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.

Is there a way to overlay or merge a Drawing.Bitmap and a DrawingImage

In a windows forms application, I have as input a Drawing.Bitmap and a DrawingImage. I need to overlay them and put there output in a Controls.Image. How can I do this?

It doesn't matter if you use Image object or Bitmap object, The Drawing.Image is abstract class and Drawing.Bitmap inherited from it. to
draw image over image, get the graphics object from the base image and then use Graphics.DrawImage which accept parameter of type Image.
So you have two images here, one should be printed "overlay" over the other image:
System.Drawing.Image primaryImage = Image.FromFile(#"Your file path");//or resource..
using (Graphics graphics = Graphics.FromImage(primaryImage))//get the underlying graphics object from the image.
{
using (Bitmap overlayImage = new Bitmap(primaryImage.Width, primaryImage.Hieght,
System.Drawing.Imaging.PixelFormat.Format32bppArgb)//or your overlay image from file or resource...
{
graphics.DrawImage(overlayImage, new Point(0, 0));//this will draw the overlay image over the base image at (0, 0) coordination.
}
}
Control.Image = primaryImage;
Not that if the overlay image doesn't have some transparent, and its size is equals or larger than the base image, it will overlap the other image completely, so you the overlay image must have some opacity.

I realize it has been awhile, but the answers here weren't quite working for me. A little tweaking, though made them work fine. For what it is worth, here is my final version.
SCENARIO:
background image is RGB 24
overlay image is ARGB 32 with alpha channel already set properly.
images created from a memory stream
PROBLEM:
Creating the overlay image from the memory stream assumed I meant: Format32bppRgb
But what is needed is Format32bppArgb since the transparency is already in place..
SOLUTION:
pictureBox1.Image = MergeImages( backgroundImage, overlayImage);
using System.Drawing;
using System.Drawing.Imaging;
// ...
private Image MergeImages(Image backgroundImage,
Image overlayImage)
{
Image theResult = backgroundImage;
if (null != overlayImage)
{
Image theOverlay = overlayImage;
if (PixelFormat.Format32bppArgb != overlayImage.PixelFormat)
{
theOverlay = new Bitmap(overlayImage.Width,
overlayImage.Height,
PixelFormat.Format32bppArgb);
using (Graphics graphics = Graphics.FromImage(theOverlay))
{
graphics.DrawImage(overlayImage,
new Rectangle(0, 0, theOverlay.Width, theOverlay.Height),
new Rectangle(0, 0, overlayImage.Width, overlayImage.Height),
GraphicsUnit.Pixel);
}
((Bitmap)theOverlay).MakeTransparent();
}
using (Graphics graphics = Graphics.FromImage(theResult))
{
graphics.DrawImage(theOverlay,
new Rectangle(0, 0, theResult.Width, theResult.Height),
new Rectangle(0, 0, theOverlay.Width, theOverlay.Height),
GraphicsUnit.Pixel);
}
}
return theResult;
}

text not showing on bitmap image in C#

I can't seem to get the text I've written to show up on my image Here's the code I'm using
//Creates a bitmap with the path to the current image
Bitmap LabelImage = new Bitmap(dtImages.Rows[intCurrentImage]["ImageURL"].ToString());
Graphics graphic = Graphics.FromImage(LabelImage);
graphic.DrawString("Hello", new Font("Tahoma",40), Brushes.Azure, new System.Drawing.Point(0,0));
//put Image that I just created and put the text on into an Infragistics UltraPicureBox
picImage.Image = LabelImage

You did not update your original image (LabelImage), so why should the text you added to the Graphics object show up?.
From MSDN, Graphics.FromImage:
Creates a new Graphics from the specified Image.
(emphasis mine)
After you have added the text, you need to save the changes:
graphic.Save();
Unrelated to your question, you should really put the creation of the Graphics object in a using statement, to ensure proper disposal:
using(Graphics graphic = Graphics.FromImage(LabelImage))
{
// use graphic here
}

I just tried this
Bitmap bitmap = new Bitmap("C:\\Untitled.png");
Graphics g = Graphics.FromImage(bitmap);
g.DrawString("Hello", new Font("Tahoma", 40), Brushes.Azure, new System.Drawing.Point(0, 0));
pictureBox1.Image = bitmap;
and it works fine for me. Just try to pick a contrasting brush.

Saving System.Drawing.Graphics to a png or bmp

I have a Graphics object that I've drawn on the screen and I need to save it to a png or bmp file. Graphics doesn't seem to support that directly, but it must be possible somehow.
What are the steps?

Here is the code:
Bitmap bitmap = new Bitmap(Convert.ToInt32(1024), Convert.ToInt32(1024), System.Drawing.Imaging.PixelFormat.Format32bppArgb);
Graphics g = Graphics.FromImage(bitmap);
// Add drawing commands here
g.Clear(Color.Green);
bitmap.Save(#"C:\Users\johndoe\test.png", ImageFormat.Png);
If your Graphics is on a form, you can use this:
private void DrawImagePointF(PaintEventArgs e)
{
... Above code goes here ...
e.Graphics.DrawImage(bitmap, 0, 0);
}
In addition, to save on a web page, you could use this:
MemoryStream memoryStream = new MemoryStream();
bitmap.Save(memoryStream, ImageFormat.Png);
var pngData = memoryStream.ToArray();
<img src="data:image/png;base64,#(Convert.ToBase64String(pngData))"/>
Graphics objects are a GDI+ drawing surface. They must have an attached device context to draw on ie either a form or an image.

Copy it to a Bitmap and then call the bitmap's Save method.
Note that if you're literally drawing to the screen (by grabbing the screen's device context), then the only way to save what you just drew to the screen is to reverse the process by drawing from the screen to a Bitmap. This is possible, but it would obviously be a lot easier to just draw directly to a Bitmap (using the same code you use to draw to the screen).

Try this, works fine for me...
private void SaveControlImage(Control ctr)
{
try
{
var imagePath = #"C:\Image.png";
Image bmp = new Bitmap(ctr.Width, ctr.Height);
var gg = Graphics.FromImage(bmp);
var rect = ctr.RectangleToScreen(ctr.ClientRectangle);
gg.CopyFromScreen(rect.Location, Point.Empty, ctr.Size);
bmp.Save(imagePath);
Process.Start(imagePath);
}
catch (Exception)
{
//
}
}

Graphics graph = CreateGraphics();
Bitmap bmpPicture = new Bitmap("filename.bmp");
graph.DrawImage(bmpPicture, width, height);

You are likely drawing either to an image or on a control. If on image use
Image.Save("myfile.png",ImageFormat.Png)
If drawing on control use Control.DrawToBitmap() and then save the returned image as above.
Thanks for the correction - I wasn't aware you can draw directly to the screen.

How can I replace an existing image on a winforms ImageList?

How can I replace an existing image on a winforms ImageList?
I tried this:
this.CoolPics.Images [ 2 ] = // new image
this.ListViewControl.SmallImageList = this.CoolPics;
However the new image is not rescaled the way the others are, when I used the this.CoolPics.Images.Add method.
What am I doing wrong?

I know this is old but here is how I solved the problem. It looks like the image list will not resize the image upon assignment (even though it does when using the Add() function). So basically, you need to resize the image manually before assigning.
Image img; //used to load new image from disk
Bitmap bmp = new Bitmap(160, 120); //canvas where the new image will be drawn/resized
Graphics graph = Graphics.FromImage(bmp); //used to draw/resize the new image
img = new Bitmap(fileDialog.FileNames[0]); //load new image from disk
graph.DrawImage(img, new Rectangle(0, 0, 160, 120)); //resize new image to proper size
imgList.Images[index] = bmp; //assign the new resized image to the list (overwrites the old image)

after your code try
listView1.Refresh();

I have run into this before and if I remember right the assignment operator had this behavior but the Imagelist.Images.Add(myImage) did the right thing.
Try changing your code to do the .Add(myImage) and see if that doesn't look better.