Develop Reference

How to get Graphic's object with out using a control in c# using GDI+?

I need to create a drawing with a circle and text embeded to it .This drawing is outputted as Image file (Jpeg/Jpg/svg/Png) using c# GDI+ .
Since i dont want to display the UI directly on a form ,how do i get the graphic's object to start drawing.
Thanks in advance.

You can create a new Bitmap passing the size for the image:
using (Bitmap myBitmap = new Bitmap(100, 100)) {
using (Graphics g = Graphics.FromImage(myBitmap)) {
// do your drawing here
}
myBitmap.Save(#"C:\path\for\image.bmp");
}
Optionally you can set the ImageFormat for the image when saving
myBitmap.Save(#"C:\path\for\image.png", ImageFormat.Png);

You create a Bitmap, and get the graphics object from it to draw on:
Bitmap myBitmap = new Bitmap(#"C:\MyImg.bmp");
Graphics g = Graphics.FromImage(myBitmap);
Note that the Bitmap does not need to be created on disk, it can be created in memory too!

Dynamically generated Bitmap image with aligned data in it

I'm developing an Winforms application to be used for Led displays. The Led display is size 64x32. I created a test bitmap image with 4 cells size 64x16, so I can output it it to the LED display.
When the user enters 4 numbers in the input form, those Strings are then converted to Bitmap Image and placed inside the cells. I somehow got it to work with this method; It edits the same bitmap image, inserts the numbers, and saves it into a new bmp (or am I wrong?).
public static Bitmap Convert_Text_to_Image(string txt, string fontname, int fontsize)
{
//creating bitmap image
Bitmap bmp = new Bitmap("cells.bmp");
//FromImage method creates a new Graphics from the specified Image.
Graphics graphics = Graphics.FromImage(bmp);
// Create the Font object for the image text drawing.
Font font = new Font(fontname, fontsize);
// Instantiating object of Bitmap image again with the correct size for the text and font.
SizeF stringSize = graphics.MeasureString(txt, font);
bmp = new Bitmap(bmp, (int)stringSize.Width, (int)stringSize.Height);
graphics = Graphics.FromImage(bmp);
//Draw Specified text with specified format
graphics.DrawString(txt, font, Brushes.Red, 0, 0);
font.Dispose();
graphics.Flush();
graphics.Dispose();
bmp.Save("cells2.bmp", System.Drawing.Imaging.ImageFormat.Bmp);
return bmp; //return Bitmap Image
}
The output in the PictureBox is This
Now I've created myself multiple problems with the alignment, since I just pasted "bmp numbers" directly onto the "bmp cells"... is there a function of "mapping" the numbers correctly inside the cells, depending if its a single-digit or a two-digit number?
I'm pretty certain there's a way easier way to do all of this, maybe with the DataGridView? I only started using C#, any help would be appreciated.
The image "cells.bmp" is just a test image i created in Paint (xd), rather than that, I'm trying to write a function that will create the Bitmap cells through code
if (want_x_number_cells) {
//create bmp with appropriate number of cells
}

Icon to Image - transparency issue

I'm trying to build a treeview like file list in a richtext box.
It should look like an explorer treeview. My code is able to get an resize the icon, but the transparency is missing (light gray background instead of transparency). What do I need to change here? Is the Image format wrong?
Is there a better way to add an image to a richtextbox?
// Get file info
FileInfo f = new FileInfo("myfile.name");
// Get icon for fileinfo
Icon ico = Icon.ExtractAssociatedIcon(f);
// Convert icon to bitmap
Bitmap bm = ico.ToBitmap();
// create new image with desired size
Bitmap img = new Bitmap(16,16,PixelFormat.Frmat32bpRgb);
// Create graphics with desired sized image
Graphics g = Graphics.FormImage(img);
// set interpolation mode
g.InterpolationMode = InterpolationMode.HighQualityBiCubic;
// draw/resize image
g.DrawImage(bm, new Rectangle(0,0,16,16), new Rectangle(0, 0, bm.Width, bm,Height), GraphicalUnit.Pixel);
// Paste to clipboard
Clipboard.SetImage(bm);
// Paste in RichtextBox
rtb.Paste();
Example:
Edit:
I've figured out that the image is transparent, but using Clipboard.SetImage() doesn't publish it as transparent image.
Any ideas why and what can I do to fix it? Do I need to switch to a differn textbox control?

I've had some luck going through Graphics.
Bitmap b = new Bitmap(pbAssetLoaded.Width, pbAssetLoaded.Height);
using (Graphics g = Graphics.FromImage(b))
{
g.DrawIcon(SystemIcons.Information, 0, 0);
}
This draws the icon with transparency to the Bitmap.

Try
img.MakeTransparent();
after you contruct it.
Note that this will change your PixelFormat to Format32bppArgb.

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.