement.Default;
TextMeasurement measurement = new TextMeasurement();
Rectangle textBound;
wholeText = (wholeText ?? text);
var location = container.Location;
var measureWholeText = point == null;
measurement.UserPoint = point ?? Point.Empty;
textBound = hdc.textBound(wholeText, container, flags: flags);
var rect = textBound;
var p = point ?? new Point(container.Right, container.Y);
if (!measureWholeText)
{
if (p.X > textBound.Right)
p.X = textBound.Right;
else if (p.X < textBound.Left)
p.X = textBound.X;
}
var charIndex = 0;
var result = hdc.charRectangle(text, ref p, rect, flags, measureWholeText);
charIndex = Math.Max(0, result.Item2);
var rectangles = result.Item1;
measurement.Bounds = rectangles[0];
measurement.TextBounds = (measureWholeText) ? rectangles[1] : textBound;
rectangles[1] = measurement.TextBounds;
if (!measureWholeText && adjustByPoint && charIndex > 0)
{
float middle = (float)measurement.Bounds.Left +
measurement.Bounds.Width / 2;
if (p.X > middle - 1)
{
Rectangle r;
Dimension r1 = measurement.TextBounds;
var newresult = hdc.charBound(text, charIndex + 2, ref r1,
(int)flags.getMeasureFlag(false), out r);
if (!newresult.Equals(measurement.Bounds) &&
newresult.X > measurement.Bounds.X)
{
charIndex++;
measurement.Bounds = newresult;
}
}
}
if (measurement.Bounds.Size.Width<=0)
measurement.Bounds = new Rectangle(measurement.Bounds.Location, new Size(2, 2));
measurement.CharIndex = charIndex;
measurement.Char = '\0';
measurement.Char = text[Math.Min(charIndex, text.Length - 1)];
return measurement;
}
static Tuple<Rectangle[], int> charRectangle(this IntPtr hdc, string text, ref Point p, Rectangle rect,
DrawTextFlags? flags, bool measureWholeText = false)
{
int i = 0;
int middle = text.Length / 2, start = 0;
bool first = true;
do
{
var upto = hdc.Measure(text.Substring(0, middle), null, rect, flags);
bool found = upto.Has(p);
if (!found)
{
start = middle;
middle += (text.Length - middle) / 2;
first = false;
if (start == middle) break;
}
else break;
} while (middle > 1 && text.Length - middle > 1);
if (first)
{
return hdc.charRectangle(text.Substring(0, middle),
ref p, rect, flags);
}
else
{
Rectangle[] list = new Rectangle[2];
for (i = start; i <= middle; i++)
{
if (hdc.Measure(text, out list, p, i + 1, rect, flags))
break;
}
i = Math.Max(i, 0);
return new Tuple<Rectangle[], int>(list, i);
}
}
static Rectangle charBound(this IntPtr hdc, string text, int len,
ref Dimension bounds, int flag, out Rectangle whole)
{
DrawText(hdc, text, len, ref bounds, flag);
whole = bounds;
var rc = bounds;
if (len - 1 > 0 && len <= text.Length)
{
DrawText(hdc, text.Substring(0, len - 1), len - 1, ref rc, flag);
rc = Rectangle.FromLTRB(rc.Right, bounds.Top, bounds.Right, bounds.Bottom);
}
return rc;
}
static Rectangle rangeBound(this IntPtr hdc, string text, Rectangle container, int start, int end,
out Rectangle textBound, out Rectangle uptoIndex, DrawTextFlags? flags = null)
{
textBound = Rectangle.Empty;
uptoIndex = Rectangle.Empty;
if (string.IsNullOrEmpty(text)) return Rectangle.Empty;
var location = container.Location;
textBound = hdc.textBound(text, container, flags);
Dimension rect = textBound;
var flag = flags.getMeasureFlag(false);
start++;
var text1 = text.Substring(0, start);
var rc = hdc.charBound(text1, text1.Length, ref rect, (int)flag, out uptoIndex);
end++;
var text2 = text.Substring(0, end);
DrawText(hdc, text2, text2.Length, ref rect, (int)flag);
return Rectangle.FromLTRB(rc.Left, rect.Top, rect.Right, rect.Bottom);
}
static Rectangle textBound(this IntPtr hdc, string text, Rectangle container, DrawTextFlags? flags = null)
{
Rectangle rc = Rectangle.Empty;
if (string.IsNullOrEmpty(text)) return rc;
Point p = container.Location;
var r = hdc.Measure(text, text.Length, flags: flags);
return new Rectangle(p, r.Size);
}
static DrawTextFlags getMeasureFlag(this DrawTextFlags? flags, bool textboxControl = false)
{
DrawTextFlags flag = DrawTextFlags.CalculateArea;
if (flags != null) flag |= flags.Value;
flag |= DrawTextFlags.WordBreak | DrawTextFlags.NoPrefix
| DrawTextFlags.NoPadding | DrawTextFlags.NoClipping;
if (textboxControl) flag |= DrawTextFlags.TextBoxControl;
else flag |= DrawTextFlags.SingleLine;
return flag;
}
static Rectangle RangeBound(this IntPtr hdc, string text,
Rectangle container, int start, int end, DrawTextFlags? flags = null)
{
Rectangle textBound, uptoIndex;
return hdc.rangeBound(text, container, start, end, out textBound, out uptoIndex, flags);
}
static Rectangle Measure(this IntPtr hdc, string text, int? length = null,
Rectangle? rect = null, DrawTextFlags? flags = null)
{
if (string.IsNullOrEmpty(text)) return Rectangle.Empty;
Dimension bounds = rect ?? dummy;
var len = length ?? text.Length;
var flag = flags.getMeasureFlag(false);
var i = DrawText(hdc, text, len, ref bounds, (int)flag);
return bounds;
}
static bool Measure(this IntPtr hdc, string text, out Rectangle[] rectangles, Point p,
int? length = null, Rectangle? rect = null, DrawTextFlags? flags = null)
{
rectangles = new Rectangle[2];
if (string.IsNullOrEmpty(text)) return true;
Dimension bounds = rect ?? dummy;
var len = length ?? text.Length;
var flag = flags.getMeasureFlag(false);
Rectangle rc, rc1;
rc1 = hdc.charBound(text, len, ref bounds, (int)flag, out rc);
rectangles = new Rectangle[] { rc1, rc };
return (rectangles[0].Left < bounds.Left || rectangles[0].Has(p.X));
}
static bool Has(this Rectangle rect, int x = -1,
int y = -1, int checkRightUpto = -1, int checkBottomUpto = -1)
{
if (x == -1 && y == -1)
{
x = 0;
y = 0;
}
else
{
x = x == -1 ? rect.X : x;
y = y == -1 ? rect.Y : y;
}
if (checkRightUpto == -1)
{
checkRightUpto = rect.Width;
}
if (checkBottomUpto == -1)
{
checkBottomUpto = rect.Height;
}
return x >= rect.Left && x <= rect.Left +
checkRightUpto && y >= rect.Top &&
y <= rect.Top + checkBottomUpto;
}
static bool Has(this Rectangle rect, Point p,
int checkRightUpto = -1, int checkBottomUpto = -1)
{
return rect.Has(p.X, p.Y, checkRightUpto, checkBottomUpto);
}
#endregion
}
#region structs
[StructLayout(LayoutKind.Sequential)]
public struct Dimension
{
public int Left, Top, Right, Bottom;
public Dimension(int left, int top, int right, int bottom)
{
this.Left = left;
this.Right = right;
this.Top = top;
this.Bottom = bottom;
}
public Dimension(Rectangle r)
{
this.Left = r.Left;
this.Top = r.Top;
this.Bottom = r.Bottom;
this.Right = r.Right;
}
public static implicit operator Rectangle(Dimension rc)
{
return Rectangle.FromLTRB(rc.Left, rc.Top, rc.Right, rc.Bottom);
}
public static implicit operator Dimension(Rectangle rc)
{
return new Dimension(rc);
}
public static Dimension Default
{
get { return new Dimension(0, 0, 1, 1); }
}
}
[StructLayout(LayoutKind.Sequential)]
public struct Trivertex
{
public int x;
public int y;
public ushort Red;
public ushort Green;
public ushort Blue;
public ushort Alpha;
public Trivertex(int x, int y, Color color)
: this(x, y, color.R, color.G, color.B, color.A)
{
}
public Trivertex(int x, int y, Color color, Color other)
: this(x, y, color.R, color.G, color.B, color.A, other)
{
}
public Trivertex(int x, int y, ushort red, ushort green, ushort blue, ushort alpha)
{
this.x = x;
this.y = y;
Red = (ushort)(red << 8);
Green = (ushort)(green << 8);
Blue = (ushort)(blue << 8);
Alpha = (ushort)(alpha << 8);
}
public Trivertex(int x, int y, ushort red, ushort green, ushort blue, ushort alpha, Color other)
{
this.x = x;
this.y = y;
Red = (ushort)((red + other.R / 2) << 8);
Green = (ushort)((green + other.G / 2) << 8);
Blue = (ushort)((blue + other.B / 2) << 8);
Alpha = (ushort)((alpha + other.A / 2) << 8);
}
public static ushort R(Color c)
{
return (ushort)(c.R << 8);
}
public static ushort G(Color c)
{
return (ushort)(c.G << 8);
}
public static ushort B(Color c)
{
return (ushort)(c.B << 8);
}
public static ushort R(Color c, Color c1)
{
return (ushort)(((c.R + c1.R / 2)) << 8);
}
public static ushort G(Color c, Color c1)
{
return (ushort)(((c.G + c1.G / 2)) << 8);
}
public static ushort B(Color c, Color c1)
{
return (ushort)(((c.B + c1.B / 2)) << 8);
}
}
#endregion
#region textmeasurement interface + class
public interface ITextMeasurement : ICloneable
{
int CharIndex { get; set; }
int PreviousIndex { get; }
Rectangle Bounds { get; }
Rectangle TextBounds { get; }
char Char { get; }
Point UserPoint { get; }
void CopyFrom(ITextMeasurement other);
}
public class TextMeasurement : ITextMeasurement
{
Rectangle now, textBound;
public virtual Rectangle Bounds
{
get
{
return now;
}
set { now = value; }
}
public virtual Rectangle TextBounds
{
get
{
return textBound; ;
}
set { textBound = value; }
}
public virtual int CharIndex { get; set; }
public virtual int PreviousIndex { get; set; }
public virtual char Char { get; set; }
public Point UserPoint { get; set; }
public virtual void CopyFrom(ITextMeasurement tm)
{
PreviousIndex = tm.PreviousIndex;
CharIndex = tm.CharIndex;
Bounds = tm.Bounds;
Char = tm.Char;
TextBounds = tm.TextBounds;
UserPoint = tm.UserPoint;
if (UserPoint.IsEmpty) UserPoint = Bounds.Location;
}
public virtual object Clone()
{
var tm = new TextMeasurement();
tm.CopyFrom(this);
return tm;
}
protected virtual void ResetBounds(Point p)
{
ResetBounds(p.X, p.Y);
}
protected virtual void ResetBounds(int? lineX = null, int? lineY = null)
{
if (lineX.HasValue)
{
now.X = lineX.Value;
textBound.X = lineX.Value;
}
if (lineY.HasValue)
{
now.Y = lineY.Value;
textBound.Y = lineY.Value;
}
}
protected virtual void ResetEmptyBounds(Rectangle rc)
{
now = rc;
textBound = rc;
}
public static TextMeasurement Default
{
get { return new TextMeasurement(); }
}
}
#endregion
#region enums
public enum DrawTextFlags
{
CalculateArea = 0x00000400,
WordBreak = 0x00000010,
TextBoxControl = 0x00002000,
Top = 0x00000000,
Left = 0x00000000,
HorizontalCenter = 0x00000001,
Right = 0x00000002,
VerticalCenter = 0x00000004,
Bottom = 0x00000008,
SingleLine = 0x00000020,
ExpandTabs = 0x00000040,
TabStop = 0x00000080,
NoClipping = 0x00000100,
ExternalLeading = 0x00000200,
NoPrefix = 0x00000800,
Internal = 0x00001000,
PathEllipsis = 0x00004000,
EndEllipsis = 0x00008000,
WordEllipsis = 0x00040000,
ModifyString = 0x00010000,
RightToLeft = 0x00020000,
NoFullWidthCharacterBreak = 0x00080000,
HidePrefix = 0x00100000,
PrefixOnly = 0x00200000,
NoPadding = 0x10000000,
}
public enum Angle
{
A0 = 0,
A45 = 45,
A90 = 90,
A135 = 135,
A180 = 180
}
#endregion
}
Suppose your ItemText at index 2 is "StackOverFlow is a wonderful site" and you want to highlight "StackOverFlow" then your startIndex =0 and endIndex = 12.
To highlight portion of text use HighlightItemText method:
listBox.HilightItemText(2, 0, 12, Color.Black, Color.Gold, Color.Yellow);
To get highlighted coordinates use GetPortionRectangleToHighlight method to get co-ordinates of text portion to highlight. Please note that you just need to pass start and end index as well of portion text.
so call the function like:
var portionRectangle = listBox1.GetPortionRectangleToHighlight (2, 0, 12);
Have a look at the attached image as working proof of concept.

A simple example would be something like this:
private string[] _sentences = {
"Old height on pictureOne: 766",
"New height on pictureOne: 900",
"",
"Forcing width on objectX"
};
private void Form1Paint(object sender, PaintEventArgs e) {
int y = 10; //Start position
int x;
foreach (string s in _sentences) {
x = 0; //Start position
foreach (string word in s.Split(' ')) {
if (ShouldHeighlightWord(word)) {
e.Graphics.DrawString(word + " ", this.Font, new SolidBrush(Color.Red), x, y);
}
else {
e.Graphics.DrawString(word + " ", this.Font, new SolidBrush(Color.Black), x, y);
}
x += (int)e.Graphics.MeasureString(word + " ", this.Font).Width;
}
y += (int)Math.Ceiling(e.Graphics.MeasureString("I", this.Font).Height);
}
}
private bool ShouldHeighlightWord(string word) {
switch (word) {
case "on":
case "Old":
return true;
default:
return false;
}
}
This code is just drawing the strings onto an empty form and instead of highlighting it just changes the color to Red.
But i think you understand what i mean.
Since i dont have more code its hard to make a better example for you.
When you check:
if (SomethingToHighlight(item)) {
That only returns true/false i guess and you need something that returns all words to be highlighted, but since a word can occur twice (or more) in one sentence you need to be able to get a position in the string as well. Or just take one word at a time and check if it should be highlighted or not and then draw it to the control.

MouseInput moves mouse to the left at start of loop

When I do this;
Point startpoint = Cursor.Position;
startpoint.Y -= 1;
DoMouse(MOUSEEVENTF.MOVE | MOUSEEVENTF.ABSOLUTE, startpoint);
The mouse doesn't just move up.. it moves a bit to the left as well. But if I do it in a loop, it only moves to the left at the first iteration.
Here is a fully working console program presenting the problem. You have to Add Reference -> .NET -> System.Drawing and System.Windows.Forms to get it to compile.
When starting the program type start to move the mouse up 5 pixels once or type start X (X being a number) to move the mouse up 5 pixels X times. You will see that each new loop the mouse will move a bit to the left; it shouldn't be doing that at all.
using System;
using System.Text.RegularExpressions;
using System.Threading;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace mousemove_temp
{
class Program
{
//Capture user input
static void Main(string[] args)
{
while (true)
{
string s = Console.ReadLine();
switch (s)
{
case("start"):
moveMouseTest(1);
break;
default:
//Get # of times to run function
Match match = Regex.Match(s, #"start (.+)", RegexOptions.IgnoreCase);
if (!match.Success || match.Groups.Count != 2) break;
//Copy # to int
int amnt = -1;
try
{
amnt = Int32.Parse(match.Groups[1].Value);
}
catch (Exception) { break; } //fail
if (amnt <= -1) break; //fail
moveMouseTest(amnt); //aaaawww yeah
break;
}
Thread.Sleep(10);
}
}
//Move the mouse
static void moveMouseTest(int repeat)
{
int countrepeat = 0;
//Loop entire function X times
while (countrepeat < repeat)
{
Point startpoint = Cursor.Position;
int amount = 5; //Move 5 pixels
int counter = 0;
//Move 1 pixel up each loop
while (counter < amount)
{
startpoint.Y -= 1;
DoMouse(MOUSEEVENTF.MOVE | MOUSEEVENTF.ABSOLUTE, startpoint);
counter++;
Thread.Sleep(100); //Slow down so you can see it only jumps left the first time
}
countrepeat++;
Console.WriteLine(String.Format("{0}/{1}", countrepeat, repeat));
Thread.Sleep(1000); //Wait a second before next loop
}
}
/*
* Function stuff
*/
//Control the Mouse
private static object mouselock = new object(); //For use with multithreading
public static void DoMouse(MOUSEEVENTF flags, Point newPoint)
{
lock (mouselock)
{
INPUT input = new INPUT();
MOUSEINPUT mi = new MOUSEINPUT();
input.dwType = InputType.Mouse;
input.mi = mi;
input.mi.dwExtraInfo = IntPtr.Zero;
// mouse co-ords: top left is (0,0), bottom right is (65535, 65535)
// convert screen co-ord to mouse co-ords...
input.mi.dx = newPoint.X * (65535 / Screen.PrimaryScreen.Bounds.Width);
input.mi.dy = newPoint.Y * (65535 / Screen.PrimaryScreen.Bounds.Height);
input.mi.time = 0;
input.mi.mouseData = 0;
// can be used for WHEEL event see msdn
input.mi.dwFlags = flags;
int cbSize = Marshal.SizeOf(typeof(INPUT));
int result = SendInput(1, ref input, cbSize);
if (result == 0)
Console.WriteLine("DoMouse Error:" + Marshal.GetLastWin32Error());
}
}
/*
* Native Methods
*/
[DllImport("user32.dll", SetLastError = true)]
static internal extern Int32 SendInput(Int32 cInputs, ref INPUT pInputs, Int32 cbSize);
[DllImport("user32.dll")]
public static extern bool GetAsyncKeyState(Int32 vKey);
[StructLayout(LayoutKind.Explicit, Pack = 1, Size = 28)]
internal struct INPUT
{
[FieldOffset(0)]
public InputType dwType;
[FieldOffset(4)]
public MOUSEINPUT mi;
[FieldOffset(4)]
public KEYBDINPUT ki;
[FieldOffset(4)]
public HARDWAREINPUT hi;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
internal struct MOUSEINPUT
{
public Int32 dx;
public Int32 dy;
public Int32 mouseData;
public MOUSEEVENTF dwFlags;
public Int32 time;
public IntPtr dwExtraInfo;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
internal struct KEYBDINPUT
{
public Int16 wVk;
public Int16 wScan;
public KEYEVENTF dwFlags;
public Int32 time;
public IntPtr dwExtraInfo;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
internal struct HARDWAREINPUT
{
public Int32 uMsg;
public Int16 wParamL;
public Int16 wParamH;
}
internal enum InputType : int
{
Mouse = 0,
Keyboard = 1,
Hardware = 2
}
[Flags()]
internal enum MOUSEEVENTF : int
{
MOVE = 0x1,
LEFTDOWN = 0x2,
LEFTUP = 0x4,
RIGHTDOWN = 0x8,
RIGHTUP = 0x10,
MIDDLEDOWN = 0x20,
MIDDLEUP = 0x40,
XDOWN = 0x80,
XUP = 0x100,
VIRTUALDESK = 0x400,
WHEEL = 0x800,
ABSOLUTE = 0x8000
}
[Flags()]
internal enum KEYEVENTF : int
{
EXTENDEDKEY = 1,
KEYUP = 2,
UNICODE = 4,
SCANCODE = 8
}
}
}
Can anybody tell what's going wrong?

You're doing the math wrong and as a result are getting rounding errors.
For example, 65535 / 1920 = 34.1328125. But truncation (because you are dividing an int by an int) is resulting in 34. So if on a 1920x1080 screen you had the mouse all the way at the right, you would get 1920 * (65535 / 1920) = 1920 * 34 = 65280.
This will get you better results:
input.mi.dx = (int)((65535.0f * (newPoint.X / (float)Screen.PrimaryScreen.Bounds.Width)) + 0.5f);
input.mi.dy = (int)((65535.0f * (newPoint.Y / (float)Screen.PrimaryScreen.Bounds.Height)) + 0.5f);
Though if you're determined to use P/Invoke rather than just say
Cursor.Position = new Point(newPoint.X, newPoint.Y);
then you really should use SetCursorPos - http://msdn.microsoft.com/en-us/library/windows/desktop/ms648394(v=vs.85).aspx - since that (along with GetCursorPos) is the API that .NET is using to get and set the cursor position via Cursor.Position.

Simplest way for your project is useful open-source library Windows Input Simulator (C# SendInput Wrapper - Simulate Keyboard and Mouse) on codeplex. Use it!

How to make my Windows Form app snap to screen edges?

Anyone out there know how to make your .net windows form app sticky/snappy like Winamp so it snaps to the edges of the screen?
The target framework would be .NET 2.0 Windows Form written in C#, using VS08. I am looking to add this functionality to a custom user control, but I figured more people would benefit from having it described for the application and its main form.
Thank you.

This worked pretty well, works on multiple monitors, observes the taskbar:
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
}
private const int SnapDist = 100;
private bool DoSnap(int pos, int edge) {
int delta = pos - edge;
return delta > 0 && delta <= SnapDist;
}
protected override void OnResizeEnd(EventArgs e) {
base.OnResizeEnd(e);
Screen scn = Screen.FromPoint(this.Location);
if (DoSnap(this.Left, scn.WorkingArea.Left)) this.Left= scn.WorkingArea.Left;
if (DoSnap(this.Top, scn.WorkingArea.Top)) this.Top = scn.WorkingArea.Top;
if (DoSnap(scn.WorkingArea.Right, this.Right)) this.Left = scn.WorkingArea.Right - this.Width;
if (DoSnap(scn.WorkingArea.Bottom, this.Bottom)) this.Top = scn.WorkingArea.Bottom - this.Height;
}
}

The accepted answer only snaps the window after finishing the drag, whereas I wanted the form to continuously snap to the screen edges while dragging. Here's my solution, loosely based off the Paint.NET source code:
using System;
using System.ComponentModel;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace Whatever
{
/// <summary>
/// Managed equivalent of the Win32 <code>RECT</code> structure.
/// </summary>
[StructLayout(LayoutKind.Sequential)]
public struct LtrbRectangle
{
public int Left;
public int Top;
public int Right;
public int Bottom;
public LtrbRectangle(int left, int top, int right, int bottom)
{
Left = left;
Top = top;
Right = right;
Bottom = bottom;
}
public Rectangle ToRectangle()
{
return Rectangle.FromLTRB(Left, Top, Right, Bottom);
}
public static LtrbRectangle FromRectangle(Rectangle rect)
{
return new LtrbRectangle(rect.X, rect.Y, rect.X + rect.Width, rect.Y + rect.Height);
}
public override string ToString()
{
return "{Left=" + Left + ",Top=" + Top + ",Right=" + Right + ",Bottom=" + Bottom + "}";
}
}
/// <summary>
/// A form that "snaps" to screen edges when moving.
/// </summary>
public class AnchoredForm : Form
{
private const int WmEnterSizeMove = 0x0231;
private const int WmMoving = 0x0216;
private const int WmSize = 0x0005;
private SnapLocation _snapAnchor;
private int _dragOffsetX;
private int _dragOffsetY;
/// <summary>
/// Flags specifying which edges to anchor the form at.
/// </summary>
[Flags]
public enum SnapLocation
{
None = 0,
Left = 1 << 0,
Top = 1 << 1,
Right = 1 << 2,
Bottom = 1 << 3,
All = Left | Top | Right | Bottom
}
/// <summary>
/// How far from the screen edge to anchor the form.
/// </summary>
[Browsable(true)]
[DefaultValue(10)]
[Description("The distance from the screen edge to anchor the form.")]
public virtual int AnchorDistance { get; set; } = 10;
/// <summary>
/// Gets or sets how close the form must be to the
/// anchor point to snap to it. A higher value gives
/// a more noticable "snap" effect.
/// </summary>
[Browsable(true)]
[DefaultValue(20)]
[Description("The maximum form snapping distance.")]
public virtual int SnapDistance { get; set; } = 20;
/// <summary>
/// Re-snaps the control to its current anchor points.
/// This can be useful for re-positioning the form after
/// the screen resolution changes.
/// </summary>
public void ReSnap()
{
SnapTo(_snapAnchor);
}
/// <summary>
/// Forces the control to snap to the specified edges.
/// </summary>
/// <param name="anchor">The screen edges to snap to.</param>
public void SnapTo(SnapLocation anchor)
{
Screen currentScreen = Screen.FromPoint(Location);
Rectangle workingArea = currentScreen.WorkingArea;
if ((anchor & SnapLocation.Left) != 0)
{
Left = workingArea.Left + AnchorDistance;
}
else if ((anchor & SnapLocation.Right) != 0)
{
Left = workingArea.Right - AnchorDistance - Width;
}
if ((anchor & SnapLocation.Top) != 0)
{
Top = workingArea.Top + AnchorDistance;
}
else if ((anchor & SnapLocation.Bottom) != 0)
{
Top = workingArea.Bottom - AnchorDistance - Height;
}
_snapAnchor = anchor;
}
private bool InSnapRange(int a, int b)
{
return Math.Abs(a - b) < SnapDistance;
}
private SnapLocation FindSnap(ref Rectangle effectiveBounds)
{
Screen currentScreen = Screen.FromPoint(effectiveBounds.Location);
Rectangle workingArea = currentScreen.WorkingArea;
SnapLocation anchor = SnapLocation.None;
if (InSnapRange(effectiveBounds.Left, workingArea.Left + AnchorDistance))
{
effectiveBounds.X = workingArea.Left + AnchorDistance;
anchor |= SnapLocation.Left;
}
else if (InSnapRange(effectiveBounds.Right, workingArea.Right - AnchorDistance))
{
effectiveBounds.X = workingArea.Right - AnchorDistance - effectiveBounds.Width;
anchor |= SnapLocation.Right;
}
if (InSnapRange(effectiveBounds.Top, workingArea.Top + AnchorDistance))
{
effectiveBounds.Y = workingArea.Top + AnchorDistance;
anchor |= SnapLocation.Top;
}
else if (InSnapRange(effectiveBounds.Bottom, workingArea.Bottom - AnchorDistance))
{
effectiveBounds.Y = workingArea.Bottom - AnchorDistance - effectiveBounds.Height;
anchor |= SnapLocation.Bottom;
}
return anchor;
}
protected override void WndProc(ref Message m)
{
switch (m.Msg)
{
case WmEnterSizeMove:
case WmSize:
// Need to handle window size changed as well when
// un-maximizing the form by dragging the title bar.
_dragOffsetX = Cursor.Position.X - Left;
_dragOffsetY = Cursor.Position.Y - Top;
break;
case WmMoving:
LtrbRectangle boundsLtrb = Marshal.PtrToStructure<LtrbRectangle>(m.LParam);
Rectangle bounds = boundsLtrb.ToRectangle();
// This is where the window _would_ be located if snapping
// had not occurred. This prevents the cursor from sliding
// off the title bar if the snap distance is too large.
Rectangle effectiveBounds = new Rectangle(
Cursor.Position.X - _dragOffsetX,
Cursor.Position.Y - _dragOffsetY,
bounds.Width,
bounds.Height);
_snapAnchor = FindSnap(ref effectiveBounds);
LtrbRectangle newLtrb = LtrbRectangle.FromRectangle(effectiveBounds);
Marshal.StructureToPtr(newLtrb, m.LParam, false);
m.Result = new IntPtr(1);
break;
}
base.WndProc(ref m);
}
}
}
And here's what it looks like:

Just retrieve the current pixel height/width of the monitor you're on...
How to determine active monitor of the current cursor location
... and process the location changed/moved events for the form. When you get within, say 25 pixels or so of an edge (your main form's Location.Left + form width) or height (your main form's Location.Top + form height), then go ahead and set the .Left and .Top properties so that your application "docks" in the corners.
Edit: One other note - when you actually do the "snapping" you may also want to move the cursor position the relative distance to make it stay on the same point on the window bar. Otherwise your form may become a giant ping pong ball between the cursor position and your "snappy" functionality as the MouseMove and form location changed events fight against each other.

I don't know if you found your solution, but I created a small component for just that: http://www.formsnapper.net - it snaps accross the process boundaries!

https://github.com/stax76/staxrip
Protected Overrides Sub WndProc(ByRef m As Message)
Snap(m)
MyBase.WndProc(m)
End Sub
Private IsResizing As Boolean
Sub Snap(ByRef m As Message)
Select Case m.Msg
Case &H214 'WM_SIZING
IsResizing = True
Case &H232 'WM_EXITSIZEMOVE
IsResizing = False
Case &H46 'WM_WINDOWPOSCHANGING
If Not IsResizing Then Snap(m.LParam)
End Select
End Sub
Sub Snap(handle As IntPtr)
Dim workingArea = Screen.FromControl(Me).WorkingArea
Dim newPos = DirectCast(Marshal.PtrToStructure(handle, GetType(WindowPos)), WindowPos)
Dim snapMargin = Control.DefaultFont.Height
Dim border As Integer
If OSVersion.Current >= OSVersion.Windows8 Then border = (Width - ClientSize.Width) \ 2 - 1
If newPos.Y <> 0 Then
If Math.Abs(newPos.Y - workingArea.Y) < snapMargin AndAlso Top > newPos.Y Then
newPos.Y = workingArea.Y
ElseIf Math.Abs(newPos.Y + Height - (workingArea.Bottom + border)) < snapMargin AndAlso Top < newPos.Y Then
newPos.Y = (workingArea.Bottom + border) - Height
End If
End If
If newPos.X <> 0 Then
If Math.Abs(newPos.X - (workingArea.X - border)) < snapMargin AndAlso Left > newPos.X Then
newPos.X = workingArea.X - border
ElseIf Math.Abs(newPos.X + Width - (workingArea.Right + border)) < snapMargin AndAlso Left < newPos.X Then
newPos.X = (workingArea.Right + border) - Width
End If
End If
Marshal.StructureToPtr(newPos, handle, True)
End Sub