Rotate Bitmap 1

[BBousman1]

On my form I have a section that's created using some code I found online. What it does is basically simulates the Microsoft Magnifier so I can view what's on my extended monitor while only being able to see my primary monitor.

Here's the dilemma I'm facing: On the extended monitor will be a PDF document, it will be rotated clockwise so that the whole page will fit in a portrait style layout. When it is rotated, the Magnifier section on the primary monitor is rotated as well, I need that to be rotated -90 degrees so it appears normal.

Here's the code that takes the constant screen shots:

Dim e As Graphics = Me.CreateGraphics
Dim hr As Integer = Screen.PrimaryScreen.Bounds.Width
Dim vr As Integer = Screen.PrimaryScreen.Bounds.Height

'Get Zoom Percentage
Dim percent As Single = 1
Dim lengthX As Single = 1010
Dim lengthY As Single = 728

'Center Image Around The Mouse
Dim offsetX As Single = (lengthX - 585) \ 2
Dim offsetY As Single = (lengthY - 390) \ 2

'Actual Area To Blit To
Dim blitAreaX As Integer = 1010
Dim blitAreaY As Integer = 728

'New Bitmap & Graphics Object
Dim b As New Bitmap(CInt(blitAreaX), CInt(blitAreaY))
Dim g As Graphics = Graphics.FromImage(b)

'Try to make things faster
g.SmoothingMode = Drawing2D.SmoothingMode.HighSpeed
g.CompositingQuality = Drawing2D.CompositingQuality.HighSpeed
g.PixelOffsetMode = Drawing2D.PixelOffsetMode.HighSpeed
g.InterpolationMode = Drawing2D.InterpolationMode.Low

'Try to make things faster
e.SmoothingMode = Drawing2D.SmoothingMode.HighSpeed
e.CompositingQuality = Drawing2D.CompositingQuality.HighSpeed
e.PixelOffsetMode = Drawing2D.PixelOffsetMode.HighSpeed
e.InterpolationMode = Drawing2D.InterpolationMode.Low


'DC Of Desktop And Graphics Object
Dim hWndWindow As IntPtr = GetDesktopWindow()
Dim hdcWindow As IntPtr = GetDC(hWndWindow)
Dim hdcGraphics As IntPtr = g.GetHdc()

'BitBlt & Graphics.DrawImage Solution
'------------------------------------------

'BitBlt the Screen (Captures Transparent Windows & Prevents Mirror Effect)

BitBlt(hdcGraphics.ToInt32, 585, 390, blitAreaX, blitAreaY, hdcWindow.ToInt32, Cursor.Current.Position.X - offsetX, Cursor.Current.Position.Y - offsetY, SRCCOPY Or CAPTUREBLT Or NOMIRRORBITMAP)

'Free Memory
ReleaseDC(hWndWindow.ToInt32, hdcWindow.ToInt32)
g.ReleaseHdc(hdcGraphics)

e.DrawImage(b, New Rectangle(0, 0, blitAreaX, blitAreaY), 0, 0, lengthX, lengthY, GraphicsUnit.Pixel)

e.Dispose()

 

[Qik3Coder]

You're going to have to load the image into an array then "walk" the array moving one pixel at a time from it's current location to it's new location. I don't know if there is a rotate command built in, but seeing as you are looking for an easy 90^ then thats easy

EX:

Start:
ABCDEF
ABCDEF
ABCDEF
ABCDEF
ABCDEF

End:
FFFFFF
EEEEEE
DDDDDD
CCCCCC
BBBBBB
AAAAAA

You may want to start with a small example like this, using text values or something similar, so you can identify whether or not you are having logic issues.



-Sometimes the answer to your question is the hack that works

 

[Craig0201]

private Bitmap rotateImage(Bitmap b, float angle)
{
//create a new empty bitmap to hold rotated image
Bitmap returnBitmap = new Bitmap(b.Width, b.Height);
//make a graphics object from the empty bitmap
Graphics g = Graphics.FromImage(returnBitmap);
//move rotation point to center of image
g.TranslateTransform((float)b.Width/2, (float)b.Height / 2);
//rotate
g.RotateTransform(angle);
//move image back
g.TranslateTransform(-(float)b.Width/2,-(float)b.Height / 2);
//draw passed in image onto graphics object
g.DrawImage(b, new Point(0, 0));
return returnBitmap;
}

The above is how to rotate a bitmap by any degree in C#. Translation to VB.Net is simple.

I trust this helps as you are passing a bitmap for drawing.

C

 

[chrissie1]

you don't want to do the transform yourself because that will be ever so slow.

use the method described here

http://www.xtremevbtalk.com/showthread.php?t=205134

or use c# and pointers which is the fastest but unsafe way of doing things.

Christiaan Baes
Belgium

The future is out there

 

[RiverGuy]

Nice code, Craig.

 

[Craig0201]

Have to admit its not mine. I pinched it years ago and just looked it up.

Props to the original author (whoever you are)

C