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Ecco qua il modo per utilizzare un PNG semi trasparente come sfondo per i vostri Form. Riporto qua la procedura completa:
Traslation in english. This is the way to use PNG semitransparent background for yours form:
Notes:
None.
Tips & Tricks:
Ecco qua il modo per utilizzare un PNG semi trasparente come sfondo per i vostri Form. Riporto qua la procedura completa:
Traslation in english. This is the way to use PNG semitransparent background for yours form:
public void SetBackground(Control control, Bitmap bitmap)
{
/*Parametri accettati dalla procedura:
control = il form o controllo da renderizzare
bitmap = la PNG da utilizzare come sfondo*/
// Imposta le dimensioni del controllo come quelle della bitmap
control.Width = bitmap.Width;
control.Height = bitmap.Height;
if (bitmap.PixelFormat != System.Drawing.Imaging.PixelFormat.Format32bppArgb)
{
//Se l'immagine รจ in formato errato...
throw new ApplicationException("L'immagine deve essere in formato a 32 bpp con canale alpha");
}
IntPtr hBitmap = IntPtr.Zero;
IntPtr oldBitmap = IntPtr.Zero;
IntPtr screenDc = Win32.GetDC(IntPtr.Zero);
IntPtr memDc = Win32.CreateCompatibleDC(screenDc);
try
{
hBitmap = bitmap.GetHbitmap(Color.FromArgb(0));
oldBitmap = Win32.SelectObject(memDc, hBitmap);
Win32.Size size = new Win32.Size(bitmap.Width, bitmap.Height);
Win32.Point pointSource = new Win32.Point(control.Left, control.Top);
Win32.Point topPos = new Win32.Point(0, 0);
Win32.BLENDFUNCTION blend = new Win32.BLENDFUNCTION();
blend.BlendOp = 0;
blend.BlendFlags = 0;
blend.SourceConstantAlpha = byte.MaxValue;
blend.AlphaFormat = 1;
Win32.UpdateLayeredWindow(control.Handle, screenDc, ref topPos, ref size, memDc, ref pointSource, 0, ref blend, 2);
}
catch (Exception ex)
{
throw ex;
}
finally
{
Win32.ReleaseDC(IntPtr.Zero, screenDc);
if (hBitmap != IntPtr.Zero)
{
Win32.SelectObject(memDc, oldBitmap);
Win32.DeleteObject(hBitmap);
}
Win32.DeleteDC(memDc);
}
}
public class Win32
{
//Classe che contiene le dichiarazioni API e i tipi
public enum Bool: int
{
@False = 0,
@True = 1
}
public struct Point
{
public int x;
public int y;
public Point(int x, int y)
{
this.x = x;
this.y = y;
}
}
public struct Size
{
public int cx;
public int cy;
public Size(int cx, int cy)
public Point(int x, int y)
{
this.cx = cx;
this.cy = cy;
this.x = x;
this.y = y;
}
}
public struct BLENDFUNCTION
public struct Size
{
public byte BlendOp;
public int cx;
public byte BlendFlags;
public int cy;
public byte SourceConstantAlpha;
public byte AlphaFormat;
public Size(int cx, int cy)
{
this.cx = cx;
this.cy = cy;
}
}
public const int ULW_ALPHA = 2;
public struct BLENDFUNCTION
{
public byte BlendOp;
public const byte AC_SRC_OVER = 0;
public byte BlendFlags;
public const byte AC_SRC_ALPHA = 1;
public byte SourceConstantAlpha;
public byte AlphaFormat;
[DllImportAttribute("user32.dll")]
public extern static Bool UpdateLayeredWindow(IntPtr handle, IntPtr hdcDst, ref Point pptDst, ref Size psize, IntPtr hdcSrc, ref Point pprSrc, int crKey, ref BLENDFUNCTION pblend, int dwFlags);
}
[DllImportAttribute("user32.dll")]
public extern static IntPtr GetDC(IntPtr handle);
public const int ULW_ALPHA = 2;
[DllImportAttribute("user32.dll", ExactSpelling=true)]
public extern static int ReleaseDC(IntPtr handle, IntPtr hDC);
public const byte AC_SRC_OVER = 0;
[DllImportAttribute("gdi32.dll")]
public extern static IntPtr CreateCompatibleDC(IntPtr hDC);
public const byte AC_SRC_ALPHA = 1;
[DllImportAttribute("gdi32.dll")]
public extern static Bool DeleteDC(IntPtr hdc);
[DllImportAttribute("gdi32.dll")]
public extern static IntPtr SelectObject(IntPtr hDC, IntPtr hObject);
[DllImportAttribute("user32.dll")]
public extern static Bool UpdateLayeredWindow(IntPtr handle, IntPtr hdcDst, ref Point pptDst, ref Size psize, IntPtr hdcSrc, ref Point pprSrc, int crKey, ref BLENDFUNCTION pblend, int dwFlags);
[DllImportAttribute("gdi32.dll")]
public extern static Bool DeleteObject(IntPtr hObject);
}
[DllImportAttribute("user32.dll")]
public extern static IntPtr GetDC(IntPtr handle);
[DllImportAttribute("user32.dll", ExactSpelling=true)]
public extern static int ReleaseDC(IntPtr handle, IntPtr hDC);
Sample Code:
This blog entry by Mike Swanson includes a downloadable sample called AlphaWindow that calls UpdateLayeredWindow from Windows Forms for a cool alpha blended effect.
[DllImportAttribute("gdi32.dll")]
public extern static IntPtr CreateCompatibleDC(IntPtr hDC);
[DllImportAttribute("gdi32.dll")]
public extern static Bool DeleteDC(IntPtr hdc);
Alternative Managed API:
Do you know one? Please contribute it!
[DllImportAttribute("gdi32.dll")]
public extern static IntPtr SelectObject(IntPtr hDC, IntPtr hObject);
[DllImportAttribute("gdi32.dll")]
public extern static Bool DeleteObject(IntPtr hObject);
}
Sample Code:
This blog entry by Mike Swanson includes a downloadable sample called AlphaWindow that calls UpdateLayeredWindow from Windows Forms for a cool alpha blended effect.
This is not a real function. It does not exist in user32.dll!
10/31/2009 12:46:47 PM - -82.78.57.221
The UpdateLayeredWindow API
3/7/2011 7:07:34 PM - -24.22.0.163
This is not a real function. It does not exist in user32.dll!
10/31/2009 12:46:47 PM - -82.78.57.221
The UpdateLayeredWindow API
3/7/2011 7:07:34 PM - -24.22.0.163
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