Develop Reference

After taking a picture using bitmap, it saves to black image

I want to save digit signatire which I create using pictruebox control to jpeg or png(doesn't matter which file extension). After saving picture it shows black picture. How to avoid black background and save what really is drawn on the picturebox to jpg or png. My code:
public Form4()
{
InitializeComponent();
bm = new Bitmap(pic.Width, pic.Height);
g = Graphics.FromImage(bm);
pic.Image = bm;
}
Bitmap bm;
private void button1_Click(object sender, EventArgs e) // button save to jpg file
{
Bitmap bmp = bm.Clone(new Rectangle(0, 0, pic.Width, pic.Height), bm.PixelFormat);
bmp.Save("Signature.jpg",ImageFormat.Jpeg);
bmp.Dispose();
}
How to avoid this result:
enter image description here
//Code for drawing a signature:
float firstX = 0;
float firstY = 0;
float LastX = 0;
float LastY = 0;
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
LastX = e.X;
LastY = e.Y;
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
firstX = e.X;
firstY = e.Y;
pictureBox1_Paint(this, null);
}
}
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
Pen pen = new Pen(Color.Black, 7);
g = pic.CreateGraphics();
g.DrawLine(pen, firstX, firstY, LastX, LastY);
LastX = firstX;
LastY = firstY;
}

Save in a Jpg file a part of a Picturebox Image

I use the code provided by Erno with some modification like using DrawRect instead of FillRect to draw the selected area.
You can see the sample code in this thread :
How to select an area on a PictureBox.Image with mouse in C#
private Point RectStartPoint;
private Rectangle Rect = new Rectangle();
private Pen pen = new Pen(Color.Black, 2);
private void VisuelArchive_Load(object sender, EventArgs e)
{
pictureBox1.ImageLocation = fichierArchive;
pen.DashStyle = System.Drawing.Drawing2D.DashStyle.Dash;
}
private void PictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button != MouseButtons.Left) return;
Point tempEndPoint = e.Location;
Rect.Location = new Point(Math.Min(RectStartPoint.X, tempEndPoint.X), Math.Min(RectStartPoint.Y, tempEndPoint.Y));
Rect.Size = new Size(Math.Abs(RectStartPoint.X - tempEndPoint.X), Math.Abs(RectStartPoint.Y - tempEndPoint.Y));
pictureBox1.Invalidate();
}
private void PictureBox1_MouseDown(object sender, MouseEventArgs e)
{
// Determine the initial rectangle coordinates...
RectStartPoint = e.Location;
Invalidate();
}
private void PictureBox1_Paint(object sender, PaintEventArgs e)
{
// Draw the rectangle...
if (pictureBox1.Image != null)
{
if (Rect != null && Rect.Width > 0 && Rect.Height > 0)
{
e.Graphics.DrawRectangle(pen, Rect);
}
}
}
However I have some problem saving the selected area in a Jpg. I use this code but it seems that the Rect references are not good for that, i save a nearby area not the exact location.
Someone have an idea about how to save the exact location on the PictureBox Image ?
private void ButtonExport_Click(object sender, EventArgs e)
{
//exporter la sélection
Bitmap bmp = new Bitmap(Rect.Size.Width,Rect.Size.Height);
using (Graphics gr = Graphics.FromImage(bmp))
{
gr.DrawImage(pictureBox1.Image, new Rectangle(0, 0, Rect.Size.Width, Rect.Size.Height), Rect, GraphicsUnit.Pixel);
}
bmp.Save(Directory.GetCurrentDirectory() + "\\Archives\\" + numFiche.ToString() + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
}

C# paint program won't create any lines on the screen since I tried to draw using a bitmap

Here is my source code. I can't seem to get the bitmap to show the lines drawn on the panel when I move the mouse with the button pressed. Frustrated and looking for someone to help me finish the code so I can complete the app for my 9-yo daughter. Thank you in advance...
namespace TV_PAINT
{
public partial class ALANA_PAINT : Form
{
Graphics g;
Pen p = new Pen(Color.Black, 7);
Point sp = new Point(0, 0);
Point ep = new Point(0, 0);
int m = 0;
Bitmap BP;
public ALANA_PAINT()
{
InitializeComponent();
tb1.Text = p.Width.ToString();
BP = new Bitmap(pnl1.ClientSize.Width, pnl1.ClientSize.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
}
private void closeButton_Click(object sender, EventArgs e)
{
pnl1.Dispose();
p.Dispose();
this.Close();
}
private void clearButton_Click(object sender, EventArgs e)
{
//pnl1.Invalidate();
p.Color = System.Drawing.Color.Black;
p.Width = 7;
tb1.Text = p.Width.ToString();
//pnl1.Invalidate();
}
private void pnl1_MouseDown(object sender, MouseEventArgs e)
{
sp = e.Location;
if (e.Button == MouseButtons.Left)
m = 1;
if (e.Button == MouseButtons.Right)
m = 1;
}
private void pnl1_MouseMove(object sender, MouseEventArgs e)
{
if (m == 1)
{
ep = e.Location;
//g = pnl1.CreateGraphics();
Graphics g = Graphics.FromImage(BP);
g.DrawLine(p, sp, ep);
}
sp = ep;
}
private void pnl1_MouseUp(object sender, MouseEventArgs e)
{
m = 0;
}

BP is just a variable in the form. As I can see, it is not displayed anywhere in your form. Why do you need a bitmap for it.
You can do something like this, just get the graphics of your form, and draw using that graphic. https://msdn.microsoft.com/en-us/library/ztxk24yx(v=vs.110).aspx
Noted: you need to do it on PaintEvent of the form, otherwise your drawing will be removed after the next repaint, so you need some variables to store all of your lines, then draw all of them in the paint event.
System.Drawing.SolidBrush myBrush = new System.Drawing.SolidBrush(System.Drawing.Color.Red);
System.Drawing.Graphics formGraphics;
formGraphics = this.CreateGraphics();
formGraphics.FillRectangle(myBrush, new Rectangle(0, 0, 200, 300));
myBrush.Dispose();
formGraphics.Dispose();
Updated:
If you want to save your change to a bitmap. You can use Form.DrawToBitmap to save your drawing in the form to a bitmap, then call bitmap.Save() to a file in directory.

C# Save modified image in panel

I am attempting to save an image as modified by graphics tools such as pens and shapes that can be drawn onto the image. I have done this using a panel with background image and trying to set up a bit map that will save changes within this panel:
private void saveToolStripButton_Click(object sender, EventArgs e)
{
//sets panel1 contents as bit map to be saved at set locations
int width = panel1.Size.Width;
int height = panel1.Size.Height;
using (Bitmap bmp = new Bitmap(width, height))
{
panel1.DrawToBitmap(bmp, new Rectangle(0, 0, width, height));
bmp.Save(#"C:\Users\Me\Pics\testBitmap.jpeg", ImageFormat.Jpeg);
}
MessageBox.Show("Your image has been saved");
}
Once the save button is clicked, the image saves ok but the changes made with the graphics tools do not show up. Can anyone suggest a solution?
Here is some code regarding the graphics tool i've set up for use within the panel:
{
InitializeComponent();
//Create graphics object in panel1
g = panel1.CreateGraphics();
}
private void btnExit2_Click(object sender, EventArgs e)
{
this.Close();
}
Graphics g;
//set a drawing boolean
bool draw = false;
private void panel1_MouseDown(object sender, MouseEventArgs e)
{
draw = true;
if (drawSq)
{
SolidBrush brush = new SolidBrush(Color.FromArgb(128, 255, 0, 0));
if (toolStripTextBox1.Text != "")
{
g.FillRectangle(brush, e.X, e.Y, Convert.ToInt32(toolStripTextBox1.Text), Convert.ToInt32(toolStripTextBox1.Text));
}
else if (toolStripTextBox1.Text == "")
{
MessageBox.Show("Please enter a shape size");
}
draw = false;
drawSq = false;
}
}
and more:
private void panel1_MouseUp(object sender, MouseEventArgs e)
{
draw = false;
mouseX = null;
mouseY = null;
}
//null values allow freehand style drawing
int? mouseX = null;
int? mouseY = null;
private void panel1_MouseMove(object sender, MouseEventArgs e)
{
//creates a pen tool and sets properties by mouse location
if (draw)
{
Pen pen = new Pen(btnColor.ForeColor, float.Parse(txtBox1.Text));
g.DrawLine(pen, new Point(mouseX ?? e.X, mouseY ?? e.Y), new Point(e.X, e.Y));
mouseX = e.X;
mouseY = e.Y;
}
}

Let's try to fix this.
Start by creating your image first:
Bitmap bmp;
protected override void OnLoad(EventArgs e) {
base.OnLoad(e);
bmp = new Bitmap(panel1.ClientSize.Width, panel1.ClientSize.Height);
}
Now when you want to draw on it:
void panel1_MouseMove(object sender, MouseEventArgs e) {
if (e.Button == MouseButtons.Left) {
using (Graphics g = Graphics.FromImage(bmp)) {
g.FillEllipse(Brushes.Red, new Rectangle(e.X - 4, e.Y - 4, 8, 8));
}
panel1.Invalidate();
}
}
And display the results:
void panel1_Paint(object sender, PaintEventArgs e) {
e.Graphics.DrawImage(bmp, Point.Empty);
}
To save, just use your bitmap:
bmp.Save(#"c:\filename.png", ImageFormat.Png);
Use Double buffering with Panel to avoid the flickering.

This will works fine. I tested it and worked well........
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace drawing
{
public partial class Form2 : Form
{
Graphics g;
bool startPaint = false;
int? initX = null;
int? initY = null;
bool drawSquare = false;
bool drawRectangle = false;
bool drawCircle = false;
public Form2()
{
InitializeComponent();
bmp = new Bitmap(panel1.ClientSize.Width, panel1.ClientSize.Height);
}
Bitmap bmp;
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
}
void panel1_MouseMove(object sender, MouseEventArgs e)
{
if (startPaint)
{
using ( g = Graphics.FromImage(bmp))
{
// g.FillEllipse(Brushes.Black, new Rectangle(e.X, e.Y , 5, 5));
Pen p = new Pen(btn_PenColor.BackColor, float.Parse(cmb_PenSize.Text));
g.DrawLine(p, new Point(initX ?? e.X, initY ?? e.Y), new Point(e.X, e.Y));
initX = e.X;
initY = e.Y;
//g.DrawImage(bmp, new Rectangle(e.X - 4, e.Y - 4, 8, 8));
}
panel1.Invalidate();
}
}
private void pnl_Draw_MouseDown(object sender, MouseEventArgs e)
{
startPaint = true;
if (drawSquare)
{
//Use Solid Brush for filling the graphic shapes
SolidBrush sb = new SolidBrush(btn_PenColor.BackColor);
//setting the width and height same for creating square.
//Getting the width and Heigt value from Textbox(txt_ShapeSize)
g.FillRectangle(sb, e.X, e.Y, int.Parse(txt_ShapeSize.Text), int.Parse(txt_ShapeSize.Text));
//setting startPaint and drawSquare value to false for creating one graphic on one click.
startPaint = false;
drawSquare = false;
}
if (drawRectangle)
{
SolidBrush sb = new SolidBrush(btn_PenColor.BackColor);
//setting the width twice of the height
g.FillRectangle(sb, e.X, e.Y, 2 * int.Parse(txt_ShapeSize.Text), int.Parse(txt_ShapeSize.Text));
startPaint = false;
drawRectangle = false;
}
if (drawCircle)
{
SolidBrush sb = new SolidBrush(btn_PenColor.BackColor);
g.FillEllipse(sb, e.X, e.Y, int.Parse(txt_ShapeSize.Text), int.Parse(txt_ShapeSize.Text));
startPaint = false;
drawCircle = false;
}
}
private void pnl_Draw_MouseUp(object sender, MouseEventArgs e)
{
startPaint = false;
initX = null;
initY = null;
}
void panel1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.DrawImage(bmp, Point.Empty);
}
private void button1_Click(object sender, EventArgs e)
{
bmp.Save("D://filename.jpg", ImageFormat.Png);
}
}
}

Draw rectangle C# Mouse_down working Mouse_up not

I want to draw an rectangle on an form the mouse_down event is working fine, but how do i programm the mouse_up. Should how do i dertermine the starting coordinates.
http://oi49.tinypic.com/2wcnof8.jpg
Rectangle rect = new Rectangle();
Color rastercolor = Color.Black;
private void drawGrid(Color rastercolor)
{
Graphics gfx = this.CreateGraphics();
Pen pen = new Pen(rastercolor);
for (int i = 0; i <= 2000; i = i + 20)
{
gfx.DrawLine(pen, 0, i, 2000, i);
}
for (int x = 0; x < 2000; x = x + 20)
{
gfx.DrawLine(pen, x, 0, x, 2000);
}
}
protected override void OnMouseDown(MouseEventArgs e)
{
rect = new Rectangle(e.X, e.Y, 0, 0);
if (e.Button == MouseButtons.Middle)
{
ColorDialog coldial = new ColorDialog();
coldial.ShowDialog();
Color rastercolor = coldial.Color;
tekenGrid(rastercolor);
}
}
protected override void OnMouseMove(MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
rect = new Rectangle(rect.Left, rect.Top, e.X - rect.Left, e.Y - rect.Top);
}
}
protected override void OnPaint(PaintEventArgs e)
{
tekenGrid(rastercolor);
using (Pen pen = new Pen(Color.Red, 2))
{
e.Graphics.DrawRectangle(pen, rect);
}
}
private void Frm1_MouseUp(object sender, MouseEventArgs e)
{
Graphics g = this.CreateGraphics();
Pen pen = new Pen(Color.Red, 2);
g.DrawRectangle(pen, rect);
}
private void Frm1_Load(object sender, EventArgs e)
{
}
private void Frm1_MouseDown(object sender, MouseEventArgs e)
{
Graphics g = this.CreateGraphics();
Pen pen = new Pen(Color.Blue, 2);
g.DrawRectangle(pen, rect);
}
}
}
Any help would be greatly appreciated,

Not sure if this is what you are upto. Please try this code.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
this.DoubleBuffered = true;
}
Rectangle rect = new Rectangle();
Color _rastercolor = Color.Black;
private Pen _pen=new Pen(Color.Red,2);
private void tekenGrid(Color rastercolor, Graphics gfx)
{
Pen pen = new Pen(rastercolor);
for (int i = 0; i <= 2000; i = i + 20)
{
gfx.DrawLine(pen, 0, i, 2000, i);
}
for (int x = 0; x < 2000; x = x + 20)
{
gfx.DrawLine(pen, x, 0, x, 2000);
}
}
protected override void OnMouseDown(MouseEventArgs e)
{
rect = new Rectangle(e.X, e.Y, 0, 0);
if (e.Button == MouseButtons.Middle)
{
ColorDialog coldial = new ColorDialog();
coldial.ShowDialog();
Color rastercolor = coldial.Color;
tekenGrid(rastercolor,this.CreateGraphics());
}
else
base.OnMouseDown(e);
}
protected override void OnMouseMove(MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
rect = new Rectangle(rect.Left, rect.Top, e.X - rect.Left, e.Y - rect.Top);
this.Refresh();
}
base.OnMouseMove(e);
}
protected override void OnPaint(PaintEventArgs e)
{
tekenGrid(_rastercolor,e.Graphics);
e.Graphics.DrawRectangle(_pen, rect);
}
private void Frm1_MouseUp(object sender, MouseEventArgs e)
{
_pen = new Pen(Color.Red, 2);
this.Refresh();
}
private void Frm1_Load(object sender, EventArgs e)
{
}
private void Frm1_MouseDown(object sender, MouseEventArgs e)
{
_pen = new Pen(Color.Blue, 2);
}
}