Develop Reference

Redrawing a picturebox drawing without flickering or lag

I've drawn a grid on a picturebox with .drawline I then let users click a cell on this grid to change the colour. I'm doing this through setting a value for colour for each cell (clicking sets it to 1)
The only way I can get it to update is on mouse up which causes problems with the pathfinding algorithms I'm testing. I tried putting it on a timer but it flickers too much.
You can see the problem here
The pathfinding algorithm finishes but the grid doesn't update until I click the grid.
private void pictureBox1_MouseClick(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
GetX(this, e);
GetY(this, e);
if (DrawCase == "Wall") {
if (gridmatrix[XClick, YClick].COLOUR == 0) //If tile is white and left mouse is pressed
{
gridmatrix[XClick, YClick].COLOUR = 1; //Set colour to 1 (place a wall)
}
else if (gridmatrix[XClick, YClick].COLOUR == 1) //If tile is a wall and left mouse is pressed
{
gridmatrix[XClick, YClick].COLOUR = 0; //Set to empty
}
}
Grid is updated on MouseUp... (How else could I update the grid?)
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
mousedown = false;
int rowcolumn = Convert.ToInt32(textBox1.Text); //Gets the dimensions from the users input
cellsize = (pictureBox1.Width / rowcolumn);
if (pictureBox1.Image == null)//if no available bitmap exists on the picturebox to draw on
{
//create a new bitmap
Bitmap bmp = new Bitmap(pictureBox1.Width, pictureBox1.Height);
pictureBox1.Image = bmp; //assign the picturebox.Image property to the bitmap created
}
for (int i = 0; i < gridmatrix.GetLength(0); i++)
{
for (int j = 0; j < gridmatrix.GetLength(1); j++)
{
Rectangle rect = new Rectangle(gridmatrix[i, j].X * cellsize, reverseYvalues[gridmatrix[i, j].Y] * cellsize, cellsize, cellsize); //Positioning and sizing for the rectangle
if (gridmatrix[i, j].COLOUR == 0)
{
using (Graphics g = Graphics.FromImage(pictureBox1.Image))
{
g.FillRectangle(Brushes.White, rect);
}
}
else if (gridmatrix[i, j].COLOUR == 1)
{
using (Graphics g = Graphics.FromImage(pictureBox1.Image))
{
g.FillRectangle(Brushes.Blue, rect);
}
}
}
}
}

Crop and Print Image Documents without Distortion In C#

I'm using WinForms. In my form I have a picturebox I use to display image documents. The problem is when I crop the image and then print the document out the image becomes slightly distorted. If I don't crop the image document and print it regularly the image document does not become distorted.
How do I crop and print the image documents without them being distorted?
Or is there a better way to code this so it can crop and print without the image document being distorted? If so, how can i do it?
Notes:
My picturebox is set to Zoom because the images i work with is big:
Example of image document Dimensions: 2500 x 3100
My picturebox does not have a border
int _cropX, _cropY, _cropWidth, _cropHeight;
public Pen _cropPen;
private State _currentState;
private enum State
{
Crop
}
private void Open_btn_Click(object sender, EventArgs e)
{
// open file dialog
OpenFileDialog open = new OpenFileDialog();
if (open.ShowDialog() == DialogResult.OK)
{
// display image in picture box
pictureBox1.Image = new Bitmap(open.FileName);
}
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
try
{
if (Crop_Checkbox.Checked == true)
{
Cursor = Cursors.Default;
if (_currentState == State.Crop)
{
if (_cropWidth < 1)
{
return;
}
Rectangle rect = new Rectangle(_cropX, _cropY, _cropWidth, _cropHeight);
//First we define a rectangle with the help of already calculated points
Bitmap originalImage = new Bitmap(pictureBox1.Image, pictureBox1.Width, pictureBox1.Height);
//Original image
Bitmap img = new Bitmap(_cropWidth, _cropHeight);
// for cropinf image
Graphics g = Graphics.FromImage(img);
// create graphics
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
//set image attributes
g.DrawImage(originalImage, 0, 0, rect, GraphicsUnit.Pixel);
pictureBox1.Image = img;
pictureBox1.Width = img.Width;
pictureBox1.Height = img.Height;
}
}
else
{
Cursor = Cursors.Default;
}
}
catch (Exception)
{
}
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (Crop_Checkbox.Checked == true)
{
if (_currentState == State.Crop)
{
Cursor = Cursors.Cross;
if (e.Button == System.Windows.Forms.MouseButtons.Left)
{
//X and Y are the coordinates of Crop
pictureBox1.Refresh();
_cropWidth = e.X - _cropX;
_cropHeight = e.Y - _cropY;
pictureBox1.CreateGraphics().DrawRectangle(_cropPen, _cropX, _cropY, _cropWidth, _cropHeight);
}
}
}
else
{
Cursor = Cursors.Default;
}
}
private void Crop_Checkbox_CheckedChanged(object sender, EventArgs e)
{
if (Crop_Checkbox.Checked == true)
{
this.Cursor = Cursors.Cross;
}
}
private void Print_btn_Click(object sender, EventArgs e)
{
System.Drawing.Printing.PrintDocument myPrintDocument1 = new System.Drawing.Printing.PrintDocument();
PrintDialog myPrinDialog1 = new PrintDialog();
myPrintDocument1.PrintPage += new System.Drawing.Printing.PrintPageEventHandler(printDocument1_PrintPage);
myPrinDialog1.Document = myPrintDocument1;
if (myPrinDialog1.ShowDialog() == DialogResult.OK)
{
myPrintDocument1.Print();
}
}
private void printDocument1_PrintPage(object sender, PrintPageEventArgs e)
{
e.Graphics.DrawImage(pictureBox1.Image, 10, 10); //(Standard paper size is 850 x 1100 or 2550 x 3300 pixels)
}
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
if (Crop_Checkbox.Checked == true)
{
if (_currentState == State.Crop)
{
if (e.Button == System.Windows.Forms.MouseButtons.Left)
{
Cursor = Cursors.Cross;
_cropX = e.X;
_cropY = e.Y;
_cropPen = new Pen(Color.FromArgb(153, 180, 209), 3); //2 is Thickness of line
_cropPen.DashStyle = DashStyle.DashDotDot;
pictureBox1.Refresh();
}
}
}
else
{
Cursor = Cursors.Default;
}
}
Test: Slightly Distorted:
Test: Not Distorted:
Test:
The picture above is a test. This is what happened when i took the below code out from pictureBox1_MouseUp:
Bitmap originalImage = new Bitmap(pictureBox1.Image, pictureBox1.Width, pictureBox1.Height);
And edited/replaced (originalImage to pictureBox1.Image):
g.DrawImage(pictureBox1.Image, 0, 0, rect, GraphicsUnit.Pixel);

Bitmap originalImage = new Bitmap(pictureBox1.Image, pictureBox1.Width, pictureBox1.Height);
That is most likely where the problem started. This can cause pictureBox1.Image to be rescaled to force-fit it to the pictureBox1 size. Depends on whether the picturebox has borders and its SizeMode property value. Rescaling causes the image to be resampled, the color of a pixel in the new bitmap is calculated from the values of its neighboring pixels in the original image as directed by the selected InterpolationMode.
This in effect blurs the resulting image. That works well on a photo but this is text that critically depends on anti-aliasing pixels to look decent on a low-resolution monitor. Slight changes to those pixels ruins the effect and they no longer smoothly blend the letter shape against the background anymore. They become more visible, best way to describe it is that the resulting text looks "fat".
I see no obvious reason to do this at all in the posted code. Delete the statement and replace originalImage with pictureBox1.Image.
Also beware that printing this image is likely to be disappointing. Now those anti-aliasing pixels get turned into 6x6 blobs of ink on paper. That only ever looks good when you have long arms. As long as the font size is this small and you have no control over the anti-aliasing choice then there's very little you can do about that. Printed text only ever looks good when you use PrintDocument and Graphics.DrawString().

Why when i create the bitmap it's empty all white?

private Bitmap CropImage()
{
Bitmap pic = pictureBoxSnap.Image as Bitmap;
Bitmap cropped = new Bitmap(rect.Width, rect.Height);
using (Graphics g = Graphics.FromImage(cropped))
{
g.DrawImage(pic, new Rectangle(0, 0, rect.Width, rect.Height),
rect, GraphicsUnit.Pixel);
}
pic.Save(#"c:\temp\testingitimage.jpg");
cropped.Save(#"c:\temp\testingitimage1.bmp");
return cropped;
}
I added this two lines of Save to test what i get. The first one pic i see the correct image that is in the pictureBox.
But the second one cropped is all white and empty.
And i call this method from the pictureBox paint event:
private void pictureBoxSnap_Paint(object sender, PaintEventArgs e)
{
if (pictureBoxSnap.Image != null)
{
{
if (ClearGraphics == false)
{
if (cropRect == false)
{
if (rectangles[listBoxSnap.SelectedIndex] != Rectangle.Empty)
{
e.Graphics.DrawRectangle(Pens.Firebrick, rectangles[listBoxSnap.SelectedIndex]);
}
}
else
{
if (rect.Width > 10 && rect.Height > 10)
{
e.Graphics.DrawRectangle(Pens.Gray, rect);
pictureBoxSnap.Image = CropImage();
Image img = CropImage();
img.Save(#"c:\temp\testimageing.jpg");
}
}
}
}
}
}
I used a breakpoint on the: e.Graphics.DrawRectangle(Pens.Gray, rect); and rect is not empty ( rect is Rectangle i draw on the pictureBox then when i click on a button it's making validate for the pictureBox).
I also did a save here too and testimageing i see it black on the hard disk but when i edit it with Paint i see it's white empty.
For exmaple when i draw a rectangle on the pictureBox then i use a breakpoint in the CropImage method i see that the variable rect is for example: X = 136 Y = 149 Width = 131 Height = 106
Also in the paint event this rect variable have the same values.
And the pictureBox size is: 640x480
And the pictureBox property SizeMode is set to: zoom
Wo why i get empty white image ? And not the cropped rectangle with the part of the image inside ?
EDIT:
This is the code im using now:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;
using DannyGeneral;
using System.Diagnostics;
namespace MinimizeCapture
{
public partial class Form1 : Form
{
Boolean bHaveMouse;
Point ptOriginal = new Point();
Point ptLast = new Point();
bool cropRect;
Bitmap cloneBitmap;
Rectangle recttest;
private Rectangle Rect;
private Rectangle[] rectangles;
private Rectangle RectClone;
private bool btn = false;
private Point RectStartPoint = Point.Empty;
private Point RectEndPoint = Point.Empty;
private Brush selectionBrush = new SolidBrush(Color.Red);
private Pen pen;
private string selectedIndex;
private List<string> drawnItems = new List<string>();
private bool ClearGraphics;
public Form1()
{
InitializeComponent();
cropRect = false;
var windows = OpenWindowGetter.FindWindowsWithText();
ClearGraphics = false;
this.DoubleBuffered = true;
btn = false;
pen = new Pen(selectionBrush);
buttonSnap.Enabled = false;
backgroundWorker1.RunWorkerAsync();
}
private void buttonSnap_Click(object sender, EventArgs e)
{
ClearGraphics = true;
this.listBoxSnap.Items.Clear();
this.pictureBoxSnap.Image = null;
backgroundWorker1.RunWorkerAsync();
}
private void listBoxSnap_SelectedIndexChanged(object sender, EventArgs e)
{
WindowSnap snap = this.listBoxSnap.SelectedItem as WindowSnap;
selectedIndex = this.listBoxSnap.SelectedIndex.ToString();
this.pictureBoxSnap.Image = snap.Image;
for (int i = 0; i < rectangles.Length; i++)
{
if (rectangles[i] != RectClone)
{
ClearGraphics = false;
}
else
{
ClearGraphics = true;
}
}
}
private void checkBoxForceMDI_CheckedChanged(object sender, EventArgs e)
{
WindowSnap.ForceMDICapturing = (sender as CheckBox).Checked;
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
listBoxSnap.Invoke(new MethodInvoker(delegate { this.listBoxSnap.Items.Add("Minimized Windows"); }));
listBoxSnap.Invoke(new MethodInvoker(delegate { this.listBoxSnap.Items.AddRange(WindowSnap.GetAllWindows(true,true).ToArray()); }));
}
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
}
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
rectangles = new Rectangle[listBoxSnap.Items.Count];
buttonSnap.Enabled = true;
}
private void pictureBoxSnap_Paint(object sender, PaintEventArgs e)
{
if (pictureBoxSnap.Image != null)
{
{
if (ClearGraphics == false)
{
if (rectangles[listBoxSnap.SelectedIndex] != Rectangle.Empty)
{
e.Graphics.DrawRectangle(Pens.Firebrick, rectangles[listBoxSnap.SelectedIndex]);
}
}
if (cropRect == true)
{
if (recttest.Width > 10 && recttest.Height > 10)
{
//e.Graphics.DrawRectangle(Pens.Gray, recttest);
e.Graphics.Clear(Color.White);
/*pictureBoxSnap.Image = CropImage();
Image img = CropImage();
img.Save(#"c:\temp\testimageing.jpg");*/
}
}
}
}
}
private void pictureBoxSnap_MouseMove(object sender, MouseEventArgs e)
{
if (btn == true)
{
ClearGraphics = false;
RectEndPoint = e.Location;
int currentindex = listBoxSnap.SelectedIndex;
rectangles[currentindex] = RectClone;
Rect = getRect(RectStartPoint, RectEndPoint);
RectClone = Rect;
pictureBoxSnap.Invalidate();
}
Point ptCurrent = new Point(e.X, e.Y);
// If we "have the mouse", then we draw our lines.
if (bHaveMouse)
{
// If we have drawn previously, draw again in
// that spot to remove the lines.
if (ptLast.X != -1)
{
MyDrawReversibleRectangle(ptOriginal, ptLast);
}
// Update last point.
ptLast = ptCurrent;
// Draw new lines.
MyDrawReversibleRectangle(ptOriginal, ptCurrent);
}
}
private void pictureBoxSnap_MouseDown(object sender, MouseEventArgs e)
{
RectStartPoint = e.Location;
btn = true;
Rect = Rectangle.Empty;
RectClone = Rectangle.Empty;
bHaveMouse = true;
// Store the "starting point" for this rubber-band rectangle.
ptOriginal.X = e.X;
ptOriginal.Y = e.Y;
// Special value lets us know that no previous
// rectangle needs to be erased.
ptLast.X = -1;
ptLast.Y = -1;
}
private void pictureBoxSnap_MouseUp(object sender, MouseEventArgs e)
{
recttest = rectangles[listBoxSnap.SelectedIndex];
ClearGraphics = false;
btn = false;
RectEndPoint = e.Location;
pictureBoxSnap.Invalidate();
int currentindex = listBoxSnap.SelectedIndex;
rectangles[currentindex] = RectClone;
// Set internal flag to know we no longer "have the mouse".
bHaveMouse = false;
// If we have drawn previously, draw again in that spot
// to remove the lines.
if (ptLast.X != -1)
{
Point ptCurrent = new Point(e.X, e.Y);
MyDrawReversibleRectangle(ptOriginal, ptLast);
}
// Set flags to know that there is no "previous" line to reverse.
ptLast.X = -1;
ptLast.Y = -1;
ptOriginal.X = -1;
ptOriginal.Y = -1;
pictureBoxSnap.Invalidate();
}
Rectangle getRect(Point p1, Point p2)
{
Point p = new Point(Math.Min(p1.X, p2.X), Math.Min(p1.Y, p2.Y));
Size s = new Size(Math.Abs(p1.X - p2.X), Math.Abs(p1.Y - p2.Y));
return new Rectangle(p, s);
}
private void ConfirmRectangle_Click(object sender, EventArgs e)
{
ConfirmRectangle.ForeColor = Color.Red;
ConfirmRectangle.Enabled = false;
StreamWriter w = new StreamWriter(#"c:\temp\Settings.txt", true);
w.WriteLine("Rectangle Location: " + RectClone.Location + " Rectangle Size: " + RectClone.Size + " Selected Index: " + selectedIndex);
textBoxIndex.Text = selectedIndex.ToString();
w.Close();
cropRect = false;
//pictureBoxSnap.Invalidate();
Image img = CropImage();
img.Save(#"c:\temp\testimageing.jpg");
pictureBoxSnap.Image = img;
}
// Convert and normalize the points and draw the reversible frame.
private void MyDrawReversibleRectangle(Point p1, Point p2)
{
Rectangle rc = new Rectangle();
// Convert the points to screen coordinates.
p1 = pictureBoxSnap.PointToScreen(p1);
p2 = pictureBoxSnap.PointToScreen(p2);
// Normalize the rectangle.
if (p1.X < p2.X)
{
rc.X = p1.X;
rc.Width = p2.X - p1.X;
}
else
{
rc.X = p2.X;
rc.Width = p1.X - p2.X;
}
if (p1.Y < p2.Y)
{
rc.Y = p1.Y;
rc.Height = p2.Y - p1.Y;
}
else
{
rc.Y = p2.Y;
rc.Height = p1.Y - p2.Y;
}
// Draw the reversible frame.
rect = new Rectangle(pictureBoxSnap.PointToClient(rc.Location), rc.Size);
ControlPaint.DrawReversibleFrame(rc, Color.Gray, FrameStyle.Dashed);
}
Rectangle rect = Rectangle.Empty;
private Bitmap CropImage()
{
//rect = recttest;
Bitmap pic = pictureBoxSnap.Image as Bitmap;
Bitmap cropped = new Bitmap(rect.Width, rect.Height);
using (Graphics g = Graphics.FromImage(cropped))
{
g.DrawImage(pic, new Rectangle(0, 0, rect.Width, rect.Height),
rect, GraphicsUnit.Pixel);
}
pic.Save(#"c:\temp\testingitimage.jpg");
cropped.Save(#"c:\temp\testingitimage1.bmp");
return cropped;
}
}
}
Moved the CropImage call method from the paint and added it to the button click here:
private void ConfirmRectangle_Click(object sender, EventArgs e)
{
ConfirmRectangle.ForeColor = Color.Red;
ConfirmRectangle.Enabled = false;
StreamWriter w = new StreamWriter(#"c:\temp\Settings.txt", true);
w.WriteLine("Rectangle Location: " + RectClone.Location + " Rectangle Size: " + RectClone.Size + " Selected Index: " + selectedIndex);
textBoxIndex.Text = selectedIndex.ToString();
w.Close();
cropRect = false;
//pictureBoxSnap.Invalidate();
Image img = CropImage();
img.Save(#"c:\temp\testimageing.jpg");
pictureBoxSnap.Image = img;
}
This lines:
Image img = CropImage();
img.Save(#"c:\temp\testimageing.jpg");
pictureBoxSnap.Image = img;
But what i get in the pictureBox is this:
Not sure why. The rectangle is in the position i drawed it's ok but instead showing the part of the original image cut in the rectangle it's doing like zoom in.

You are cropping multiple times.
pictureBoxSnap.Image = CropImage(); // First Time
Image img = CropImage(); // Second Time
img.Save(#"c:\temp\testimageing.jpg");
You just need to crop once. Here you are using same picturebox for source and for cropped image. first time when you crop then image. the cropped image will be set correctly to the picturebox. but, second time application will try to crop that image again.
You should do like this
Image img = CropImage();
img.Save(#"c:\temp\testimageing.jpg");
pictureBoxSnap.Image = img;

private Bitmap CropImage(){
Bitmap pic = pictureBoxSnap.Image as Bitmap;
Bitmap cropped = new Bitmap(rect.Width, rect.Height);
using (Graphics g = Graphics.FromImage(cropped)){
g.DrawImage(pic, new Rectangle(0, 0, rect.Width, rect.Height),
rect, GraphicsUnit.Pixel);
}
using (Graphics g = Graphics.FromImage(pic)){
g.DrawImage(cropped , 136, 149, rect.Width, rect.Height);
//Draw the rectangle
}
//pic.Save(#"c:\temp\testingitimage.jpg");
//cropped.Save(#"c:\temp\testingitimage1.bmp");
return pic;
}
valter

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);
}
}
}

How to draw multiple rectangles using c#

I have drawn and saved the Rectangle on the image i loaded in the picture box. How i like to draw multiple rectangles for that i tried array in the rectangle but it gives error ("Object reference not set to an instance of an object." (Null reference Exception was unhandled).
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
if (mybitmap == null)
{
mybitmap = new Bitmap(sz.Width, sz.Height);
}
rect[count] = new Rectangle(e.X, e.Y, 0, 0);
this.Invalidate();
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (stayToolStripMenuItem.Checked == true)
{
switch (e.Button)
{
case MouseButtons.Left:
{
rect[count] = new Rectangle(rect[count].Left, rect[count].Top, e.X - rect[count].Left, e.Y - rect[count].Top);
pictureBox1.Invalidate();
count++:
break;
}
}
}
}
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
if (stayToolStripMenuItem.Checked == true)
{
button1.Visible = true;
button2.Visible = true;
if (mybitmap == null)
{
return;
}
using (g = Graphics.FromImage(mybitmap))
{
using (Pen pen = new Pen(Color.Red, 2))
{
//g.Clear(Color.Transparent);
e.Graphics.DrawRectangle(pen, rect);
label1.Top = rect[count].Top; label1[count].Left = rect[count].Left; label1.Width = rect[count].Width;
label1.Height = rect[count].Height;
if (label1.TextAlign == ContentAlignment.TopLeft)
{
e.Graphics.DrawString(label1.Text, label1.Font, new SolidBrush(label1.ForeColor), rect);
g.DrawString(label1.Text, label1.Font, new SolidBrush(label1.ForeColor), rect);
g.DrawRectangle(pen, rect[count]);
}
}
}
}
}
How can i do this.....

You're incrementing the count variable after filling the rect array. By the time pictureBox1_Paint is executed, this increment has already taken place, so rect[count] is now a null reference, which you then try to draw :)
Also, there appears to be a compiler error in pictureBox1_MouseDown. The count++ inside the switch statement doesn't belong to any case block. Put it before the break; statement.
I imagine your intention is something like this:
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
if (mybitmap == null)
return;
using (g = Graphics.FromImage(mybitmap))
using (Pen pen = new Pen(Color.Red, 2))
{
g.Clear(Color.Transparent);
for (int i = 0; i < count; i++)
{
// Code to draw rect[i], instead of rect[count]
}
}
}
How large is your rect array, by the way? Arrays do not automatically grow to accommodate your needs. You may want to look at using List<Rectangle> instead.

Have change the code little bit. Instead of mouse move event used Mouse click event.
On using mouse move event it calls every time when mouse move on the picture box. so list rectangle count gets increased. for this i used mouse click event.
When list rectangle added in Mouse down event, it's only get the values for height and width of the rectangle (if use (0,0,e.X,e.Y))and also rectangle always starts from top left corner (not able to start the rectangle point where user likes) and it's gets only X and Y values (if use(e.X, e.Y,0,0))
to over come this I used the list rectangle in the mouse click event, so I get all values.
List<Rectangle> rectangles = new List<Rectangle>();
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
if (stayToolStripMenuItem.Checked == true)
{
if (mybitmap == null)
{
mybitmap = new Bitmap(sz.Width, sz.Height);
}
rect = new Rectangle(e.X, e.Y, 0, 0);
this.Invalidate();
}
}
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
if (stayToolStripMenuItem.Checked == true)
{
button1.Visible = true;
button2.Visible = true;
if (mybitmap == null)
{
return;
}
using (g = Graphics.FromImage(mybitmap))
{
using (Pen pen = new Pen(Color.Red, 2))
{
//g.Clear(Color.Transparent);
e.Graphics.DrawRectangle(pen, rect);
label1.Top = rect.Top; label1.Left = rect.Left; label1.Width = rect.Width;
label1.Height = rect.Height;
if (label1.TextAlign == ContentAlignment.TopLeft)
{
e.Graphics.DrawString(label1.Text, label1.Font, new SolidBrush(label1.ForeColor), rect);
g.DrawString(label1.Text, label1.Font, new SolidBrush(label1.ForeColor), rect);
g.DrawRectangle(pen, rect);
}
}
}
private void pictureBox1_MouseClick(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
rect = new Rectangle(rect.Left, rect.Top, e.X - rect.Left, e.Y - rect.Top);
rectangles.Add(rect);
pictureBox1.Invalidate();
f = 0;
}
}
What ever rectangle I draw get saved in the list rectangles and get saved when i saved the work (could see all the drawn rectangles when i opened the saved file).
Now the problem is, when I draw a new rectangle the previous one get disappeared (on run time. However this added in list rectangle).
How to display all the rectangles drawn on run time, so user can know how many rectangles drawn and where.