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Arbel

[.net] C# - GDI Points to Pixels

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I'm working on an editor for our game and I noticed that when trying to draw images based on the mouse coordinates and the image width/height, that it is off by a small amount. I figure this is because the cursor position is in points and the image width/height is in pixels. Is there any easy way to convert? I haven't found any built-in functions, but I can't imagine there would be none. This has got to be a common issue.

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GDI uses pixel coordinate system by default (System.Drawing.GraphicsUnit.Pixel), so I'm not sure if this the problem here unless your changing it in code.

If your drawing to a PictureBox, then use the MouseMove or MouseDown events for the PictureBox not the Form as they are relative to the top left of the control.

Perhaps if you paste some code or give more info it might help me understand what is going wrong.

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Basically I have it set up so that you drag items from the left (the images in the image library) and drag them onto the drawing area. Here is the code for my drag function:

Image img = Image.FromFile(itemDragged.ToolTipText);

Point point = this.PointToClient(Cursor.Position);
int x = point.X;
int y = point.Y;

x = x - (img.Width / 2);
y = y - (img.Height / 2);

objectList.Add(new PlaceableObject()
{
FilePath = itemDragged.ToolTipText,
PosX = x,
PosY = y,
});

I want x and y to be /2 so that when you paste and image the mouse cursor is directly in the middle of it, but it's always off by a little. Then I call the paint method

Graphics g = e.Graphics;

foreach (var item in objectList)
{
Image img = Image.FromFile(item.FilePath);
g.DrawImage(img, item.PosX, item.PosY);
}

****Sorry I don't remember how to put code in tags :/

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