How I can quickly draw into texture with alpha? C#

You can do it by rendering pimitives forming the shape you want with the alpha vlaue you specify to their colors. GetGraphics() will give you back a GDI graphics object which isn't capable of filling the alpha channel (not to mention that it's usually not a good solution in terms of performance).

Are you rendering to that texture? If so could you post a full example, I have not been able to successfully render to a texture using surfaces.

OK, after some more messing about. This works 100% on my machine.

Load the bitmap.

Create a texture using the bitmap size + bug fix.

Create another bitmap attached to the texture bitstream.

Use the temp bitmap (attached to the texture's unmanaged data) and draw to that bitmap.

(remeber DrawImage() might scale if you don't specify the Units).

Dispose of all the goodies.

And there you go.

using (Bitmap fileBitmap = new Bitmap(filename))

{

Size size = new Size(fileBitmap.Width + 1, fileBitmap.Height + 1); //

FIX: texture seems to have some nasty bug where the size is not used

properly

_texture = new Texture(Control.Device, size.Width, size.Height, 1, Usage.None, Format.A8R8G8B8, Pool.Managed);

using(GraphicsStream graphicsStream = _texture.LockRectangle(0, LockFlags.None))

using(Bitmap texBitmap = new Bitmap(size.Width, size.Height, size.Width

* 4, PixelFormat.Format32bppPArgb, graphicsStream.InternalData))

using (Graphics texGraphics = Graphics.FromImage(texBitmap))

{

// draw the image using it's pixel measurement. (Not DPI, Texture DPI not always the same as image DPI)

Rectangle rect = new Rectangle(Point.Empty, fileBitmap.Size);

texGraphics.DrawImage(fileBitmap, rect, rect, GraphicsUnit.Pixel);

}

_texture.UnlockRectangle(0);