Develop Reference

How to save the painted control as a bitmap?

I have a picturebox (pictureBox1), and it gets lines drawn on it, from the paint event. I was wondering how to convert that drawing (with the lines) to a bitmap, and save it as a file. I've tried:
Bitmap bmp = new Bitmap(pictureBox1.Width, pictureBox.Height);
pictureBox1.DrawToBitmap(bmp, pictureBox1.Bounds);
bmp.Save("MyImage.bmp");
But that is a blank image, without the lines. Does anyone know how I can save it with the lines? Thank you.

int bitmapX = 100
int bitmapY = 100
Bitmap imgToSave = new Bitmap(bitmapX, bitmapY);
Graphics gfx = Graphics.FromImage(imgToSave);
// draw on the image with
gfx.DrawLine() // or whatever you want to draw
// save the screenshot
string saveFilePath = Application.StartupPath + "\<name of the image>.png";
imgToSave.Save(saveFilePath, ImageFormat.Png);
This is a code snippet that works for me.

Don't use the PictureBox.Bounds property but instead use a simple Rectangle object/structure filled with the `PictureBox' width and height like this:
var bitmap = new Bitmap(pictureBox1.Width, pictureBox1.Height);
pictureBox1.DrawToBitmap(bitmap, new Rectangle(0, 0, pictureBox1.Width, pictureBox1.Height));
bitmap.Save("c:\\temp\\image.bmp");
Using the Bounds property you are fetching the correct size of the picture box control, but depending on the position not the 0,0 coordinate, but the control position, which leads to an empty bitmap.

Capturing screenshot of Form and elements on form

I'm trying to capture a screenshot of the MainWindow and content on the main window. The MainWindow will sometimes be behind other elements and need to get screen capture without those other overlaying elements. This code currently returns a bitmap of the blank MainWindow form without any content. The form has a bunch of different dynamic UI elements. How can I take a current screenshot/capture of MainWindow and it's content? Code for the MainWindow content is waay to long to post so I hope that this is enough.
Rectangle bounds = new Rectangle();
bounds.Width = Program.MainWindow.Width;
bounds.Height = Program.MainWindow.Height;
screenShot = new Bitmap(Program.MainWindow.Width,
Program.MainWindow.Height,
PixelFormat.Format32bppRgb);
Program.MainWindow.DrawToBitmap(screenShot, bounds);

You should be able to get it by using the CopyFromScreen method of the Graphics class
Rectangle bounds = Program.MainWindow.Bounds;
Bitmap b = new Bitmap(bounds.Width, bounds.Height, PixelFormat.Format32bppArgb);
using (Graphics g = Graphics.FromImage(b))
{
g.CopyFromScreen(bounds.X, bounds.Y, 0, 0, bounds.Size, CopyPixelOperation.SourceCopy);
}
b.Save("YOUR FILE NAME HERE");

C# graphics calculate image and keep it

I have seen, that the drawing of two images is time consuming, so I want to reduce drawing these images as much as possible. I use pictureedit and have overriden the ondraw event.
Here I added the below part, but it ends up uin a black image. I do want to check, whether I need to draw at all. This check works. Then I draw the background and overlay it by another one and I want to store this as image and put it as background for my control.
If I do not redraw the background I just call:
g.Clear(Color.Transparent);
in my pictureEdit paint event.
Did I something wrong?
Best Regards,
Patrick
//Recalculate the background
if (redrawBackground)
{
g.FillRectangle(Brushes.White, 0, 0, backGroundImage.Width, backGroundImage.Height);
g.Clear(Color.White);
//this is drawn without aspect ration. The matrix is stored, since drawing images is expensive
GenerateTransformation(g, false);
g.DrawImageUnscaled(backGroundImage, new Rectangle(0, 0, backGroundImage.Width, backGroundImage.Height));
lastTransformation = g.Transform;
GenerateTransformation(g, true);
g.DrawImage(foreGroundImage, new Rectangle(0, 0, backGroundImage.Width, backGroundImage.Height));
lastTransformationAspect = g.Transform;
//Save bitmap as background
Bitmap bmp = new Bitmap(backGroundImage.Width, backGroundImage.Height, e.Graphics);
//Trick the background by a new image
pictureEdit.Image = bmp;
}

Your code (new Bitmap(backGroundImage.Width, backGroundImage.Height, e.Graphics);
) does not copy the image to the Bitmap; it only associates the Graphics object with the bitmap.
Try this:
Bitmap bmp = new Bitmap(width, height);
Graphics g = Graphics.FromImage(bmp);
g.DrawSomething(); // This draws to the bitmap

Capturing an image behind a rectangle

I have written a small application which will be used in my work environment for cropping images. The windows form (.NET 3.5) that contains the image has a transparent rectangle which I use for dragging over a section of an image and hitting a button to get me whatever was behind the rectangle.
Currently I am using the code below, this is causing me issues because the area that it is capturing is off by quite a few pixels, and I think it's something to do with my CopyFromScreen function.
//Pass in a rectangle
private void SnapshotImage(Rectangle rect)
{
Point ptPosition = new Point(rect.X, rect.Y);
Point ptRelativePosition;
//Get me the screen coordinates, so that I get the correct area
ptRelativePosition = PointToScreen(ptPosition);
//Create a new bitmap
Bitmap bmp = new Bitmap(rect.Width, rect.Height, PixelFormat.Format32bppArgb);
//Sort out getting the image
Graphics g = Graphics.FromImage(bmp);
//Copy the image from screen
g.CopyFromScreen(this.Location.X + ptPosition.X, this.Location.Y + ptPosition.Y, 0, 0, bmp.Size, CopyPixelOperation.SourceCopy);
//Change the image to be the selected image area
imageControl1.Image.ChangeImage(bmp);
}
If anyone can spot why when the image is redrawn its quite a bit out, I'd be eternally grateful at this point. Also, the ChangeImage function is fine - it works if I use a form as a select area but using a rectangle has jazzed things up a bit.

You've retrieved the relative position to the screen as ptRelativePosition, but you never actually use that - you add the rectangle's location to your form's location, which doesn't account for the form's border.
Here's that fixed, with a few optimizations:
// Pass in a rectangle
private void SnapshotImage(Rectangle rect)
{
// Get me the screen coordinates, so that I get the correct area
Point relativePosition = this.PointToScreen(rect.Location);
// Create a new bitmap
Bitmap bmp = new Bitmap(rect.Width, rect.Height, PixelFormat.Format32bppArgb);
// Copy the image from screen
using(Graphics g = Graphics.FromImage(bmp)) {
g.CopyFromScreen(relativePosition, Point.Empty, bmp.Size);
}
// Change the image to be the selected image area
imageControl1.Image.ChangeImage(bmp);
}

Interestingly, this was because of the space between the main form and the control that the image was on and the toolbar at the top of the form separating the control and the top of the main form. To get around this I simply modified one line in capture screen to account for those pixels, as shown below:
g.CopyFromScreen(relativePosition.X + 2, relativePosition.Y+48, Point.Empty.X, Point.Empty.Y, bmp.Size);
Cheers

Save Image from user Drawn PictureBox whose SizeMode=stretch in C# winforms

Im drawing an image on picture box which is in stretch mode,I translate the mouse coordinates on the mouse click event by using a function to obtain the real coordinates and draw the image by overriding the on-paint event and using the paint event Graphics.
Since the picture box is set to stretch i only obtain a small size image when i try to save the image by using picturebox.DrawtoBitmap Function.The extra parts are padded with Black colour.Please help me out.

You can try this:
using (Bitmap bmp = new Bitmap(pictureBox1.ClientSize.Width,
pictureBox1.ClientSize.Height)) {
using (Graphics g = Graphics.FromImage(bmp)) {
g.DrawImage(yourBitmap,
new Rectangle(0, 0, bmp.Width, bmp.Height),
new Rectangle(0, 0, yourImage.Width, yourImage.Height),
GraphicsUnit.Pixel);
}
bmp.Save(#"c:\yourfile.png", ImageFormat.Png);
}